Need a Bilge Heater

[sbbamafan]

I need to add a bilge heater in my (new to me) Doral 270 SC for the winter - keeping it in the water. Is the Caframo 9510 big enough or do I need to go bigger? That is a 400W heater. The surface temp of the water stays between 46 -50 F in the winter at Lake Lanier. My boat will be enclosed by the camper canvas and that seems to create quite a bit of warmth (solar) within it. Our winters are usually pretty mild with a handful of cold days thrown in. There can be a string of 3 days of cold weather in the low teens but that is about as bad as it gets. I just need to make sure I am protected.
Also - do you plug the blower vents to prevent air from blowing through?
Thanks in Advance!!

 

[alldodge]

Opinion:
I have not kept a boat in the water all year but have done it for a month or so with my 23 footer. I used a 60 watt light bulb placed in the blige and did not close the vents. Opened the engine hatch and it was toasty warm inside

The water staying 40-50*F will not need a lot to keeps your above freezing. I wouldn't completely close the vents because of the battery out gassing.

The heater you found should have more then enough power to keep things from freezing

 

[Chris1956]

I attached a 40W heating pad to the oil pan. The bay water never froze, but the air was below freezing quite a bit. Of course, I wanted the engine to stay warm, for those cold starts during Striper season.