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-   -   UHMW as winch pad...other applications? (https://www.sailnet.com/forums/gear-maintenance/34339-uhmw-winch-pad-other-applications.html)

geste 07-02-2007 11:53 PM

UHMW as winch pad...other applications?
 
I have a teak winch pad that is pretty beat. I started to wonder: how about replacing it with white UHMW?

I have made a couple of small custom pieces for the boat out of UHMW, but none in a deck application where I should be concerned about leaks.

So my question is: Since nothing wants to stick to UHMW, will it be likely to keep a good seal if used in an application like a winch pad? Folks seal up polycarbonate port lights with good success, but polycarb doesn't have the "no-stick" rep of UHMW.

I even wondered: would it make more sense to roughen up mating surface of UHMW with a wire brush to create a not-so-smooth surface that would perhaps hold polyurethan caulk better?

Handy material.

Jim

sailingdog 07-03-2007 06:47 AM

Generally, to get stuff to stick to the really slick plastics, you need to flame-treat the surface. Personally, I wouldn't use UHMW PE in that application. I would go with either a replacement teak pad, or making a fiberglass pad for the winch instead. West Systems has a pretty good section on doing just that.




hellosailor 07-03-2007 10:54 AM

Jim, I wouldn't worry about the sticking. Sticking means "sealant" or "adhesive" and all that you need is "bedding" or "gasket". Grainger and McMaster both sell various rubber and silicon sheet materials (high density neoprene with a UV-filler should also be fine) and I'd just lay a sheet of gasket material under the base to seal it down. A properly compressed gasket works just fine--even without "gluing" itself to anything.
Bed it, tighten it lightly with some bedding compound around the bolts, and let it set up as spec'd, often 24-48 hours. Then retorque, and the bedding compound plugs the bolt holes while the gasket makes the deck watertight.
Old tech--but it still works just fine.<G> Unless someone like Sika has a special UHDPE primer and caulk combination, which wouldn't surprise me at all.

geste 07-04-2007 12:32 AM

Uhmw
 
Thanks for your replies. I am fairly motivated to look at using more UHMW as it seems like I am getting lazier and lazier, and UHMW cleans up real well. Standing around with a pressure washer is my idea of "real work". I have done some fiberglass work (like an improvement of a mast step) but, not being somebody who can do gelcoat, I was eventually disappointed by the durability of the epoxy paints I used to finish those.

I find UHMW very easy to work with, even if a bit messy if hitting it with a router or power planer. I machined a little custom saddle/collar to hold the base of a radar mast. Great. And I built a 1-inch thick adapter plate to let me fit a new Raritan head in place of the original Groco.

Now, rather than get hung up on sealants. I think I will start exporting the gasket route. In some respects, easier than figuring out when the sealant has cured enough to allow a bity more tightening. And less messy.

This may be part of a trend. I am starting to think about how to get rid of most of my teak.

Jim

marlers 07-04-2007 12:23 PM

Jim,
I have used UHMW for base pads under many of our deck hardware components with great sucess. I first did a test sample by sanding the block in two directiones to create tooth in the pad then applied 3M 5200 to the pad and fastened the test block to a finished fiberglass block after two weeks I removed the fasteners and used the hammer test to remove the block, I found that it wac as well bonded as any teak pad that I have removed from our boat. Isand the blocke after shaping them to provide a uniform satin finish which is easy to clean and as an added bonus I dont need to varnish these small pads as there is ample other surfaces to maintain the varnish on.
Fair winds, Steve

Valiente 07-04-2007 12:53 PM

I believe I asked about this in another thread involving the installation of a straight traveller track over a cambered deck...I was debating the use of this type of plastic as shallow, wedge-shaped "shims" instead of using teak. At the time, the idea was discouraged. How is this different?

geste 07-18-2007 11:04 PM

UHMW for structural pieces
 
Quote:

Originally Posted by Valiente
I believe I asked about this in another thread involving the installation of a straight traveller track over a cambered deck...I was debating the use of this type of plastic as shallow, wedge-shaped "shims" instead of using teak. At the time, the idea was discouraged. How is this different?

While I have used UHMW for several shims/pads with great success, I did wonder about rigidity and compression characteristics for some applications. For instance, I daydreamed about the idea of replacing my PITA teak coaming boards with white UHMW (tacky, I know, but easy to clean!) but I was dubious about whether they would resist bending (the aft 1/3 of these boards are pretty unsupported).

However. I happened to spend some time in a bathroom stall that was completely constructed of 5/8" UHMW -- sides, doors, everything. I did some testing. It is pretty darn rigid!


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