Randy, When I use the bent nail trick, I actually us allen wrenches and dig progressively deeper and deeper by going larger and larger on the choice of wrench. You'll want a shopvac. You may also have trouble getting the thickened epoxy to wet out all of the inner surfaces and then you may have trouble getting the thickened epoxy to not sag. When you do such a large volume be careful of thermal runaway and if you do it in smaller batches just be careful of the possibility of amine blush not allowing a good bond between layers.
Here are my suggested solutions: Seal the bottom of the void completely. For small holes on smooth interior surfaces masking tape, duct tape, or gorilla tape works fine. For uneven interior surfaces you may need a strongback. A piece of wood plank wrapped in waxed paper with 1 or 2 long bolts through it would probably work. You'll want to consider some type of inner gasket. Playdow or plasticine should work pretty well to eliminate the possibility of leaks. Nobody wants epoxy leaking into their cabin. The long bolts let you attach an outer backing plate which will pull the wood tight to the inner surface. Once you have confidence in your setup, mix up a small batch of 5 MINUTE epoxy. Spread this on the inner surfaces which might leak, just to create one more barrier. It doesn't need to be a lot. 5 minutes later you can use a low viscosity epoxy to completely wet out the void (I like smith's CPES). A syringe and/or a piece of tubing may be helpful. To avoid amine blush between layers I would try to do a single "monolithic" pour of your thickened epoxy. To avoid thermal run away find an epoxy that has a painfully long cure time in hot weather. Then with your unthickened epoxy of choice fill the cavity to the brim. As you're filling focus on the areas nearest the boat's centerline since these are elevated and won't get covered as the liquid reaches the lower brim. Use your syringe to suck out the epoxy into a container. Add your filler and then refill the cavity. Something with a consistency of peanut butter (like Six/10) is great since it won't sag but it is also flawed in that unless you can hydraulicly push the mix into the voids you are at risk of not getting a complete fill. A little thinner and gravity will help fill the voids but then it runs out the lower holes and flows over the lower brim. In an ideal world you would have an outer strongback which is gasketed the same as the inner one. Drill a small hole (1/8th or 3/16ths) near the outboard edge of the void and another near the inboard edge. Use the bottom (outboard) hole to inject thickened epoxy into the void until it comes out the vent at the top (inboard). Use a wood screw to plug the fill hole and then make sure it is topped up at the vent. If you feel like it, those long bolts are useful for holding down a cover on your project. A day or two later you can remove the vent screw to test how the epoxy has curred. Can't get the screw out? That's probably a good thing. Try to unbolt your strong backs but if they are stuck a little heat from a torch will make them slide right out. Waxed paper should release and the plasticine will unstick. Now you have a perfect plug of epoxy. Just drill a series of holes to get a saw blade in and then cut your slot for the chain plate. Once you get the slot wide enough a small sanding drum is invaluable for dressing up the area. I would hesitate making the slot any wider than necessary. I don't think the chain plate needs to move side to side in the slot so wider than necessary just makes sealing the hole more difficult. Chamfer the edges of the slot to create a funnel for the sealant. Predrill the holes for the cover and counter sink them to funnel sealant too. I don't know of a good reason not to use butyl tape so once your plate is bolted back in place make sure to pack any gap around the chain plate and make a doughnut around the chain plate. Layer the cover plate with a thin layer of butyl (stay about 1/4 of an inch from the edges). Tighten everything down. Having an extra set of hands will help at almost every step of the process. Good luck, Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Jan 30, 2017 10:17 PM, "RANDY via CnC-List" <cnc-list@cnc-list.com> wrote: I'd really like to thank everyone for all the responses on this. Went back to the boat today and carefully re-examined the core around the chainplate cutouts, and did a bunch of testing - percussion testing, weighting the area and looking for deflection, etc. Put a few pictures up at https://drive.google.com/open?id=0B-NqAxQ6JxFTcTV6UlEwMmlqZkk. I don't think the extent of coring warrants peeling the top skin and replacing core material; I think digging out some core around the edges, and filling with thickened epoxy, will be enough of an improvement and repair. The deck, especially outboard and downslope of the chainplate cutouts, doesn't sound dull and doesn't deflect downward. It seems solid enough. The chainplates themselves show no signs of corrosion or moisture damage. Only one bolt (lowest inboard starboard) out of 14 showed any rust, and it was superficial (nowhere near twisting the head off). I'm fortunate that my boat has had a freshwater life its entire life. You can see in the pictures I've got a bit more old sealant to clean away, but then I think a dig, fill, and re-seal job should suffice. Really appreciate everyone's responses. Someday I'll need to work up the courage to do a peel & re-core job under my starboard aft bow pulpit foot - I have a small soft spot there. Best Regards, Randy Stafford S/V Grenadine C&C 30-1 #7 Ken Caryl, CO ------------------------------ *From: *"Dave S via CnC-List" <cnc-list@cnc-list.com> *To: *"C&c Stus List" <cnc-list@cnc-list.com> *Cc: *"Dave S" <syerd...@gmail.com> *Sent: *Monday, January 30, 2017 9:43:00 AM *Subject: *Re: Stus-List Deck Coring Around Chainplates FWIW, and I agree with much below. Will assume you are dealing with balsa and not plywood as a core. Have repaired both and will share the following, YMMV, etc... Probably way too much info, but: 1) Damp balsa does not mean structurally unsound.... (yet) 2) I prefer to remove more rather than less. This allows you a large enough area to work, makes it easy to clean/prep the surfaces, as well as being certain that you are not building any voids into the finished result. You can also use really thick glass-loaded epoxy that simply cannot be injected into a small hole. As with drywall/sheetrock, it is sometimes easier when doing repairs to give yourself space to work, and to prep the surfaces. 3) I like the hole saw approach, cutting through one skin only. The hole saw also allows you the opportunity to install a structural filler piece, well bedded in glass-filled epoxy. Rather than just troweling in the schmutz. you can laminate a sheet of fibreglass into a high density layup of the appropriate thickness, (even tapered, or curved) then use the same hole saw to cut out a "puck" from that sheet and install into the hole. Bulletproof. 4) IMO Working from below is best if you have the space/access, for a number of reasons, including the fact that any holes won't move. Working from above can be easier, though the cosmetic redemption is harder. 5) Epoxy is available in a range of cure times. "hot in the pot" should not be an issue if you pick the right one. Never had that happen, but I have had it get a little warm and further shorten the cure time. (have had polyester resin get pretty hot....) 6) To make a patch that feathers on the edges, laminate progressively smaller pieces of cloth (alternate mat and cloth with polyester resin, I like biaxial stitch mat with epoxy) on a sheet of waxed paper, then lift that and stick it onto the wound like a bandaid, peeling off the waxed paper. Best is to do this (or any sequential application of epoxy) on top of the previous epoxy application while it is at its B stage (gelled but not cured) Not only is the putty still it pliable, but it will not need prep to achieve a good chemical bond. You can not simply epoxy over top of cured epoxy and expect a bond. (google "amine blush") 7) when done, (but not cured) you can carefully lay some PE film (or waxed paper) over top and smooth. this can help tame any stray edges and depending on the repair, actually functions a bit like a vacuum bag, assisting in adhesion to curves. You can also shape any putty into smooth shapes or radii for a more professional result. 8) Read up on fillers. If you expect to fill space, you don't want the epoxy to flow, you need colloidal silica, If you want it to be strong you need to load with glass, you want to sand it microspheres. (don't put yourself in the position of having to sand the structural part of a repair....) 9) make a notched trowel and use appropriate fillers for fairing/finishing. The notches leave little ridges in the epoxy. Sand those off and stop. OK, that's enough... Dave ---------- Forwarded message ---------- From: <cnc-list-requ...@cnc-list.com> Date: 30 January 2017 at 09:25 Subject: CnC-List Digest, Vol 132, Issue 70 To: cnc-list@cnc-list.com Send CnC-List mailing list submissions to cnc-list@cnc-list.com To subscribe or unsubscribe via the World Wide Web, visit http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com or, via email, send a message with subject or body 'help' to cnc-list-requ...@cnc-list.com You can reach the person managing the list at cnc-list-ow...@cnc-list.com When replying, please edit your Subject line so it is more specific than "Re: Contents of CnC-List digest..." Today's Topics: 1. Re: Deck Coring Around Chainplates > Chainplates (Danny Haughey) 2. Re: Deck Coring Around Chainplates > Chainplates (Danny Haughey) 3. Re: Deck Coring Around Chainplates (Hoyt, Mike) ---------- Forwarded message ---------- From: Danny Haughey <djhaug...@juno.com> To: cnc-list@cnc-list.com Cc: Date: Mon, 30 Jan 2017 09:08:16 -0500 Subject: Re: Stus-List Deck Coring Around Chainplates > Chainplates Hi randy, It seems you are definitely going in the right direction. I had a problem like this on one of my old boats but, under the bow rail feet. I traced out the size of the plate and oped things up a bit with a hole saw to give deeper >>>snip _______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated! _______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated!
_______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated!
