I understand the bubbler is bringing warmer water to surface but it's not also keeping water moving, preventing from freezing?
It's not a question of $$$, I would like to keep the boat close to my house, keep her longer in the water (yard are lifting boat early and putting them back late in spring) and tired to have to move/remove mast with boom truck (there is a power line to acces the yard)
+ there is a rapid waters (don't know how to call them in english) so I think water is freezing less deeply with below water current where I project to leave to boat.
Shacleton is old story, I saw a 41 from my eyes in deep freeze last winter: no damage, nothing...some aluminium ans steel boat can stay in freezing water, why not a heavily and thick Morgan 41 hull? I think that if something happen, it will lift the boat with the flat shape of the hull, the morgan I saw did not seem to have moved.