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Backing Plate Material?

GJ Jones

Junior Member
Greetings All. First, thanks for sharing all of your advice in these forums. I noticed that the POs of my ('73) E27 had never installed any kind of backing plates for the lifline stanchions, or anything for that matter. I was getting ready to make up some SS when a friend at the YC mentioned that it would be quicker to use G10, available at a local plastic supplier. G10 is Epoxy Glass board made under pressure, from what I could grasp from a quick browse through the net. I am going to ask the supplier, and call a couple of plastics guys I know to get their take, but what do the EY.c community think? Would I be wasting time? I also found out yesterday that the Edson pedestal had leaked-the wood underneath the deck that was used to support/mount it has delaminated big time, so I was thinking about using the G10 here too, as a backing instead of the current marine plywood. Thanks! Gary
 

jwolfgra

Member II
Very very interesting. I used to be an avid windsurfer, 80+ days per year on the SF bay, CA coast and Hawaii. The fins on all my boards were made of G10, and I never had one break. The fin would actually tear out of the board before it would break. This sounds like a fantastic idea, I'm presuming the material is relatively cheap, and can be worked with standard wood working tools.
 

Geoff Johnson

Fellow Ericson Owner
When I was repairing my below decks autopilot, my yard reinforced the plywood mounting point with a backing plate made of something it called "mil spec fiberglass board". Sounds like the same thing.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Just like your hardrive, Always back up!

I researched this particular frp board when trying to decide whether to fab up my own custom water tank. I finally decided that whether I made my own panels out of cloth and epoxy or bought theirs, it was going to cost more than I wanted to invest. Small G10 panels were about $80, as I remember. OTOH, making up quarter inch panels myself was going to take some serious amounts of epoxy and cloth and not save any real money.

The most common material I have used for backing plates over the years is quarter (or 3/8) inch aluminum plate. It is easy to shape and cut and has the needed strength. Sheet poly plastic is used by some boatbuilders, also. I consider it potentially too brittle, but that's just my opinion.

One other source you might consider is the local boatyard. I saw a local yard junk out an old Cal 20 last year -- they cut it up with a saber saw into pieces and put it into a dumpster. There were LOTS of flat areas where anyone could have sawed off parts of laminate about a quarter inch thick for future backing plates...
One nice thing about using frp or aluminum is that if there is a leak in the future, you will not have rot damage to deal with like you would with plywood.
:(
You did not ask, but I would advise never to caulk *under* the deck where you are putting the backing plate and nuts. Caulk only on top, under the fitting or stanchion. If it should ever leak, you do not want to trap water inside the laminate or coring. You need to see the leak and then re-bed the offending fitting.
;)

Good luck on your project,

Loren
 
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GJ Jones

Junior Member
Follow Up

Thank You all for your input. Loren, I appreciate your extra words, I hadn't planned on caulking the plates in, but know I would have probrably done it ''while I was in there'. I stopped by the yard where the boat is resting, and spoke with my rigging company about their ideas for back plates. They had G-10 in stock, and use it without problem. They also recommended a material that looked like Delrin to build up under the pedestal. I think that the G-10 may be a little lighter. As for $/performance, I have not found the G-10 to be expensive. I did find some pieces in stock at the local plastics house, so they were less expensive than usual. It also depends on the type of material. The Web yielded a price difference of 20% between two local offices of multi-state operations, comparing apples to apples. Now, as I am frugal, I will also ask all of my machine shop friends if they have any scraps (including aluminum plate) to trade for cheap beer.
 

GJ Jones

Junior Member
My final answer

I have found that there are Stainless Steel backing plates for trapazoidal 4 hole stanchions available at: www.catalinadirect.com, for $3.95 ea.
Since I am running out of time (I know, why should I feel special?), and patience (with the whole world-I need to be on a boat), I am going to order these and make them fit for now. I haven't checked to see what the delivery time is, so I may be backordering them while I work on the other more pressing repairs.
 

tilwinter

Member III
G10 FR4 Epoxy glass: how thick?

I have been able to locate a source here in Baltimore for the G10, but the thickness can be anything from .010 to 5". Those of you who have used this: how thick do you recommend?

Rod Johnson
E 30+ 1981 "Til Winter":confused:
 
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