tophatyachts.com

Removed and brought one chain plate home (starboard aft lower). Cleaned it up. Few interesting things about it. Firstly u-bolt threads are not too bad, but nuts definitely need to be replaced. The one end of the u-bolt is bent outwards, which is curious. The thread is 3/8 inch UNC 16 pitch. I am now trying to buy a button nut of this size to clean the bolt threads. Will straighten the bolt and and refit when next on the water. Not sure whether or not to put tefgel (or similar) onto the threads. Will probably add extra nuts on the underside (inside cabin.
If anyone else had removed chainplates, what did you find?

See viewtopic.php?f=6&t=558&p=2718#p2718

I would not advise using a die nut on the threads. I used a stainless steel wire brush to clean off the old sealant.

If the threaded part is bent, it is very dangerous to reuse, especially do not straighten.

Cheers,

Tom

Hi John,
I have an annoying habit of erasing from my memory anything that I think i'm not going to need again...rigging/chainplates etc is one of those things .
A photo would help...dont all chainplates have a bend formed into them to acheive a better angle from deck to top of mast.
I agree with Tom that if something as important as a chainplate needs bending back into shape, better to think about replacing it, you dont want to cause any weak points.
cheers
Shaun

Add to that, stainless steel needs to have good air around it to remain stainless....

No paint, no other stuff just bare stainless.

Michael

This is good input. Tom, why would you not use a die nut to tidy up the thread? Shaun, yes the u-bolts are bent to line up the wire. My concern is that one of the legs of the u-bolt is splayed, this is in the area in the cockpit, not above deck. Maybe better to let things stay as they are.With the bend it is not a good idea to 'screw' nuts along the bent portion, as they bind and damage is done to nut and bolt component. I have not removed the one nut that sits above the deck, as I have been unable to get it past the bent part of the 'bolt' for fear of causing damage, but I can leave this nut where it is (after all it does not take strain). The nut that goes on the bottom does not have to be 'screwed' past the bend, so a replacement here won't be subjected to having to pass across bent portion of the 'bolt'. So in effect I will be able to clean up all of the bolt thread and replace 3 of the 4 nuts. Then onto the next chainplate. Anyone know whether the u-bolts are 304 or 316, what about the nuts?

Die nut will remove metal which you don't want.

The 'U' bolts on the Top Hat have 'rolled' threads, not cut threads.

The thread rolling process actually makes the bolt stronger than cutting the thread.

Bending any metal which has a notch in it is very likely to make the metal crack at that point.

Think of a bolt as metal with a series of notches along it so bending a thread is really bad news.

The 'U' bolts are very corrosion resistant so I would expect them to be 316. Some of the nuts have been known to corrode so more likely to be 302 or 304.

'storm petrel' may have spare 'U' bolts if you ask him.

Cheers,

Tom

Yes I have a few spare chain plate U-bolts, if you need one.

Cheers,
Mark
Storm Petrel

Tom, what you said about the thread being rolled makes sense. What about the nuts to go with the rolled thread, are these different and special? Thanks Mark, I might be chatting to you about this later, will see how things work out. Will keep you all updated on progress. John

John,

Normal stainless nuts are fine.

Story going around is that it is good practice to use different types of stainless for nut and bolt to minimise galling (or welding) of threads.

I think the nuts tend to corrode because of leakage down the 'U'' bolt.

Good idea to keep an eye on them and if they drip, get them out and reseal, fit new nuts.

Cheers,

Tom

storm petrel wrote:Yes I have a few spare chain plate U-bolts, if you need one.

Cheers,
Mark
Storm Petrel

Mark, have you got any v bolts left? I need 2 small and one large and can find them nowhere

regards
Rob