Back Plates for Deck Cleats

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Island Ranger

New member
I'm looking for advice to add the required (for a Coast Guard Auxiliary vessel facility) backing plates to the bow, side and stern cleats on Two Lucky Fish. There is plenty of room and access isn't bad so I hope the project is managable for me. I am planning to remove the current bolts/washers/nuts, add backing plate, replace the bolts with longer ones and reassemble. I'm looking for advice on:

Backing plate - what material? I assume one of the stainless alloys is appropriate, but which one? (The Coast Guard manual recommends against aluminum - probably because it is too soft) How thick - is 3/16 OK? Can I cut and drill it easily or should I find someone to cut and drill? Any recommendations where to buy it?

Bolts - the local hardware carries stainless bolts that might work, but should I be looking for a specific type of stainless for salt water use?

Re-assembly - what bedding compound do you recommend to reseal the screw holes?

Thanks for your help.

Mac
 
Mac
I would imagine that 3/16 would be thick enough.you would probably have to use about 1.5 to 2 in. wide material for that. I will look out in my collection of material and see what I have . I might have what you need here and we can cut and drill them on my drill press. all you need is the cleats for measurements
 
Thanks Roger!

I did a quick measurement (not accurate for drilling) and found:

1) the 4 bow cleat bolt centers are 1 3/4" by 3 3/4". So I was thinking that the backing plate would be 4-5" wide and 7-8" long.
2) The side cleats are on 1 1/2" by 2 3/4" centers. So a plate 4" by 7"?
3) The stern cleat bolts are 1 1/4" by 2 3/4". So another plate 4" x 7"?

Or maybe these would be way too large? I was looking more at what would fit as opposed to what is needed. I would think 3 inch wide min? so maybe 3x7 for the bow, and 3x6 for the stern and side cleats?

Thanks for your help

Mac
 
It looks like you already have a helpful friend so I wont get too into your project. But as a Machinist of over 30 years I do feel compelled to offer some thoughts. For salt water service the prefered material will be 316 stainless. 304 or 309 would work but in time you will notice that they are not nearly as good from a corrision standpoint. Any of the above materials are readily drilled with about any drill and drilling equipment, the important thing is to turn the drill slow. If your drilling a 1/2 inch hole for example the drill speed should not exceede 80 rpm. Slower is better. Good luck with your backing plates, Mike on Huda Thunkit
 
Mac,
I have used 1/4" aluminum many times for backing plates. The underdeck plates shouldn't get wet and the only corrosion issues would be due to galvanic action between the aluminum and stainless steel. I have isolated them before with teflon tape around the bolt shank and hard nylon washers under the nuts. If you have or can find SS it is great but I have a lot scrap aluminum on hand and no SS. My experience with SS is get a cobalt bit and drill slow and with a lot of pressure. You want the bit to be always cutting-if it spins it get very hot and even high speed steel dulls quickly.
 
Why not use StarBoard?

I've used it, along with big fender washers for all my backing plates. It's more than adequate, will never rust, and easier to cut/shape/drill than metal.
 
Interesting suggestion regarding Starboard. I'll try to check the regulations, although I would guess that since they don't like aluminum, they aren't gonna like Starboard either

Thanks for the help,
mac
 
I was in th Aux for several years. Don't recall that there were any specific requirements for backing plate material. On my previous boat I installed some with aluminum and some with ss. However, it was an aluminumboat and used in fresh water. Better than starboard would be that nominal 1/2 inch nylon kitchen cutting board from Walmart. Might have to buy two for enough material. I used this as backing plate for new cleat I put forward of bow cleat (to tie off anchor when on roller and leave main bow cleat clear). I also used as backing plate for the two spring cleats. My 04 didn't even have fender washers installed ondthe spring cleats. I will do the bow cleat and stern cleats someday. The nylon material is denser, less compressible than starboard. You would only need longer bolts, provided you had proper fender washers to begin with.

Mark
 
Thanks Mark,

Item 9 under section VIII under requirements for an operational facility calls for full backing plates on the stern and bow cleats. Interesting though, the "no aluminum" seems to have been dropped from the current manual. Looks like I gotta keep researching...

Mac
 
Mac
I just checked my scraps out in the machine shed and I don't have what you are looking for.
From where you live it is a toss up for which direction to go. Everett Pipe & Steel is a good place if you take the ferry. if you want to drive, Skagit River Steel in Burlington would be the place. also right close to them is the Fastenall store. they have or can get any stainless bolts you might need in any gonfiguration. if you get the metal, you are welcome to come on over and use the shop to make your pieces. I have the cutoff saw and drill press and whatnot.
 
Yellowstone - couldn't pass up without commenting on this one. I know nothing about about Coast Guard Auxilary requirements for backing plates on cleats, but I suspect this is one of those must do kinds of regs based on some experiences of cleat failure. On the Far West II I put backing plates (aluminum) on all cleats with a simple anti-galvanic process, viz., drilling the holes in the plates large enough to prevent SS bolt from touching and gluing neoprene sheeting material to the bottom of the SS washers which bears against the plates. Water sealant goop on the bolts keeps the water out, plus thin neoprene sheeting on the bottom of the cleats makes a nice snug and waterproof fit - no seepage at all. I was so proud of my work that I mentioned it to Mark Toland. He laughed. Really unnecessary. And he was right. The factory will sling fully loaded C-Dorys around hanging by the front and aft cleats. The construction is so robust, the the cleats will not pull loose when used as intended. But if backing plates comforts you, by all means do it. I will only consider plating the forward main cleat on my next 22' cruiser. John
 
Thanks Roger for checking and for the offer to use your shop. I probably will - if I go with the stainless solution. I'm still looking into whether Aluminum is now acceptable - if so, I can probably cut/drill that here.

Mac
 
Mac (on Two Lucky Fish . . .
From my experience it really doesn't matter what is used to back cleats, if you tow another boat that is too heavy or tow in conditions that increase the force exerted on the cleats (do the "Tow Worksheet"), you will have problems.
Since no one seems to sell cleat backing fittings any more (and since manufacturers don't seem to be too concerned about the backing of cleats), whatever material (1" wide aluminum or fender washers) seems to be appropriate. No matter what is used, if torque forces are too high, the cleat (and a portion of the fiberglass hull) will pull out. The main factor is trying to distribute the pressure over an area that is wider than just a through-bolted fastening...again, that can be done using variety of materials and methods . . . but you still have to know your boat's limitations I(not only for the cleats, but for the stress on the motors).
I have usually ended up using the largest fender washers that I can find (which often overlap).
Bruce
therevdr
 
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