Backstay Chainplate Discussions [pg 152 in Manual]

[tha3rdman]

I think he was going for that high tech sail shape . . .

[mbd]

I just got this back. This is the replacement for the one in post #28. The original was flattened to make the template for the new one. I'm confident in saying, my Backstay Chainplate will no longer be the weak link back there. It was made with 316 stainless. A couple of more holes were added as per the manual also...

[Hull376]

Mike, looks like the one I had made, real beefy!!

[mbd]

Hey Kent, you got any pictures/pointers on your installation?

PS. The heat up here this week reminds me why I moved from Austin a few years back - only there's no AC to retreat to up here! Yuck!

[Scott Galloway]

Here is a question on the backstay chainplate. I had a new backstay chainplate made and I installed in 2002. It was made from 304 stainless and is pretty beefy. The argument for 304 at the time was that it was stronger than 316 stainless, which is true apparently, until it corrodes. I want to eventually replace it with 316 stainless, since the darn thing seems to be rusting in the salty lazarette environment. To date, the rust seems to be superficial, so I have not been in a hurry.

All seemed well for four years, but after a couple of days of heavy wind (30-35 mph) last month, I noted that the backstay chainplate cover had risen somewhat at the forward end. I removed the screws, cleaned the chainplate cover and chainplate of old polysulfide caulk and superficial rust and rebedded the cover. The cover slipped very nicely back over the chainplate, but the screws that hold the cover to the fiberglass deck now seem to be somewhat forward of the original holes in the fiberglass deck. They fit in the holes, but at an angle sloping aft from top to bottom.

So this is a concern to me. I took the boat back out on a 30- 35 mph day and sailed lose hauled and on a broad reach in four foot swells both unreefed and later double reefed, and the plate popped up in front again slightly. The front screws are loose in their holes, so they are not really holding in the deck, but there must still be some upward or forward pressure to pop the plate up, and to have moved the plate forward slightly so that the screws are no longer vertical. I can't recall for sure whether the screw holes were actually vertical in 2002, but I can say that the cover has never popped up before. If the width of my (new in 2002) backstay chainplate was slightly greater than the original, the screw holes would not have aligned.

Inspection below tells me that the backstay chainplate still seems to be well secured to the knee with the original three bolts and two additional bolts that I added at the time of installation in 2002. One of these additional bolts runs through an extension that I glassed on to the top of the knee. The extension seems to be solid. So all seems well below, but yet the chainplate must have somehow bent forward or slipped forward slightly. For four years this was not a problem. Now I seem to have a problem. Or do I?

In intend to remove and inspect the chainplate and then order new one made from 316 stainless and of thicker stock, but I am curious about why this might happen, as the thickness of my 304 stainless steel chainplate is substantially greater than what was there originally.

I replaced the original based on the experience of others on this forum and the recommendations of the Ariel Manual. A thicker chainplate seemed to be in order. My original chainplate, scrawny though it was, was not deformed in any way. The new chainplate was supposedly cut out of 304 stainless using the original as a template, so the width, length and forward to aft sloping angle of the top section should be the same as the original. Any thoughts?

[Bill]

. . . but yet the chainplate must have somehow bent forward or slipped forward slightly. Any thoughts?

From our experience tuning the boat for racing, I've found that the tightened backstay will pull the chainplate forward. I don't believe it's moving where attached to the knee. The bolts and all are fine. Rather, the stern portion of the hull may actually be "bending" a bit from the stay's pulling force against it. As noted in the manual, probably the real fix is to reinforce the weakest part of the boat -- its stern.

[tha3rdman]

I was looking at the A286 on ebay and noticed his back stay,