Mounting Ladder to sandwich transom

Inselaffe

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Hi,

I removed the ladder from the transom last season when I realised it was just held in with self tappers into the outer skin.

Now I want to through bolt it. There are 4 mounting pads with three holes in each.

The Etap is double skin with foam in between, so the transom is a kind of sandwich, and the core must be about 6 or 7cm thick here.

I want to put in inserts to stop core crushing, but what should I use and any practicle tips?

I thought about scooping out the core and filling with a putty etc but then I'd have to scoop a lot of core out and I'm worried about exotherm.

I thought about wood, but don't like the idea of sealing wood in in case (when?) it gets wet.

Metal tubes, but how do I get a good bond to it to seal properly?

I worry too much!

many thanks

Leigh

PS i have gathered that whether or not a transom hung ladder is the best solution is a whole other question, and I'd rather not go into that here /forums/images/graemlins/smile.gif
 

Strathglass

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Can you get at both faces of the transom?

If you can this is what to to.

On the outside face of the transom you will have the original holes where the self tappers were. Drill them out to the diameter of the new bolts and continue drilling right through the transom and through the inner skin.

Get yourself a 50mm diameter holesaw and drill the inner skin from the inside and partially through the core, but not through the outer skin with this hole saw.
Scrape out the debris until you get a nice 50mm hole in the core right up to the outer skin.

Use the hole cutter to cut out plugs from ply. They will be a loose fit in the holes. This can be made from several pieces to fill the depth of each of the 2" holes.

Cut another set of disks, one for each hole, from about 12mm ply this time 4" in dia and with a 45 degree taper on the edge (easy with a jigsaw) and a hole in the middle.

Coat each hole in the hull liberally with an epoxy mix and set the plugs in position (epoxy between them if they are in several pieces) then coat the back of the 4" disk with epoxy and through bolt, with big washers on either side, at each hole position.

Clean off any excess epoxy before it is set. Then when set remove the bolts and fit the ladder in place.

If you were brave you could actually fit the ladder in place at the same time as you epoxy the whole thing together and not have to remove the bolts. BUT you would have to use slow setting epoxy.

You may wish to change the sugested size of the plug holes to suit your precise application. Perhaps one plug for each set of three holes.
Using that method you will end up with a strong waterproof fitting and there will be no evedance of the strengthening on the gell coat outside the hull.

Hope that helps

Iain
 

tcm

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hi

tis tempting to have summink massively incredibly strong - but remebering the old ladder was on self-tappers, i wd be fine to drill holes, then put plastic tubes epoxied in to waterproof the sandwich rather than to win strength, then backing wood/ply each side, and A4 nyloc'd bolts. I wd mask around the holes once cut, lard up the tubes with epoxy, then cutttem back or countersink when dry. Black tubes are more forgiving colour-wise. Or, that brown polypipe would accept a decent size bolt
 

snowleopard

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alternative approach...

depending on whether you prefer to work in wood or plastic.

drill a hole for each bolt, but only through the outer skin.

take a 4" nail, saw off the head and bend the end over at right angles about 10mm from the end. put this in a drill and insert the bent-over end into the hole. run the drill on low speed and it will chew away the foam core around the hole, most of which will fall out. it isn't essential to get every scrap out.

make up a mixture of polyester resin with filler powder so it is still runny enough to pour. use that to fill the cavity. working on a vertical surface you'll need to cover the drill hole with masking tape and drill another hole at the top of the cavity to pour through. (do it from the back to avoid visible holes in the gelcoat)

sand off the back of the transom and apply a patch of glass cloth or mat with polyester resin. cover the patch with polythene and use a knife or scraper to squeegee out any surplus resin.

when set, re-drill your original hole, add a penny washer or steel plate at the back and bolt up.

the plug of resin prevents the compression of the bolt squashing the foam, prevents ingress of water into the core and the load is transmitted to both skins.
 
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