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  Topic Review (Newest First)
2 Days Ago 07:57 PM
wsmurdoch
Re: chainplate followup

Quote:
Originally Posted by jnewcomer View Post
I did investigate having custom, button-head, socket cap screws made but the cost was prohibitive.
One of my favorite merchants is McMaster Carr. Long ago their yellow and green catalogue sat on every maintenance foreman's desk. If you think it should exist, they have it... now on the internet.
McMaster-Carr

Grainger also has them in 18-8.
2 Days Ago 06:25 PM
jnewcomer
Re: chainplate followup

We have a 1980 C37 yawl and replaced the six shroud chainplates while in Mexico in 2009. This is because the Admiral found small cracks on two of them while polishing. The cracks were on the inside surface above the caprail.

We did them one by one with the rig up. I can add a few tips for replacing them. After removing the carriage bolts (I have other tips for that fun part), pulling on the shroud will pull the chainplate free of the rubbing strake. We could only get 316 plate in 5/16 inch thickness in Mexico so we went with that. Fortunately the fabricator we used had a water jet cutter which makes very precise, stress free cuts. Cleaning up and enlarging the rubbing strake openings to remove the 5200 and to take the thicker stock was made possible using a Fein tool with a saw blade. Without such a tool it would have been nearly impossible.

To avoid the point loading of the carriage bolts in a round hole I had a machine shop turn down the squares under the heads to 1/2 inch. The jet cut holes were also 1/2 inch. I wound up sanding flats on the sides of the heads so I could hold them while the Admiral tightened the nuts. Had I known I would have had the machine shop put the flats on or maybe slots. NB, I did investigate having custom, button-head, socket cap screws made but the cost was prohibitive. I polished all the bolts to a mirror finish; the chainplates were already a mirror finish. For the aft stay, which is split on our yawl, I had the same machine shop make SS adapter rings to so the new bolts would fit the existing chainplates since we were not replacing them. The old aft chainplates plus the four for the mizzen were all taken off, inspected and mirror polished and re-installed. I did not remove the head stay.

I hope this is of some use for your chainplate project.

John
s/v Pelagic
1980 C37 Yawl (#22)
Seattle, WA
4 Days Ago 07:30 PM
wsmurdoch
Re: chainplate followup

Quote:
Originally Posted by MarcHall View Post
Bill

Did the new 316 chainplates from PSC come with round holes or square holes like your old chainplates ?
Square holes with slightly rounded corners polished to a mirror finish...

Thumper said not to worry about stress risers in the slightly rounded corners, and my experience matches his opinion. He says hex head bolts catch sheets and do damage to boats rafted alongside. I followed his advice - square holes and carriage bolts.

Bill Murdoch
1988 PSC 34
Irish Eyes
4 Days Ago 06:54 PM
Lantau
Re: chainplate followup

Quote:
Originally Posted by Hush34 View Post
When I was searching for a sailboat a top priority was finding one that had easy to replace chainplates. ...
Yup. I was considering an IP until I discovered their nightmare chainplate setup -- half the interior has to be removed to get at the chainplates, but even then they are glassed in so impossible to inspect without removal. And glassing them in creates huge corrosion problems, so inspection is extra important. Some folks don't like seeing the chainplates on the outside of a PS hull, but those people probably don't do much work on boats...
4 Days Ago 05:10 PM
Hush34
Re: chainplate followup

When I was searching for a sailboat a top priority was finding one that had easy to replace chainplates. I am like Dave...all parts of the standing rigging are suspect if once they are 10 years old. Hush has brand new rigging except for the stem. I was worried about that but agree it is built very stout. Will have to monitor. Why put off for tomorrow what you can do next year?
4 Days Ago 04:41 PM
MarcHall
Re: chainplate followup

Bill

Did the new 316 chainplates from PSC come with round holes or square holes like your old chainplates ?

Replacing the chainplates is on the list of projects to be done this year.

Regards
Marc Hall
Crazy Fish - Maintaining, Upgrading and Sailing a Crealock 37
5 Days Ago 09:54 PM
wsmurdoch
Re: chainplate followup

Looking at my chainplates this fall, I saw a crack in the one for the port top shroud. The crack ran from the top bolt hole to (and through) the side of the plate. It was open, brown, and easily seen.

Later, closely examining the other five chainplates, I found smaller closed cracks in all but one. The small cracks were in groups and were visible in the sun when the chainplates were clean and shiny. Several of the chainplates had cracks that were covered by the carriage bolt heads. The one good chainplate was in an area where the boat had been damaged before I owned it, and because of some small differences between that chainplate and the others, I don’t think it was original.

Four of the cracked chainplates only had cracks in their visible surfaces. One had cracks in its face that was against the hull. That was the only chainplate which had failed caulking. It had a small bend away from the hull, perhaps from some past accident, that had separated the caulking from the chainplate.

All of the cracks were associated with the bolt holes. They did not appear to be particularly associated with the corners of the square bolt holes. Most were along the straight sides of the holes.

None of the chainplates had any crevice corrosion.

I bought and installed six new 316L shroud chainplates which I bought from Pacific Seacraft who reported that the original chainplates were 304 stainless steel. I used new 316 carriage bolts and nuts which I bought from McMaster Carr. All were ”x 1” except for one that was 2” long. I polished their heads before I installed them. I did reuse the lock washers that were under the nuts. Several of the bolts did not have lock washers, and I did not add them. I caulked the chainplates and bolts with BoatLife Thiokol Caulk.



Bill Murdoch
1988 PSC 34
Irish Eyes
04-15-2011 06:15 PM
niftynickers In the pursuit of further knowledge today we sheared the corroded chainplate 3 more times at 4" intervals.As previously noted the corroded piece was from the lowest part of the chainplate(closest to the water).The subsequent cuts were all good metal,no corrosion evident.I think this confirms what Bill Murdoch said about Chloride corrosion from seawater immersion.

Dianne and Chuck Burke S/V NiftyNickers C37 #139
04-12-2011 01:39 PM
DaveMancini Your right Chuck. The strap on the 1996 is 3/8" x 1.75" wide x 7/8" radius, pretty hefty. Yes, I would lose sleep too.

Dave
04-11-2011 10:37 PM
niftynickers Dave,

I initially felt the same way about the stem head fitting but I think that the older boats like mine may be constructed differently from yours.I don't have a bowsprit like the newer boats and the build may not be as robust.
Mine has a SS strap that bolts thru into the anchor locker and is welded to the 2 anchor rollers at the bend around the deck.The strap is 1/4 SS the same as the port and strbd chainplates.After seeing the degradation of the plates that were rpld ,I'm no longer confident in the stem or stern plates.The thought of what could happen if the stem breaks would keep me awake nights if I didnt replace it.Ditto for the stern.

Dianne and Chuck Burke S/V NiftyNickers C37 #139
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