Leak in my pontoon


Active Member
I've got an older Outcast Fishcat 13 pontoon raft with a leak. Under pressure in the bag I can hear air hissing. I've sprayed soapy water around the valve and no sign or sound of air escaping there. So...
I pulled the bladder out and put it under pressure .. but no leak? I filled the bladder tight and sprayed all the seems with soapy water and visually inspected the whole bladder.

Any suggestions? My next trick is to clean it up real good and take it to the hot tub like I used dunk inner tubes in water buckets looking for leaks.
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Chromer J

Active Member
You may have already isolated the problem, but I'd repeat your soapy water test just to make sure it isn't a small hole in the bladder somewhere.
If you heard a small leak when the bladder was fully assembled in the pontoon, but not after you isolated the bladder, I suspect that the leak you heard might have just been a loose valve (a Halkey Roberts style?). After unthreading that type of valve to remove the bladder, then re-threading sufficiently tight, that leak you heard may have disappeared. I had a HR valve loosen on a bladderless inflatable once, and it only leaked a little when the material around it was stressed or leaned into a particular way.
I would double check the bladder with soapy water and plenty of bladder pressure. If again you find nothing, I'd assume that your valve was originally too loose and leaking a little. Good luck zeroing in on it.
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Active Member
Thanks for the replies. I called Outcast, awesome customer service -- they picked up on the first ring and were happy to help. They said 9/10 times it's the valve. I think that's the case here, but I still can't get the issue to reproduce. I have the bladder outside the bag, pumped up. I don't see any leaks in the valve or anywhere else, but 2 hours later the bladder is flat... This is what we call 'yeti' bug in software.

I'll probably buy and replace the valve, not a bad idea to have an extra in my kit. And on a side note, I came in from my shop grumbing and complaining yesterday. My wife asked, "what's wrong?". I replied, "I have a leaky bladder"... She's out shopping today and will probably bring back a box of Depends for me.


Active Member
So I finally got this figured out. I bought an Aire Hurricane pump, got the bladder up to it's max output 2.3 psi and the leak is in the valve; more specifically, where the valve threads into the the bladder.

Thing is I checked that, but at lower pressures. It clearly was leaking at low pressure cuz the bladder would drain out to almost nil every night. I don't know why the soapy water trick didn't work at lower pressures...


Certified Curmudgeon - GET OFF MY LAWN!
Sometimes the mixture of soap and water isn't conducive for making bubbles. Buy a $1 bottle of Soap Bubbles at a Dollar Store for the best way of checking. Unless you have young children/grandkids it will likely be a lifetime supply.


Active Member
Quick update. Turns out it wasn't just the valve. I had 3 or 4 small leaks that I finally found by pulling the bladder out, pumping it up fairly tight (2psi or so) and going over the whole thing in a 1x1 grid pattern.

This was a lot harder to fix than I thought it would be. Hope this is helpful to anyone in the same situation. Key take-aways for me are:
  • Start with the valves, Aire and Outcast have great videos for checking them for leaks. Test the valves w/o taking the bladder out of the bag -- this is your easiest out if it's the core issue.
  • The bladder can and will form leaks without something puncturing through the outer bag. Over time little 'stress holes' can open up near the rockers where the bladder has to fold over to fit in the bag.
  • Make a good soapy water mixture, use about 3 to 1 water to Joy; or buy bubble making stuff.
  • Get a good quick pump. Chances are you're going to do lots of inflate, deflate cycles.
  • If/when you have to pull the bladder out to inspect for leaks, get a good light, check small sections at a time, use a grid search pattern.
  • WRT above, It works well to leave the soapy film on until you're all done. You can use that as a way to sort out what you've searched and what you haven't searched
  • Finally, WRT leaks; all mine were at the ends where the bladder has to scrunch a bit to fit in the bag. Over time those creases create little 'stress fractures'
Now I just have to repair my trailer and I'm back on the water. Boats, holes in the water where money falls.... sigh

Old Man

A very Old Man
I had a Buck's Bag's that had a leak in it. I did what you did with the soapy bubbles. Couldn't find the leak. Blew it up harder and found out that the seam leaked. I sold the pontoon cheap and the person that bought it sent it in and the Buck's Bag's repaired it. Cheaper than patching it.

Brandon S

WFF Supporter
Had the same trouble with a leak in my watermaster I’ve been living with for a couple years now. After reading this thread I decided to replace the valves a couple days ago. Boat has been nice and tight for two days now woohoo!


Active Member
I think the most common problem we see, after explaining the fact that air pressure inside the raft/pontoon/float tube expands and contracts with temperature and altitude, is the valves...mostly just need re-tightening and occasionally replacing.

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