Believe it or not, we had a great white shark take a bite out of our 30 ft Nautica and I couldn't get my repair to hold air so I tried a similar sealant sold by West Marine with no success. We then tried Slime, a tire and inner tube sealant and so far so good. It seems to be holding just fine. We used the type sold for inner tube applications.
The other problem with our "little" RIB was spreading it around the inside of the tube so we put the stuff in, aired it up, and went out and used (abused) the heck out of it on a somewhat rough day. Sometimes you just have to go out and mess around.
For pictures of the job that generated the bite, go to www.latimes.com
, do a search for "blue whale" and look at the pictures of Sept 20 and 21, 2007. There are also pictures on our website.