# cutting board as backing plate material?



## johnnyandjebus (Sep 15, 2009)

Ok before I get started I realize this may sound like a hair brained idea, with that said;

I was reading up on a product called star board
King StarBoard

It got me thinking is there any reason that a "plastic" cutting board could not be used as backing plate material? 
I guess what I am wondering is what are forces applied to backing plates?
I understand that they are used to spread load over a wider area but from a load bearing stand point why not use cutting board material?

Feel free to slap me around for suggesting such a bone head idea, curiosity is going to kill me one of these days 

John

p.s I know nothing about star board, have never seen or used it , it just reminds me of the cutting board on my kitchen counter.


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## mitiempo (Sep 19, 2008)

Backing plate for what? One for a cutter stay or a syanchion requires more strength than one for hardware with less load. 
Won't rot like plywood but I favor aluminum or fiberglass backing plates. Or G10.


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## Mark1948 (Jun 19, 2007)

I have used it for a broader base for my through hulls. It has worked fine. No compression load but no rot either.


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## pdqaltair (Nov 14, 2008)

Poor choice, though folks do it.

The trouble is that the PE will creep over time (a cutting board will quickly warp if a significant weight is placed on it), giving you far less support than you think you have, unless you go VERY thick. Prelaminated FRP is probably best, followed by SS (difficult to work) and aluminum (can corrode is wet).

Wood is respected by many; just not my choice.


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## CapnBilll (Sep 9, 2006)

I've used 3/4" Black PVC as a backing plate for things like a through bolt for mounting brackets. It works very well and lasts forever if not exposed to sunlight. Stronger than PE and more resistant to creep. I've seen starboard used as a backing plate for an outboard bracket, after a few years it cracked.


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## nigglesworth (Nov 6, 2010)

what about starboard? I just finished drilling out my new thru-hulls and am moving on to backing plates tomorrow. Not sure i have the patience to make backing plates out of fiberglass... so its wood, or starboard if people think that may work?


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## chef2sail (Nov 27, 2007)

Cutting boards not made of wood are generally thin and warp easily with repated use and heat. Try and put one flat on your counter after you have had it more than 1 year and notice its bowed in some way.

Also they tend to "creep". Thats why Chefs usually put a damp cloth under them when they use them repeatedly

Dave


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## mitiempo (Sep 19, 2008)

Best backing for through hulls is G10 or fiberglass, epoxied to the hull where it adds a great deal of strength in an area that couls use it. Starboard is just a washer as nothing sticks well to it, including sealant.


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## DonScribner (Jan 9, 2011)

Cutting boards are usually HDPE (High Density PolyEthylene). If you are interested in using a plastic, use UHMW (Ultra High Molecular Weight polyethylene). It's more expensive but still affordable in the sizes that you would require. We shim skylights weighing many tons with the stuff. It is available, among other places, at McMasterCarr.com


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## Baywind (Dec 7, 2008)

I got a used SS sheet that was a toe kick off a door at a building for free. I cut it with my grinder and then sand the edges smooth and corners round. It is tough to drill the holes but it is strong and looks good.


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## asdf38 (Jul 7, 2010)

I'm about to add backing plates myself. G10 was recommended and it certainly makes sense but I was thinking about hardwood oak for convenience and cost. Home depot sells 0.5"x6"x4' for $13 that would make several plates. Also in my boat many of these backing plates would be visible and stained oak would blend in nicely.

How much advantage is there to epoxying to the hull? I don't like permanently attaching anything and second, I think I have an interior liner that would make this less useful?


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## sfchallenger (May 17, 2011)

I wouldn't use cutting board, or any other plastic, for a backer plate. Plywood is easy to work and lasts a pretty long time. 

Solid stock is not a good idea if you are considering using wood. The cross lamination of the grain in plywood is preferred, it won't split and doesn't have internal tension like a piece of oak. I use 3/4" marine ply for through-hulls and I soak them in Smith's epoxy at least twice. I wouldn't epoxy to the hull, as the washer will be removed when the thru-hull is next replaced. Hopefully after I don't own the boat anymore.


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## mitiempo (Sep 19, 2008)

I partially agree with the above - plywood is better than solid wood. But the backing plate, whatever it is made of, should be on the underside of the deck, not the liner as there is a gap between the liner and the deck. Tightening the bolts will move the liner closer to the deck. I would try to get the backing block right under the deck.

As far as epoxying the backing block to the deck, or the inside of the hull in the case of a through hull, I think it is the best idea as it will become part of the hull or deck, strengthening it a great deal.

For through hull installation, see this link: Replacing Thru-Hulls and Seacocks Photo Gallery by Compass Marine at pbase.com

And fiberglass or G10 is ideal. What I do is save any fiberglass scraps I remove from any boat - mine or others as I work on boats - and cut backers from them for my use. Any boatbuilder should have offcuts as well, probably free for the asking.

Example here


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## jacob30 (Dec 3, 2010)

McMaster Carr sells a 12"x 12" 3/4" thick fiberglass sheet for $30. I just used it for my backing plates. So far worked great. Search GPO3 for the part.


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## Maine Sail (Jan 6, 2003)

Any of the HDPE products lack the stability to prevent flex and properly "back", unless VERY thick. The ability for anything, even 5200, to stick to them for long is what really makes them a poor choice though..

I had a customer use 3/4" HDPE for backing plates, Sea Board (same as Starboard) and in one season 3 out of 7 were known to be leaking. They provided no support and the flexing when turning the handles cause the seal to leak.

A small batch of boat builders tried this over the years, mostly small power boat builders, and I suspect also ran into problems. At the last boat show I did not see any of them using it for backing blocks any more, even ones I'd recalled seeing in the past... HDPE is very flexible and you might as well be trying to bed a Teflon frying pan, sealant wise... Nothing really stocks to it...

Leave the cutting boards in the galley and use known time tested and proven methods below water to keep your boat from sinking or leaking...

Of course you don't need to take my advice here's what the manufacturer says:

"*King StarBoard®*, King StarBoard® ST, King ColorCore®, King ColorBoard® and King CuttingBoard® *can not be glued using standard adhesives*. *Products like 3M's 5200* work well as a water sealing caulk *but will not adhere King StarBoard® to itself or other materials in a permanent bond.*"


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## BELLATRIX1965 (Jan 2, 2007)

Can anybody recommend a good source for G10 plate? Preferably about 5/8" thick, and maybe about 12" by 12" size? Just need a backing plate for an anchor windlass - not a full sheet of the stuff!


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## Maine Sail (Jan 6, 2003)

BELLATRIX1965 said:


> Can anybody recommend a good source for G10 plate? Preferably about 5/8" thick, and maybe about 12" by 12" size? Just need a backing plate for an anchor windlass - not a full sheet of the stuff!


McMaster Carr has smaller sheets and does stock 5/8".. Don't know about 12X12, pretty sure they do offer it, but I have bought 12X24 a number of times..


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## pdqaltair (Nov 14, 2008)

BELLATRIX1965 said:


> Can anybody recommend a good source for G10 plate? Preferably about 5/8" thick, and maybe about 12" by 12" size? Just need a backing plate for an anchor windlass - not a full sheet of the stuff!


What is the basis for the thickness? If it is stiffer an stronger than the deck layup, it is wasted. Given the limits of the windlass, deck, and chain, I seriously doubt anything over 1/4-inch will have value to you, but some simple engineering calculations would tell. Additionally, bonding it to the deck will greatly decrease the required thickness, as the deck and plate will act as a unit. If the plate doesn't conform to the curve of deck, the load distribution is haphazard.

Really, the load on the windlass should not be great if a proper chain stopper is used. That is where the big snatch loads are.


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