My wierd chain plate covers - is this right?

jarcher · #1 (**permalink**) 04-24-2009

Hi All...

In various threads I have made reference to my unusual chain plates. I have two on each side. On each side, the aft ones support a single shroud, while the forward ones (about 18 inches forward of the others and even with the mast step) support two shrouds.

The aft ones I'll reserve for another thread (these are the welded ones) but the forward ones are strange. One of the shrouds connects to the chain plate as expected. The other one, however, connects to a mounting point on the chain plate cover. The chain plate cover is through bolted through the deck to a mounting point just below the deck.

I took some pictures here:

Jims Scampi 30 - wierd chainplate covers

The first four pics are various shots of the chain plate and its cover, the next four are the mounting point directly below, under the deck. I apologize for the strange angles. The boat is still under shrink wrap and it was hard working on the edge of the boat.

I see there is a second, unused hole on the chain plate itself. Why would the chain plate cover have a mounting point? Why not use the second hole in the chain plate? Should I replace the chain plate cover with one without a mounting point?

I don't know anything about rigging, so maybe this is normal? The only thing I can think is that the shroud mounted on the chain plate cover might go lower on the mast so it is at a steeper angle, and so can not mount on the chain plate? Because the shrink wrap is still up I could not tell where it connects to the mast, so i don't know for sure.

I would appreciate any comments. I need to rebed this as it leaks like a sieve, and I need to pull the mast for a week. I am wondering is when I put it back up, i should secure the shrouds on the chain plate?

Thanks very much...

Jim

sailingdog · #2 (**permalink**) 04-25-2009

Hate to break it to you, but those chain plates aren't weird. The cover is through bolted to the lower chainplate, but isn't connected to the upper section that is passed through the deck. If it was, you'd never be able to install them. You can see the bedding compound around the upper section of the chainplate, where it passes through the hull pretty clearly.

BTW, don't tape your rigging. Taped rigging is a great way to get crevice corrosion going and ruining the rigging prematurely. I've seen quite a few cases where taped rigging was about to fail due to crevice corrosion.

The reason the second shroud is going to a welded mounting point on the the chainplate cover is the main chainplate coming up through the deck doesn't lead fair for the lower shroud by the looks of it.

Not too sure what the second hole on the main chainplate is for. It could be for a slightly different angle to the shrouds, to alter the rigging tension a bit.

knothead · #3 (**permalink**) 04-25-2009

Quote:

Originally Posted by jarcher

Hi All...

In various threads I have made reference to my unusual chain plates. I have two on each side. On each side, the aft ones support a single shroud, while the forward ones (about 18 inches forward of the others and even with the mast step) support two shrouds.

The aft ones I'll reserve for another thread (these are the welded ones) but the forward ones are strange. One of the shrouds connects to the chain plate as expected. The other one, however, connects to a mounting point on the chain plate cover. The chain plate cover is through bolted through the deck to a mounting point just below the deck.

I took some pictures here:

Jims Scampi 30 - wierd chainplate covers

The first four pics are various shots of the chain plate and its cover, the next four are the mounting point directly below, under the deck. I apologize for the strange angles. The boat is still under shrink wrap and it was hard working on the edge of the boat.

I see there is a second, unused hole on the chain plate itself. Why would the chain plate cover have a mounting point? Why not use the second hole in the chain plate? Should I replace the chain plate cover with one without a mounting point?

I don't know anything about rigging, so maybe this is normal? The only thing I can think is that the shroud mounted on the chain plate cover might go lower on the mast so it is at a steeper angle, and so can not mount on the chain plate? Because the shrink wrap is still up I could not tell where it connects to the mast, so i don't know for sure.

I would appreciate any comments. I need to rebed this as it leaks like a sieve, and I need to pull the mast for a week. I am wondering is when I put it back up, i should secure the shrouds on the chain plate?

Thanks very much...

Jim

What you are calling a chainplate cover can just as rightly be called a chainplate in and of itself.
The fitting on deck which is through bolted to the fitting below the deck, which in turn is attached to a tie rod attached to a sturdy part of the hull, is pretty normal. Yours is interesting in that the attachment for the lowers are welded while the attachment for the uppers is the same piece that passes through the deck. I would think that the reason for this is because of the higher loads on the uppers.

You are correct in your thinking about why the lower shrouds aren't attached to the extra hole in the upper chainplate. You will notice that the attachment for the lower is perpendicular to the upper. If it were attached to the fore and aft plate, the force of the shroud would be constantly trying to bend the plate. Leading to metal fatigue.

Be sure to inspect the fittings carefully when you remove them and definitely replace the bolts. There has obviously been some corrosion there.

jarcher · #4 (**permalink**) 04-25-2009

SD, don't hate to break it to me, you and knothead just made my day, thanks guys! I had been thinking I had a problem that needed to be fixed, but I'm glad I don't (at least not this one). Very glad. I have enough to do in the next two weeks.

SD, I realize the chain plate cover is not connected to the chain plate, but it is on the other chain plate (which I forgot to photograph). I'll post some photos of that once I have them.

This one is seriously leaking, so I'll rebed it like anything else.

Oh, and I'll remove that tape, thanks also for that tip.

Thanks again!

sailingdog · #5 (**permalink**) 04-25-2009

Glad to help out.

BTW, I don't know how old the chainplates on your boat are, but it might be worth taking them completely out and thoroughly inspecting them for signs of crevice corrosion.

Also, get some new clevis pins and cotter pins... and replace any that look at all questionable. The pins are not very expensive, and replacing them is cheap insurance. Make sure you get the right sizes, as getting ones that are close but not the right size can lead to a lot of problems of their own later on. Also, get the largest cotter pins that will fit the hole in the clevis pin, and cut it to 1.5x the diameter of the clevis pin and open it to just 20˚. That will be secure, but still allow you to remove the cotter pin quickly in an emergency, as well as reduce the chances of snagging things on the cotter pin tips. Rounding the tips after cutting them to length is another good idea.

sailingfool · #6 (**permalink**) 04-25-2009

The second, unused hole in the chainplate is the connection point for intermediate shrouds that would be required with a twin spreader rig. Either the builder used hardware from a larger boat, or planned to offer a taller mast utilizing twin spreaders, or maybe offered such as an option.

The setup in place looks pretty well engineered to me.

jarcher · #7 (**permalink**) 04-25-2009

Thanks again everyone...

timebandit · #8 (**permalink**) 04-26-2009

Looking at the pic SD showes it looks like something was attached long enuff to leave a shadow on the empty hole.

jarcher · #9 (**permalink**) 04-26-2009

Quote:

Originally Posted by timebandit

Looking at the pic SD showes it looks like something was attached long enuff to leave a shadow on the empty hole.

Good catch, I'll take a closer look. The other set of chain plates I mentioned don't seem to exist on other Scampi pictures I have seen, so maybe that's related. I have been trying to find another Scampi owner who has original chain plates and would photograph them for me...

jarcher · #10 (**permalink**) 04-26-2009

Okay, here are the pics of the aft chain plate and it's cover on the starboard side (port side is basically the same):

Jims Scampi 30 - wierd chainplate covers

This one is typical of the views of the top:

And this one is typical of the 3 views below:

On top, the chain plate cover is welded to the chain plate. Its thru-bolted through the deck to a backing plate. The actual chain plate goes up through the deck and is not welded to the backing plate.

If this is normal, what is the point of welding the cover to the chain plate? It seems like all it will do is transfer stress to the deck.

Thanks again...