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Winterising a jet ski: the cooling system and the battery
Short answer
The expensive winter damage does not happen on the outside of the machine.
It happens inside, where water left in the cooling circuit freezes,
expands and splits whatever surrounds it.
A personal watercraft cools its engine with the water it is running in, drawing it through passages in the engine and the exhaust and returning it overboard. After the last run of the season some of that water stays behind. When it freezes it expands, and the pressure it generates is more than a passage, a manifold or a casing can withstand. The crack goes unnoticed in October and announces itself in April at the first attempt to start, by which time the damage is done and it is rarely cheap.
The order of work is always the same. Flush with fresh water so that salt and deposits are cleared out, then drain or blow through the cooling circuit exactly as the manufacturer's handbook describes, and introduce antifreeze only where the handbook calls for it. Fuel matters too: a full tank with stabiliser keeps condensation and stale petrol out of the system. The battery should be disconnected, removed and stored somewhere frost free, with an occasional charge, because a battery left flat through the winter is seldom worth recovering.
None of this is a side issue when a claim is made. Frost damage to engines and water carrying parts is commonly excluded in boat wordings, or made conditional on ordinary care having been taken, and ordinary care is measured against what the manufacturer specifies. So make the work traceable. Note the date, keep the yard invoice, and if you do it yourself take a few photographs of the drained circuit and the battery on the bench. It costs nothing and it is the difference between an explicable loss and an unexplained one.
Worth remembering
Trapped water
splits passages, manifold and exhaust as it freezes
The handbook
sets the standard your care will be measured against
Flush, drain, battery out, and record the date with a couple of photographs.
Questions
What owners ask us about this
Is frost damage to a jet ski usually covered?
Frost damage to water carrying parts is commonly excluded, or conditional on the craft having been properly winterised. What applies to you is in your own wording under the exclusions.
Is storing it in a shed enough?
An unheated shed keeps off rain and snow, not frost. Water left in the cooling circuit freezes there just the same, so the circuit has to be drained whatever the machine is standing in.
Does the battery really have to come out?
Removing it and storing it frost free is the safe route, at the very least disconnect it and charge it occasionally. A battery left flat all winter is wear and tear, not an insured loss.
How do I show the work was done properly?
With the yard invoice, or if you did it yourself with a date and a few photographs of the drained circuit and the removed battery. That is enough to have something to point at later.
Related
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Whether it is “Winterising a jet ski: the cooling system and the battery” or another question: send us your residence and the flag your boat flies. You will get a straight answer in one email; including a no, if that is the answer.
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