Repair of Loose Screw Fasteners

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Bigbear
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Repair of Loose Screw Fasteners

Postby Bigbear » Wed Mar 21, 2018 4:25 pm

There is a loose screw that holds the bow pulpit to the deck and a loose boat cover snap. I plan to drill out the pulpit screw hole and fill with a hardwood dowel and wood glue. Then I may cover the top of dowel with epoxy with filler.

I will repair loose cover snap by filling the hole with epoxy and filler, and then oil small hole to snap. Does this seem appropriate?

Thanks, Barry

jimh
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Re: Repair of Loose Screw Fasteners

Postby jimh » Wed Mar 21, 2018 7:46 pm

Repair of loose fasteners for rail bases is described in the FAQ;

http://continuouswave.com/whaler/reference/FAQ/#Q7

I tend to use WEST System epoxy resin mixed with their high-density filler to create new material in existing fastener holes that have become loose. After a fastener hole has been filled with a resin-filler mixture and the mixture has completely cured, I drill a new pilot hole in the new resin. Then I enlarge the pilot hole in the upper layer where the gel coat resin is present. Then I carefully enlarge the pilot hole so it will give good purchase for the new fastener, but not so small that the new fastener will have to be forced into the hole with great effort and cause a fracture in either the gel coat or the underlying laminate.

Some others have made repairs to loose screw fasteners by using an L-shaped tool, such as a small Allen wrench, to act as an auger to remove foam under the laminate, creating a void or cavity below the gel coat and laminate. A vacuum is used to suck out debris of the foam. Into the void a mixture of resin and filler is injected through the existing hole and allowed to cure. This creates a puck or annulus around the original fastener hole.

Bigbear
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Re: Repair of Loose Screw Fasteners

Postby Bigbear » Thu Mar 22, 2018 2:19 pm

Thanks for the response. How thick of an epoxy/filler do you recommend and how do you get that mixture into a hole without air pockets occurring. I’m a little nervous about drilling such a large hole (1/2”) in the deck.

Regards, Barry
Midland, MI

jimh
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Re: Repair of Loose Screw Fasteners

Postby jimh » Thu Mar 22, 2018 2:30 pm

To make a void in the foam under the gel coat and laminate layers, you can break down the foam by using a small L-shaped tool, perhaps made from an old Allen wrench or other hardened steel rod. The L-shaped tool is pushed into the hole and manipulated to break down the foam. The tool is withdrawn and the foam debris vacuumed from the hole. This is repeated until a cavity or void in the foam is created around the hole in a suitable width and depth. At some point you may be able to chuck the tool into a variable speed drill or hand power tool and rotate the tool under power. A sketch shows a side view of the process:

makeAnnulus.jpg
Use a small L-shaped tool as a crude auger to cut away and remove foam under the laminate layer, creating a void or pocket. Into this void a mixture of epoxy and filler can be introduced to create additional material for retaining a screw fastener.
makeAnnulus.jpg (10.03 KiB) Viewed 2682 times


To introduce resin into this cavity you can use a plastic syringe. WEST System sells these accessories.

The resin should be mixed with fillers to avoid creating a pocket of pure resin. Epoxy resin is exothermic, and a large volume of pure resin left to cure will become very warm; sometimes so warm that it is quite hot and will tend to melt the foam, creating a "China Syndrome" effect. For this reason, use a resin-filler mixture. The consistency of the mixture can be somewhere between catsup and creamy peanut butter, but with enough viscosity that it can be pushed into the cavity by the syringe. Of course, this works best if gravity is assisting the movement of the resin into the bottom of the void. If you must work against gravity, try to let air escape as you inject the resin mixture, then immediate cover the hole with tape when you pull out the syringe. You can also experiment with adding some thinner resin at the end of the process to better flow into any remaining voids.

The outcome should look like this:

resinPocket.jpg
When the resin cures, it creates a reinforced area into which a new pilot hole can be made, and a new fastener threaded. The resin will spread the load of the fastener over a larger area of the deck laminate.
resinPocket.jpg (7.94 KiB) Viewed 2682 times


Although the process mentioned in the FAQ specifies a hole of a particular diameter (0.5-inch), for this annulus method I would not enlarge the original fastener hole any more than necessary to eliminate the old, broken down laminate. With care I think you can easily create an annulus of at least 0.5-inch width or more, as you think necessary. The FAQ method refers to securing rail bases which have a rather wide base around them and their mounting holes, so the open 0.5-inch hole that is created is mostly or completely covered by the rail base. With the annulus method the hole needs only to be large enough to remove any fractured laminate and to permit the L-shaped tool to be inserted.

Always relieve the gel coat layer of the hole so the threads of the fastener are not forcing the gel coat layer apart; the gel coat is brittle and can easily fracture if you try to force a screw fastener threads into it.

jimh
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Re: Repair of Loose Screw Fasteners

Postby jimh » Thu Mar 22, 2018 2:39 pm

Also, if you are talking about a fastener that actually holds the bow pulpit--not just a bow rail base--the actual pulpit (the part you can stand atop) was usually attached with through-bolt fasteners or fasteners that threaded into heavy wood or WHALEBOARD reinforcement.

cinegamma
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Re: Repair of Loose Screw Fasteners

Postby cinegamma » Wed Mar 28, 2018 10:31 am

Jim,

Thanks for the detailed description. Do you know if the West repair kit that is available has both the resin and filler? For my project, the bow rail mounts that attach to the deck on the port and starboard side of the bow locker are stripped and loose. Based on your description above, after the epoxy fully cures, and the pilot holes are drilled, would you recommend using the same coarse-threaded stainless wood screws that Whaler originally used? If not, do you have a suggestion of what might work better?

Thanks again,
Jon

jimh
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Re: Repair of Loose Screw Fasteners

Postby jimh » Wed Mar 28, 2018 7:38 pm

The WEST System repair kits include resin, hardener, two fillers, gloves, spreaders--about everything you need to make a repair and that is why they are repair kits.