Can't find leak on 8' Mercury Inflatable

[CapeCodBubs]

Hi, I have an 8' inflatable that goes limp in one of the sections over night (~ 8 hours or so). I've tried spraying the entire outside with diluted dish washing soap, kids bubbles, & filled the entire inside with soapy water and yet no air bubbles anywhere, yet in ~ 8 hours it will lose some air.... This is driving me crazy.... I tried searching for maybe a chemical or dye I could put inside to make the leak visible, but doesn't appear to be any products like this...
Any ideas guys and/or gal sailors?
Best Regards,
Bubs

 

[rgranger]

Could you partially fill it and then jump into a pool with it. Submerge a section at a time and squeeze... looking for bubbles.

 

[dmax]

Get a young person (with really good hearing) to listen for a leak - that's how I found one in mine, it was right in plain sight but very hard to see (mouse bite). Couldn't find it with soapy water.

 

[Rich Stidger]

Concentrate on the valve- I think valves are the most likely leak source. The second most likely is any area that is worn thin from beaching or from the painter rubbing on the tubes.
Use the pre-mixed kids bubble solution- It has always worked better for me that anything I have made up myself.
Be patient with the bubble solution. It may take a minute for a very tiny bubble to appear. If you see ANY bubbles, no matter how small, that is a suspect spot. Then concentrate on that spot and determine guilt or innocence.

 

[shemandr]

I was surprised to learn of the relative low pressure in the tubes. Maybe only a few lbs/inch. So maybe juicing up the pressure with a vacuum (Reversed) would make the soapy water work better.

 

[Rich Stidger]

I was surprised to learn of the relative low pressure in the tubes. Maybe only a few lbs/inch. So maybe juicing up the pressure with a vacuum (Reversed) would make the soapy water work better.

I normally use my shop vac in "blow mode" to inflate my Achilles. It is a LOT less work and way faster. But my vac won't get to the full tube pressure so I have to "top-off" my tubes with my hand pump. Maybe if I had a shop vac that was endorsed by the Tool Time guys, the vac would do it all! But I don't think that over-pressurizing the tubes within a safe margin would help very much. My tubes have a target pressure of 3.8 psi, and I would be very hesitant to go much higher in fear of stressing the seams. I have no idea what the seams will withstand. But the inflatable floor's target pressure is 8.6 psi, and I *think* the seams are similar. YMMV.

 

[rgranger]

My tubes have a target pressure of 3.8 psi, and I would be very hesitant to go much higher in fear of stressing the seams. I have no idea what the seams will withstand. But the inflatable floor's target pressure is 8.6 psi, and I *think* the seams are similar. YMMV.

One atmosphere of pressure is 14.7-ish psi.
So your 3.8 psi is really (14.7+3.8) 18.5 pushing on 14.7…that is a %delta-PG of (3.8/14.7)*100% = 26%. That’s probably enough to make bubbles

 

[MikeHoncho]

Use a bottle of the sealant you put inside of it and roll it around. It works really well. Same concept as Fix-A-Flat but different product. I kept my precious dink going for 3 additional season with it. It will foul the check valves though so you have to clean them after.

 

[ggrizzard]

On the valve check.

If the fabric is worn so thin that air is escaping, you need a new dinghy!

 

[RoyS]

Carefully check the cones at the stern. Mine developed a tiny leak (much slower than yours) where the fabric is glued to the tube end cones. Find with soap bubbles.

 

[jviss]

One atmosphere of pressure is 14.7-ish psi.
So your 3.8 psi is really (14.7+3.8) 18.5 pushing on 14.7…that is a %delta-PG of (3.8/14.7)*100% = 26%. That’s probably enough to make bubbles

That's among the whackiest analyses I've ever read here.

 

[jviss]

To the OP:
What kind of material is it, PVC or CSM/Hypalon?
How old is it?