Do you want to run an Inverter

 The Inverter is an electronic device that converts a DC voltage to AC voltage. Cruisers usually want to convert ships 12 volts DC battery power to 110 or 230 volts AC. 

 We love having an inverter on board and it gets used on a daily basis, we do use the inverter to power the washing machine, kitchen and workshop tools and it really makes our life on board easier . 

A bare bones Pure Sine Wave inverter fitted in Matilda. 

This inverter is a combi unit and includes a built in battery charger for when we are connected to the shore power at the dock. By bare bones I mean it does what its meant to do very well, it outputs a single phase  pure Sine Wave and charges the batteries when connected to the dock power. It doesn't have a lot of the bells and whistles that most cruisers dont really need. While they may be necessary for complex installations, for most of us they are unused and are just an added expense and that money could have been used elsewhere.   

--------------------------------------------------------------------------------------------------------

Before we get started basic abbreviations and power rating.

A well used electrical calculation:  Watts = Voltage multiplied by the current in Amps;  W = V x A

AC is an abbreviation for alternating current:   an electric current that reverses its direction many times a second at regular intervals, in Australia its 50 times per second and in the US its 60. also known as Hertz or Hz. Output is from a portable generator, inverter or mains (the big generator at the power station) 

The AC wave form, output from a Sine Wave Inverter or generator. 

DC is an abbreviation for direct current: an electric current flowing in one direction only. Output is from solar cells, batteries. 

RCD Safety switch: An RCD switch will operate when there is an imbalance in the current flow in the active and neutral conductors. Once this imbalance reaches the set threshold, usually 30mA, it opens the circuit, cutting the power output.  A lot of people believe that an inverter is safe and will cause no harm because it runs off batteries. However this is a false sense of security, the power from even the smallest inverter can kill as quickly as a mains power point. So it is certainly recommended a RCD safety switch be fitted.  For a discussion on safety switches

RCD Safety switch to reduce the chance of being electrocuted from the output of an Inverter

--------------------------------------------------------------------------------------------------------- 

Why have an Inverter when you go cruising?

In Australia we all have 230 volts AC as the primary mains voltage source at home, we already have many appliances that run off 230 volts, it may be the high powered microwave oven or the very low power charger for a laptop, tablet or camera. An Inverter allows you to use the appliances you already have when you are away from the shore power. The disclaimer here is that the inverter type and size has to be matched to the appliances you want to use.

Benefits of using an Inverter

Instant power with the flick of a switch, no turning on the gen set, or switching over the source of the power. The main reason for most people is that there is a wide variety of appliances. Using an Inverter can save you the cost of replacing the appliances you already have at home with 12 volt equivalents. In some cases 12 volt appliances are more expensive due to lower sales, or possibly they are not available for every application.

Why a lot of Cruisers buy an Inverter

A lot of cruisers like to take the convenience of household appliances out on to the water with them. There are so many appliances used in the kitchen or workshop that make quick work of tedious jobs. I use a powerful mixer on a daily basis to knead bread dough so we can have a fresh loaf of bread while we sail offshore miles from land. Using the appliance we reduce the kneading time from 20 min to just 5, not that we don't like the upper body workout, we like using that time to do other jobs. There is just about an appliance or power tool to help with most jobs, and we have met people who use some appliances we never thought of taking on board, it's only limited by imagination, storage and of course battery bank endurance.

During our travels we have met with dozens of cruisers who had planned fitment of their inverter during preparations before going cruising. The cruisers then executed the install and had the 12 volt side of the inverter connected with the right gauge wire, fuses and safety grounds. They can also have wired in power points outlets to make the inverter use convenient. By having the inverter properly installed they were able to install and configure a RCD safety switch and circuit breakers to protect the people and appliances. Add on kit for an RCD info here

There is also another good reason a lot of people buy an inverter, they do not know there are 12 volt alternatives for the most commonly used items. So what are these commonly used items? most of the time its battery chargers (phones laptops, cameras) and TV’s, and this is why so many people buy an inverter, they head off to the marine/camping/electronics/tech shop to get something to charge their laptop, phone or even the head torch, and really the list is almost endless these days. The sales person quickly takes the customer to the inverter section and gets a quick sale. The customer goes home not realising there are other products out there that can charge and run their small appliances and in nearly all cases are a lot safer and much more efficient at doing it than an inverter. But more on that in another post.

Being on a yacht we want products that make use of stored electricity in the most economical and safe way. Unfortunately for just charging laptops, phones and these types of appliance, a small inverter isn't always the best and or safest option. This is why we feel its a great idea to have a balance of electronics to do the jobs on board. This way should the inverter fail (happens from time to time) you can carry on with minimal disruption. 

Please read on, for other uses an inverter can come into its own, if set up correctly.

Operation

A great reason for using an Inverter is, being much quieter than using a generator to produce the AC power, and when your running off batteries, there are no concerns about fumes or heat from the exhaust, and no flammable fuel to handle. If the generator isn't built in and running on the ships fuel, most of the small portable generators popular with cruisers run on petrol. This adds the complexity of firstly safely storing the generator and secondly the fuel to run it. The storage of petrol does have its complexities on a vessel designed and fitted out as a diesel fuel craft.

Versatile

An Inverter can be used whilst the vessel is running, and therefore not draining the house battery. Unless your a sailboat and having a good day out in a nice breeze. When motoring this has practical applications; ie arrive at the anchorage with fully charged batteries, camera batteries, laptop, and so on and so forth. 

For safety an Inverter must never be switched on when you go to start the engine unless you have a totally isolated motor start battery. If you don’t the surge of current required to start a boat motor can drop the voltage down below 10V DC. After the motor is running and the alternator kicks in, it will surge back up to 12 V DC, the combination of surges can damage the inverter, the appliance running on the inverter at the time or of course both.

Interpreting the numbers written on the inverter

An Inverter changes the voltage and current, the power it puts out is always less than the input power, due to inverter efficiency being less than 100%. Most, but not all inverters list the operating power in watts, a big inverter may output 2500 watts so if it really is outputting 2500 watts at 230 volts that will be 10.86 Amps output, just over the maximum of a standard power outlet in Australia. This large inverter is capable of running most appliances easily. However keep in mind most of the numbers on the case i.e. 2500, the inverter will not really output 2500 watts. One that I know of will output 2300 W and another that has 3000 on the case outputs 2200W, so the reality is that you need to read the spec sheet to see the real out put value.

On the other end of the inverter scale is small inverters with an output of, for example 300 watts, this will be 230 V at 1.3 amps, and would be enough to run most laptop chargers. 

An inverter is usually between 80% and 90% efficient. The 10 – 20 % of power that is lost as electrical energy escapes as heat energy in the Inverter. While this doesn't sound too bad if you crunch some numbers when operating at higher power it can be a significant current (in Amps) drawn from the batteries that is wasted energy. 

So as an example of power loss, if an inverter is drawing 100 Amps and is 80% efficient then 20 amps  will be wasted power and converted into heat. 

Electrical Power

Electrical power is usually measured in Watts (1000 W = 1 kilowatts, 1 kW). So to keep it simple an inverter that outputs 240 volts at 10 Amps is 2400 Watts (240V x 10A =2400W)

Some Inverters output are rated in VA (Volt-Amps) rather than Watts and for many appliances this will equate to the number of Watts with a power factor of blah blah blah, well beyond our ability to calculate the actual value. The simple truth of the matter is VA means nothing. If you want to know how much power your inverter is going to give you then ask for the rating in watts at 40 deg C, all the other ratings should be kept for the fairy tale books where they belong. Some brands of inverters have a lower value in the model name but, in fact, are the more powerful of the bunch when apples are compared with apples (watts with watts). So shop around for a unit where you get what you think you should be getting, and it does what it says on the box it does. Do the comparison in Watts at 40 deg C apples with apples, (watts compared with watts). I do know some manufactures use lower temp rating to give better figures, however unless your operating your vessel in the lab then the 25 deg C isn't really achievable. Its all in the advertised wording. 

Peak and Continuous

Two numbers are used to describe the output of an Inverter, Peak and Continuous.

Peak (or surge) describes the output deliverable for several seconds the Inverter components won't blow up at that amount of load, but they will heat up really quickly. Continuous ratings are usually limited by the heat that needs to be removed when running continuously. Ideally you would find out the Peak and the instantaneous ratings of your appliances and check that they were less than the Inverter output, but you can't rely on this because most appliances don't state the start-up or peak power and the length of the peak really needs to be known too. Unfortunately, the only way to be sure, is to test the appliance with the inverter.

For safety never run the inverter continuously at full power for long times, I have a safety margin in the order of 10% factored in to our calculations for long run times as this allows for the odd surge. 

Size of Inverter Needed

The following table is only a rough guide as there is a lot of variation in startup surge load and continuous load for similar appliances between makes and different models.

Size of Inverter Required Type of Appliance

150 watts - Charger for cameras, laptops, some power tools, DVD player; coffee grinder

250 watts - TV, slow cooker, desktop computer, electric blanket, kitchen mixer, printer

500 watts - Small fridge, freezer, small angle grinder, drill, TV, washing machine (no water heater)

1000 watts - Bread maker, low power microwave (some microwaves are very hungry appliances).

1500 watts - Small air conditioner, vacuum cleaner, small iron, pie maker

2000 watts - Microwave (1200 watts), hair dryer, fan heater, iron, electric kettle, toaster

Types of Inverters the all important “Wave” output

When generating AC from a spinning generator, it’s very easy to generate the sine wave that AC has, but when inverting DC to AC, the easiest wave shape to output is a square wave. Unfortunately a square wave has more energy for longer at frequencies other than the 50Hz or 60Hz (Hertz or Cycles per second), and this can cause problems of overheating in transformers and some motors.

A sine wave, this is the same power wave output at the mains power point on shore and is the same as output by a rotating AC generator, or a Pure Sine Wave Inverter. 

A comparison of the three waveforms laid on top each other 

Today Square Wave Inverters are rare except in the smaller sizes or the real cheap ones and most output either a Modified Square Wave (MSW) or a Sine Wave/Pure Sine Wave. Inverters advertised as Modified Sine Wave are just a marketing department creation and are really only a Modified Square Wave. Nevertheless modified sine wave (MSW) does have a good ring to it when you have been told that the sine wave unit is the best one to get.

A square wave display, as can be seen this wave form quickly switches between positive and negative and stays positive or negative at full power for longer, this quick switching can overwhelm some electronic appliances connected to the inverter.  

Most small plug in pack chargers and power supplies for cameras, laptops etc these days use switching or switch mode power supplies. So how do we know if this is the case most of the time its in the weight, feel the weight of it and if it feels like it is full of copper wire it more than likely has a conventional transformer in it (most probably needs Sine Wave), if it is much lighter, then it is a switch mode. In theory the switch mode power supplies should work ok on any wave shape input, because they firstly convert the AC to DC, however if the components inside aren’t rated adequately, they may overheat due to the quickly fluctuating square wave shape.

Modified Square Wave Inverter (MSW) A.K.A Modified Sine Wave Inverter (MSW)

Most appliances will work from these basic Inverters, but unfortunately unless you can look at the internal electronic design of the appliance, you can’t be sure if you will really need a Sine Wave Inverter. The squarish wave shape can also confuse the timing circuits in some appliances that use Frequency as a timing control. If the appliance doesn’t work normally or makes unusual noises, then disconnect it or you may have expensive damage. 

These Inverters also generate more interference to TV's, AM and HF radio reception than Sine wave Inverters and can cause buzzing in CD players and stereos. 

When using an inverter in the marine environment tests need to be carried out to make sure the inverters electrical noise isn't enough to compromise reception on VHF frequencies used for radiotelephone, Digital Select Calling,(DSC) and Automatic Identification System (AIS).

Modified Square Wave AKA Modified Sine Wave, as can be seen this wave form is certainly has a lot quicker notchy rise and fall times when compared to the Sine Wave gentle undulation of rise and fall. Also keep in mind the number of additional steps in the modified square wave will influence how the inverter and connected appliances will perform. 

Electric motors for an example in washing machines, bread makers, power tools, microwaves, vacuum cleaners may give trouble if used with a modified square wave inverter. 

Can I run computers with my modified square wave inverter? Most laptop/notebook computer AC power adaptors work perfectly well with the Modified Square Wave Inverter. Desktop computers and some laptops/notebooks may be more sensitive so they may not function correctly or cause a humming noise, in which case a pure sine wave inverter is recommended.

Mac/Apple products are extremely sensitive in the way they use their power, and will require a Pure Sine Wave Inverter to run successfully. We also found a good power filter was also required when using apple products. 

You may have trouble using an AA battery charger with any inverter due to the way the battery chargers draw energy. You will also find that a pure sine wave inverter is a better option for battery chargers due to the fact that there's much less ‘electrical noise’ interference compared to a modified square wave inverter. This ‘electrical noise’ can often wear away at the sensitive components in lower quality battery chargers. The rechargeable batteries, recharging transformer and Inverter may be damaged when trying to recharge devices of 10 volts or higher.

However, it is always a good idea to double check your appliance's manufacturer's guidelines first. If they can't be charged via a modified sine wave inverter, they will mention something similar to "Charge via Mains power only" or not as we have found out.

Sine Wave Inverter (marketed as Pure Sine Wave or Pure Sine or even the S model)

Sine Wave Inverters are more expensive than Modified Square Wave, some times up to twice as much because more components are needed to electronically generate the Sine Wave. You may consider that If the appliance has a Transformer or an Induction Motor think washing machines and appliances listed earlier, then it most probably needs a Sine Wave Inverter to prevent overheating. Now this is not always true, since some fridges and freezers can work fine off Modified Square Wave inverters, and in fact you shouldn't really notice any difference powering a fridge from a Modified Square Wave inverter, however the notchy waveform can interfere with timing circuits.

The wave form output by the an inverter, same shape as the mains power from shore. 

-------------------------------------------------------------------------------------------------

A list of optional features that are listed as inverter options/specifications.

Isolated Input-Output

If you are using only double-insulated appliances (i.e. they have no third Earth-pin on the Mains plug) with your inverter, then it doesn’t matter to the appliance if the inverter has total electrical isolation between the DC input and AC Output (provided there is no fault to earth). In larger installations with an earthed neutral, or if you have earthed appliances such as Washing Machine.  If the Inverter input and output is not isolated, the DC input (battery power 12V) will be up to 115-120 volts AC above the mains earth and this is a very dangerous situation. The out come could be …….. see the next

Electrocution I am lead to believe from years of health and safety briefings it only takes 35 milliAmps (that's 0.035 Amps) in the right conditions to kill a person. The 230 volts from an Inverter can kill you instantly, just like the 230 volt at home, so you need to take precautions. So if you do purchase an inverter that doesn't have total electrical isolation between the DC input and AC output there are several things to do for your safety.

1. Don't use it, return it to the store for a refund, probably the safest but most ignored advice.

2. Make sure the appliance you use doesn’t have an internal connection from earth to neutral.

3. Make sure any appliance is double insulated and does not have a ground pin on the plug.

4. Never make live connections e.g plug in the appliance when the inverter is running.

5. Never disconnect a running appliance with the inverter running.

6. Never work on the batteries or battery connections with the inverter running.

Earth leakage protection or RCD (residual current device)

Bigger Inverters may have these built in, however if not, there are kits available so it can be easily added so operators (consumers i.e. you) are protected by an RCD safety switch and overcurrent circuit breaker. However you cannot get this level of protection unless the inverters input and output are isolated.

A RCD safety switch, while we will never know for sure, we believe it saved us from a nasty accident when our washing machine developed a fault, and another time when I accidently dropped the hand mixer into the sink full of water and with out thinking tried to stop it sinking. 

Example of a kit to add an RCD switch, circuit breakers and power outlets. 

Earth – Neutral link

An automatic earth to neutral link when on inverter mode (no shore power). When disconnected from shore power the unit makes the earth to neutral connection so RCD safety switches can operate.

This feature is also very important if the inverter is also a battery charger when plugged in to shore power. Most are marketed as combi units to designate an inverter and battery charger combination. When the unit is plugged into mains power the connection from earth to neutral is turned off to make use of the earth to neutral link from the shore power receptacle/power box, this enables the shore RCD safety switch's to work. 

Soft Start

Some loads draw much more current when starting up compared with steady operation e.g. an electric kettle draws a lot more current when first turned on, and motors can also draw very high currents as they come up to operating speed. To reduce these massive current surges, some Inverters bring the output voltage up to full voltage progressively over several seconds. This means you will be able to use an Inverter with a smaller continuous power rating, for a particular load.

Low Voltage Cut Out, Shutdown or Battery Disconnect

To prevent damage to your battery, it’s important that the Inverter can switch itself off and remove all current drain, when the battery voltage drops below a set limit. It helps if the cut off voltage can be set by the user, based on the type of battery. Keep in mind that as battery voltage drops, the inverter will draw more current to keep the output power constant. This means that voltage will drop a lot quicker as it reaches the point of full discharge, therefore manual monitoring of battery voltage is not really practical.

Automatic Fan Cooling

To keep the internal components operating properly the waste heat in inverters must be controlled, it is imperative to have an internal fan that is automatically switched on at a set temperature when needed.

Meters 

You can get by without voltage, current and a frequency meter, but with them it’s easier to check if your system and appliances are healthy, or if you’re close to overloading your Inverter. 

Autostart (may go by different names)

Some larger Inverters automatically can sense when any appliance is connected or switched on, so that the inverter only draws significant power when it’s actually needed. This is particularly useful in larger vessels, caravans or buildings, because you don’t have to switch the Inverter off and on when using appliances.

Not all manufacturers include an Auto start feature especially when it comes to Pure Sine Wave inverters, some have a hard wired remote and the more modern units Bluetooth. The major drawback to this auto start feature is the power used while in standby. This can be significant and should be included in the planned daily power usage.

Remote Control

For inverter installations in vessels, caravans or buildings, it’s handy to control and monitor it remotely, the inverter should be mounted in a cabinet near the batteries to simplify and shorten the wiring necessary to connect the batteries to the inverter. Installing the inverter close to the battery, will allow you to minimise the amount of heavy cabling that is needed in the 12 volt part of the circuit. For operations the remote should also function to alarm fault conditions to the operator.

Inverter/Charger (combi units)

For permanent Installations, the Inverter may be able to charge the batteries when mains or onboard generator is available. These units are sold with a variety of current outputs for the charger, most have the function to connect a remote monitoring panel. Most are advertised as Combi units due to the combination of charger and inverter. They can simplify the connection of shore power due to being an automatic switch between inverter and shore power. No need to clunk over a heavy duty switch to select shore power or inverter. A separate battery charger is no longer necessary.

Some units also switch the Earth Neutral connections so RCD switches work as intended, very important for crew safety.

Overload cut-out

The more sophisticated inverters will protect against over temperature, current, voltage or under-voltage, any of these conditions can cause damage to the inverter or the appliances connected to it.

Overheating of Inverter & Wiring

It’s important not to install Inverters in confined spaces where the heat can’t escape, either through air movement or conduction. It’s very important not to cover the case of the inverter or obstruct any fan intake for example by mounting it too close to a bulkhead or furniture. Never mount an Inverter in the engine compartment, I know some vessels have very large engine bays and I would make sense to mount them in this space. However a separate well ventilated insulated compartment should be constructed to keep the heat of the engine room from entering the well ventilated cabinet.

Twelve volt inverters, can draw high current from the battery banks, the general rule is to divide the output power by 10 to understand how much current will need to be supplied. So a 1000 watt inverter will draw 100 amps from the battery and this means using battery cables which can supply this level of current without overheating, while also keeping total voltage-drop in the positive and earth lead to less than 1.5% in each - i.e. less than 0.2 volts.

Inverter Grounding

I am sure most of us know the high voltage of the AC system presents a shock hazard and can certainly be lethal. The DC system is not normally an electrocution hazard but can provide a lot of current, and so is potentially a source of fire. A suitable ground must be installed between the AC and DC system. During my inverter fitment I noticed in the operating instructions the requirement for grounding connections on both the AC side and DC side of the unit’s case. This grounding can prevent shocks from AC, and fire hazard from DC. 

My previous unit only had the  smaller AC grounding connection made. A fault in the DC side of the system could provide enough current to overheat the AC grounding conductor (think enough heat to melt insulation and start a fire) without blowing the large DC fuse. Keep in mind the fact that the AC ground is not fused and current will flow through the conductor until it burns out. A high amperage capacity DC grounding path back to the DC system should be made. The conductor size for the ground needs to be of sufficient cross sectional area (bigger is better) to be able to sustain enough current to blow the supply fuse.

The installation instructions for older inverters (as I had previously) typically do not include this precaution, but most newly designed units do. Though looking into some different manufactures install instructions this connection is not addressed in any depth, most only state or draw the connection in on the installation schematic. Due to the fuse size in my inverter we needed a 70 mm2 ground wire for the DC ground. 

Limitations

Battery capacity

All the power for the load has to come from the battery, so with high power Inverters or appliances you want to run for a long time, you need large battery banks. If you wanted to run a small Air Conditioner that used 1000 watts on average, it would draw 84 amps, so you need to have a battery bank capable of supplying 2000 amp hours in a day. However we are not done yet, we still need to factor in the losses incurred (the 10-20% mentioned earlier) by running the 12 V DC through the inverter to output 230V AC the figure would be closer to 2400 amp hours draw on the batteries. That means big, heavy and expensive batteries, more importantly a way of recharging them or keeping them charged.

----------------------------------------------------------------------------------

Alternatives to an inverter

Use 12 volt appliances

Many appliances are available as both 12 volt DC or 230 volt AC versions, but the 12 volt version uses less power and is always more expensive. A 12 volt fridge will mostly have thicker insulation and use a more efficient motor/compressor. The designers of mains powered appliances don't factor in the same level of efficiency as they do for 12 volt powered appliances, due to the design spec being for an unlimited mains power source.

A 12 volt electric kettle will use less power because there are no losses in converting the 12 volts to 240 volts first, how ever a lot of people don't actually realise how much power an electric kettle draws and the install of the unit can be more expensive due to power cable size. Using only 12 volt appliances, may reduce your power needs, so you won’t need a generator or run the motor to recharge your batteries on shorter outings. However you need to ensure you use heavy enough cable to run the appliances connected to them. 

Generator

These can easily generate the high power level often needed and they produce a 230 volt output directly. However an inverter is totally silent and much smaller than a generator and doesn't need regular servicing. Keep in mind that most portable generators exhaust can output deadly carbon monoxide gas and in the right conditions this lethal gas can find its way below and slowly kill you while you cook dinner or have a few beers.

Dangers With LED Lighting

 LED lighting found to interfere with VHF-FM radio and AIS reception

There is potential for LED (light-emitting diode) lighting on vessels to compromise reception on VHF frequencies.

Keep in mind the problems are more than likely not with the LEDs but the power supplies that run the lights. Some LED lights have power supplies externally or built in to the bulbs. While this is off the target similar problems can also be encountered with USB 3 equipment running on a laptop, navigation equipment including GPS reception can be affected and can be tested in a similar manner.

The United States Coast Guard has sounded the alarm over the potential for LED lighting on vessels to compromise reception on VHF frequencies used for radiotelephone, Digital Selective Calling (DSC) and Automatic Identification System (AIS).

The distance at which the LED lighting starts to have an impact and whether the issue is limited to certain makes of lighting or navigation equipment. The United States Coast Guard has asked the United States marine industry to provide more detail of known incidents.

Due to their energy-saving capability and longer service life, LED lights are commonly used for navigation lighting, searchlights and floodlights, as well as interior and exterior lighting—including those used for visual effect.

The United States Coast Guard said that in one case, radio-frequency interference caused by LED lighting created a hazard that led to a serious safety incident.

‘The maritime rescue coordination centre in a United States port was unable to contact a ship by VHF radio that was involved in a traffic separation scheme incident. That ship also experienced very poor AIS reception. Other ships have also experienced degradation of their VHF receivers (including AIS), caused by their LED navigation lights. LED lighting installed near VHF antennas has also been found to reduce reception.’

Strong radio interference from LED sources may not be immediately apparent to marine radio users, but there is a way to test for LED interference (see below).

If you have experienced LED-lighting interference on your vessel please report it to your local marine authority, in Australia its AMSA.

How to test for LED interference.

1. Turn off your LED light.

2. Tune your VHF radio to a quiet channel, such as Channel 73.

3. Adjust your VHF radio’s squelch control until the radio outputs audio noise.

4. Re-adjust the squelch control until the audio noise is quiet—just slightly above the noise threshold.

5. Turn your LED light back on.

6. If the radio starts crackling when you turn on the LED lights, it is likely that the LED lights are affecting both your shipboard VHF marine radio and AIS reception.

Our Tender Experiences

The best tender for a yacht has to fulfill a whole range of criteria and that will partly be dictated by your own personal needs and experiences.

There are so many different styles and shapes of tender on the market, some lend themselves to being work horses hauling the food supplies and beverages out to a yacht at anchor with ease.  Then there are the show ponies, centre console and a large outboard. These are more suited to a quick run to the beach, most of the time they are heavy due to the configuration and dragging them up to the high water mark while ashore is likely to give you a hernia or heart attack whichever comes first. We have found due to the configuration its hard to do a resupply thanks to the lack of space, and these boats are not really suited to remote location cruising.  It can be done of course by hiring a run about to bring out the supplies. Then there are of course the tenders that spend a second life as a fishing boat.  We have found waterline length certainly makes a difference to speed, and while there are those who are fine with a small out board when venturing into remote areas, it could be a lot safer to have a bit of horse power under the hood so to speak.  We have been in areas where the currents can run at 6-7 knots, so a bit of horse power is needed to get around. I also remember zooming over a large sandbar strewn bay near sunset to take photos before the light changed too much. If we were not able to get up on the plane then we would have missed the opportunity, of course we could have started our trip earlier but we would not have been back until well after the sun had set. These are the things to consider when purchasing a tender, we found the bigger the tubes the better, a bit of length certainly helps get on the plane, a flat floor or a floor added over a deep V floor is good and is a lot safer getting in and out of the tender when tied along side.  

While its a difficult ask these days, a two stroke engine can be a useful addition to a cruising yacht when going offshore. This is our experience, we went off shore with a nice new four stroke engine and after a few short months of relying on it we were celebrating when we sold it and purchased a two stroke. Yes there will be a lot of people thinking we are environmental vandals, how ever our safety and the ability to head ashore and actually make it were high on our list of desirable things an outboard should be capable of.  The only thing and this is the only plus is the four stroke fuel economy was good, unfortunately the four stroke wasn't reliable, it had a poor weight to HP ratio, and the ongoing repairs and need for maintenance was cutting into the cruising budget. So what was the problems, consistent condensation in the carburettor fuel bowl causing the engine to stop when a drop of water blocked the jet. In a two year period the rubber drive in the propeller(s) was replaced or the propeller replaced eighteen times  (18). Changing the oil was a real pain in the neck due to design. The next safety issue was the slightest kick back when starting would smash the plastic pieces in the pullcord mechanism. Then to add to the grief of the pull cord becoming unoperational, the way the flywheel was cast did not lend itself to easily using an emergency start cord.  The connector for the external tank would take a chunk out of the seal when plugging it on to the outboard, then after 2-3 connections the motor would suck air through the damaged seal. Then to add insult to injury if you didn't use the outboard for a week or fortnight the interior of the carburettor would start to corrode when the fuel evaporated. The white powder from the corrosion would then block the jet in the carburettor when you next start the motor. Yeah happy happy times! All that aside I hope some of the info collected here is of use. 

The smashed plastic parts in the pull starter, from a back kick when starting

As we have become more knowledgeable through our own experiences we have also learnt from others. I would like to share some of what we have learnt about reducing the risks when using tenders. These little boats really are our connection to the outside world and hard working pack horses come resupply day. Unfortunately the risks are real and some have paid the ultimate price by not recognising the potential danger. 

When we are sailing around our local bay enjoying the anchorages it’s a very rare occurrence to be there alone.  In the bay most anchorages allow us to anchor close to the beach and it’s possible to easily row back to the boat or summon help from passing or anchored vessels.  When we started exploring out side the bay we didn’t give a great deal of thought to how easy it would be to become like Robinson Crusoe using the tender to go ashore.  

We found it’s not hard to become stranded in sight of your own vessel.  In some cases it has been much worse for a few people. Since moving further afield, talking with others and after our own personal experiences we have been wakened out of our complacency.  You know Complacency:   a feeling of contentment, especially when coupled with an unawareness of danger.  So what’s the danger?  If you haven’t thought about it here are a few. 

We have heard through the grapevine and read several stories about others experiences both good and bad; these have ranged from forced overnight stays on mosquito infested beaches to being washed away on a tide. What if the weather turns? and you are not able to return to your anchored vessel. Or you could become stranded if the motor fails and you’re against the tide or it’s too far or perhaps you are injured and are unable to row back.  Those that have been washed away on the tide and have travelled for miles with no water and little protection from the elements, luckily in these cases they were found by passing ships but it was several days later. One couple we read about was almost washed from a mid ocean coral cay when their tender motor wasn’t powerful enough against the outgoing tidal flow.  They found themselves standing barefoot on coral holding their tender to stop it from being washed away while waiting for the tide to turn. Then once the tide turned it allowed them to motor back to their vessel on the little remaining fuel they had.  

One other danger that was highlighted during a recent incident was that a person using a tender fell over board. If being in the water wasn’t bad enough the real trouble began when they could not reboard their tender from the water. It is a worthwhile experiment to test your tender has sufficient stable buoyancy to accommodate a person being able to climb back on board from the water.  I know that with some inflatable’s even moderately unfit persons can reboard over the stern using the outboard as a step, if the out board is fitted with a wing. Unfortunately this may not be possible for all combinations of motor and tender.  What if you cannot reboard your tender from the water? It is certainly in your best interests to look at ways to make it possible to get back on board.  This is especially important if you are in the higher latitudes, hypothermia will quickly set in once you’re in the water and make it almost impossible to swim back to shore or climb up on to the main vessel.  While there are ever growing lists of problems people find themselves in, I think this small cross section should have given you an idea of the multitude of perils if you ignore the hazards. Since writing this we made a fold up ladder  to keep in the tender just in case we  or someone else fall overboard. 

We now carry additional gear in our tender as well as a safety box so we can summon help or do minor repairs should they be necessary.  However the safety box is only good if you take it with you. We didn’t once and when we had finished our walk and swim at the beach we couldn’t get the motor back down.  Luckily we were able to flag down a passing fisherman. Incredibly he didn’t have any tools on board but was kind enough to run us to our vessel and back with the tools for the repair. I have listed the contents of our tender safety box and what we carry in our tender.  While the lists may look excessive it’s a matter of adjusting it to suit the situation. 

Our tender safety box and the contents of what we carry. 

Our safety box is a medium size commercially available water resistant box. Into the box we put our outboard spares and these include dewatering fluid, start rope, shear pins, split pins, stainless plier, adjustable spanner, spark plugs, screw driver, propeller and the spanners to change them. We do carry a spare propeller as we have had more than experience where the rubber drive sheared and we lost or had reduced drive. While it appears to be a bit of an over kill by the manufacturer to have a shear pin and rubber drive fitted to the propeller to protect the gearbox.  In our experiences the rubber protects the shear pin. We also have room for a V sheet, knife, a couple of flares, handheld VHF, a whistle, torch, small first aid kit, water, sunscreen, insect repellent.  Someone said to add some waterproof matches to the list in case you need to light a fire on the beach, it’s a good idea and they take up next to no room.  We have the basic tools to undertake minor motor repairs, and these have come in handy on a number of occasions.  While carrying out the repair we were able to protect our selves with the basics like sunscreen and insect repellent.  Having a drink of water didn’t go astray on those warm days either. While I hope we never need to use them we do have the basic signalling equipment to summon help or aid a rescue for ourselves or render assistance to some one else.

Don’t be tempted to use the V sheet as shelter from the rain if you do not need help.  I heard of a case recently where a couple of guys out fishing put their girlfriends under the V sheet to keep the light rain off, a passing aircraft saw the V sheet and alerted the authorities, who arrived to find the embarrassed fishermen and girlfriends.  However in situations where you require help use the V Sheet as protection while you are waiting for help to arrive. If we were going to the outer reef or find a remote anchorage empty I would also pack the vessels EPIRB in case we run into trouble. Trouble need not necessarily be related to the tender but could be a medical emergency, for example if one of the crew falls and injures themselves while ashore. The uninjured party may not be able to move the injured crew into the tender or for that matter get them from the tender back on to the main vessel.  

While hard to see in the dark green pouch the small repair tool kit tucked away in under the cowl of the motor. 

The small tool kit supplied with the motor, we store ours under the cowl of the motor, better there when needed than on the boat rusting away in one of the lockers. While there is an emergency start cord you have to remove the pull start mechanism to use the cord, just keeping the cord on board the tender isn't enough

Tender anchor chain and rode connected and ready to deploy, we keep ours in a bucket so if we don't get all the mud or sand off it doesnt coat the floor of the tender. 

Stainless steel cable fitted with a plastic hose to stop chafe should it rub against the tender tubes while in use. We like a large combination lock so we don't need to worry about losing the key.

The additional gear we carry in the tender is, shoes, anchor, oars/paddles and bailer. The bits and pieces we keep in the tender are all secured on lanyards in case the worst happens and the tender capsizes. PFD’s can be secured into the tender with a stainless steel cable and padlock when you tie up at the dock while going ashore. Our anchor is rigged for use at a moments notice should it be needed to hold position. We keep shoes in the tender so we can wear them while stepping ashore. It’s better to find there are things on the beach that could slice your bare feet apart while you’re wearing shoes or sandals than if you weren’t. 

Additional water proof storage attached under the seat

Made from cheap easily available storm water plumbing pipe and glue. Sewerage pipe will also work but is more expensive and slightly heavier gauge wall thickness.

To prolong your outboard motors life it’s a good idea to carry out monthly checks and engage in some proactive maintenance.  Firstly buy or make a cover for the motor and fuel tank, keeping the sun and weather off can certainly extend the life of exposed components. A plastic fuel tank left exposed to the weather has a very limited life before it will become brittle and capable of splitting from internal pressure if the vent is closed.  It’s worthwhile to get a small grease gun and marine grade grease and identify grease points and squeeze in fresh grease regularly. Learn how to check the gearbox oil level and condition.  It doesn’t take long to give the outboard ten or fifteen minutes of your time once a month to do some preventative maintenance. I also try to flush the motor with fresh water after use, that’s not every day if using it daily but before storage for a week or more. It’s not always possible to do a fresh water flush when the water tanks are getting low, however if you have sufficient fresh water it is well worth the effort. When you can spare ten to fifteen litres of water, small motors can be held and run in a bucket but with larger motors you will not need much more water but a little ingenuity and mechanical help may be needed. I have seen a larger size bucket filled with water held in place with the motor lifting davit and clever cruisers have made electric camping showers connect to the flush port or ear muffs and use a bag to collect and recycle the water.  I think it’s a case of finding an easy way to do an engine flush on your vessel and use it before storage. 

Check over your inflatable tubes for nicks and scratches, again buy or have a cover made if you can afford it, the UV damage starts the moment its outside.  While we didn’t understand the significance at the time, our inflatable was slowly being destroyed by the sun and was wearing away.  The signs were a white/grey stain on our pants after sitting on the tubes, as it turns out this was the UV damaged layer coming off. The damage was happening for several years; eventually the outer cover was worn away and was almost down to the fabric.  We didn’t really notice the wear until we had to replace a patch and found the height difference between the area under the patch and the surrounding area was very noticeable. On closer inspection of the tubes we saw just how thin the outer cover had become. 

Other things to look at are if you have a tender with an inflatable floor it’s possible to get a build-up of sand and grit under the floor and over time this will damage the fabric. I have seen the inflatable tube under the floor cut to pieces after the boat was used to collect shells. Broken shell fragments worked their way under the floor boards and in no time the damage was done.  The space between the hull and tubes of a RIB can also do with a clean out once a season or more depending on how you use your boat. Let down the tubes slightly and with a hose, spray in between hulls and tubes to clear out any sand and grit then reinflate the tubes.  

Tender Checklist 

Motor monthly between services 

• Remove the outboard motor cowl and inspect starter rope, spark plug wires and the fuel lines for wear, cracks, splits or tears also visually check the  fuel filter for any signs of water and clogging. • Check for salt water or oil weeping at gaskets

• Check Gear box oil

• Check propeller shaft and seal for fishing line (remove propeller)

• Grease as per manufactures instructions

• Lightly spray power head with protective coating (dewatering fluid/anti –corrosion, lanoline or inox) 

Hull monthly

• Check inflation level of tubes

• Clean sand coral and or shell fragments from inside, RIBs between hull and tubes

• Check over hull & tubes for chafe, scratches and corrosion (repair chafe using patches, if hull is aluminium touch-up paint might be necessary on scratches to minimize corrosion

• Check paddles / oars & rowlocks for UV damage

Before use check:

• Fuel tank – full

• No fuel leaks

• Kill switch – MOB lanyard connected

• Start the motor and check that it spurts water

• Safety strap attaching outboard to tender (to keep motor on if the clamps work loose)

• If an inflatable, ensure it’s properly inflated

• Anchor

• Bailer

• Paddles / Oars & Rowlocks

• Long painter - for towing, tying it to a dock.

• Cable with marine padlock – for locking to jetty when leaving it unattended

• Shoes

• PFD’s

• Safety equipment in water resistant box or bag, V sheet, knife, signal mirror, 1 orange smoke, 1 red flare, handheld VHF, whistle, torch/strobe, small first aid kit, water, sunscreen, insect repellent, water proof matches. Outboard spares: dewatering fluid, shear pins, split pins, multipurpose plier & adjustable spanner, sparkplugs and spanner, screwdriver, propeller, MOB lanyard, secured with padlock & cable.

After use:

• Close fuel tank vent and cock on fuel tank.

• When the motor cools refuel, helps stop condensation in fuel tank. 

• Flush and rinse/wash motor with fresh water to minimize corrosion.

If the outboard motor won't start:

• Kill switch – MOB motor stop lanyard not plugged in?

• Gear shift in wrong position? (Shift into neutral) 

• Choke in wrong position? 

• Throttle in wrong position? (Too far open or not open at all, experiment)

• Perhaps flooded? if flooded unclip fuel hose or turn fuel off, open throttle and pull cord until motor starts then reconnect fuel hose and try to start (possibly no need for choke now)

• Fuel: Check fuel level?  Is Fuel tank cap vent open?  Is fuel tap on?

• Fuel supply line connection loose or is hose kinked?  Fuel line bulb should get hard when squeezed

• Is there water in the fuel?  Check fuel filter next

• Clogged fuel filter? Visually inspect filter, remove and flick contents into a dry bucket for inspection 

• Fuel not primed? With engine cowl open see if fuel moves in filter when bulb is squeezed

• Pull fuel line from carburettor, crank motor to see if fuel flows evenly (catch fuel in can)

• Clogged / water in carburettor?  Not easy to check unless experienced   

• Got spark? Not easy to check and dangerous unless experienced   

• Dirty spark plug?  (When changing spark plugs check for correct gap) 

• Damp ignition components (spray high tension leads & ignition wires with dewatering fluid)

• No compression? (Loose spark plugs, broken or jammed reed valve, previously over heated)

• Pull cord not turning over motor, problem with recoil spring. Use spare start cord, check operation manual

Tender outboards are usually simple small engines and thankfully have not gone the way of their larger brothers with complex computer controlled engine management systems and fuel injection or specialist carburetion. The reason a tender outboard motor will not start is usually not a complex problem.  While having said that, it’s probably not the time to check out the motor when it’s on the tender tied off behind the vessel.  Get the engine on to a stable level work area on the main vessel. This is a better place to work and a dropped tool will hopefully mean it’s not lost forever into the large blue tool box. 

If you don’t know what you’re looking at have some one skilled in engine repair go over some of the basics with you. Work safely; it can be dangerous when checking for spark on an outboard that will not start. Get to know and understand the safety aspects of dealing with high voltage and sparks around highly flammable fuel. 

Carburettor, the drain screw is easy to see, the use of the screw does not guarantee any contaminates will drain out of the bowl 

After market fuel filter fitted to the fuel tank hose, this clear filter housing can give an  instant up to date visual of the state of fuel in the tank and hose.

Standard equipment fuel filter under the motor cowl, some only filter out large particles 

Water droplet in the carburetor fuel bowl, this was big enough to cause problems and was a common occurrence with our old four stroke.

To reduce the build up we would use fuel doctor in the fuel every fill, this reduced the on going problem. I believe the water is combined into the fuel doctor and can then pass through the jets and be burnt. I think this condensation build up of a water droplet was cumulative so passing it continually as it formed made it easy to deal with.

Checking the fuel system isn’t complicated once you know the lay out; but work carefully and don’t spill fuel. Most problems we have encountered are from water in the fuel or a clogged filter. If you remove the fuel filter flick the contents of the filter into a container, this will let you see the contents of the filter. Water will ball up in beads in the fuel and any debris will also be visible. Don’t just blow the filter out as this will not give you any idea of what’s causing flow problems.  If you suspect water in the fuel and find small amounts in the filter, remove the fuel bowl off the carburettor and clean and dry it out before reassembly. Water in the fuel may also mean the whole system needs to be cleaned out, draining the fuel tank and lines then refilling with fresh fuel.  

We had an ongoing problem with water in the carburettor bowl, once enough built up the motor would break down until we cleaned the carburettor bowl. How does water get into the fuel? In our experience it could from the vent on the tank cap. If your not transporting the motor in a vehicle you could leave the vent open. Rain showers or spray during rough weather could be enough to find a way into the tank. 

As a visual check we installed a pre filter inserted in the main fuel line, water was going to be easy to see in the large filter housing, we didn't see any.   

As it turned out this problem with water in the fuel wasn't from the fuel tank, the best explanation we can come up with is the water in our carburettor was from condensation in the bowl itself. After a intensive search for the cause we eliminated the fuel tank lines and filters, spent a lot of time and money chasing this particular problem. We never had the problem with our previous out board, we had the problem with the four stroke and then no longer had the problem once we sold on the four stroke, used the same fuel tank lines and filter on the new engine and all was good. 

Unleaded fuel containing ethanol should not be used in outboard motors as it has been found that the ethanol can separate from the base fuel if left to sit for a while.  Most fuel supply outlets now have instructions on the fuel pumps notifying customers not to use unleaded fuel containing ethanol in boats.  

Make sure your two stroke outboard is running the correct oil fuel mixture (motor manufactures recommendation); there is nothing to be gained by using extra oil in the fuel, if there is too much oil in the fuel the motor will not perform as it should and can run lean as the oil replaces the fuel in the mixture and running lean can increase maintenance costs.  

MOB Stop Lanyard

A motor safety lanyard, in this case made from a short length of dyneema with a stainless steel clip for quick attachment 

What else?  Make sure you have a safety lanyard attaching your motor to the tender (not to be confused with a motor stop MOB lanyard); just recently we witnessed the loss of an outboard. The owner didn’t have a lanyard attaching the motor to the outboard bracket, from what we saw it was a small motor that could be started in gear, while giving the motor a mighty pull on the start cord it jumped off the bracket, the owner held the throttle handle in his left hand. As the motor twisted the throttle opened up while the owner desperately tried to wrestle it back onto the outboard bracket. Unfortunately the motor won the tug of war and off it went to a watery grave spitting and spluttering as it sunk.  This safety lanyard could be a short cable and padlock so your motor is still there when you come back with the shopping on re-supply day.    

Use an additional safety lanyard when you remove the outboard, make sure that you have a safety line tied from the engine to the main vessel. Outboards can be heavy and if you lose balance or some crazy zooms into the anchorage while you’re doing the transfer and drop it in the water, you will be very glad to have that safety line in place.

Start the outboard first before casting off from the boat or jetty, not after. If you don't and the motor doesn’t start, you may firstly look silly, and secondly the tide will determine how hard you have to paddle against the current to get back to the boat. If the current is flowing strongly and your not making head way drop the anchor and you may need to wait it out. 

Put on a life jacket before boarding; make sure that kids and people who are not strong swimmers do the same.  Is climbing into the dinghy difficult for you or your crew? If it is you will need to plan your trip or work out ways to make it easier. To board use the painter to bring the dinghy as close as you can to the boat. I get in first and bring the dinghy up and across the boat's transom to make it easy to board for kids or those with short legs. When you step in the dinghy, try to get straight inside it putting your feet on the floor. Use a balancing rope, I have even see people use an extended topping lift or rope hung from the davits to hold while climbing aboard. Don’t stand on the on the side tube to get in, depending on the design of the vessel stern, it may be better to get the little ones and older people to sit on the tubes or swim deck then slide into the tender.  Once one of the crew is on board ask others to hop on board but don’t jump in as this can be unstable.  It can certainly make people stumble around in the boat, there is a strong possibility falling on to others in the tender, or stubbing toes or standing on things on the floor. Make sure to spread the load and not have all the weight on one side or in the aft, and do not overload the tender read the capacity label.

For the first trip of the day warm the motor up, get in the tender first and run the motor on low RPM for a couple of minutes to make sure it starts and is running smoothly while you load the passengers and luggage.  Like any other trip, plan ahead, make sure you have enough supplies, fuel, water, food for the trip your about to embark on. 

When using the tender at night it’s a legal requirement to carry a torch at a minimum to mark your presence or attract attention. We store a torch and a few other bits in an under seat storage canister made from 90 millimetre stormwater pipe and fittings.  A good torch can be used to spot obstacles like anchored boats, crab pot floats, mooring buoys and to help find your boat in the dark.  Mark your boat before heading to the beach for the night, we have put several bands of SOLAS reflective tape high up on the mast to give us a good visual which is our boat in the anchorage by shining a torch around.  If you know you’re not going to return before dark turn on a few lights and don’t forget your anchor light.

Quiet Sundowners Towed Stern Too stops the gargling and the dog lapping at water noises 

So when it’s time to be enjoying sun-downers in the cockpit or you’re headed off to bed we have found a tender will make all sorts of noises. It might gently or noisily tap against the hull or make slapping sounds like it’s a dog noisily drinking water.  In the past we would pick ours up out of the water of an evening so it didn’t ruin the serenity as we were enjoying our drinks. On investigation we found that like a lot of RIB’s there is a pocket or tunnel that forms where the tubes join the hull, it’s the motion of the waves in this pocket that makes all the noise. The solution that works for us is to tie the dinghy with its bow the other way. That’s right facing away from the boat, turn it around 180˚ from the usual towing position and secure it from the stern on one or two short painters while you’re enjoying your time in the cockpit. The tender stern with the motor on is heavier and rides deeper in the water, so there are no pockets for the waves to slap and slosh into.  Problem solved the drinking water noise disappears and with two painters securing it we found that it didn’t sneak up the side of the boat and tap on the hull at O’ dark thirty.   

Large inspection port used as a quick drain for when the tender is on the davits, could also double as an anti theft device if removed when on the beach. 

Ready to go the large stern drain has the cover in place the motor is locked and has a safety lanyard. 

Tenders hanging from the aft davits or for that matter any tenders stored upright on deck or over the side need some way of clearing the water quickly so as not to put a large strain on the davits, deck chocks or halyards.  During a heavy down pore it doesn’t take much to overwhelm the small drain hole most tenders have. A leaf, loose line or just the shear volume of water during a storm can quickly see a tender fill with water.  To help clear water from inside the tender we installed an inspection hatch in the transom. If we are in a heavy downpour or take a large wave over the stern the water can quickly empty. Also when we tie up at the beach and are going to be out of sight of the tender we can take the inspection plate with us, anyone wanting to steal the tender is going to have to try and row a water filled inflatable away unless of course they carry their own motor kill switch lanyard. 

Another lesson learnt. During a trip south to Tasmania we lost our tender one evening while anchored in Twofold Bay. Following along with the proverb: the battle was lost because of a nail.  Our story started in Jervis Bay when I injured myself; I had a fall while over extending to get one of the davit lifting lines. When in Eden I returned to the vessel one afternoon the worst for wear due to the injuries I sustained in Jervis Bay rather than lifting the tender up out of the water I secured just the painter to the back of the boat.  Some time during the evening the clip securing the painter came apart.  Off went the tender on a nocturnal trip finishing upside down on the rocks at the southern end of the bay. We did get the tender back and after a new motor, some patches and work tidying up the numerous scratches we had a tender again.  So what was our nail? A short length of line was all that was needed so I didn’t need to over extend to start picking up the tender into the davits.   We now have extended both davit lines so we don’t have to over extend to start the retrieval process. Now we secure the tender in two places to the vessel if we don’t pick it up out of the water. 

A simple fuel tank cover made from sunbrella canvas and sewed on board using a house hold sewing machine we keep as much of the hoses under cover as well,

Fuel tank secured in place so it will not fall out, this tank is starting to show sun damage, its best to cover the tank from new to stop the sun damage.

What else? Securely mount (tie or strap) your loose items including the fuel tank into the tender. We were hoisting the tender up into the davits one windy afternoon as we got ready to sail back across the bay. About half way up into the cradle a strong wind bullet caught the tender turning it onto its side trying to spill the contents into the bay. Everything but the fuel tank was secured in some way. To cut a long story short we were able to up anchor and give chase to the tank as it was quickly disappearing on the outgoing tide.  Luckily the only loss was the fuel in the tank that we had to dispose of on shore at a disposal station due to contamination, sea water had trickled in the vent as it floated away semi submerged.

  Something that has fallen from grace over the years is the use of a long painter to tie up at the local jetty; the reason to do this is to allow others to get in to the jetty by being able to move your tender off to the side. If you tie up tight then only a very limited number of tenders can tie up and use the jetty at one time, and as we know that with beach parties the more the merrier. 

Lastly and very important, when you finally get to the anchorage or jetty and before you start manoeuvring your boat, shorten the painter until the dinghy almost touches the boat. This should stop the painter from getting fouled in the boat propeller.