Freshening up a winch grippy surface

BigART

BigART

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My 25 year old Barbarossa 10cm dia genoa winches are a little smooth (but otherwise healthy) after 25 years and my new sheets slip alarmingly easily. Is there. way of sharpening up the barrel surface (such as sand blasting, or machining) to save having to buy and install new winches.

Angus
 
I had mine straight knurled across the core of the drum. Local engineer did the knurling and it's made a huge difference.

That said they are now hugely grippy and quickly abrading the sheets, they also seem more dangerous during demanding conditions. I will at some point take some sandpaper to them and smooth the knurling off a bit.
 
Assuming the surface is metal, a machining process called knurling could be used. Think of the grippy bit on a thumb screw, this knurled.
The problem with this is a lot of pressure needed as the tool doesn't cut the metal, it forms it, and this could put the winch out of shape. Your machine shop could get over this by making a fixture, quite how would depend on the assembly of your winch.
I've not seen a shot blast medium course enough to achieve what you want.

It could milled in a dividing head, but would be a lot work

Edit!! Sorry Chippy, posted at same time
 
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The knurling sounds an interesting idea but a fair point about the corrosion. I assume thay are anodised at present. Hmm. I shall have to think about this one.
 
Hi BigArt, my winches have chrome plated brass drums, the chrome from the core dia. of the drum had long since gone. The knurling looks fine and I haven't been tempted to get them re-chromed.

Can't imagine your genoa winches are of a carbon steel so corrosion is not an issue, the constant use would keep the clean anyhow.

I have seen drums that have been patterned by, one was chiselled just randomly all over the grip surface using a 1/2" chisel, the other guy had used a centre punch, very time consuming and ideally you have to strip the winch down, but it will have desired effect.
 
The barrels are some sort of anodised aluminium alloy. I don't know what sort, but i would imagine that it would be reasonably stable even with a damaged/knurled surface being intended for marine use. Any corrosion would be worn away I would think although that may mean the knurling may be worn away quickly too.

I am pretty sure that any spay on or sticky surface coatings won't work. Our boat is steel with painted bollards. The two part epoxy paint is fine with static loads, but any sliding loads, like slipping lines in a lock (such as the Panama Canal) tears the paint right off. Probably something to do with the friction heating. As this would be a regular event with a winch, I don't think such coating would work too well.

I think a careful light knurling may be the way to go for a neat appearance and see how we get on.

Thanks all

Angus
 
another (cheap) way

I'll probably get hoots of derision for this but....

when my bronze winches got soo glassy smooth that they became pretty useless I did a cheap and dirty. I masked of the top and botton third, got a heavily knurled punch out of my toolbox and, using a small tack hammer, hammered it against the middle third. I worked round the drum slowly setting the punch in a random pattern and hitting hard enough to just imprint the knurl onto the surface. The end result was a roughened surface but no real sharpness and worked a treat. It was free, the forces involved could not warp the drum and the roughening wasn't so drastic that if it didn't work I wouldn't be able to refinish them and try something else.
 
Matt Braid

alahol2 said:
Just one other thought, is it worth trying matt braid for the sheets? I find the 'shiny' braid slips rather more easily on my winches than the matt.
Click to expand...

You are absolutely right, our previous sheets were matt braid and they were fine - in that they had good friction, the new ones are horribly slippery. But I have been astounded at how difficult is has been to get hold of the matt braid in 16mm. We are on a circumnavigation and have have been looking for matt braid/cotton finish for two years, I have asked at dozens of chandlers in over ten countries between New Zealand and South Africa and response has been either "Never heard of it" or "We will have to get it shipped it, it will take X weeks and cost Y extra" and it is the X weeks that defeats me, I would pay the Y extra.

The old sheets are now looking so shabby with bits hanging off them that I have had to buy something. We are currently in South Africa were the local rope manufacturer (Southern Ropes at www.southernropes.com) also don't do matt braid. So I have had to accept defeat and have purchased the shiny stuff, hence my problem.

As you may guess, this has become a sore point. There are some aspects of Blighty that I have come to appreciate, like the NHS and ready supply of most things - such as matt braid.

Angus
 
I would have thought that abrading the surface with a fine wet and dry would produce the desired affect: enough roughness to grip, smooth enough to slip when slackening the tail, smooth enough not to damage the rope.

I would be inclined to start at 600 grit, say with a flat sander working round the drum. If that was no good, then move to 400 grit.

It must be worth trying before getting the drum knurled. Knurling will produce quite rough edges which would be very detrimental when easing the sheets, maybe even dangerous.

Many winch drums have negligible roughness to allow both slipping and winching operations. I would not go for knurling as a first option.
 
To get a very pleasing Finnish both visually and practically consider shot peening these by someone like Metal Improvement Company. A reasonably high intensity application of steel shot with a second light glass decontamination will leave an even Finnish of Matthew dimples. If used on high load Stainless items the increase in fatigue life is beneficial.
 
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