Source for metal backing plate

Roger Long · Mar 7, 2011

http://www.waterjetme.com/

jrussnogle · Mar 7, 2011

You should be able to buy 1/4" aluminum at any local metal shop, and if they won't cut it for you, anybody with a band saw can cut it the size you need. Unless it's just your preference, or there are space limitations, there's really no reason that it needs to be circular, that I know of.

Roger Long · Mar 7, 2011

Snotter said:
I want to point and click and have it arrive a week later.

Those water jet parts should come out with such smooth edges that you'll just have to knock the sharp corners of quickly with a file or sandpaper and they will be ready to go.

rardiH36 · Mar 7, 2011

Alternative Material?

Another alternative is that the material doesn't necessarily have to be aluminum or metal.

If you have the space underneath for an appx 3/4" thick backing "plate", a rot resistant type of very hard hardwood, such as IPE or Teak would do as well.

The winch mounting through-bolts would need to be another 1/2" longer.

One advantage of wood is that if any of the bolt caulk seals leak, galvanic reaction between the SS bolts and an aluminum plate won't occur.

I've read that its a good idea to bevel/round just a bit the upper edges of the backing plate that mates against the underside of the boat's deck (or in this case coaming?) so there aren't any a sharp pressure points that might eventually cause cracking to the fiberglass as pressure from the winch and sheets stress/flex the area.

Joe · Mar 7, 2011

Call the guys at Garhaurer...... www.garhaurermarine.com

Ron20324 · Mar 7, 2011

A metal fabricating or air conditioning shop may have a size you need when they cut holes in plenum chambers for the duct work. They might even be "scraps"?

RAD · Mar 7, 2011

Ron20324 said:
A metal fabricating or air conditioning shop may have a size you need when they cut holes in plenum chambers for the duct work. They might even be "scraps"?

Sheet metal is not a strong backing plate

Ed A · Mar 7, 2011

make a template of the bolt pattern you want and give that to the fabricator to drill the holes for ya.
any machine shop or metal supplier in your area could easily provide these.

Ron20324 · Mar 7, 2011

RAD said:
Sheet metal is not a strong backing plate

Sheet metal is not the only thing they use- like 1/4 aluminum. I'm not talking about home heating systems here.

Ray Bowles · Mar 7, 2011

Something to keep in mind on your backing plates is that they must be exactly parallel to the winch base. If they rest at any other angle the pre-drilled and tapped threads will foul. If the holes aren't tapped then I'd have them drilled slightly larger than the bolt diameter to allow for any mishaps in alignment.
I truely understand your want of convenence.
Ray

Joe · Mar 7, 2011

Why go through the impossible stress of trying to match up six, circular patterned, threaded holes on a plate to six individually drilled, perfectly straight holes, through 1 of 2 inches of deck without a drill press?

There are easier ways. One would be glassing in a 1/4 inch aluminum plate below the deck, then drill through the winch mount plate and deck from the top into the plate. Labor intensive, yes, but at least you don't need machine shop tolerances.

Or... you could use a piece of epoxy coated marine plywood as a backing plate, thru bolted with fender washers to the winch. Hmmm, that sounds like it might work.

catsailor · Mar 8, 2011

Ron20324 said:
Sheet metal is not the only thing they use- like 1/4 aluminum. I'm not talking about home heating systems here.

Second the industrial AC source; I have done that. Also Industrial sheet metal businesses that focus on roofing and construction; they often work up to 1/4-inch and do heliarc welding also.

However, I have used FRP for mounting winches; no chance of corrosion. My source has been scrap from chemical processing equipment manufacture, but it can be found on-line.

Tejas · Mar 8, 2011

Snotter,

Here is a link to a company that sells steel, aluminum, stainless steel and brass disks in various sizes and thicknesses. I've purchased and used the stainless steel disks from them for backing plates. They do not offer the 7 1/2" size you mentioned, but they do offer 7" and 8" which might meet your application.

https://shopwagner.com/nxc/nxcli.nsf

BTW, I spent several hours over several days finding them two years on the Internet, so I saved the receipt in case I ever needed them again.

Also BTW, here is link for rectangular material that I've also used for backing plates.

http://www.onlinemetals.com/index.cfm

catsailor · Mar 8, 2011

Snotter said:
The hole patterns aren't an issue. I am currently using plates that are too small. I'll use the old plates as a pattern for the new.

Someone mentioned FRP. Aluminum is good enough for the winches; however, since I will be relocating a number of seacocks soon, I would like to use FRP under under them and need a source for FRP too.

McMaster/Carr. Many grades. Garolite G10 if you are going to thread it, FRP or GP03 if you are less particular. All say indoor use, but that is only UV resistance.

It is also likely that any FRP shop at the marina buys pre-laminated materal.

Tejas · Mar 9, 2011

Snotter,

If you are not already aware, you might want to look at Maine Sail's article on sealing deck hardware.

http://www.pbase.com/mainecruising/sealing_the_deck

I'd agonized about installing hardware for about a year, and it was his article that gave me the confidence to start drilling holes in the deck.

Joe mentioned the problem of drilling several straight, perfectly positioned holes. I used a purpose-made drill-guide, essentially a 1" inch thick piece of mild steel with pilot holes drilled with a drill press. In the deck, I drilled one hole, set the hardware to be installed on the deck and dropped a bolt into the hole. Using the the hardware as a guide for the next hole, I then drilled only about 1/4" into the deck, removed the hardware, and used the drill-guide to finish that hole. For the next holes, I again placed the hardware on the deck, dropped bolts into the already drilled holes and repeated the process. I only had three holes to drill, and backing plate fit.

Following Maine Sail's tutorial, I actually did this twice, first to drill the through-the-deck-holes, which I then enlarged and filled with epoxy, and then into these epoxy plugs to mount the hardware.