connecting deck to hull

[Sgray]

Hello everyone im building a 21' bass boat which planning on hopefull starting soon but i have a question about after i get the hull and deck built what would be the best way to connect the deck and the hull. I have kind of read up on it and heard that i should use 3M 5200 sealent using a 1/8 bead and pop rivet the hull & Deck every 3" Also to fiberglass the whole Hull &deck around if anyone has any ideas please leave a post. Thank You

[ErikG]

But I would never rivet the deck hull bond. Then you simply have no idea how good it'll seal up.

I'd use a proper FRP seal. Watertight AND strong!

Erik

[Polarity]

http://www.sika.co.uk/industry/hull2deck.htm

and try
hull deck bond
in google for a list of how all the major manufacturers do it ( all different and all the best!)

Cheers

Paul

[mmd]

I agree with the sealant. There are also some pretty good non-flexible adhesives out there, such as the high-build stuff by Plexus. Access to the seam on the inside is always a pain, but if access is good, I prefer stainless bolts with large backing plates or washers. If access is difficult, rivets are the next best thing, but use as big as you can, use big washers, and space the rivets close together. Bass boats boats are usually driven pretty fast, so this seam is gonna take a lot of abuse.

I like working with 5200 - it's easy to deal with and I have yet to see a 5200 seal go bad, but the oldest 5200 seal I've done is only 6 years old. I've also worked with silka and don't ahve a preference of sika over 5200. I don't have any experience with plexus. Is it a stronger bond than 5200 or sika?

The strongest would be a solid fiberglass bond if you have good access to the inside, but that's probably not the case in a bass boat.

[ISLNDMRN]

I'd go with the a bead of 5200 and bolts w/ fender washers and lock nuts. Every 6 inches or so will be fine. Then attach the rubrail the same way. This isn't going to come apart no matter what you do to it! Thats the way I do and have never had a problem . www.Island-Marine-Products.com
VINNIE

[gonzo]

What is the design of the hull to deck joint. Is it a exterior flange, an interior flange or does it overlap? There are different solutions for each. Also, if there is access to all the seam from the inside, laminating it is a good attachment.

[Sgray]

the hull and deck design overlaps

[gonzo]

One option is to use 5200 or other adhesive sealer and screw the deck to the hull. To have a good backing for the screws, you can put a pressure treated wood strip on the inside of the shear.
Pressure treated plywood is better because it doesn't split as much as solid wood. The advantage of screws or bolts over rivets is that their torque can be controlled. Pop-rivets break at a preset point. Hull and decks never fit perfectly, so the bolts or screws let you adjust one to the other.

My old boat's hull to deck joint was done with some type of sealant and screws every 8 inches. When it came time to replace the rubrail due to some dings over the years and a dull finish, it was a real pain removing the screws. In addition to a few I stripped, about two dozen twisted off rather than coming out so they had to be drilled out. I would much prefer to see bolts used if the interior is accessible.

I'm not sure why the screws were so difficult to remove, whether it was due to the pressures and slight flexing of the hull to deck joint over the years of use fatiguing them, or if they were simply not the strength which should have been used...

[Polarity]

"whether it was due to the pressures and slight flexing of the hull to deck joint over the years of use fatiguing them, or if they were simply not the strength which should have been used..."

Either that or it was put together with 5200 - cement in a tube!

I worked on a large production boat that put the windows in with the stuff!