You should post this question to rec.boats.cruising .

Alcohol
Pro-
It's safer- alcohol will not explode and fires can be put out with water.
Some alcohol stoves are simple and compact.
Con-
Most alcohol stoves don't heat very hot. A few do.
Fuel is expensive.
It takes a couple of minutes to start a pressurized alcohol stove.
It's hard to find a big-oven alcohol stove.

Propane-
Pro-
Fuel is widely available and inexpensive
Most stoves heat vigorously
Stoves available in small and large sizes, including ovens and broilers
Con-
Propane is heavier than air and , at the right concentration, can explode. Not
a good thing.
Making a propane stove system safe on a boat is complicated. The design of tank
enclosures, piping, shutoff systems and bilge sniffers is nontrivial and can
add significant cost and complication.

Compressed Natural Gas (CNG)
My knowledge of this is old. Dunno if these are still viable.
pro-
gas is lighter than air, so much safer than propane
The other plusses of propane
con-
tanks and equipment were expensive and distribution never got widespread.

Butane
I'll let others fill this in.

For some people, kerosene or diesel could be a good solution, too.



Grainger Morris wrote:

What are the pros and cons of these two types of stoves for a small boat
(20')?
Thanks, Grainger