Backing riveted hardware on an SOT hull (Sabalo)

[ayjay]

I've got a score of padeyes to start planning the placement of on my sabalo hull. I've got to decide how to properly back them for riveting, as a single later of 4mm okume really isn't adequate for load bearing hardware. I won't be able to reach some of them again once the seatwell and tankwell are in place, so riveting is the only solution and I want to do it right the first time.

I can back the 4mm okume with another layer of 4mm okume, a backing block an inch or so wider than the rivet points of the hardware all around. Then drill out the holes 3/8 inch, fill with epoxy putty, and re-drill 3/16. A 1/2 or 5/8 aluminum rivet is just long enough to rivet through hardware and 2 layers of 4mm okume. I am still a little worried about pull through. I'll probably mix some milled fiber into the fill for the hardware holes to make it a little extra solid.

I can also back the hardware with an aluminum backing block of 1/8 or 1/16 aluminum epoxied to the inside of the hull. I feel a little more confident that the rivet won't wallow this out or pull through it, but it was mentioned that aluminum introduces differential expansion issues when heated and cooled relative to the wood/glass hull, and it might pop loose from the epoxy eventually, and also that it might want to sweat and accumulate moisture in the hull. None of my hull is going to be a totally inaccessible completely sealed space, so that shouldn't be a problem.

I could also back with 2-3 layers of glass and resin, but I don't see much of an advantage over wood if I'm going to drill it out and refill and drill it again.

Advice?

[ayjay]

Also, link to my build, if anyone is interested:

http://www.texaskayakfisherman.com/foru ... 1&t=120281

[OnkaBob]

Nice build Ayjay - going to be very elegant when finished.

Have you considered stainless steel thread inserts and SS screws for mounting fittings? Have a look at this post in "Tips and tricks"

viewtopic.php?f=7&t=3018

The advantage is that you can remove the bolt ons easily when repainting or replacing parts. You also mention that you won't be able reach the backing points after finishing and this could be a problem if a rivet does pull. I'm not certain but I think a threaded insert replacement could be done to a high standard provided there is a good piece of hardwood backing.

Good luck with the rest of the build.

[craiggamesh]

On my Sabalo, I backed with a second layer of 4mm okoume where hardware was to be mounted, drilled an over-sized (slightly) hole, filled with epoxy/wood-flour, drilled a small pilot hole, and attached everything with stainless steel screws. That way I could easily remove things.

[jem]

On my Sabalo, I backed with a second layer of 4mm okoume where hardware was to be mounted, drilled an over-sized (slightly) hole, filled with epoxy/wood-flour, drilled a small pilot whole, and attached everything with stainless steel screws. That way I could easily remove things.

that's the ideal method. Large fender washers could work as well but you have to glue them to the hull.

[craiggamesh]

Have you considered stainless steel thread inserts and SS screws for mounting fittings? Have a look at this post in "Tips and tricks"

I did this for my foot braces. It worked great.

[dangermouse01]

On my WF, I attached a wooden block every where I wanted to put a pad-eye, footman loop, what ever you want to call 'em. I attached them to the tankwell or cockpit so they would be flush with the inside surface of the deck piece that went over them. I also drilled a small hole from the tankwell or cockpit side at the center of the block and then pressed in a small brass brad so when the decks where on I knew where they were located and where the center was. The brads all got over coated with glass or epoxy.
You see the blocks on the tank well, and just make out the brads here:

When I put the decks on, I put a good slather of epoxy on the top surface of the block to fill any gap. When I was fitting it out. I put blue tape on the deck surface (longer than the footman loop. Transferred the center point up to the deck. I made a little drill template of the footman loop and the drilled pilot holes and then ran wood screw (sized to fit the footman loop) into the hole to form the threads. Mixed up a very small amount of epoxy (no filler) and would let it drip into a hole until it was filled, then do the same to the next hole, this gave the wood in the first hole time to absorb some of the epoxy. After the second hole was filled, I went back to the first and using a spare screw (same size as used for thread forming) I ran that down into the hole and back out, which forced out all the excess epoxy (wipe it up with a paper towel), blue tape keeps the epoxy off the deck if you are doing this after you varnish. Then fill the next hole with epoxy and run the screw in the second hole and keep going, filling one hole ahead of the one you are running the screw into. Threaded surface is now coated with epoxy.
Then after the epoxy has cured and time to attach the footman loops for real, I coated the treads of the screws with marine silicon and ran them in tight.

Hope it all makes sense.

DM

[Bemm 52]

On my Sabalo I glued a plywood doubler under fittings I wanted to mount directly to the hull.
mines the one in your build thread....i'm flattered
I would strongly recomend you try to build in some handles in the gunnels they are very handy for tying off stuff etc......sabalos triangular hull cockpit join makes this very doable ..........it was a bit more difficult in my wadefish build.........good luck
Cheers paul

[ayjay]

Bemm, your build is what made me decide to go Sabalo over wadefish. Nice work!

[craiggamesh]

Bemm, your build is what made me decide to go Sabalo over wadefish. Nice work!

Me Too!