I tried to drill a screw into the top of my fiberglass hull from the interior. I did a pre drill and hand twisted the screw but it made a loud crack and the screw didn't hold. There doesn't seem to be structural integrity damage and I can't see any visible damage but there is vinyl on the interior ceiling so I can't actually see the fiberglass unless I wanted to rip away at that cosmetic plastic covering. My fear is that the fiberglass around the hole is going to crumble and or spider crack and leak or cave in when I walk on top of it. The screw is .9 inch long. I pre drilled with a smaller bit. There is no visible damage to the outside of the boat.
Is my fiberglass hull okay?
- Thread starter skins189lbs
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,390
If you heard a crack and it was not the metal screw than it was fiberglass at or near the hole you drilled.
Lets start with terms.
Lets start with terms.
- “into the top of my fiberglass hull from the interior” By hull I am interpreting that to mean the ceiling from inside the boat. The out side would be the deck and you did not see any cracks or holes in the area that you drilled and attenpted to screw into from beneath.
- the deck is made from two skins of fiberglass and a sandwiched material “core” between them. The skins can have varied thicknesses. The core can come in a variety of materials. Depending on the builder it could be balsa, plywood, foam etc.
- ”there is vinyl on the interior ceiling”. This covering may be glued or not. In order to repair the skin damage you will need to get the vinyl out of the way to do any repairs.
- If the skin is not repaired you might go for years with no bad experiences. Then you might have water seep beneath the outer skin and water being water, it will find it’s way to your screw hole and drip into the cabin.
Along with what was previously posted ,I'd like to suggest the following . There wont be much strength in the screw threads . What we do is mounted a teak ,mahogany wood block with 4200 where we would like the hook . Before mounting we drill the hole and counter sink a larger hole on the back side for a stainless nylock nut . Mount the block and screw the hanger in . No holes in the fiberglass ,the block may be removed later . The block looks more finished and professional
I like Timm R's method. Those pesky coffee cup hooks have very small threads. Hanging a hammock style net, a basket of fruit, or a decorative lamp will challenge the small hook. Perhaps patch the cracked fiberglass on the overhead and rethink the installation.
I wouldn't use a steel hook, it will rust, expand, and cause further damage.
Thank you. I just used gorilla marine grade construction adhesive. I'm not at all concerned about the cosmetics of it. I was just afraid that I weakened the entire hull or at least the surrounding area of where I drilled. It not, it'll look fine once I paint it. That's the least of my worries. If the adhesive fails I'll use epoxy. It's just the interior. Nothing went through the deck so I don't think water will be an issue.
I think "Skins" is referring to a hole he drilled into the overhead from the inside, that he incorrectly called the "ceiling". I don't think an older Ranger 29 had a 'cored' deck, so he's crunched old fiberglass at a location that may have delamination.
If I am correct, I would have the area behind the vinyl checked for delam or
other damage and repair same.
I also agree with Capta and not use a mild steel fastener there or anywhere on my boat.
I too would install a wood block at the location before re-installing any fastener.
If I am correct, I would have the area behind the vinyl checked for delam or
other damage and repair same.
I also agree with Capta and not use a mild steel fastener there or anywhere on my boat.
I too would install a wood block at the location before re-installing any fastener.
Gizzard, you are correct. I drilled from the inside. Ceiling is probably not the ccorrect term. Checking behind the vinyl is going to be a major project if that is infact necessary.
I appreciate your input. I looked this up and it seems as though it was cored. I hope this helps my case for not having to do repairs.
Attachments
On my own boat I can see the damage done by previous owners and the factory in places that have sheet metal or wood screws. 99% of those fasteners are still holding strong 30+ years later but on the back side you can see that the damage in the fiberglass is about the size of a dime in most cases. There are a few who's damage spreads to about the size of a quarter. You can generally only see the damage if you're looking at bare fiberglass (ie no covering or gelcoat)
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Skins,
The load noise you heard was most likely the core separation from the core material. Use a syringe filled with slightly thickened epoxy squirt it slowly into the hole and allow it to fill in any cracks or voids between the damaged core and glass. Take note how much epoxy it takes to fill voids. Probably will not take much. When it cures it will be good as new plus no way for water to rot the core.
Hope this helps
The load noise you heard was most likely the core separation from the core material. Use a syringe filled with slightly thickened epoxy squirt it slowly into the hole and allow it to fill in any cracks or voids between the damaged core and glass. Take note how much epoxy it takes to fill voids. Probably will not take much. When it cures it will be good as new plus no way for water to rot the core.
Hope this helps
Capt Robbie, thank you! I will do that! I just learned about and performed the tap test, and yes I think it was definite separation. It's soft in that area. Any suggestion on what type of syringe and the epoxy.
Go to You tube videos from "Boatworks Today" or "Sail Life"
They have years of videos covering topics like epoxy injection
to re-building a fiberglass boat from a gutted hull.
They cover brands, mixing, masking, injection methods, cleaning, refinishing, curing,
fairing, sanding, moulding from soup to nuts.
Both channels are an advanced course in these topics, but if you find the beginning of a particular project, they cover the steps in clear language.
You will have to divine what project you think is the closest match to your issue.
Or, you could just start at any vlog thread and follow it to conclusion.
It's a "Glorious" adventure!
They have years of videos covering topics like epoxy injection
to re-building a fiberglass boat from a gutted hull.
They cover brands, mixing, masking, injection methods, cleaning, refinishing, curing,
fairing, sanding, moulding from soup to nuts.
Both channels are an advanced course in these topics, but if you find the beginning of a particular project, they cover the steps in clear language.
You will have to divine what project you think is the closest match to your issue.
Or, you could just start at any vlog thread and follow it to conclusion.
It's a "Glorious" adventure!