Mounting to a fiberglass boat

[BigPoppaG]

Hellow all. I have a question. I am looking to mount a small flag pole and maybe a fishing pole holder to my 1999 180 searay bowrider. I have never drilled into a fiberglass boat and am very cautious in doing so. Any tips you can give would be apprediated. Do I just drill a small hole and then screw the part in or do I need to ad an achor to hold the screws in place? THANKS!

 

[AndyL]

Re: Mounting to a fiberglass boat

To be safe I would always glue a half inch plywood backer to the underside of the area where you intend to mount your article, assuming you can get in behind it. Fibreglass, especially thin section glass is unlikely to be strong enough on its own to hold any load imposed by the fitting under duress. You can attach the backing piece using silicone sealant or polyurethane sealant and ensure that it is as big a surface area as is practicable. Drill through the fibreglass and just pilot hole the backer before attaching with good quality (A4 / 316 stainless) self tapper screws.<br />No worries after.

 

[BigPoppaG]

Re: Mounting to a fiberglass boat

Should I put a water sealing caulk around the piece that is mounted?

 

[agrazela]

Re: Mounting to a fiberglass boat

Big Poppa G,<br /><br />If you are mounting to the top of a gunwale, it just may already have reasonably thick wooden backing under the fiberglass. On the other hand, if you are mounting to an "expanse" of fiberglass (like the transom well), it probably needs added backing.

 

[Rudderman]

Re: Mounting to a fiberglass boat

Yep just bed it in some marine sealant (like silicone) and clean up the excess with mineral spirits. Depends what kinda sealant you use though.

 

[Solittle]

Re: Mounting to a fiberglass boat

Poppa - The above is good advice. The only thig I could add is that it kinda depends on what you are mounting, where and what kind of stress it might be subject to. Common sense prevails. For example if the fiberglass is 3/8" and what you are mounting is not heavy and won't get bounced a lot you probably don't need a backing.<br /><br />If you drill a hole in the wrong place - no sweat - Put in a dab of Marine tex and smooth over & go at it again.

 

[swist]

Re: Mounting to a fiberglass boat

If you are mounting something light and not critical (drink holders, boat hook hooks etc) you don't really need backing and you can use sheet metal screws BUT one thing you have to get used to is that fiberglass has no give at all - if you are using small screws the pilot hole has to be as close as possible to the thread diameter (without being greater). If not you may find it impossible to screw in. For larger screws, you can easily crack and chew up the area around the hole.

 

[BigPoppaG]

Re: Mounting to a fiberglass boat

Thanks guys you have been a big help. My concern is cracking the fiberglass or drilling the hole wrong. <br /><br />SoLittle- Never heard of Marine tex, How does it work?

 

[sangerwaker]

Re: Mounting to a fiberglass boat

Personally, I don't like to screw down anything to my fiberglass boat. I prefer to through bolt everything. Screws have a tendency to loosen up. Boats take a pounding, no doubt about it. No suspension on and not much off the water. I like to use stainless bolts, a large washer on the backside, and a nylon insert lock nut. I realize this isn't always possible, but if you have access to the backside of wherever you are mounting, I highly recommend it.

 

[Boatin Bob]

Re: Mounting to a fiberglass boat

For screwing into the fiberglass, it's best to use an oversize bit to just break through the gel coat first (sorta like a countersink) and then continue with the proper sized bit, this helps prevent the gelcoat from chiping/cracking when putting in the screw.

 

[BigPoppaG]

Re: Mounting to a fiberglass boat

You guys have great ideas. I really like the bolt through idea sangerwaker. I believ I do have access to the backside and I just might do that. Thanks<br />

 

[MFG197]

Re: Mounting to a fiberglass boat

don't forget to use some silicone on the threads and use masking tape over the are, draw on the masking tape, then drill through the tape will help prevent chipping/scratching of gelcoat.

 

[BigPoppaG]

Re: Mounting to a fiberglass boat

Good idea.