Deck fittings - backing plates

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Aug 20, 2011
75
Macgregor 25 Sacramento, CA
I'm getting ready to order some butyl tape to redo all my deck fittings. And was wondering if anyone has thoughts about using HDPE instead of metal. Seems to me it should do fine but I'm sure others have opinions.
thanks,
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
if it isnt thick enough to remain completely rigid, then its not suitable for the job. either your fastners will start to pull through the backing material and cause loose fastners, or complete failure, or it will distort and compromise the surface you are trying to protect. the theory behind the use of a backing plate is to take the applied force and spread it EVENLY over a much larger area.... if the backing plate distorts, it will not maintain an even distribution but cause extreme loading in the area that is most susceptible to failure (around the fastener hole) and none towards the outer edge...... although any type of material may help for a little while, but doing it right the first time will prevent any problems.
some boat manufactures have used high density plywood as backing plate material to save costs, which when new and good seemed ok, but over the years it has failed and needs to be replaced. it has, in some instances, caused extreme damage because of the sudden failure when needed.
so you can make it look good with about anything, but when performance counts you want the good stuff.
personally I use 1/8 stainless or 3/16 aluminum plate, but then i realize not everyone has the tools to work with stainless..... aluminum plate can be worked with wood working tools so not much excuse not to use it.
 
Nov 23, 2011
2,023
MacGregor 26D London Ontario Canada
For the strength and cost I think aluminum is the way to go. You can measure out the shapes and have a fabrication shop cut them very easily. Or cut it yourself with a jig saw.
Good luck.
Oh Don't for get to flair the deck holes before you install the butyl.
 
Jun 5, 2010
1,107
Hunter 25 Burlington NJ
In my opinion as a boatbuilder of 40 years, it doesn't matter what backing plates you use if you're going to stick down the stuff with butyl tape. Period.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
In my opinion as a boatbuilder of 40 years, it doesn't matter what backing plates you use if you're going to stick down the stuff with butyl tape. Period.

I disagree.

if the backing plate material makes no difference, then how about no backing plates at all?....
what difference would the type of sealer make in being able to use an inferior product to back up deck hardware?

in my opinion, as a boat owner of 40 years, I would say a solid backing plate is more important than what type of sealer that is used under the deck hardware, and also, any backing plate that is less than solid will eventually be the cause of a leak no matter what type of sealer you use.....
 
Mar 26, 2011
3,402
Corsair F-24 MK I Deale, MD
In my opinion as a boatbuilder of 40 years, it doesn't matter what backing plates you use if you're going to stick down the stuff with butyl tape. Period.
Ambigous. I can think of 4 gramtically correct interpretations of this statement; each is defensible, depending on other installation variables, as I've seen both failures and sucesses.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I would agree with Diana if the deck or hull was 2 inch white oak in the place of the hardware.
 
Nov 15, 2011
15
Alberg 37 Marathon Florida
If your so inclined you could try to make your own backing plates out of fiberglass. Simply lay up 5 or 6 layers of Biaxle or what ever you wish on a piece of wax paper. Give em a nice sand to round out the corners a lick of paint and your good to go. I do quite a bit of work repairing decks. I agree a solid backing plate is essential to all hardware mounting but the holes thru the deck are just as important. Remember to overdrill the hole countersink it then fill it with thickened epoxy. Then redrill the hole with the appropriate bit. Bed the backing plate and the hardware with 5200. The Butyl is perfect for wrapping around the head of the bolt as long as the deck hardware has been countersunk. Good luck with the project.
 

capta

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Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
5200??????????????????????

I'm a bit late on this thread, but I hope I'm in time.
I would NOT recommend using 5200 as a bedding compound; it is NOT a bedding compound, it is an adhesive, period. And it is a damn good one at that. Do not use 5200 on anything which one day may need to be removed, like a window, a cleat or a stanchion.
Things get broken on boats, like a window, a cleat or a stanchion; so use a good bedding compound, not an adhesive.
 
Oct 6, 2011
678
CM 32 USA
A piece of lumber, boiled in parifin wax, petrafies the wood, making it darn near indestructible and totally impervious to water.

Good solid board, 1 1\2" thick, cut and drilled to your exact size, boiled 8 hours in wax, will do the trick. Use fender washers to distribute the load, and this backing plate cost little to nothing to make, and will last year's and years. Boiling wood in parifin wax is an old waterproofing trick woodworkers used before plastics showed up.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Not all lumber is created equal. Know your wood species before you select wood for your backing plates.
 
Oct 6, 2011
678
CM 32 USA
Ross said:
Not all lumber is created equal. Know your wood species before you select wood for your backing plates.
Thumbs Up!!!

Find an old timer (any old timers on here?) that know which wood is best to boil in wax? I seem to remember oak being used and false teeth being made this way criteria CW era.

In addition to the wax, I believe a wax hardner may also be used. Leather can also be hardned in this way, but it would not be hard enough for backing plates.

To melt the wax without burning it, one needs a double boiler ideally.
 
Jun 22, 2012
39
Catalina 27 std dinette mission bay
Good solid board, 1 1\2" thick, cut and drilled to your exact size, boiled 8 hours in wax, will do the trick. Use fender washers to distribute the load, and this backing plate cost little to nothing to make, and will last year's and years.
So, you soak a 2x4 in boiling wax for 8 hours.... hmmmm... that's a lot propane or natural gas to burn to save a few bucks worth of 1/4 inch steel or aluminum. Add in the cost of changing to longer SS fasteners (not cheap, have you priced a 4 inch ss carriage bolt lately) and your "free" backing plate starts costing a bit more than just ordering metal ones from Garhauer Marine. Plus, on my boat there ain't much room under the deck to fasten a 1 1/2 inch thick board for backing up a deck cleat or a winch.... that's why they call them backing PLATES and not backing blocks.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
So you want a 2 x 4 hanging down to bang you head on to save a couple of bucks?

Go to your lock machine shop. Many of them may have scrap aluminum plates hanging around that they will give you or sell for cheap.
 
Nov 8, 2007
1,523
Hunter 27_75-84 Sandusky Harbor Marina, Ohio
Cherry and a hand grip

As shown here http://hunter.sailboatowners.com/in...7&cat_id=16&aid=7355&page=article&mn=27_75-84

I used a 3/4 inch cherry board as a backing plate for new deck hardware to lead lines aft to the cockpit. I mounted a handrail on the cherry - a great addition for moving in the cabin underway.

This works well because it is enough off to the side that we never hit our heads on the grab rail. A little varnish, and it looks great, too.
 
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