I want to mount a few things (EPIRB, etc.) down below. There are some areas that have "voids" behind the fiberglass (as I can tell by knocking) and some areas that seem to be solid fiberglass. What is the best fastening device or fastener for these aplications? Screws, "molly bolts" or ???? I haven't done any drilling on the boat or any fiberglass in general and want to make sure it gets done right the first time. Any suggestions???
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Bob Zolczer
Use West System Epoxy and Screws
Here's the method I used. Drill the mounting holes slightly undersize. Use an epoxy and microballoon mixture inserted into the hole with an epoxy "hypodermic" found at BoatUS or West Marine. Cover the hole with masking tape and let it cure (this stops the epoxy from oozing out). The epoxy will migrate into voids, solidifying them and spread out behind the material. If you redrill the new epoxy slightly undersize to the screw, the screw will self tap and hold well.
Here's the method I used. Drill the mounting holes slightly undersize. Use an epoxy and microballoon mixture inserted into the hole with an epoxy "hypodermic" found at BoatUS or West Marine. Cover the hole with masking tape and let it cure (this stops the epoxy from oozing out). The epoxy will migrate into voids, solidifying them and spread out behind the material. If you redrill the new epoxy slightly undersize to the screw, the screw will self tap and hold well.
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Justin - O'day Owners' Web
Bob's got the ticket
Another trick is to tear a tear a piece of paper in a long, thing strip. You want its width to be the same as the distance between the liner and the hull (the depth of the void). Drill the hole slightly oversized. Coil up the paper and stick it through the hole so that it expands on the otherside. This will help create a dam for the epoxy so that it doesn't run down inside the boat. Not practical all the time but it works great when it works. Justin - O'day Owners' Web
Another trick is to tear a tear a piece of paper in a long, thing strip. You want its width to be the same as the distance between the liner and the hull (the depth of the void). Drill the hole slightly oversized. Coil up the paper and stick it through the hole so that it expands on the otherside. This will help create a dam for the epoxy so that it doesn't run down inside the boat. Not practical all the time but it works great when it works. Justin - O'day Owners' Web
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Alan Liebnick
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Brian Pickton
Avoid that sinking feeling
Dec.1, 2000 Dear Steve The best way to run screws into fiberglass to mount gear is to not do it at all. You never know what your going to screw into, such as a wire or a hose. I damn near electrocuted myself once doing this, and on another occasion, She Who Must Be Obeyed drilled into a water line which made for a few exciting moments, (We're sinking, we're sinking!) so I have experience if not a prejudice in this area. Rather than blindly screwing into your fiberglass, mount the hardware onto a 3/4 inch piece of teak that is an appropriate size for the gear being mounted. Then take the equipment off the teak board and mount it in an appropriate location using PL4200 which allows the board to be removed later if you wish. The teak can be held in place while the 4200 sets up using masking tape. Clean up any excess 4200 with the appropriate solvent. Once it sets up mount the hardware with stainless steel screws that are 1/4 inch shorter than the depth of the teak and the depth of the mounting flange combined. That way you avoid accidentally screwing into something and giving yourself that sinking feeling. The job should look neat and professional when done. I like to router the edges of the boards to give them a more finished look and will varnish them in a bright finish to contrast with the low gloss oil finish of our bulkheads. Speaking of which I see I need to re-oil the bulkheads. She Who must Be Obeyed claims to be allergic to teak oil... An alternative is to glass the board to the fiberglass, but it is a lot of work to make this look good, involving sanding and filling the glass, and finally gel coating it. If you absolutely positively insist on drilling into your fiberglass no matter how bad an idea that might be ( you can tell I’m neutral on the issue) then make sure you drill the hole first and then add the screw, because fiberglass is amazingly tough stuff and I have seen number #12 and #10 stainless screws break their heads off when being screwed in where a hole has not been taped first. You have some good tips here from Bob and Justin, so if there is no other choice, try following their advice. I’m sure some of the other readers will have some good suggestions for you to, but not screwing into fiberglass is always my first choice. If I can’t make that work I would look at mounting the hardware elsewhere. While your on the docks in Vallejo if you run into my friends Micheal and Casey aboard the Bahamas Islander 30 “Freya” please say “hi” to them from me. We had a great time in Vallejo while we were there. Sorry it has taken a couple of days for me to get to you but the internet connectivity here in the Caribbean on weekends can be marginal at best. Good luck on your boat project. Brian Pickton@ BeneteauOwners.net Aboard the Legend, Rodney Bay, St. Lucia
Dec.1, 2000 Dear Steve The best way to run screws into fiberglass to mount gear is to not do it at all. You never know what your going to screw into, such as a wire or a hose. I damn near electrocuted myself once doing this, and on another occasion, She Who Must Be Obeyed drilled into a water line which made for a few exciting moments, (We're sinking, we're sinking!) so I have experience if not a prejudice in this area. Rather than blindly screwing into your fiberglass, mount the hardware onto a 3/4 inch piece of teak that is an appropriate size for the gear being mounted. Then take the equipment off the teak board and mount it in an appropriate location using PL4200 which allows the board to be removed later if you wish. The teak can be held in place while the 4200 sets up using masking tape. Clean up any excess 4200 with the appropriate solvent. Once it sets up mount the hardware with stainless steel screws that are 1/4 inch shorter than the depth of the teak and the depth of the mounting flange combined. That way you avoid accidentally screwing into something and giving yourself that sinking feeling. The job should look neat and professional when done. I like to router the edges of the boards to give them a more finished look and will varnish them in a bright finish to contrast with the low gloss oil finish of our bulkheads. Speaking of which I see I need to re-oil the bulkheads. She Who must Be Obeyed claims to be allergic to teak oil... An alternative is to glass the board to the fiberglass, but it is a lot of work to make this look good, involving sanding and filling the glass, and finally gel coating it. If you absolutely positively insist on drilling into your fiberglass no matter how bad an idea that might be ( you can tell I’m neutral on the issue) then make sure you drill the hole first and then add the screw, because fiberglass is amazingly tough stuff and I have seen number #12 and #10 stainless screws break their heads off when being screwed in where a hole has not been taped first. You have some good tips here from Bob and Justin, so if there is no other choice, try following their advice. I’m sure some of the other readers will have some good suggestions for you to, but not screwing into fiberglass is always my first choice. If I can’t make that work I would look at mounting the hardware elsewhere. While your on the docks in Vallejo if you run into my friends Micheal and Casey aboard the Bahamas Islander 30 “Freya” please say “hi” to them from me. We had a great time in Vallejo while we were there. Sorry it has taken a couple of days for me to get to you but the internet connectivity here in the Caribbean on weekends can be marginal at best. Good luck on your boat project. Brian Pickton@ BeneteauOwners.net Aboard the Legend, Rodney Bay, St. Lucia
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David Lewis
Fiberglass Screwing
NEVER NEVER NEVER NEVER screw screws directly into Glass reinforced plastic (aka GRP). This is not allowed under any circumstances in the aerospace industry and violates every rule of engineering for this material. There are a few techniques for achieving your goals. One is to install screw thread inserts into holes and bond them in place with resin, the inserts are usually knurled for good retention. Another way if you can do it is through drill and use bolts and nuts with large washers to distribute the load. Lastly is bond on a piece of wood or other suitable material using epoxy resin with microfibers for a strong bond joint and then screw directly into the wood or whatever you used. Best of luck.
NEVER NEVER NEVER NEVER screw screws directly into Glass reinforced plastic (aka GRP). This is not allowed under any circumstances in the aerospace industry and violates every rule of engineering for this material. There are a few techniques for achieving your goals. One is to install screw thread inserts into holes and bond them in place with resin, the inserts are usually knurled for good retention. Another way if you can do it is through drill and use bolts and nuts with large washers to distribute the load. Lastly is bond on a piece of wood or other suitable material using epoxy resin with microfibers for a strong bond joint and then screw directly into the wood or whatever you used. Best of luck.
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