Backing plates

[micheck]

I am confused (a normal state) - does it make sense to use a 1/2" or 3/4" piece of marine plywood for a backing plate as opposed to using a 1/8" piece of cold rolled steel dipped in epoxy paint? If/when water leaks - one turns to goo and one rusts ...

Thanks - Charles

[tommays]

I use stainless as i get it more or less free

BUT if you use the correct sealing method it will NOT leak

http://www.sailnet.com/forums/gear-m...utyl-tape.html

[PorFin]

Originally Posted by micheck

I am confused (a normal state) - does it make sense to use a 1/2" or 3/4" piece of marine plywood for a backing plate as opposed to using a 1/8" piece of cold rolled steel dipped in epoxy paint? If/when water leaks - one turns to goo and one rusts ...

Thanks - Charles

Charles,

What are you mounting? Depending on the load you can anticipate on the fastener, you may be able to use fender washers.

Given the choices you've left to us, I'd go with the plywood (after sealing it WELL with epoxy.)

However, if the choices were mine I'd go with stainless first. If that's not available then I'd go with aluminum. Neither of these will rot or rust. If you use aluminum as long as you use an isolator like TefGel or a good sealant then you won't need to worry much about galvanic corrosion between the stainless fasteners and the backing plate.

[bljones]

go stainless.
If you have one of these nearby,
METAL SUPERMARKETS - Buy Metal Online - Small Quantity Orders for Aluminum, Stainless Steel, Hot Rolled Steel, Cold Rolled Steel for Delivery or Local Pickup
you will be shocked by how cheap offcuts of stainless (sutiable for backing plates) can be.

[pdqaltair]

Pre-laminated FRP (fiberglass) also works VERY well, with few of the drawbacks of Al or SS:
* no galvanic corrosion
* easy to work, compared to SS
* light

If your looking for cheap, try to find scrap. Most FRP repair shops will have broken bits you can salvage.

I wouldn't real consider either carbon steel or plywood, when there are other easy choices.

[Faster]

If you have an old window/piece of glass laying around it's a pretty simple matter to lay up your own fiberglass panels for backing.. any shape/thickness you want, as as pdq said it's a lot easier to 'work' , trim and custom fit. Do go with large washers as well, though, if you go that route.

[PorFin]

Originally Posted by Faster

If you have an old window/piece of glass laying around it's a pretty simple matter to lay up your own fiberglass panels for backing.. any shape/thickness you want, as as pdq said it's a lot easier to 'work' , trim and custom fit. Do go with large washers as well, though, if you go that route.

Doh! I forgot that option -- also a very good one!

[LeftCoast]

Another option could be laser cutting of stainless. (or aluminum) For those of you in the PNW, we use..

Cutters Inc
3979 Hammer Drive, Bellingham, WA 98226-7630
(360) 647-1910 ‎

we e-mail them drawings and they send back parts cheaper than we can make them in our own shop. I don't know how they do it, but I'm sure glad I found 'em.

For example:



These tiller plates were $10 a pop, including material. And that was ordering just 4 of 'em. Not like we're buying hundreds to get the price down.

So if you need plates for this or that, it may be an option?

*****

Also, a trick for making fiberglass panels. We wax up a formica table, spray white gelcoat, then lay up the panel. When you are done you get a fiber panel with one side that looks -exactly- like white formica. This works really well if you are going to see the backing plate from inside the boat's cabin.

-jim lee