Pontoon Boat & Deck Boat Forum

Does underpinning installed by factory go over (on top cross members exposed ) the cross members right before wood deck goes on ?? Or does fasten from the bottom of cross members ?? Factory installed Seem like they would have to rotissire boat (flip boat on side or upside down) if at bottom of cross member

Under the framing. The idea is to present a smooth flat underside to the water being splashed up by the pontoons. Thin lightweight alum is easy to hang while on the trailer.

Underskinning makes the boats ride so much smoother, and it's so much quieter for the passengers. You just don't hear the water rushing between the toons as much.

It's a worthy addition to any boat.

Yes Yes I agree Just curious how Tracker going to install from Factory

Further question about underskinning. My Landau has a 2-3" cross member overlap outboard of the logs. I imagine most toons have this overlap. If I underskinned between the logs what about the outboard openings? I toon a lot in salt water and have concerns about corrosion above the skinning. In the 15 years I have had this Landau I have kept it corrosion free with fresh water washdown after each use. I suppose I could put expanding foam in the outboard openings.

Fair winds and following seas, Friz

53POWELL wrote:Yes Yes I agree Just curious how Tracker going to install from Factory

In the end I don't see why they would install it any differently than a dealer or an individual would in their driveway....

Friz wrote:Further question about underskinning. My Landau has a 2-3" cross member overlap outboard of the logs. I imagine most toons have this overlap. If I underskinned between the logs what about the outboard openings? I toon a lot in salt water and have concerns about corrosion above the skinning. In the 15 years I have had this Landau I have kept it corrosion free with fresh water washdown after each use. I suppose I could put expanding foam in the outboard openings.

Fair winds and following seas, Friz

Everyone tends to go at this a little differently but my plans are like many others in that I only intend to cover the flat area between the two pontoons. I do not intend on coming down the sides of the pontoon support braces at all. Leaving the sides open allows you the option of pulling wires, washing down the toons of salt in your case and should not trap water....

So, I was reading teecro's last and thought, "wait a minute that makes no sense". Than I realized I did not mention that my Landau has "U" shaped logs. Most pontoons have round logs. Teecro's reply makes sense for the majority of pontoons. If I underskin the area between the logs it is completely sealed with no access to the voids above the underskinning except by removing it. I suppose I could make the voids fairly watertight by using the expanding foam as I mentioned before. I guess my question should have been has anyone underskinned their pontoon with "U" shaped logs?

You will never "completely seal" the area between the deck and bottom of the cross members. This is not the intent of under skinning a pontoon either. The purpose is to create a smooth surface for the water that flows between the tubes while running wide open. Some people do put small strips down the side cross members, however the splash in that area is nowhere near like the center. Using foam or other techniques not found in the normal manufacturing of pontoons will usually give negative results. Instead of allowing any trapped water to flow out, you may find you have trapped it in and the end result will be a shortened life for your deck, among other issues.

ToonGuy wrote:You will never "completely seal" the area between the deck and bottom of the cross members. This is not the intent of under skinning a pontoon either. The purpose is to create a smooth surface for the water that flows between the tubes while running wide open. Some people do put small strips down the side cross members, however the splash in that area is nowhere near like the center. Using foam or other techniques not found in the normal manufacturing of pontoons will usually give negative results. Instead of allowing any trapped water to flow out, you may find you have trapped it in and the end result will be a shortened life for your deck, among other issues.

Yup that has been my impression thus far... All I want to do is stop the wake/spray action from hammering away at the cross-members which besides being annoying has got to be hurting top speed plus even on my year old boat the action manages to seep through a deck seem and wet my foot near the helm.

Here is a great video of what is going on under your 2-log toon at various speeds:

https://www.youtube.com/watch?v=a2WYtzQ37YM



You can also see by the spray pattern why under skin on the outsides of the toons would not be mandatory. I might add, if this were my toon I would do the vertical area of the pontoon risers as well.