Need for winterising engine.

[NigelCraig]

I am moving towards owning (as opposed to borrowing) first boat big enough to have inboard engine. I've read about winterising procedure for boats that are taken out of the water for the winter. But what if you keep it in a marina all year (apart from maybe month or so lift out for maintenance? I don't usually expect sea water to freeze, but don't they have a closed loop around the cylinders which is fresh - i.e. just needs anti-freeze like a car?

 

[prv]

All modern engines, and many old ones, have a freshwater side, which as you say has coolant additive in it which should prevent freezing (though its main purpose is to inhibit corrosion). There are also a lot of older engines which just pump seawater around the block, with no freshwater side.

Down south, I wouldn't worry about a boat which is in the water. Up on blocks in the yard in a hard frost, even seawater in the engine might freeze. So best to either drain it (which may risk some corrosion on the damp metal) or replace with antifreeze.

Note that when people refer to winterising, most of what they're doing is really an annual service (changing oil and filters, checking internal anodes, etc) rather than specifically defending against cold.

Pete

 

[Vara]

Would agree with prv, last three years with my boat in the water the engine compartment didnt drop below 5°C, even in the coldest spells, so apart from changing oil, filters and checking anti freeze no special measures required.

I also try and run it regularly against the warps to allow it to warm through if I haven't been out.

 

[pvb]

My boat stays in the water all year round, and I don't winterise the engine.