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Nodrog

Mounting friction ring / ferrule into deck or bulkhead

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Am taking some thin control lines through a bulkhead, and deck, couple with 180Deg change in direction, couple with negligible change. No need to be watertight, although I want to avoid a hole that is too much bigger than required. Thin dyneema lines, 2-4mm, deck and bulkhead are 4mm ply which will be sheathed with 200gsm glass. 

I'm planning on doing it with ronstan low friction rings / ferrules, like this https://www.ronstan.com/marine/low-friction-rings.asp but need to find a neat way of flush mounting these in the deck.

So far I'm planning on cutting a disc from 4mm ply, already sheathed with 200g glass, which fits nicely in the outer groove of the ring. Cut the disc in half, drill a hole thru the middle and push the 2 halves of the disc together with plenty glue so the ferrule is captive in a larger ply disc. Then I'd flush mount this into the deck by bevelling the outside of the ring to match a hole in the deck, glue it in, and try to neatly glass over the join, perhaps with a backing pad ( a do-nut shape) of more ply behind the join. 

I think this is acheivable, but sure is looking like a lot of work. Am wondering if perhaps I've missed an easier way of getting a similar outcome? Antal make a mountable ferrule, but only in much larger sizes. http://www.antal.it/eng/Mast-fairlead 

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Yup, know those, but not really what im looking for, not flush, Can't turn 180, or anything like that, and not really smooth/low friction. The antal one is the combo of the 2 designs, but only in larger sizes.

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16 hours ago, Nodrog said:

Am taking some thin control lines through a bulkhead, and deck, couple with 180Deg change in direction, couple with negligible change. No need to be watertight, although I want to avoid a hole that is too much bigger than required. Thin dyneema lines, 2-4mm, deck and bulkhead are 4mm ply which will be sheathed with 200gsm glass. 

I'm planning on doing it with ronstan low friction rings / ferrules, like this https://www.ronstan.com/marine/low-friction-rings.asp but need to find a neat way of flush mounting these in the deck.

So far I'm planning on cutting a disc from 4mm ply, already sheathed with 200g glass, which fits nicely in the outer groove of the ring. Cut the disc in half, drill a hole thru the middle and push the 2 halves of the disc together with plenty glue so the ferrule is captive in a larger ply disc. Then I'd flush mount this into the deck by bevelling the outside of the ring to match a hole in the deck, glue it in, and try to neatly glass over the join, perhaps with a backing pad ( a do-nut shape) of more ply behind the join. 

I think this is acheivable, but sure is looking like a lot of work. Am wondering if perhaps I've missed an easier way of getting a similar outcome? Antal make a mountable ferrule, but only in much larger sizes. http://www.antal.it/eng/Mast-fairlead 

Sounds over-complicated. Here is a plan that is similar, but simpler. Based on work I've done on my Whisper and UFO foilers.

Assuming you have access to the underside / other side. Get a slightly oversized (to the rope) ferrule, dremel it into 2 - to be clear, you will have two rings one for top, one for bottom (not two crescent moon shapes).

For through-bulkhead that is thicker than the ferrule... If you are opening/drilling the bulkhead hole it's going through, put some epoxy on the hole walls, so water doesn't soak into the core, ruining it (if you are positive none are cored, you can skip this). Bond the ferrule halves into place with gflex or similar. If it has to be flat, sand the "step" in the bulkhead beforehand so the half ferrule is embedded and ends up flat. Put enough gflex that it fills the gap in there, and mop up excess with a rag w acetone. 

No need to glass over or around it. As the bulkhead is thick, you don't need further ado. Reinforcements would be needed for something highly loaded (mainsheet block attachment), but that doesn't seem to be the case.

If the deck is thin relative to the ferrule, make U shaped backing plates and interlock them (on the underside of the deck) to the point where you match or exceed the ferrule thickness. Note that this is not a C shape, but a U, so you'll interlock them, they'll overlap. The simplest way is to buy an already made CF plate from amazon or similar, they are stupidly cheap if you buy them in letter size or similar because shipping is cheap. Dremel them into U shaped backing plates. Interlock them - so you want at least 2 per ferrule - and g-flex into place.

For a thin deck/bulkhead, you don't want to sand the deck to embed/hide the step because that'll weaken the deck. Instead, make a fillet - with the same thickened gflex, or 4200 or whatever. On the underside, where you have the backing plates, if exposed, it might be tidier to dress it up with a layer of glass and a thickened epoxy.

Overall, if you use the thickened g-flex (comes in tubes) it's easy to mix small amounts and thick enough that it won't drip.

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14 minutes ago, silent bob said:

That's the best solution. But simply boring a hole to fit the outside of the ferrule and then using strengthened epoxy to hold it in place would be enough. But your idea of a split plate sounds better. Learn how to do tidy epoxy work and it will be trivial to execute.

A wise friend used to say "Learn to do tidy epoxy work or become a professional sander."

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1 minute ago, El Boracho said:

That's the best solution. But simply boring a hole to fit the outside of the ferrule and then using strengthened epoxy to hold it in place would be enough. But your idea of a split plate sounds better. Learn how to do tidy epoxy work and it will be trivial to execute.

A wise friend used to say "Learn to do tidy epoxy work or become a professional sander."

My Epoxy work is well above Average.  So is my laziness factor, at times. 

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Thank you @martin 'hoffthats much simpler. I've tried cutting the rings in half as you mention before, but my god they are tough, don't know what sort of alum they are but it was hard work with a hacksaw. I couldn't find a dremel disc deep enough to get through the ring, but will try again. The VMG rings sure are nice, but too large for this job ( and also on the wrong side of the world...) 

Epoxy work and sanding, I hear you !! I think we all find the time spent sanding increases the motivation to improve epoxy workmanship with laziness being the common factor! 

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An update on this. Wasn't happy with cutting them in half and inserting one half from each side. Seemed too difficult to get the 2 halves to line up properly, and avoid having a razor sharp edge in the middle, sort of defeating the point of the whole exercise. I evolved the "U" shaped inserts slightly into what I can only describe in a series of pics. This is for 2 ferrules close together, the 6mm ply will be cut to size afterwards, and then used as an insert in foam core deck. The pics oviously just a dry fit, cameras and epoxy I don't believe mix well. 

20201011_124035 2.jpg

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20201011_123630 2.jpg

20201011_123607 2.jpg

20201011_123553 (2).jpg

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Looks great! I don't think you'll need glass cloth. I'd assemble the setup and bond it with thickened g/flex.

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Ended up using the cloth, one of the rings won't see much load, but the other will be the towing eye so wanted to be sure of some strength. I'm pretty sure that if it comes off now it will take half the foredeck with it.

I made a jig of sorts to hold everything flat, couple of recesses to fit the ferrules,  and vacuumed it all down. Pleased the level of prep work pretty much eliminated sanding afterwards per El Boracho! The piece will be an insert for foam deck. side with fairing compound will be topside, should come out fairly flush when its done.

 

Jig: 

20201016_110139.thumb.jpg.05be8eccaa5aa872edac4c9bb80a1f14.jpg

top

20201016_110046.thumb.jpg.c67191d043d181a6fa56e11af5a81d90.jpg

 

under

20201016_110052.thumb.jpg.84678b3febf8430db6b3656c97f1d5de.jpg

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