Inflatable leak tracing

[Portland Billy]

My sunsport airdeck tender has a leak in the starboard sponson
I've changed the valve and sprayed all over with soapy water, but nothing shows.
Anyone got any other suggestions.
It takes about fifteen minutes to deflate. On

 

[[70521]]

More hot soapy water.

 

[Catalina36]

Get a bottle of latex leak sealer, pour it in and swill it round.

 

[jwilson]

More very soapy water, particularly in the internal joint between floor and tube that you can't see when fully inflated? Sharp grit can get trapped there and cause leaks. Sometimes not fully inflating actually makes leak tracing easier.