Question of the Day #4 - installing hardware on deck

[Spartan]

What is the best method for installing hardware such as fairleads for a jib downhaul on a CP-16? Drilling, filling/bedding, screws/through bolts, backing plates, etc.

Thanks
Tom

[skip1930]

Drill, 3M-5200, bolt through with a backing of plywood or aluminium.

skip.

[jthatcher]

hi Tom...  lots of advice regarding this particular question...    for example,  you will find folks who love 5200 and use it everywhere  and at the other end of the spectrum  folks who think that 5200 is the right solution in very limited situations  ( like ones where you know that you will never ever want to take the fitting off again in a million years..   a slight exaggeration perhaps     )    my gut feeling is to  read a lot..  think about it... and then go with the process that makes the most sense to you..   you might find this link interesting.    http://www.pbase.com/mainecruising/rebedding_hardware     while it is possible that this fellow wants to sell you something,   it seems to me that he put a good deal of effort  into his explanation..     jt

[Salty19]

jt, I really like that link.  Based on some comments here and on other sites, I think I'll be looking at butyl tape for all future bedding needs. Seems to make way more sense than anything else.

One thing in that article that wasn't mentioned that I would do as well is to overdrill the hole slightly and dress with a light coating of epoxy to seal the fiberglass/core. So if the fitting does leak, the damage should be minimal. 

5200 is for permanent adhesion, like the hull to deck seam. Eventually you may need to remove the hardware, so why permanently attach it when all you need a seal? 

[Bob23]

Salty is right about overdrilling the hole, sealing with epoxy before attaching anything. A step further would be to drill a much bigger hole, tape the bottom of the hole and fill the entire thing with epoxy. After curring, you drill the correct size hole. The fastener never touches the fiberglass. It's a lot of work and I've only done it a few times. I like sealing things with 4200 but I've used DAP 3.0 house caulk on my rowing shell. It stays pretty flexible.
Hope this helps clear up this "sticky" question! Sorry, couldn't resist.
bob23

[Spartan]

Good stuff guys.  Drilling the oversize hole, fill with thickened epoxy and redrill is exactly what we do with wooden boats.  Especially rudder blades. 
Good backing plates also seems to be important with either selant or bedding based perhaps on load on the hardware to be used. 

Got it.

Tom

[Shawn]

"is right about overdrilling the hole, sealing with epoxy before attaching anything. A step further would be to drill a much bigger hole, tape the bottom of the hole and fill the entire thing with epoxy. "

Is that really needed in solid fiberglass? On a cored deck that is certainly the way to go and how I installed hardware on my Flying Scot (balsa core) with the additional step of putting a bent nail in a drill to route out the core so the epoxy could fill that too.

Shawn

[skip1930]

Drilling holes larger than necessary just to make room for a sealant makes for a sloppy fit.
As the attached thing works, the fiberglass holes are worked larger. No core on a CP-19. Hand layed, layered 24 oz fiberglass woven cloth, resign impregnated, rolled into the mold. No chop used anywhere. Plus 1-1/2 oz woven cloth elswhere. Strong like bull!

My rudder stock on the transom was a tight hole for 4~1/4 bolts. Had to be screwed in, had to be screwed out every bolt.
Had plywood backing on transom to screw through.
All holes were 3M-5200 sealed requiring heat and beat with rubber mallet to knock the casting loose after screws were extracted.

What is she made of? To enlare copy, hold down control key and tap + key. To shrink back down, hold control down and tap - key.

Just my

skip.

[Spartan]

Shawn: is the deck on a CP16 solid Fiberglass? 

[Shawn]

"Drilling holes larger than necessary just to make room for a sealant makes for a sloppy fit."

That isn't what anyone was saying. What they were saying was if for example you wanted to mount a 1/4" bolt in a cored deck you would drill say a 1/2" hole. You then tape off the bottom of the hole and fill the entire thing with 2 part epoxy and let it harden. After it is hardened you drill a 1/4" hole through the epoxy and mount the bolt through that. This gives you an extra layer of protection for the core material in case you get a leak in the bedding material. The epoxy seals off the core for the bolt hole so even if it leaks the water won't rot out the core. The epoxy also helps protect against someone over tightening the bolt and crushing the fiberglass/core.

Shawn

[Shawn]

"is the deck on a CP16 solid Fiberglass?  "

I don't think so. They are a cored deck but I think Compac used a type of foam core that can't absorb water. So the problem of the core material rotting out is not present in them. There are places on the deck that have wood reinforcements below the fiberglass. The mounting points for cleats are like this for example. In places like that it is a good idea to at least seal the wood with epoxy or go full out and overdrill and fill the hole with epoxy and then redrill. That way you give further protection to the wood to prevent any sort of rot problems down the line.

Shawn

[skip1930]

When I cut the holes for the chartplotter and depth/speed instrument, no core.
No core through the hull, I still have the cut-outs, and no core to drill through
when I added another deck organizer on my CP-19.

skip.

[Salty19]

Guys..there is a core on all Compacs.  It's not wood, but a micro-balloon slurry core.  It's white in color so there won't be an obvious layer from a cutout. It's pretty thin as well.

The balloon slurry core is water resistant, but get some water in there under freezing temps and it will damage it.  Water may also migrate between the core and the glass, trapping water well aside from your hole.

Also there is wood backing behind most factory hardware, inlaid into the fiberglass.  If you're resealing factory hardware or installing new hardware in the factory location, consider it cored, thus the epoxy seal barrier.

Skip,  You may have misunderstood.  The oversize hole is to allow room for the epoxy as Shawn illustrated.  The end result hole would not be sloppy if done correctly.   This step takes an additional wait period to finish the project, but is good piece of mind.

Now there may be areas where there isn't a core.  When I installed a big fat eyering under the companionway for a tether, I didn't see a core there.  May have been one but I didn't notice it.   Very thin glass right there, thinner than expected.  I put some marine plywood behind as backing, eventually I want to add more layers of glass to this area as well.