Windlass Deck Reinforcing Plate

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alla_breve

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Hello all,
Im fitting a Lewmar Horizontal windlass to a Westerly Griffon (Arthritic shoulder causing manual lift problems!!). Its nearly ready to go, but im not sure about a deck reinforcing plate, which will go UNDER the deck.
G10 fibreglass /ply/ aluminium??
Bonded in with epoxy or not??
Im not considering stainless due to the extra cutting/ drilling difficulty. Lewmar recommend 1" total deck thickness, and I think its about 1/2" already, so I thought a 10mm thick plate, a bit larger than the windlass footprint??
With large washers for the 8mm studs (3 off)
Thanks for any advice
 
Of the three you offer - grp. Wood, and to an extent alu are likely to suffer when water eventually works its way down the holes.

Either lay it up on a board and transfer it before rollering the bubbles out in place, or make a plate up and bond it in with a resin/micro balloon filler mix.
 
On my 43ft yacht I mounted the winch on a fiber glassed 20mm ply pad but ran SS angle between the No 1 bulkhead and the bow roller pad. (I can't find the relevant specoifications for your yacht)
 
If you are considering aluminium then stainless is really no more difficult to work and, in my mind, a better option. You will be using stainless bolts (studs), I assume and if you use aluminium you will need to use something too isolate the bolts from the aluminium. You will almost certainly suffer from the aluminium corroding (unless you use the 5083 alloy or have the cut and drilled plate anodised). Stainless will be more expensive, than aluminium. I would not use ply - it will need to be completely sealed and if it compresses at all - any seal you make will be compromised. If you have an angle grinder and a bench drill stainless is easy to work (and you can buy the stainless cut to the size you want (or you could here (in Sydney).

I'd make up my own plate from glass and resin, into which you could incorporate a thin piece of stainless (instead of 3 washers) and/or Coopecs stainless angle. You can make up the glass panel at home, lay up on thick polythene sheeting, it peels nicely, and cut and drill at home - you then simply need to bond under the deck - a thin shim of Sika will be fine - when you bolt.

You may find that the deck is not flat, a slight curve - in which case you might need to make up the glass pad in 2 hits and bond into the underside of the deck when the resin of the glass pad is not set hard but still bendable. You can then set another layer under the first.

Personally - I'd use 3mm SS plate under a home made glass, 2 layers of 750gm glass, pad, under the deck I'd over size the glass pad but have the stainless plate a 'bit' bigger than the footprint of the windlass. I'd make everything at home - making sure the dimensions are going to fit before you start! :)

Jonathan

A further thought - if you decide to incorporate a plate and have need to bend it to try to follow a curve of the deck - aluminium will prove very difficult but the stainless you can bend with ease.
 
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My Windlass has a Marine Ply bed of approx 18mm on the deck which raises the windlass more aligned to the naval pipe and also bow roller. Under the GRP deck - there are large penny stainless steel washers under the large nuts to take the load.

That setup has lasted for over 30 odd years and I have used the windlass to lift mooring blocks ... actually pull bow down to get stern up enough to clear underwater drains etc.

My deck is of course 1975 style of solid GRP with no sandwich infill. If I had a sandwich deck - then I would look at providing a plate under to spread the load. It does not need to be as thick as the on deck plate.

I believe the Griffon has the Balsa Core deck ... with most GRP strength in the underdeck layer ... balsa for lightweight stiffening and then primarily a thick GelCoat top layer. My preference would still be with a thick ply on-deck pad and then load bearing large washers or plate underdeck. reason being that the deck layer needs to have stress spread just as much or more than the underdeck GRP.
 
I fitted similiar to my Westerly Fulmar. Are you sure the deck is flat? Mine certainly wasn't. So to get round two problems with one solution I used a hardwood block, shaped to the curvature of the deck. Seemed to work well and still going strong after 15 years. The block was well soaked in some sort of wood preservative and also painted.
 
I have used thick polythene chopping board successfully. It's cheap, unaffected by water and tough but flexible. Get a large one and don't cut it down; just drill for the studs. Ready in minutes.
The biggest challenge is to find one that is plain and doesn't have some fancy shape moulded in.

Derek
 
cpedw said:
I have used thick polythene chopping board successfully. It's cheap, unaffected by water and tough but flexible. Get a large one and don't cut it down; just drill for the studs. Ready in minutes.
The biggest challenge is to find one that is plain and doesn't have some fancy shape moulded in.

Derek
Click to expand...
You can buy HDPE sheet cut to your requirements, from Bay Plastics.
 
Refueler said:
My Windlass has a Marine Ply bed of approx 18mm on the deck which raises the windlass more aligned to the naval pipe and also bow roller. Under the GRP deck - there are large penny stainless steel washers under the large nuts to take the load.

That setup has lasted for over 30 odd years and I have used the windlass to lift mooring blocks ... actually pull bow down to get stern up enough to clear underwater drains etc.

My deck is of course 1975 style of solid GRP with no sandwich infill. If I had a sandwich deck - then I would look at providing a plate under to spread the load. It does not need to be as thick as the on deck plate.

I believe the Griffon has the Balsa Core deck ... with most GRP strength in the underdeck layer ... balsa for lightweight stiffening and then primarily a thick GelCoat top layer. My preference would still be with a thick ply on-deck pad and then load bearing large washers or plate underdeck. reason being that the deck layer needs to have stress spread just as much or more than the underdeck GRP.
Click to expand...
Thanks for reply. I was hoping to fit the pad under the deck to spread the load, I don't want to raise the windlass any higher above deck, as its a good angle to the bow roller at the moment. Its a 1980 Westerly Griffon, solid deck, not cored.
 
Rafiki said:
I fitted similiar to my Westerly Fulmar. Are you sure the deck is flat? Mine certainly wasn't. So to get round two problems with one solution I used a hardwood block, shaped to the curvature of the deck. Seemed to work well and still going strong after 15 years. The block was well soaked in some sort of wood preservative and also painted.
Click to expand...
Thanks for reply. So, the block is above deck? As I say above, I don't want to raise the windlass more than I have to. What is there under your deck, any sort of reinforcement? Large washers only?
 
alla_breve said:
Thanks for reply. I was hoping to fit the pad under the deck to spread the load, I don't want to raise the windlass any higher above deck, as its a good angle to the bow roller at the moment. Its a 1980 Westerly Griffon, solid deck, not cored.
Click to expand...

Fair do's .... I checked about Griffon before replying and the article mentioning Balsa Cored was for Griffon 2 ... so I assumed yours was Griffon 2 ... apologies.

Putting the pad under deck is no problem - just make sure if its Ply - that you have large enough 'Penny Washers' to spread the nuts pressure and not crush the ply. Ideally because you are not taking advantage of the windlass base onto the ply - it would be better to use a metal or 'Engineering' Plastic plate.
 
alla_breve said:
Its a 1980 Westerly Griffon, solid deck, not cored.
Click to expand...

I'm surprised; I'd have expected it to be balsa-cored. I'd look at making a 10mm GRP plate and fixing it under the deck with filler to take up any irregularities. The load on the windlass will tend to give an upward force on the rear mounting points, so ideally the GRP plate should extend rearwards from there if there's room.

If you do discover that the deck is balsa-cored, be sure to remove the balsa around the windlass holes and fill with epoxy filler to seal against water ingress.
 
alla_breve said:
That sounds good. Ive used HDPE before, do you think its rigid enough for this application?
Click to expand...

No, it is terrible structural material! No engineer would ever use it for backing. It creeps. It cracks under sustained load. Engineers never use it for anything other than compression loads. Google it.

I would bond a fiberglass sheet. Then it is part of the boat. I'm not a fan of aluminum or wood in such a wet area.
 
thinwater said:
No, it is terrible structural material! No engineer would ever use it for backing. It creeps. It cracks under sustained load. Engineers never use it for anything other than compression loads. Google it.

I would bond a fiberglass sheet. Then it is part of the boat. I'm not a fan of aluminum or wood in such a wet area.
Click to expand...
Thats why I mentioned 'Engineering Plastic' in my post ... a completely different material to HDPE ...
 
Thanks to all for help, its looking like im going to use a grp pad underneath, (I see there's 10mm G10 sheet on ebay for about £16, save a lot of laminating!) Ive got some west epoxy and filler left from a previous job, so ill use that to fix it, along with large stainless penny washers. Sound ok? Anybody got a second hand relay control box for sale?
 
alla_breve said:
Thanks for reply. So, the block is above deck? As I say above, I don't want to raise the windlass more than I have to. What is there under your deck, any sort of reinforcement? Large washers only?
Click to expand...
Yes wooden block was above deck, it was actually sold as a pad for mounting an outboard on a rail, but without any fittings. I don't recall re-inforcing the underside of the deck and must have simply used very large washers ( A2A4 stainless online sells a vast range of bolts and washers ) I no longer have the boat but see it from time to time and the windlass arrangement is unchnaged hence my reference to 15 years.
 
Refueler said:
Thats why I mentioned 'Engineering Plastic' in my post ... a completely different material to HDPE ...
Click to expand...

I was responding to HDPE.

But no, restricting it to engineering plastics doesn't really solve the problem. Many of those creep, to a lesser degree, unless reinforced, and most can crack without warning. Thus glass filled nylon could work, for example, but not nylon alone. And PTFE is consider to be an engineering plastic, and creeps fast (though you were certainly not thinking of that one).
 
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