Air Escaping from toon

[MrG]

This is not a problem, just a public service announcement. 


Im guessing the bungs at the top sides of my pontoons are letting air escape or at least that's what I suspect. I will describe what is happening and perhaps you can confirm my suspicion.


in the last few outings as soon as we launch our pontoon boat I can hear air escapeing from the passenger side pontoon. No bubbles or anything to be worried about just a quiet hissing of air. What I suspect is the boat is sitting in our drive way and the sun is warming up the pontoon.  We launch our boat in the lake and the difference between the lake temp and the pontoon temp is causeing air to either be sucked in or pushed out. As soon as the boat has been in the lake for a few (30-45 mins) things equalize and the sound is gone.  Just wanted to let people know if they hear somthing like this, do some investigation see if you come up with the same conclusion as me?

 

[Spoiledrotten]

It would be blowing air out as it had expanded in the sun, and was now cooling, and drawing in some. Thanks for the report. It would most likely cause some to worry if they heard it. I've not heard that on mine, yet. 

 

[MrG]

I'm sure a few turns on the Bungs or some teflon tape on the threads would fix this but that would require me to remove the side trim and that's not gonna happen anytime soon

 

[BigKahuna]

Didn't realize the pontoons could "equalize" air pressure like that......

 

[Mike31406]

What are "bungs.?  I have never heard this term.

 

[Jack M]

Only pic I could find 

 

[lakeliving]

I didn't realize the aluminum would expand and contract to that degree. What is the air temp compared to the water temp?


I heard some areas in Cali have been getting very hot lately. My wifes aunt had her sprinklers go off because it got so hot and made a big mess.

 

[mattb]

What are "bungs.?  I have never heard this term.

Think of the top of a 55 gallon drum, the bung is a threaded plug that screws into the ever popular "bung hole".

 

[Spoiledrotten]

Air temp here is 94* while the water temp at the surface, is 83*.

 

[PonTuna Salad]

I didn't realize the aluminum would expand and contract to that degree. What is the air temp compared to the water temp?


I heard some areas in Cali have been getting very hot lately. My wifes aunt had her sprinklers go off because it got so hot and made a big mess.

It wouldn't be the aluminum expanding, it would be the air in the toon. As it sets in the sun it is heated and the pressure increases. Sitting it in the water cools it and pressure will decrease. If there is a plug that is not right, air will move as pressure changes. 

 

[lakeliving]

It wouldn't be the aluminum expanding, it would be the air in the toon. As it sets in the sun it is heated and the pressure increases. Sitting it in the water cools it and pressure will decrease. If there is a plug that is not right, air will move as pressure changes. 

I misspoke. I agree with you. My mind went to that old trick with the empty aluminum pop can and temperature trick to make it crush itself.

 

[adkboater]

Not too sure if plug them tight, maybe open up the weep hole a little more to lesson the whistle. Plugging them tight may cause them to distort you log if it get to either extreme... to much vacuum or too much pressure. Just a thought.

 

[kaydano]

They are open and not sealed. I've sent a camera through the bungs on mine trying to find the section leaking water.  I couldn't get the camera through a couple due to the holes being inconsistent in size. Either they rough puncture a hole, then weld a threaded nipple over it, and screw on a plastic cap with a pin hole on it, or the slag from welding the nipple covers the hole slightly.   Could be whistling through the plastic cap, or could be a smaller than normal hole in the aluminum. There's no way on my boat to ream out the hole further without tearing the boat apart.


Your best bet would be to try to muffle it somehow. I would not seal it lest you get to see Andy's can trick on a grand scale.  Or, you could take the plastic cap off, drill out the hole in the cap, then put it back. I think the caps are to prevent any significant water from entering the toons, while also letting air equalize. I assume they install the bungs to pressure test for leaks, then cap them before delivery. My pontoon had a hole in it from the factory, but that's a different story.


Here is the endoscope (camera) I used, in case anyone is interested...


https://www.amazon.com/gp/aw/d/B06Y6CXW5N/ref=mp_s_a_1_4?ie=UTF8&qid=1500544326&sr=8-4&pi=AC_SX236_SY340_FMwebp_QL65&keywords=borescope&dpPl=1&dpID=51yzJRYpEXL&ref=plSrch