Re: how do i make it warm
Smallboatlover, if you are working inside it shouldn't be so bad. I worked on my boat all throughout the winter, often without any heat source, and so long as it is a sunny day and not too cold the cabin has a greenhouse effect and is bearable. I recall sometimes taking layers off as the day moved on and things got warmer.
Otherwise, I think you can scrounge together the $40 to get that catalytic heater, and so long as the companionway hatch remains open there seems to be little to fear from it.