>… a bit leery of using the G10 as a backing material. Properly sized G10 and similar high density epoxy board material is likely stronger that the surrounding hull structure. For keel bolts I would use a SS washer under the nut but if additional spacers are needed, even on our 43’s 9,000 lb. keel I would use epoxy board.
A plus to the epoxy/glass board is the lack of corrosion and relative ease of machining (drilling / shaping) however epoxy/glass board will dull drill bits and other cutting tools quickly. On Calypso I have used many different thicknesses of G10 and FR4 (fire retardant) in the ongoing deck repair/restoration project. I have access to many thicknesses and types of epoxy board as my company uses it in many products. Calypso’s new deck hardware backing plates are epoxy board or a layup of several layers of epoxy board and bi-ax cloth when additional thickness is called for. Martin DeYoung Calypso 1971 C&C 43 Seattle [Description: Description: cid:D1BF9853-22F7-47FB-86F2-4115CE0BAF2F] From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Rick Brass via CnC-List Sent: Tuesday, November 24, 2015 8:31 AM To: cnc-list@cnc-list.com Cc: Rick Brass Subject: Re: Stus-List Update: Re: Keel attachment issues on a C&C 25 Ahmet; As I said before, I replaced the original steel backing plates (if I recall, they were more like steel fender washers) on my 25 when she was a bit over 20 years old. I had some square backing plates made out of 3/16” or ¼” stainless. About 3 or 4 inches square and with the proper sized holes drilled in the middle. A local machine shop could probably knock out the 5 or 6 plates you will need in not much more than an hour – or you might get a friend with a suitable shop in his garage to do it for the price of a 12 pack. I think I put a bead of 4200 under each plate when I torqued them down, but I suspect that was actually overkill. Were I to do the same job today, I would go to Fastenall, or another industrial hardware supplier, and buy a stack of stainless fender washers of the appropriate sizes and just put two washers under each nut and retorque the nuts. Proper torque on the nut is very important. I think I borrowed or rented a torque wrench and a torque multiplier from a local NAPA store when I did my project. The photo album has a listing of the proper torque values. If you had no leakage when you removed the nut, the sealant between the top of the keel and the keel stub is still doing its job after 40-some years. Proper torque on the keel boats will keep it so. Sealant on the inside of the joint is probably not going to keep any leakage out. But sealant between the washers and the bolt in the presence of water in the bilge is a potential recipe for crevice corrosion that will weaken the bolt. If your boat is like mine, that may not be a concern. Belle is a very dry boat. Every 6 months or so I clean out the bilge – usually with a sponge. I don’t recall having accumulated more than an inch of water in the bilge since I refinished and rebidded the handrails and added some butyl around the chain plates a decade or more ago. I would personally be a bit leery of using the G10 as a backing material. You have a lot of compression under the nuts, but you also might have shock loading if you ever run aground, and a fair bit of torsional loading as the boat heels and moves in the waves while sailing. I think stainless would be a stronger and more conservative choice. Rick Brass Imzadi C&C 38 mk 2 la Belle Aurore C&C 25 mk1 Washington, NC
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