Pontoon Boat & Deck Boat Forum

This boat is new to us last year. Its a 2003 JC Neptoon Dolphin 24ft. It has those U shaped toons that are flat on the top.

Anyhow back to the issue...... These toons are extreamley sensitive to temperature changes. In the morning the toons make a deep boom like you hit it with rubber mallet, and again in the evening. I know that aluminum swells and contracts with temperature but my last pontoon didnt do this. It was a 1998 but I forgot the brand.

Does anyone else have these type of toons? Is this normal?

Brad750 wrote:This boat is new to us last year. Its a 2003 JC Neptoon Dolphin 24ft. It has those U shaped toons that are flat on the top.

Anyhow back to the issue...... These toons are extreamley sensitive to temperature changes. In the morning the toons make a deep boom like you hit it with rubber mallet, and again in the evening. I know that aluminum swells and contracts with temperature but my last pontoon didnt do this. It was a 1998 but I forgot the brand.

Does anyone else have these type of toons? Is this normal?

For whatever reason I've seen more JC's do this than other boats. You can try taking the plugs out and letting the pressure equalize, but then in any severe change from whatever temperature you cap them again in, it may do it again. I heard of some type of valve that will relieve the pressure but not allow water in but I've never looked into it myself. Old neighbor had a JC that did it constantly and I think it was a late 70's/early 80's model and had done it for years with no ill effects to the toons themselves.

happens a lot on mine with Octagon shaped tubes, U shaped tube have a lot of flat surface area also and Flat = Oil canning with only the slightest of pressure changes. One fix is to SLIGHTLY pressurize the pontoons with a quick shot of air through a vent plug, and I mean slight, you just want it to have more pressure than the air outside it.

My first Manitou with the Original SHP pontoons oil canned also. They were replaced with the Barracuda nosecones and solved it. Completely under warranty. Can you see where the oil canning is coming from? I could actually watch mine move and pop! Easy to find. If its the nosecone, a welding shop could spot weld and re-inforcement bar to them to solve it.

Bryden24shp wrote:My first Manitou with the Original SHP pontoons oil canned also. They were replaced with the Barracuda nosecones and solved it. Completely under warranty. Can you see where the oil canning is coming from? I could actually watch mine move and pop! Easy to find. If its the nosecone, a welding shop could spot weld and re-inforcement bar to them to solve it.

Ive never watched it happen. Ill have to keep an eye on it now. Thanks for the tip.

The only time its really a problem is when its in the driveway and Im in bed, almost asleep then it does it and scares the dogs and they bark for an hour...

My Neptoon does it as well. In a cove with several other pontoons and only mine booms. I'm wondering if it is because of the volume of air in the tubes makes them more sensitive to temperature changes and causes them to oil can. All the others have foam in the logs; not full but most of the volume.

The tubes on the JC are bulkheaded in several spots but all the bulkheads have a small "v" cut at the bottom so that all chambers see the same pressure. I think that because of this, they can flex (expand/contract) when changing temperature quickly - as in a warm tube entering cold water or the reverse. I noticed this same effect when I test drove a JC in 2007. Jerry Rinker (my dealer) explained it at the time. I think that many other toons have completely isolated chambers - my Bennington does and has individual plugs at the top of each compartment.