Backing Plate for Swivel Cam Installation

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jbrock

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Jul 12, 2009
54
Macgregor 25 Regent Point Marina, Virginia
I am trying to install this Harken 205 swivel cam base on my Macgregor 25 to replace my mainsheet system. I am trying to find an aluminum backing plate and am having trouble finding one (old wooden plate currently there). Does anyone have any suggestions? Also, should I use any epoxies or adhesives to complete the installation? Any suggestions would be very helpful. Thanks.
 

Timo42

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Mar 26, 2007
1,042
Venture 22 Marina del Rey
I made mine of epoxy coated 3/8" marine plywood, sealed to the hull with 4200. Given the thickness of the hull in that area , that should be plenty strong. If you want aluminum, you will have to fabricate them yourself. 3/16" should be thick enough, but you will have to protect against corrosion.
Tim
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
You might visit a local air duct manufactring company. I found a great source of backing matierials from when they punch holes for pipes and ducts in aluminum panels to make plenum chambers.
 

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
Use SS and you don't have to worry about the corrosion from the SS hardware.
 

jbrock

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Jul 12, 2009
54
Macgregor 25 Regent Point Marina, Virginia
Thanks everyone. Can you purchase marine plywood at Lowes/Home Depot or do I have to go to a more specialized store?
 

jbrock

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Jul 12, 2009
54
Macgregor 25 Regent Point Marina, Virginia
Also I wanted to know if any adhesive or sealant needs to go between the block mount and topside fiberglass. I've obviously never installed my own deck hardware before. Thanks.
Justin
 
Feb 26, 2004
23,353
Catalina 34 224 Maple Bay, BC, Canada
Think about it

You want to keep the water OUTSIDE the boat, right? And you don't want to trap water that MAY get in between the outside and the inside because it'll sit there and rot the balsa core of your deck between the outside fiberglass and the inside liner (if that's what your boat is made from).

So, use sealant on the outside, not the inside.
 

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
You should also pot the holes(fill with thickened epoxy and redrill) so that if water does get in you will know it and it will not get into the core. I would use Butyl tape for an installation like this.
 
Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
Why not just make up a fiberglass backing plate. They're pretty easy to layup and you can make them almost any size/shape you need.
 

Timo42

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Mar 26, 2007
1,042
Venture 22 Marina del Rey
Your boat has no core where you are going to mount that, use 4200 between the base and the hull, I stick the reinforcement on with 4200 mostly so it stays where I put it, baltic birch plywood from HD will work if you can't source marine ply, especially if you coat it in epoxy first. sticking it to the hull with epoxy would be better, but messy and permanent if you change your mind. If you get serious about it, you are probably going to want to change to midboom sheeting and a traveller eventually. Like this.

edit, oops not the pic I thought it was,:doh: but you get the idea:D
 

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jbrock

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Jul 12, 2009
54
Macgregor 25 Regent Point Marina, Virginia
Thanks, Tim. You have tried to sell me on that traveller before. I just needed a good fix to a bad mainsheet system, and didn't want to get into all that right now. So if I use 4200 I'll be able to remove the cam base without too much trouble when I go to install my midboom sheeting system? Many thanks.
 

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
Thanks, Tim. You have tried to sell me on that traveller before. I just needed a good fix to a bad mainsheet system, and didn't want to get into all that right now. So if I use 4200 I'll be able to remove the cam base without too much trouble when I go to install my midboom sheeting system? Many thanks.
No. 4200 is not very easy to remove. Just slightly easier than 5200. Use Butyl and you will have less chance of leaking and it will disassemble very easily.
 

Timo42

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Mar 26, 2007
1,042
Venture 22 Marina del Rey
But wait, there's more...:D

Seriously some of these guys know a lot more about this stuff, I just know the boat, haven't tried the butyl on the boat, but I have used it on cars. AFAIK it only comes in black though. One thing you don't want to use is silicone sealer though.:eek:
 
Jan 10, 2009
590
PDQ 32 Deale, MD
Grey butyl is available at any good RV store.

But wait, there's more...:D

Seriously some of these guys know a lot more about this stuff, I just know the boat, haven't tried the butyl on the boat, but I have used it on cars. AFAIK it only comes in black though. One thing you don't want to use is silicone sealer though.:eek:
Fiberglass cut-outs from boat yards are a good choice for backing plates. I've used pieces from trashed boats and FRP tanks.

The ONLY time to seal a backing plate to the inside of the boat is if you are going to epoxy it in place and drill the whole stack. This can make sense if adding something like a big winch to a cored deck, or cleats to a cored deck. You will also be removing some core.

Take the pot and re-drill advise seriously; a wet core is one of the few things that will kill a FRP boat.

There is no point in getting into sailing if you aren't going to get into fabricating your own stuff!
 

jbrock

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Jul 12, 2009
54
Macgregor 25 Regent Point Marina, Virginia
Thanks for all the input. Butyl tape looks like a great adhesive option. I've learned a ton on my first project.
 
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