I think Rich is right in his comments on stress load. I have two chainplate stud assemblies cut off and am about to replace them. The 5 studs were 3/8x 3" bolts with 2 1/2" spacing welded to about a 12" stainless strap. This was embedded in maybe 2" thick mahogany plywood that was then encapsulated in fiberglass. The old laminate varied in thickness from 1/8" to almost 3/8"- not exactly great quality control. It was thinnest in the area of the studs. I had all of the chainplates remanufactured from 316 stainless 3/8" thick all other dimensions stayed the same. The new studs are 316 SS 3 1/2" so that the chainplate rest on the solid shank instead of threads. These are embedded in a 2" laminate of 1/2" marine plywood and 6 oz. glass cloth. After shaping the block, it is ready to be glassed in place. I also made a jig so that the new attach fitting will be in the same spot as the old one. I'll let you know how the rest of the job goes. I also think I have a way of keeping future water out so that they last longer than 20 years. --------------------------------------- The summary is: I cut/grinded apart the bases and replaced with marine plywood wood core, new stainless components and re-fiberglassed ... essentially a direct rebuild of the original. After I removed the chainplate, I made a jig to use in the alignment for the new studs. The old assembly was cut/ground off. We are now down to the original hull lay-up. I now formed up the plywood block, don't forget to cut the back for the strap. Drill the new holes, using a new chainplate for a guide. I now used West System Epoxy to glue the block on the hull with the use of the jig. After this sets up I double check the measurements and remove the jig. Something I added to the re-construction will hopefully keep water out. I sealed the area between the box beam,deck and hull pieces in the bulwark forward,aft and above the chainplate mount. I now drilled two small holes in the bulwark in the area I just sealed for later use. At this time I did the new lay-up using west epoxy and fabmat. The first lay-up was probably 10-12 inches out from the block and then built up to match the original. Don't forget to cover the studs during this. Now in a perfect world, the new chainplate will fit. I did have to grind the opening a bit. Now it is time for those two holes outside in the bulwark. I mixed epoxy a little at a time to fill the void above the block in the bulwark. This hopfully will keep any water out of the new wood. Now, you are ready to mount the new chainplate. This does not take into account any of the interior wood work that must be removed and re-installed from the area. I also hired a surveyor to look at this before ,during and after the job was done. about sealing. So far everything has worked fine, no leaks cracks or any movment of any kind. The best test so far was the sail out of Secret Cove to Halkett Bay, averaged over 7 knots with alot of 8½ - 9 knot surfing. Some of it was actually fun but not all of it. Give me a call any evening if you have any questions. Regards , Bruce (360) 371-2950 ============= re: the jig for mounting the bolts and chainplate: The old studs where 3/8 x 3 inches long and all thread. The new ones are 3½ inches long. This makes sure that the chainplate rests on the solid shank of the bolt and not the thread. The fact that these bolts are longer,they will make installing the chainplates harder. The opening will need to be enlarged some. This is not bad as it will open up the area between the chainplate and the deck. This will give the caulking more "flex room". I have about ¼ inch around the chainplate. Info-- Puting everything back in place a touch off shouldn't hurt any. Also, the upper chainplate was bent at the same angle as the lowers. When I had the new ones made, I left it straight. It fit better and the lead to the shroud is much better. Jig info-- After the chainplate is removed and before any cutting is done, I made a jig. I fabricated a piece of wood to go over the old studs like a chainplate and ran a couple of nuts down to secure it. I then screwed a block of wood into the bottom of the deck and attached it to the wood "chainplate" with thin stable plywood. Now, unbolt the studs and take out the screws from the block in the deck and you should have a jig that sort of looks like a "V" that is made from 4 pieces of wood and a few small screws holdiing it all together. Cut the old stuff off. Now remount the jig on the lower side of the deck. Now you can install the new block and stud assembly in the original spot. Don't foget to take into account the original lay-up thickness . I just used a spacer. Each chainplate had to have a new jig made. On two I used the deck for the base and on the others I used the top of the locker. Mine where located in the head, hanging locker and two in the main cabin. Also, it is ok to put those pictures on the web site. Hope this helps, Bruce Mailform request via a contact form on sikasolutions.com: -------Typa of Application--------------------------------------------- -- Type of Application: MarineCommercial -------Personal Data--------------------------------------------- I need a sealant to use for chainplates that go thru the deck. It needs to bond to both stainless steel and fiberglass plus allow some flex. . 291 LOT? primers, etc. “Silaprene" was also suggested. I guess a competitor. Any help or comments with your product would be appreciated. Thanks, Bruce ------------------------------------------------------------------- Request date: 22.Mar.2004 - 13:50 --------------------------- Bruce, Sikaflex 291 will work well on this. However, I would recommend cleaning and priming. Stainless is difficult to bond to and a chainplate is usually under quite a bit of stress. Scuff the fiberglass and stainless with scotchbrite, wipe with Sika Cleaner 226 and wait ten minutes. Then paint on a thin coat of Sika Primer 206G+P (black) or 210T (clear) wait 30 minutes. Apply Sikaflex 291 and assemble everything. Do not fully tighen any fasteners for a day or so. Regards, Steve Padgett Sika Corp.