Took the boat out in the gulf of Mexico
but beautiful day) and the heater did eventually blow warm air. Not quite as much as I would have hoped but it did work. Since I will probably never fully enclose the deck
with the shrunken 10 year old plastics, I could easily change the deck
vent to one that I can close. The dash vent is already closable, that would force all air to the cabin
. Could even reroute one of the other ducts to the cabin
. So success overall, but since I'm in Houston
, I probably won't spend much more time or effort on improving the heater. Thanks for all the advice.