chadxp1

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I am building a sea plane out of balsa and wanted to know how to waterproof the fuselage. I thought I have read that the some have gotten by with just the covering (monokote). Anybody have any ideas?

Thanks
Chad

JohnBuckner

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Hi Chad I have done quite a few float planes most twin float and a few single center float and while some have fiberglass over wood just because I have obtained float from someone who has glassed them.

Most all the others I have used monocoat over the sheeted wood floats with no problems at all.


John

flyinwalenda

My Feedback: (5)

I have a few seaplanes and float planes. On some it is just coating over the balsa. Others I have used water-based poly and sealed the balsa before the coating and others I have glassed the bottoms directly over the coating using lightweight cloth and water-based poly.
The WB poly is not as tough as two-part glass but it has held up fine so far.

On the seaplanes I also seal the inside as far as I can reach with WB poly.

chadxp1

My Feedback: (2)

Thanks John and Brian. Would spraying some of that expandable foam in the fuselage do any good? Im talking about the kind you get for home repair. I understand the idea is to keep the water from getting in but if it did I wonder if this stuff would keep the plane at least floating if something went wrong. Maybe a bad idea. I don't know.
Chad

JohnBuckner

My Feedback: (1)

Chad using that expandable foam stuff is really a bad idea you could very easily blow out the structure and its really not needed. It is extremely rare that the airplane would go under completely. About the only time I,ve seen that is something like a vertical arrival back on the water and the airplane breaks up so completely that extra floation is of no help.

It would help a lot if you explained what airplane you are going to build or at least the type.. Is it going to be a conventional twin float ship or is it going to be flying boat setup? If you new to floats I would highly recommend that you stick with the conventional twin float setup and I feel the very best first setup is any of the Sig Cadet variations.

So whatcha building?

John

flyinwalenda

My Feedback: (5)

Ditto on what John said about that foam. Besides blowing out the fuse and adding weight it will hold in any moisture and the wood will rot from the inside out. Most seaplanes will get water inside or at least built-up moisture and that's what rots them out. The few seaplanes I have seen crash (for whatever reason) were black with mold in the tail section where water got in and never dried out.

AMA 74894

My Feedback: (1)

I've always had great luck by simply spraying painting the entire interior with epoxy based paint.

also, COMPLETELY agree, don't use the expanding foam!

Hydro Junkie

If you're really worried about water soaking your structure, either coat it with epoxy and, prior to the epoxy completely setting up, scrape off the excess or coat the structure with sanding sealer. Both will prevent water from getting into the wood and will add minimal weight. I use the epoxy coating on my hydroplanes and have never had an issue with rotting wood since going to that method of waterproofing

chadxp1

My Feedback: (2)

John, I am building my own version of the SeaWind, so yes it is a flying boat! (I hope) haha. Unfortunately I already started the design so going to a two float system is to late. I really liked the way that plane looks. I'm really just playing around with some left over parts. I think I will add some pontoons to the ends of the wings. Do you think that will help stability in the water? I will try to get some pictures posted soon.

Thanks
Chad

Gray Beard

My Feedback: (-1)

During the build of my one and only float plane I painted on Deft sanding sealer throughout the inside of the plane. I'm sure anything like Poly-U would work just as well but I use the deft for glassing too so I had a lot on hand. After trying to sink my plane I discovered how well the deft worked, the wood stayed dry and I have no warps. I did have a tank rupture and discovered the Deft isn't fuel proof though.
I once used the expanding foam in a plane for some reason? Can't remember why but I do know it will split balsa when it expands. OK, now I remember why.
Just an FYI, John is one of my go to guys for anything in the way of float planes. He is a big help.

HighPlains

My Feedback: (1)

Just use wood that comes from waterlogs.