Big boom when air temperature changes

[TXMurd]

I have been on the water almost my entire life, but a first time pontoon owner.

My boat is sitting in my drive in TX and my wife and I hear a big boom in the middle of the night and when the sun is highest. I have ask a number of people that own pontoons, a local service company, and Bennington. I have yet to have any9ne know what I am talking about. I have seen some comments online, but I don’t want to do any mods until I talk to someone that knows what I am talking about. I was told to loose the plugs and every section had some pressure, some high, some low, but everyone had some.

The current plugs are nylon and I don’t see any type of relief system.

I have two questions;
Anyone experienced a loud banging noise like a mallet hitting the pontoon when out of the water?
Are the pontoons normally supposed to have a level of air pressure all the time?

Thanks in advance to any help.

Semper Fi

 

[PartyBarge]

Ha! First I've heard of this for a pontoon. The action is commonly referred to a "beer canning". For airplanes it can happen as the pressurization deferential changes with altitude and can indicate some portion of the of the skin/frame has an attachment issue. That said, it can also be caused by expansion/contraction of sheet metal with temperature changes...again due to some section of skin that needs better frame support.

Guess the first problem is to determine where the beer canning is happening...or, you might just park the pontoon differently to decrease the temperature differential. I'd expect the pontoons would be vented to avoid some of these problems, but maybe not.... I know the floats for our dock are vented to avoid blowouts. However, be aware the what you have may be related to metal expansion/contraction (not pressure change) as the pontoons/skin shift relative to the rest of the boat. As more speculation, the source of the noise may not be visible as it may be something going on with the baffles in the pontoons and then the pontoons acting as a resonance chamber. Happy hunting and good luck!

As an after thought, ancient aliens would be looking for some sort of extraterrestrial possession, just sayin'.

 

[TXMurd]

Thank you for the response.

No one seems to have hear of this but I have number of people that have heard it. I read one post on another forum that talked about it, but provided no solutions. The post described it perfectl, like being hit with a mallet.

I have looked over the pontoons a number of times and cannot see of feel any indication that the metal has or is moving.

It is just so random that it is hard to zero in on it.

Are the pontoons supposed to have some air pressure or be equal to the outside pressure?

I also read where the pressure caps have a relief valve or port, mine are solid.

I don’t think is hurting anything, but is annoying to myself and my neighbor.

 

[Michiman]

Once upon a time, I had a furnace duct that would do the same thing. As it heated up, it would bang/boom, which was annoying, particularly during the night. A bit of additional bracing did the trick.

It’s my understanding that our toons are indeed pressurized, although quite low. I might suggest attempting to get a video of it (Ring camera??) and then approaching your dealer with a warranty issue.

Good luck!

 

[DVW]

Ha! First I've heard of this for a pontoon. The action is commonly referred to a "beer canning". For airplanes it can happen as the pressurization deferential changes with altitude and can indicate some portion of the of the skin/frame has an attachment issue. That said, it can also be caused by expansion/contraction of sheet metal with temperature changes...again due to some section of skin that needs better frame support.
Guess the first problem is to determine where the beer canning is happening...or, you might just park the pontoon differently to decrease the temperature differential. I'd expect the pontoons would be vented to avoid some of these problems, but maybe not.... I know the floats for our dock are vented to avoid blowouts. However, be aware the what you have may be related to metal expansion/contraction (not pressure change) as the pontoons/skin shift relative to the rest of the boat. As more speculation, the source of the noise may not be visible as it may be something going on with the baffles in the pontoons and then the pontoons acting as a resonance chamber. Happy hunting and good luck!
As an after thought, ancient aliens would be looking for some sort of extraterrestrial possession, just sayin'.

Good advice above. My 2021 Bennington tubes have chambers that are vented with drilled plastic plugs. The tubes are not pressurized. Differences in thermal expansion from dissimilar materials or even the same material exposed to a different heat source can create symptoms as you have discribed. Most pontoon boats do not go boom because the internal loads created by this expansion is typically lower than the strength of the bolted connections. One possibility is the clamp load on one or more of your big bolts is sub par. This could allow a high force small displacement movement that could create a big boom. While not a solution rotating the boat or removing the cover could help you trouble shoot. Good luck.

 

[Bill N]

DVW is correct, tubes are indeed vented via small hole in plastic plugs.
I am guessing that debris may have plugged one of these and the temperature differential is causing expansion/contraction of one of the chambers.
I could be wrong as I often am.