You are not correct. You have far more of a chance of blowing yourself up with your propane
stove than you do with a gas outboard. The outboard and often the
fuel tanks are exposed to the atmosphere or located in ventilated lockers not connected to the interior of the boat. The propane
lines and the
stove are in the interior of the boat where even turning on a light can ignite the fumes. Nearly every sailboat explosion that I have heard of in my life has been a diesel engine equipped boat with a propane
stove.
Jeff