I've tried several 12 volt vacs over 40 yrs of boating and conclude that
they just can't match a good small AC
--
My opinion and experience. FWIW

Steve
s/v Good Intentions shop vac.

For this boat I went on a search for the best since I currently have some
area rugs that are large and difficult to remove for cleaning..

What I did was pick of various models of the one gallon wet/dry shop vacs at
different stores (Home Depot, Lowes, Sears, etc). I only got them where I
knew I wouldn't have a problem returning them if they didn't pass my tests.

I was after suction power, so I got a 5ft section of 1 1/4" clear plastic
hose. I fitted it to each shop vac and suspended it vertically over a bucket
of water.

Turned on the vacuum and measured the water column.

I don't have the test results any more, but the Shop Pro from Lowes won out
with a lift of nearly 4 ft of water.

Now this may seem anal, but my bilges are very deep, about 30 inches in the
deepest sump. Plus my fuel and water tanks are about 20 inches deep.

I figure, over time the shop vac will loose some efficiency, but the winner
of this test stands a better chance of doing the job the longest.

BTW. Didn't have any problem returning the other contendors.