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Old 02-05-2010, 09:24   #1
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Securing Gear without Drilling

What do you think about this idea for securing gear to fiberglass?

Create fiberglass mounting pads in a tupperware: pour resin and hardener into tupperware. Drop a layer of matting in, then stainless steel bolts with fender washers spaced properly to fit footman's straps. Build up the pad with more fiberglass woven matting. Let cure. Sand or "mar" the bottom surface for good adhesion.

Mount the pads on the fiberglass where drilling is verboten (in my case, the hull). I've done this with 5200, though perhaps I could have just West System'd it.

Finally, strap in the gear.

In my case, am strapping about 130lbs using five pads. Sound ok?
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Old 02-05-2010, 09:55   #2
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that would be 130lbs static loading correct? what about dynamic loading? what exactly are you trying to secure, will the mounts be in tension/shear or a combination of both? "Arr shiver me timbers" comes to mind. I have no idea if this will work, try it and let us know how!
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Old 02-05-2010, 18:43   #3
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130 lbs static load... it is a PVC water ballast pipe secured to the inner hull below waterline. It would be filled to max, so the water within should not carry momentum, but the momentum of the boat would cause it to have dynamic loading, you are correct.

The mounts would be under a combination of shear and tension. They are holding straps which wrap around the pipe.

Starts to sound like I should make small "bulkheads" fore and aft with limber holes, and fiberglass them to the hull.

BTW.. I didn't include this under the securing hardware thread, because that seemed to be more about major stress items (winches, cleats, anchor windlass).
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Old 02-05-2010, 18:58   #4
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Originally Posted by phillysailor View Post
What do you think about this idea for securing gear to fiberglass?

Create fiberglass mounting pads in a tupperware: pour resin and hardener into tupperware. Drop a layer of matting in, then stainless steel bolts with fender washers spaced properly to fit footman's straps. Build up the pad with more fiberglass woven matting. Let cure. Sand or "mar" the bottom surface for good adhesion.

Mount the pads on the fiberglass where drilling is verboten (in my case, the hull). I've done this with 5200, though perhaps I could have just West System'd it.

Finally, strap in the gear.

In my case, am strapping about 130lbs using five pads. Sound ok?
Looks sound to me.

Five pads, look like about ~ 3" x 5" so 15in square x 5 so that sounds like about 75" of surface area.... Numbers on bond strength vary, but the LOW end of the spectrum for 5200 would likely be somewhere around 50 PSI.... that would suggest that you would have a safety factor of 28... pretty darn good.

Take a look at this thread; 3M 5200 (IMHO) Make sure those pads are where you want them to be forever... cause there will be no turning back.
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Old 02-05-2010, 19:04   #5
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Now I don't own a boat myself and am only 23 however I do believe fiber-glassing directly to the hull via gussets would be best the least risky. Constructing the gussets with a "c" notch to hold the pipes would be a good method, if the pipes are long then place the gussets such that they are 1/4 the length of the pipe away from the ends so the middle of the pipe won't be bouncing up and down like if it were just supported on the ends. Then strap the pipes into the gussets. If they are overly long and not filled all the way to the top you could have a bunch of sloshing which would have unknown consequences. It may be a good idea to add baffles every 2 or so feet within the pipe.

We the forum would be better able to help you if you gave us pictures of the install location and the size of the pipe (length and diameter), you say 130lb so we already know it's about 16 gallons.
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Old 02-05-2010, 20:28   #6
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I agree that just tabbing in some pieces of wood that have been cut to the shape of the pipe and have the screws mounted would be easier. Stick them to the hull first with a little thickened epoxy and hold them with tape until dry. Then wet out a little fiberglass tape and put it on each side lapping a few inches onto the hull. This will also be easier to remove - should you ever have to - than the 5200 pads.

If you do go with the pads, put some micro-fiber filler or other thickener in the epoxy not just the mat. This will make the pads much stronger.

Carl
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Old 02-05-2010, 20:31   #7
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If you could see behind the interior sidewalls you would notice lots of "pads" for attaching this and that. They are covered with fiberglass tabbing. A simple piece of appropriate sized stainless steel which is tabbed over with fiberglass cloth and resin should do the trick fine. Making pads out of pure poured/cast resin is not smart. Pure resin - polyester or epoxy - is very brittle and any shock loads or continuously cycling loads will cause fractures in the resin and the mounting bolts will fall out. The strength of a FRG boat is primarily in the fiberglass cloth and not the resin which is merely the "glue" that holds the fiberglass cloth layers together.
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Old 02-05-2010, 20:34   #8
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.....Making pads out of pure poured/cast resin is not smart. Pure resin - polyester or epoxy - is very brittle and any shock loads or continuously cycling loads with fracture the resin and the mounting bolts will fall out......
Quote from the OP's post;

Quote:
Create fiberglass mounting pads in a tupperware: pour resin and hardener into tupperware. Drop a layer of matting in, then stainless steel bolts with fender washers spaced properly to fit footman's straps. Build up the pad with more fiberglass woven matting. Let cure. Sand or "mar" the bottom surface for good adhesion.
No, pure epoxy or pure resin would not be smart... does not sound like that was the case here though.
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Old 02-05-2010, 20:37   #9
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what I've done with some success is to attach a thick block of marine ply to the hull with sikaflex adhesive, and then fiberglass over the block--maybe three layers of matting that would extend six inches to each side of the block. Then, use screws to attach what I'm mounding to the block.

The reason to use the sikaflex first, rather than just beginning with fiberglass, is because the weight of the block will cause the glass to slide down the hull before it has a chance to set up. Don't ask me how I know this.
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Old 02-05-2010, 23:00   #10
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The reason to use the sikaflex first, rather than just beginning with fiberglass, is because the weight of the block will cause the glass to slide down the hull before it has a chance to set up. Don't ask me how I know this.

Wax paper and duct tape...
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Old 10-04-2013, 08:28   #11
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Just realized I never followed through on this thread, was scanning, and thought I might complete a reply to all the thoughtful responses. I plunged ahead after reading that I had a wide safety margin, but have since realized that tabbing in wood is a better solution.

In any event, the plan worked well enough, primarily because I've seen no need to remove or change the location of the pads. They were designed to hold a water ballast system which it turns out isn't necessary... If I am carrying any payload the weight is there anyways, and in any event a new storm jib with a shorter 'J' (via a new tack slightly aft of the original) has minimized lee helm to the extent that the water ballast pipe system is not even installed dry.

I use the pads now just to secure extraneous gear, and Velcro or webbing works well with the footman's straps.

Thanks for the solid advice.
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Old 10-04-2013, 08:43   #12
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Re: Securing Gear without Drilling

I know the thread is old . . . . But someone has already soved this problem . . . click bond is an excellent answer.
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