How to fit a winch on a curved surface?

[Aeolus]

I'm planning to run lines back to the cockpit and want to mount a winch for the main halyard. The cabin roof alongside the hatchway is flat in a fore and aft direction but slightly curved side-to-side. So how to create a flat surface to mount the winch? I could shape a piece of wood but that would have to be very precise and I'm a bit of a wood butcher. So are there any other ways? Some form of molten plastic that could be poured into a mold and would form a compression-resistant pad? Or something else?

And as a backing-plate, would a piece of ply suffice? - it would presumably flex to fit the slight curve. Or should I be thinking of a steel plate? I'm not sure what the halyard tension would be but she is a 30 foot bermuda-rigged sloop.

Jonathan

 

[PCUK]

I used Isopon P40 as the base for a pair of heavy davits on a curved deck. This has worked well and shown no problems in 15 years. P40 is the stuff with matting mixed into the resin and is designed for bridging holes in car bodywork. Another maker calls it 'Bridger'.
Easy to work and shape, it is ideal for making base pads. To get a perfect finish, skim the pad with epoxy filler and flat off before painting.

 

[twisterkai]

Recently had the same problem fitting a windlass to the foredeck. Solution was to make up a piece of teak for the unit to sit on and then spile the shape of the deck to the underside. Then, with either judicious use of an angle grinder with a sanding disk, or a plunge router, carefully remove the unwanted timber until the shape matches the profile of the deck. As the winch will be bolted down, the pad can be held down with the same bolts with sealant below, ie sika, and then use a non bonding sealant between the winch and the pad. If the deck is grp and has a foam or balsa core you'll need to remove that under the pad bolts and replace it with either hard wood or epoxy to stop the deck from crushing.

If you decide to use epoxy most of the manufacturers provide definitive advise on the reinforcing of the deck. Good luck with it, it's not really that difficult, just time consuming.

 

[tcm]

More info needd i think, regtarding the exact spot to be chosen - I'd be a bit careful just heyho plonking a winch for the main just anywhere, esp given your (admirable) brutal honesty of your practical skills!

The exact nature of the spot in terms of flexibilty and construction (cored?) is important. Even before you start, you should not be able to flex these area at all with your full weight, imho. If you can, i wd choose another spot. If you can't, you still need a decent backing plate.

 

[Poignard]

If you contact info@wessex-resins.com they will send you a very clear description of how to cast an epoxy winch pad in-situ

 

[William_H]

I find it surprising that the curve of the cabin top is so great. The winch will have 4 holes in the base that are closer to the centre of the winch than the perimeter by a fair amaount. So first off simply screw the winch down and see how it looks or consider putting washers under the winch at the hole points to allow roomn for some curve in the middle, The outside of the winch drum does not have to be close to the cabin top surface. (It will look better if it is not too far off.) I agree with the need for a filler piece it is a soft cored roof. Obviously the nearer the aft corner of the cabin roof the stiffer the roof will be.
Regarding the height of the winch bear in mind that the halyard should approach the winch from a point slightly lower or level with the bottom of the drum rope grip area. If it arrives too high you will get overides so this may dictate the use of a spacer block to lift the winch. This is not normally a problem if the halyard emerges from a clutch or organiser pulley box that is close to the cabin roof top. This aspect is particularly important for jib sheet winches.
good luck olewill

 

[tom52]

Go to your local library and get the Gougeon brothers boat building with epoxy book. It describes how to do this job in some detail.

 

[Aeolus]

Thanks very much for your invaluable advice and tips. I'll contact Wessex Resins.

Jonathan

 

[BrianJ]

Why not build a template to fit the curve , then just level off the top ... do it with thin ply glued together , till the height is right, level off the top ( base of winch) then your in business. Mind you this will take a few days for the glue to set ( particularly in your climate).. Then cut out ( or have it done professionally ) the desired base shape.
I have about the same ability with wood as you do, however I had a steel yacht, was able to cut a piece of teak to the shape of the deck, then round it off to the size of the winch.. with care it worked. Now if a dumb bum like me can do it , so can you.... go for it
I didnt need a backing plate as it was steel.. however I would suggest you do need something solid. A lot of force and pressure is on those winches....good luck
BrianJ