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Old 23-08-2009, 13:20   #1
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Pulling & Re-Bedding Chain Plates

My next project will be pulling and rebedding my chain plates. So.... How do I do that?

I am not planning to take the entire rig down. I want to tackle one shroud at a time. My chainplates are inboard and access is excellent. So I can get at the bolts and see how to remove the plates but what happens to the rig when I go to disconnect the toggle on a shroud? What do I need to do? Should I rig a line to the toggle and fitting and then run it to a block on the toe rail and tension on a winch? How critical is this?

Thanks ahead for the input!!!


Terry
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Old 23-08-2009, 13:45   #2
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Ease the rigging screws ("yours" and the one that balances the piece of rig you are working on) to the point where the opposite piece of rigging loses tension (beware - not to the point where the screw falls out and the mast remains without support. You want the mast to remain straight or almost straight. For lowers you may have to ease all four screws (if you have double lowers).

When the corresponding/opposite piece of rigging is under no tension you can disconnect "your" piece of rigging and then pull out the plate.

For fore / aft stays you will want some sort of support line (a halyard perhaps) unless they are doubled - like in a cutter rig.

Go slow and plan ahead - and there is very little to go wrong.

Off course - for a keel stepped mast the process is way 'safer' - the stick will be there even if you ease all pieces of rig at the same time.

My final comment is - I do not know the reason you do not plan on taking the stick out, but since you have some issue with the chain plates perhaps it is a good excuse/moment to pull the stick out completely and check the mast tangs/fitting/hardware?

Tell us how it went!
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Old 23-08-2009, 14:18   #3
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The loads when you have no sail up in the slip or hauled out are very very low. @ years ago I was hauled out and had no backstay. I had to remove it the get in the travel lift. We were out for 3 weeks doing assorted jobs. The mast is 51 ft in the water. While I did add some lines at no point was there ever any tension on those lines, including some days with over 30 knot wind. I would still add the line just because it's not hard to do it and it can't hurt. You don't need much tension at all. On a toe rail it could be a problem over tensioning it. Working one at a time should be fine. Mark the threads with tape so you can set the tension close to what it was before after you finish each plate and consider retuning the whole rig after completion.
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Old 23-08-2009, 21:47   #4
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Thanks for the replies!

I am pulling the chain plates basically as a precaution. There are no issues that I known of but unlike the rest of the rigging I cannot easily inspect the chain plates and it's been 10 years since there were last out.

Terry
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Old 23-08-2009, 22:14   #5
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I would first note the position of all turnbuckles. The best way is using a caliper to measure the distance between the two threaded terminals/rods and keep that info safe. Tape can easily "disappear" when working on the rigging.

Next, take the tension off every stay and shroud. Not so much that they start flapping around, just enough so that they aren't stretched anymore.

Now just take the most convenient halyard toward the plate you want to remove and connect it to something more solid than the lifelines and tension it until the stay/shroud to be removed is slack. Leave it like that for the duration, assuming you tackle the plates one by one.

The ultimate bedding between chain plate and the surface that they are bolted onto is a gasket cut from neoprene rubber sheet: the same material as an impeller. They are easy to get, I just ordered some more (1/16" and 1/8" thickness are best) from Amazon.com. Cut them in the same shape or a little smaller (they will expand a bit later). The holes for the bolts must be cut oversize for the same reason. Use a hole cutter (the pipe-like tool that you hit with a hammer.

The surface that the plate bolts onto must be nice and flat so that the plate touches everywhere before tensioning the bolts. Fair it with epoxy/high-density filler mixture if needed. Use some contact cement (spray glue) to put the gasket on either the surface or the plate before installing, just to keep it in place until the bolts are tight.

If the bolts and nuts are stainless steel, replace them. Grease the part of the thread where the nut (use nylock nuts) goes on with Lanocote (linseed grease to prevent galling) and tension them with a torque wrench to the optimum torque for the bolt diameter for bolts loaded in sheer (I can look that up for you when you tell me the diameter of the bolts).

Now the detail: make it so that every bolt is lined up the same (if it's head is slotted, all slots point in the same direction or if it's a hex-head or the nut that you see, the facets are all lined up). The heads can be held in position while tightening the nuts but when the nuts are what you see, tighten them a little more for line-up, not less. Now you have an easy indicator if anything moves there.

cheers,
Nick.
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Old 23-08-2009, 22:39   #6
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Hi Tspringer. I'm a boatwright, and we often do this type of thing. There's been some great advice about removing your chainplates, etc... But when it comes time to install them remember -1) Stainless will corrode when it is sealed-off from oxygen. 2) If you put excessive bedding compound or gasket between your chainplate and hull (or bulkhead), the chainplate will move under load. That's bad. The only places you would use bedding compound would be where the chainplate bolts penetrate the hull, in which case you would countersink the holes so they would retain a small "doughnut" of sealant around each bolt beneath the chainplate, and of course to seal around a chainplate exiting through a side deck. Jedi mentioned lubricating the stainless fasteners, this is a must to prevent galling, and assist in future disassembly.
Fair winds!
Bob
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Old 11-09-2009, 19:45   #7
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I have a question along these lines. I'm in the process of buying a boat with encapsulated chainplates. According to the surveyor, some of them exhibit "light coffe staining". Obviously they have suffered some corrosion. How hard is it to remove the ecapsulating material? Is it fibreglass, some sort of epoxy resin? Will I have to go nuts with a sawzall or something?
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Old 16-09-2009, 22:13   #8
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Quote:
Originally Posted by s/v Jedi View Post
The ultimate bedding between chain plate and the surface that they are bolted onto is a gasket cut from neoprene rubber sheet: the same material as an impeller. They are easy to get, I just ordered some more (1/16" and 1/8" thickness are best) from Amazon.com. Cut them in the same shape or a little smaller (they will expand a bit later). The holes for the bolts must be cut oversize for the same reason. Use a hole cutter (the pipe-like tool that you hit with a hammer.)
OMG, I'm quoting myself...

Anyway, today I made a similar gasket like that again and I attached a photo here. It took me 5 minutes to make the pattern using a sheet of copier paper and 5 minutes to cut the gasket. All the tools used are visible.... well, not the big hammer but that's the secret weapon ;-)

cheers,
Nick.
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Old 12-05-2014, 06:30   #9
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Re: Pulling & Re-Bedding Chain Plates

I am confused, you indicate that neoprene should be used between the chainplate and the knee that is fiberglassed in and the next post says that if I put a gasket between that this will shorten the lifte of the stainless??
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Old 12-05-2014, 10:55   #10
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Re: Pulling & Re-Bedding Chain Plates

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Originally Posted by s/v Jedi View Post
...The ultimate bedding between chain plate and the surface that they are bolted onto is a gasket cut from neoprene rubber sheet...
A huge negative on this! You don't want any movement relative to the chain plate and the surface to which it is attached.

As for loosening the rig, only loosen one at at time, counting the same number of turns on each, so you can re-tension it precisely as it was.
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Old 13-05-2014, 06:22   #11
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Re: Pulling & Re-Bedding Chain Plates

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Originally Posted by S.V.Arebesque View Post
I am confused, you indicate that neoprene should be used between the chainplate and the knee that is fiberglassed in and the next post says that if I put a gasket between that this will shorten the lifte of the stainless??
I read that too and assume there are multiple views on this. However, every chain plate that I have seen disassembled, had a gasket or sealant on it. All of that was on fiberglass.
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Old 13-05-2014, 06:30   #12
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Re: Pulling & Re-Bedding Chain Plates

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Originally Posted by Terra Nova View Post
A huge negative on this! You don't want any movement relative to the chain plate and the surface to which it is attached.

As for loosening the rig, only loosen one at at time, counting the same number of turns on each, so you can re-tension it precisely as it was.
A huge negative on that!

A gasket does not equal movement under load. Only excessive gasketing or use of the wrong materials (too soft) can do this. The 1/16" neoprene is the standard which is still unbeaten by any liquid gasket imo. Liquid is used because of being cheaper in materials and labour.

Counting turns on turnbuckles for a project like this, is a no-no too. Mistakes will be made using that method. Measuring and recording the distance between the two threaded studs is a foolproof method. Yes it requires the correct tool but calipers should be on every boat ofcourse.
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