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LAY UP & REFIT (Winterise/dewinterise)

Exactly what an individual lay up involves depends upon use and personal preference. Will the boat be used during the winter? What sort of cooling system is involved? What facilities are there for transport and storage off the boat?

Refitting is just the opposite of lay up.

This is also the ideal time to do certain maintenance tasks, such as:

Change lubrication oils and filters

Change fuel filters, clean lift pump strainer, and clean sedimentors and aglomerators.

Check all fuel unions for tightness, but do not tighten unless they are loose.

Check coolant hoses for perishing and hardness.

Check coolant hose clips for corrosion & security.

Check antifreeze strengths.

Change\clean air filter element

Change drive (fan) belts and Jabsco impellors.

On proper marine engines change coolant anode (if fitted)

A general look round for problems and potential problems.


What we are guarding against

Electrical deterioration


The domestic water system should also be protected from frost. You can fill it with potable antifreeze, but it might be rather expensive. If you do not do this you should drain it down, although modern plastic plumbing makes frost damage to pipes less likely, there are still metal parts that could be damaged.

If the boat is staying afloat in the south of the country there is less danger of frost damage – but who can forecast the odd very cold snap?

Turn on all taps and run pump until they run dry.

Remove pipes from shower mixer and turn on to drain (or dismantle the valve body).

Remove drain from instant gas water heater water diaphragm chamber or loosen clamping screws.

Remove lower domestic water connection from calorifier and drain.

Loosen covers or remove drain plugs from domestic water pump.

Antifreeze shower pump as described under cooling.


All indirect cooling systems (heat exchanger/keel cooling) should be kept filled with a 50% antifreeze mixture. This is probably more important as a corrosion inhibitor, but it will also prevent the cooling system freezing. This mixture should also be used in wet central heating systems.

Depending upon the type/quality/price of antifreeze used it should be changed at 2 to 3 years/10 year/ life of car (15 year?) intervals. Dispose of at approved sites and take the drain down opportunity to reverse flush the system and check all heat exchangers and oil coolers for blockages.

It is vital that the raw water side of indirect cooled systems and the whole of direct cooled systems are totally drained of water. This means removing all drain bungs/taps and poking each with wire to ensure it is not blocked with rust. It may well be easier to get help, mix a 50% antifreeze mixture in large bucket. Get another bucket held under the exhaust outlet (hoping its above the waterline). Turn the seacock off and remove the strum/mud box cover. Set the engine to fast idle and pour the antifreeze mixture down the strum/mud box. When the antifreeze mixture flows from the exhaust stop the engine. You can now be 98% sure all the water in the engine is protected by antifreeze.

On direct cooled boats it would be as well to remove the thermostat  before you do this.



One of the biggest benefits of the BSS is the virtual elimination of condensation during the winter. This is because of the enhanced ventilation.

If you have a sea boat or if you insist in covering your ventilators during the winter, you would be well advised to remove all soft furnishings, mattresses and cushions to a dry store for the winter. If you have the correct ventilation only remove clothes etc, the rest will stay perfectly safe.

You would also be advised to ensure your bilges are checked regularly throughout the lay up period - water in the bilges will evaporate and cause a lot of damp in the boat.

Dehumidifies will only be a benefit if you seal your boat, even then they may fail because of ice build up on the evaporator plates – not the best idea in my view.

The one place where damp can wreck havoc is in the fuel tanks. You have to have them vented so they do not collapse when fuel is being drawn off them, but this allows condensation to from on the inside. The way to combat this is to:

Keep the fuel tank as full as possible throughout the winter.

If possible drain tank, from lowest point, at refit time.

Use a fuel additive.

And as belt and braces fit a sedimentor & agglomerator in case the additive does not work.



The early autumn is used to touch up/repaint hull/topside damage etc.

All external lockers, gas tanks, and battery boxes need cleaning, de-rusting and painting as required.

Bilges should be cleaned of debris to ensure any damp can evaporate away. Ideally floor boards should be raised to allow air circulation.

Hinges and locks need lubricating.

One should also consider protecting the engine from corrosion. The outside is easy – just wipe the whole thing over with an oily rag, but the inside is different. One can obtain special to pour down the injector holes, but this opens the way to damage from hydraulic lock, odd things dropped into the engine, and even the oil softening carbon on the valves, so upon starting the next season the carbon holds the valves open. The loss of compression then prevents the engine starting (I never said this, but using a domestic battery to supply the starter with 24 volts - disconnect the alternator first – often solves this problem).

My view is that for a late October to early March lay-ups, all that is required is an oil and filter change before laying up. This minimizes corrosion from the sulphuric acid caused by combustion blow by.

With a dry exhaust I would do very little apart from running the engine every few weeks to keep the batteries fully charged.

As long as you remember to remove it, one could remove the exhaust hose and stuff a piece of oily rag into the mixing elbow. This will prevent water vapour from the water trapped in the exhaust from finding its way back into a cylinder and causing rust. The dangers are that:-

If left off the exhaust elbow the hose may fall into the bilge of the boat when it’s afloat and allow the boat to fill up (depending upon competence of installation).

You may forget the rag and then you will suffer from overheating (not keel cooled boats), loss of power, bad starting etc.


Your batteries should be kept fully charged. This could mean removing them, taking them home, and cycling them. That is putting them on a slow charge and discharge cycle.

With dry exhaust keel/tank cooled boats it is probably better to visit them once a month to run the engine until the ammeter (if you have one) drops to 2 - 3 amps per battery (Three batteries = 6 to 10 amps).

All external connectors require dressing with petroleum jelly.

The batteries need cleaning and their terminals need dressing.



Remove or hide anything that looks as if it is easy to move and can be sold in a pub. (TV, navigation equipment etc).

Remove expensive external TV aerials - they tell everyone you can afford the odd £100 and a TV is likely to be aboard. This goes for VHF etc as well.

The poorer you can make the interior look the less likely you are to be broken into!  What about a dirty knife, fork & plate left in the galley together with a bottle of sour milk and an empty bean can?


The following table will allow you to develop your own lay up plan.


  Date done

Change engine oil


Change engine oil filter


Change gearbox oil


Change gearbox oil filter


Clean gearbox oil cooler


Clean heat exchanger


Check/top up/replace antifreeze


Check all hoses & clips


Check alternator belt


Antifreeze raw water system


Remove Jabsco impeller.


Check tightness of mounts.


Drive line


Check stern gland/repack


Refill shaft log


Check flexible rubber hose


Check coupling bolts


Fuel system


Change fuel filter


Change & clean agglomerator filter


Clean sedimentor


Clean lift pump


Get injectors overhauled


Bleed system


Fill up diesel tank


Check for leaks


Check all unions












Throughout the season I keep a little black book that I record the things that need attention, but can wait. This includes such things as sorting out loose hinges, changing door/draw handles, tightening door bolts, tightening hinges, lubricating draw runners etc.

I also record a wish list of improvements I want to make (It gives the rest of the cruising season for thought and to realise some were not as clever as one first thought).

This book is also useful for noting such things as the Crossland or Fram filter numbers (to save the cost of buying identical products through expensive outlets), and technical things like heater plug current draw.



Best practice is to ensure your boat does not breakdown, rather than to try to learn to fix it if it does.

Because of the virtually infinite combinations of equipment and installation methods, the only way to prevent breakdowns is to get to know your own boat - what is normal, what is not. Investigate oddities in performance of equipment, 90% of the time you will not find anything wrong, and the other 10% of the time you will prevent a breakdown.

The only way to get to know it is to spend time investigating it, finding out where the cables run, the water pipes run, and what type of equipment is fitted.

Having identified a piece of installation or equipment you are unsure of, seek advice on what it does, seek advice on how it works and what maintenance it needs. Boaters are, by and large, a helpful lot and will be happy to pass on their experience.

In these modern times use the Internet - Join the news group uk.rec.waterways - just read the postings for a while and then you will be happy to ask for help when you need to.

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