Pontoon Boat & Deck Boat Forum

I've seen all kinds of suggestions for underskinning materials.

There's less than 24" between my tubes.

I'm thinking of underskinning with a single continuous piece of "Valley Flashing".

24" by 50 feet long by 0.019" thick is only $80. That'll do my entire underside, with material left over.

I'm calling this "cheap enough for an experiment". I'm betting that it will work very well for underskinning, with just a few handfuls of rivets. We should know in a few weeks!

46 views, and no comments?

I think I would use self tapping stainless screws instead of rivets. That way if it doesn't work you won't have to drill out all the rivets.

Even though I used rivets, I like the screw idea also, just in case it does not work out. if it does, you can always replace with rivets.

I used self tapping screws (with the rubber seating) on our last boat. After 3 years, only one came out. I just ran in another.

I would probably just buy the sheeting and do it right the first time. I cannot imagine it being too expensive.

I thought underskinning was somewhat of a no-no. I'd be afraid of moisture taking too long to dry when it's all trapped between the underskinning and bottom of the plywood.

What's the main reason for installing this?

STEVEBRENDA wrote:I used self tapping screws (with the rubber seating) on our last boat. After 3 years, only one came out. I just ran in another.

I would probably just buy the sheeting and do it right the first time. I cannot imagine it being too expensive.

When you say rubber seating, do you mean rubber washers? I am not far from skinning my new project. I will be using .040 5025 aluminum with 3/4 Stainless self tappers. Gonna try to bend it myself (over a fencepost) into the graceful curves that South Bay uses.

DonCabo wrote:I thought underskinning was somewhat of a no-no. I'd be afraid of moisture taking too long to dry when it's all trapped between the underskinning and bottom of the plywood.

What's the main reason for installing this?

It keeps the water (waves) from hitting the crossmembers. That way you get a nice smooth ride.

BobG wrote:I've seen all kinds of suggestions for underskinning materials.

There's less than 24" between my tubes.

I'm thinking of underskinning with a single continuous piece of "Valley Flashing".

24" by 50 feet long by 0.019" thick is only $80. That'll do my entire underside, with material left over.

I'm calling this "cheap enough for an experiment". I'm betting that it will work very well for underskinning, with just a few handfuls of rivets. We should know in a few weeks!

46 views, and no comments?

I think .019 might be a little thin and as it flexes will elongate the screw holes. I would use .040.

I just did mine with .032" aluminum and stainless screws.



The panels were 48" x 10' so I cut them in half and worked with 48" x 5' sections. The crossmembers are 24" on center and I think anything thinner would sag unless some additional bracing was installed between crossmembers.

No possibility of moisture getting trapped above the skin, from the outside of the hull you can see all the way through to the other side with 3" of airspace between the skin and the deck.

I just used a truck bed liner to do the back half of mine. So far after a few days of beating its holding up perfectly. Need to find another 20$ bedliner or two to finish the job.

Hey BOB G!!! How did the underskinning workout? I too am currently looking for cheaper types of material to underskin my tri toon with.

cuttymcgavin wrote:Hey BOB G!!! How did the underskinning workout? I too am currently looking for cheaper types of material to underskin my tri toon with.

Man, that stuff looks GREAT...in my living room...

Too busy BOATING, to install it yet, but when I DO, I think I may put some stainless washers under the rivets, to mitigate the possibility of elongation of the holes.