Leaning Post Installation - 18SF

[duncansf75]

I have a '75 18 foot SF and I recently purchased a leaning post that I will need to install. It has two feet on either side that are spaced about 28" OC apart. The question is: when I drill the mounting holes, will I drill into the stringers and/or the foam in the stringers? Ideally, I would be inboard of the two stringers and could easily install some mounting brackets under the deck (the boat is in winter storage right now and can't get access to measure it). So I will take any suggestions for a sturdy install. - Thanks

[steel686]

Great to hear of yet another 1975 18SF. I have mine wide open right now and just crawled out of the bilge. The box stringers are 26.5" apart which corresponds more or less to the coffin box and also the first set of steps from the keel. My stringers (which I am in the process of rebuilding) are 3/4 - 1" below the liner sitting on plywood and Potter Putty. If you want to be safe, you might drill oversized through skin and 1/2" plywood core and fill with thickened epoxy. My lean post landed with one screw on the cover of the livewell which I have also removed. Happy to send pictures.

[duncansf75]

Thanks for the reply! Are the pictures looking forward or towards the stern? It looks like I can drill through the skin and the plywood (if the plywood is there) but NOT the stringer and the foam. So I will drill down about 1 to 1.5". If their is no plywood there then I might be able to use toggle screws for some added support and of course I would fill with west systems. Thoughts?

[uncleboo]

These pics are looking forward. If the deck coring is still good, you can screw right into the deck. It's approximately 1/4"of glass, 3/8"+ plywood coring and another skin of glass on the underside yielding about 3/4" of substrate. There may or may not be enough room to use toggle bolts, (I'm thinking not). I would 5200 it down as well, unless you're going to do other work later which would require removing it. If I hadn't raised my deck, I wouldn't have a problem screwing through the deck into the top of the stringer. Good luck!

[thealife]

Duncan,
If you are redoing the deck, figure out where the footprint of your leaning post and t-top is going to eventually be, If you want to be a real stickler, do it for the console as well,

cut some alu backing plates 3/16 ish thickness (i think you can get 6061 plate that's just over 3/16 thick) for everything you are mounting, make them a couple of inches larger than they need so you have a larger margin for error

Transfer all your measurements including the size of the backing plates to both the top and bottom sides of your new core sheets,

using a router, set to the thickness of the alu plate, route out the shape of your backing plates on the underside of your core sheets,

Sand or grind the shit out of your alu plates to expose fresh metal, remember, you have 4 hours of exposure with freshly sanded or ginded alu before it develops a corrosion layer and it loses its adhesion properties,

Epoxy them into the areas you previously routed out, do not encapsulate the alu plates into the core, if any moisture makes its way in through the bolt holes, you want it to have a way out,

once you install your new deck and glass it, you can come back with your measurements and drill/tap/bolt down everything in place, make sure you use tef gel (do not skip this step)

This setup is bullet proof,

[duncansf75]

@uncleboo - So you're not worried about the potential of water getting into the stringer? I know the 5200 will seal it up but over the years I'm sure some water will get in and rot the wood or even the foam. Should I throw some epoxy in the pilot hole before I put the screw in?

@thealife - no deck rebuild for me. the boat was rebiult in '09 so im going to leave her as is. The aluminum backing plates would have been the way to go tho!

[steel686]

alife - I have been wondering about the aluminum backing plate issue and bonding with epoxy. If you skinned over the core and backing plates but drilled and tapped through would that be enough to let moisture out. Is that inviting water and would it be best to router out, skin the recess, and then epoxy glue plates to new cloth wet on wet. Not worried about huge stresses on the lean post but I am also trying to figure a way to put a pylon back with three or four solid mounting points behind the lean post.

[uncleboo]

Originally Posted by duncansf75

@uncleboo - So you're not worried about the potential of water getting into the stringer? I know the 5200 will seal it up but over the years I'm sure some water will get in and rot the wood or even the foam. Should I throw some epoxy in the pilot hole before I put the screw in?

Not on top of the stringer. Mine had holes in the top from one end to the other. If you get that much water in the bilge, you got bigger problems. Anything you do to prevent water intrusion is good. If your deck coring is solid, it'll hold with the right size screws and sealant/adhesive. I had a Todd leaning post that mounted on a single pedestal, original from the factory. I used to sit on it while running, 200 lbs. and it never even creaked. was only screwed in on a bed of silicone into the original deck, of course.

[uncleboo]

If you haven't seen it, look at my 'deck replacement' thread for the pictures.

[duncansf75]

Thanks for the reply! Sounds easy enough to just deck mount it. Also, I enjoyed reading through the deck replacement thread. always a lot of good stuff to learn about on these threads