alanro
08-06-2011, 08:09 PM
My new to me Windward 850 is a 30 year old 28' sloop.
I love just about everything about her except the back stay, or more accurately, the "chainplate" for the stay. Rather than a conventional chainplate, a U bolt is used, through the rear deck.
I think the boat was designed with a split stay in mind, but some previous owner had gone with the U bolt.
What they didn't do was add a backing plate, just some big washers. Worse, they didn't attach it to the hull in any way.
The end result is that the desk has deformed, with a graceful "bulge" under the U bolt, so graceful it almost looks normal.
However, the deck has also lifted away from the hull in the area of the U bolt by about 3/4" of an inch.
This clearly has to be fixed.
Sadly, engineering texts on the subject seem to be sorely lacking, so I thought I would just take a tour of the marina and see what other designers of similar sized boats had done.
And what I found left me even more confused. Looking at external chainplates only, at one extreme I found one that used a 1" x 1/8" x 6" strap held on with a couple of 1/4" bolts.
At the other extreme, I saw a 2" x 3.8" x 12" strap held by six 1/2" bolts.
My tentative plan is somewhere in the middle.
A piece of 1/2" x 1" x 10" will be bolted (on the narrow edge) to a 6" high x 8" wide x 1/4" plate. It will also be welded ('cuz I'm chicken).
A similar plate will be used as a backing plate.
Four 3/8" bolts, holes drilled in a "V" pattern, will be used to fasten the two plates to the transom.
After that, it's all conventional; 1/2" hole, clevis holding a toggle, etc.
Am I off base here? Overkill? Brave?
Any thoughts or opinions on this plan gratefully accepted.
And pointers to anything technical also much appreciated.
Thanks in advance.
Alan
I love just about everything about her except the back stay, or more accurately, the "chainplate" for the stay. Rather than a conventional chainplate, a U bolt is used, through the rear deck.
I think the boat was designed with a split stay in mind, but some previous owner had gone with the U bolt.
What they didn't do was add a backing plate, just some big washers. Worse, they didn't attach it to the hull in any way.
The end result is that the desk has deformed, with a graceful "bulge" under the U bolt, so graceful it almost looks normal.
However, the deck has also lifted away from the hull in the area of the U bolt by about 3/4" of an inch.
This clearly has to be fixed.
Sadly, engineering texts on the subject seem to be sorely lacking, so I thought I would just take a tour of the marina and see what other designers of similar sized boats had done.
And what I found left me even more confused. Looking at external chainplates only, at one extreme I found one that used a 1" x 1/8" x 6" strap held on with a couple of 1/4" bolts.
At the other extreme, I saw a 2" x 3.8" x 12" strap held by six 1/2" bolts.
My tentative plan is somewhere in the middle.
A piece of 1/2" x 1" x 10" will be bolted (on the narrow edge) to a 6" high x 8" wide x 1/4" plate. It will also be welded ('cuz I'm chicken).
A similar plate will be used as a backing plate.
Four 3/8" bolts, holes drilled in a "V" pattern, will be used to fasten the two plates to the transom.
After that, it's all conventional; 1/2" hole, clevis holding a toggle, etc.
Am I off base here? Overkill? Brave?
Any thoughts or opinions on this plan gratefully accepted.
And pointers to anything technical also much appreciated.
Thanks in advance.
Alan