As long as you have access to a tank storage area on the boat that can be open to airflow at the bottom, Propane is just fine for a boat. It should be as it's already been installed on 10's of thousands of boats.
I've seen some misleading information in this thread. Propane contains double the BTU per volume than cng.
As far as conversion of the current stove. The proper way is to rejet the burners. However there is another way to address this and that's at the regulator on the tank. Adjustable regulators can he had for around $30.00. Put it on your new propane tanks and dial the gas volume down to less than 1/2 lb (that's not a typo), and you'll be good to go.
I became familiar with pressure levels by accident. My regulator and hose was shot. I went to Ace Hardware for a replacement. The clerk sold me a new hose and regulator. When I connected the stove and lit it, I had flames coming out of the stove 3 feet high.
The bottom line was the clerk, not understanding propane regulators, sold me a 20 lb/ sq inch regulator, when my 28,000 BTU stove required a 1/2 lb regulator. Ace exchanged it no charge. Thankfully I learned the lesson with just singed eyebrows.
The stove conversion can work with the proper regulator.