Last winterisation worry

[pcatterall]

Boat is being left afloat in central France over winter. It gets very cold,minus 20 and 2 boats sank in the marina last season. ( seacocks we think)
I have done everything by the book and am as confident as can be that I have missed nothing.
A poentially weak area seems to be in the water pipe to the propellor seal, this is a plastic pipe, removing it lets sea water water run in. I have flushed through the sea water side with antifreeze and (of course) closed the sea cock. I could not be sure that the antifreeze had filled the plastic pipe to the shaft seal. Following the makers advice I have disconnected the pipe and replaced it with a 5cm length of pipe sealed with a bolt and jubilee clips.
I am suprised that there is not a valve at the fitting acting in just the way that a seacock would.
Anyone else with a similar problem? and how best to resolve it

 

[lw395]

Isn't the shaft seal itself a worry?
The small bore pipe is possibly more likely to survive freezing than something bigger.
But presumably the prop shaft will conduct heat up from the water to some extent, although as metals go, Stainless is a poor conductor of heat.

 

[greeny]

Just a thought - if it's freezing and subsequent expansion that's going to cause that pipe to rupture. What about fitting a length of pipe instead and fixing the open end up in air above the water line. Then the ice has room to expand and not cause the damage.
You are correct about the temperatures down there, I spent a week on the boat there few years ago and woke up in the morning with ice on the bulkheads from my condensation.
Greeny