Winch plates bent on my mast winches

[Pollux]

Hopefully someone can help me with an explanation of why both our mast winches bronze plates have been bent, even though we never use them (they are Lewmar 40).
We've are actively cruising the world, and sailed 13,000 NM the last year in our brand new boat. Nobody else has sailed the boat.
I rotate them regularly by hand just to make sure they don't clog up. Noticed that they got harder and harder to rotate. Took them apart and can see that both have their plate bent. The mast, the back plate are really strong. And all screws holding the winches are intact and tight.
How can that happen, and what can I do to fix it, and make sure it doesn't happen again.

[SVTatia]

Originally Posted by Pollux

Hopefully someone can help me with an explanation of why both our mast winches bronze plates have been bent, even though we never use them (they are Lewmar 40).
We've are actively cruising the world, and sailed 13,000 NM the last year in our brand new boat. Nobody else has sailed the boat.
I rotate them regularly by hand just to make sure they don't clog up. Noticed that they got harder and harder to rotate. Took them apart and can see that both have their plate bent. The mast, the back plate are really strong. And all screws holding the winches are intact and tight.
How can that happen, and what can I do to fix it, and make sure it doesn't happen again.

Do you have pictures? which part of the winch is the plate?

[Pollux]

Yes, here are a couple of pics. The bend is between the screws, and of course max in between the screws.

[SVTatia]

This does not look like it was done by any kind of load or stress, and it looks very suspicious to me, like someone was trying to steal the winch and did not know how to remove it.

[Jim Cate]

The pix suggest that it may be due to corrosion between the bronze winch base and the aluminium mast and mounting plate. The corrosion products have greater volume than the base metals and can generate considerable force.

Good practice is to put an insulating layer between the bronze and the aluminium, like mylar sheet or such. This helps prevent the dissimilar metal corrosion.

Jim

[Emmalina]

Originally Posted by SVTatia

This does not look like it was done by any kind of load or stress, and it looks very suspicious to me, like someone was trying to steal the winch and did not know how to remove it.

+1 Looks like you had a visitor that liked the shiny bits !

[SVTatia]

Originally Posted by Jim Cate

The pix suggest that it may be due to corrosion between the bronze winch base and the aluminium mast and mounting plate. The corrosion products have greater volume than the base metals and can generate considerable force...

I agree with Jim, but in this case it would take substatial force to lift the base of that winch and my feel is that it was done mehanically. I can see what looks like kinks (clear marks on the base edge) from a pry bar or whatever was used to bend the base.

[OS2Dude]

You should be able to remove the winch and use a hammer and block of wood to persuade that section to lay flat again. I once dropped a winch onto a concreate floor and bent the drum enough it would not turn. I cut a disk out of a hardwood board with the same OD as the drum and a slightly beveled edge so it would fit snuggly, I little gentle persuasion with another block of wood and a hammer eventually got it round again.

[.Paul.]

Originally Posted by Pollux

Hopefully someone can help me with an explanation of why both our mast winches bronze plates have been bent, even though we never use them (they are Lewmar 40).
We've are actively cruising the world, and sailed 13,000 NM the last year in our brand new boat. Nobody else has sailed the boat.
I rotate them regularly by hand just to make sure they don't clog up. Noticed that they got harder and harder to rotate. Took them apart and can see that both have their plate bent. The mast, the back plate are really strong. And all screws holding the winches are intact and tight.
How can that happen, and what can I do to fix it, and make sure it doesn't happen again.

The Lewmar Ocean Series two or three speed winches have a preferred orientation for the base of the winch relative to the direction of the load. This is shown in this installation guide

https://www.p2marine.com/documents/l...tion-guide.pdf

The installation guide shows the load (halyard for a mast winch) coming onto the outside of the winch drum over the middle of the gear that drives the drum from the inside. The drawing in the installation guide makes this clear.

The halyard will contact the drum at the three o'clock position. So, the middle of the contact between the drive gear and the drum gear should also be at the 3 o'clock position.

Paul

[Jim Cate]

Originally Posted by SVTatia

I agree with Jim, but in this case it would take substatial force to lift the base of that winch and my feel is that it was done mehanically. I can see what looks like kinks (clear marks on the base edge) from a pry bar or whatever was used to bend the base.

If the distortion was from some jerk trying to pry them off the mast then how do you explain the OP saying that the winches gradually became hard to turn... over a longish period?

And anyone knowledgeable enough to realize that mounted winches are worth stealing would know that you can't pry them off. I don't buy that explanation!

Jim

[Tillsbury]

A brand new boat? How many years old are those winches supposed to be?

I agree that theft sounds unlikely, but on the other hand I cannot see how that damage could have been caused on brand new winches that you don't use.

[a64pilot]

Take the winch off, it may not be bent, or if bent only slightly, from corrosion, corrosion can bend sheets of steel, we’ve all seen that. It’s very powerful, like ice is.
They need to come off, be cleaned up, I’d zinc chromate the base and fashion a plastic piece to go between them, or at least use anti chafing tape.

Just looking at it, it appears the drum may be in contact with the mounting base, something has cleaned off that aluminum, looks like circular scratches to me, maybe from the drum?

[Old_Geezer]

When you take the winch off the mounting plate I believe you will find the casting is not flat on the bottom, but concave. The edge of the winch has cracked and broken off. I can see another crack there also. Always separate dissimilar metals with wood, plastic, nylon.

[Yahoo]

I have experienced exactly the same problem with the same size winch. I eventually replaced the winch base but that cost almost as much as a new, discounted, winch and took six weeks for delivery. I didn't want to try to straighten the bend as I assumed that would only weaken it and make it even more susceptible to bending in the future. I assumed the problem was caused by an over zealous crew member determined to get the halyard really tight. I did not find any corrosion between the mast mounting plate and the winch base but I wish I had thought to isolate the winch base from the mast with a non conducting material. I'll do that at the next service.

[svHyLyte]

How many wraps do you place on that winch before running the tail through the take-up arm to the self-tailer jaws? If an insufficient number, the load of the halyard fall will be nearer the center of the drum than at the shoulder near the base. The tension on the fall as you crank down on the winch will place an eccentrich load on the winch that attempts to rotate the winch in the vertical direction. This rotation effect (or "moment") must be offset by the compression on the upper face of the winch base and tension on the lower face. The "tension" must be provided by the bolts through the winch base into the mounting pad. The mounting pad on the mast itself must be very stiff and the bolts through the winch base must be very tight such that they thoroughly preload the bolts and take the "stretch" out of them. If they are insufficiently tightened, as the winch load up, the bolts will stretch somewhat, allowing the base to rotate which, (alone) it is insufficiently stiff to resist hence it will "bend" along a horizontal axis at the lower end of the compression face, causing the condition you describe and appears in t=your photograph. This is the same as a column base plate failure in a building structure where insufficiently pre-loaded base plate bolts allow the column to rotate.

If you disassemble the winch you might find a machine shop that can remove the bend, at least enough so that the base of the barrel does not come into contact with the mast mounting pad as it loads up. Then, ensure that the mounting bolts are sufficiently tight (you might contact the winch manufacturer for the base plate mounting torque specification). I could speculate on a torque but it would be pure speculation and of little merit.

Then, ensure that you have sufficient wraps on the winch such that the fall of the hallyard is forced as close to the shoulders of the barrel as possible; and, only apply as much load on the halyard as necessary to straighten the luff of the sail;and, in snotty weather when the sail may become over loaded in gusts, reef early and be prepared to "blow" the main sheet, or at least the traveler, in big gusts. Latly, instead of relying on the jaws of the self tailer to secure the hailyard tail, lead the tail to a mast mounted cleatand make the lead from the winch to the cleat as tight as you can to counter, to the extent possible, the tendancy of the winch to rotate

FWIW...