Lasko 5150
I use this Lasko model 5150 ceramic at home, and am happy with its output. I am going to try one on my boat. Being a tower model, it is less stable than the low flat, wire coil model that I have on the boat now, but the Lasko has a shutoff switch in the base in case of tip over. Also, being a tower design it will take up a little less floor space. I got it at Lowes for forty some dollars.The problem I think we have, is that most electric portable heaters run only to 1500 watts maximum, which can only produce so much heat. With the standard 30 amp dock power, I can't even run two of them, or one plus my water heater. I might be able to run one at full power, and a second one at the half power setting. That would also help to spread the heat out.I really don't want to get into fuel heaters for various reasons, but that would be the logical answer for more heat.