Building up my courage to drill 4 holes into the top deck of my gelcoat fiberglass boat to install some rails. Triple checking the proper way to do this so I dont get spider cracks!
1) Masking tape over the drill area
2) Drill slow in reverse?
3) Chamfer the holes after drilling through
Is that it? Am I missing anything?
You got it covered 
Just make sure your countersink goes all the way through the gelcoat to the fiberglass (especially if your hole is undersized to hold a screw). If through-bolting, countersinking isn’t really necessary.
Also, You may want to use a step drill.
You got it covered
Just make sure your countersink goes all the way through the gelcoat to the fiberglass (especially if your hole is undersized to hold a screw). If through-bolting, countersinking isn’t really necessary.
its a couple of bow rails that have through bolts with large washers
I have heard many different stories about the best way to do this. I have heard that spot drilling with a larger diameter bit than you plan for the through hole is a good practice. Then drill the through hole concentric with the larger diameter shallow counter sink. I haven’t ever done it or seen it demonstrated though so I don’t really know. Anyone have a good video reference on how to get the job done with as little damage as possible?
I have heard many different stories about the best way to do this. I have heard that spot drilling with a larger diameter bit than you plan for the through hole is a good practice. Then drill the through hole concentric with the larger diameter shallow counter sink. I haven’t ever done it or seen it demonstrated though so I don’t really know. Anyone have a good video reference on how to get the job done with as little damage as possible?
I would imagine YouTube has 100s
just think clamping force can spider crack the top gel coat..
warm or hot temp is a good thing when drilling good new glass boat…
i used to have fun drilling new corvettes for antennas!
every second was another thousand off the car value! GRIN!yea drill 1/16 piolet hole.
then move up to 1/4.
then step drill.oh yea how big of hole do you need??
make sure to use stainless hardware.
I believe it’s just 1/4 inch bolts
1) Masking tape over the drill area
2) Drill slow in reverse?
3) Chamfer the holes after drilling through
1) tape is fine while you’re building confidence
2) run the drill in reverse through the gel coat
3) chamfer the gelcoat
4) run the drill forward to get through the fiberglass
5) chamfer the gelcoat at the edge of the hole again
it’s easier than it seems. post some pics of your project!
Measure six times, have trusted friend confirm, drill! I would use the masking tape, pilot holes, and other advise as stated above. Also, use flat washers and either lock washers or Nylon nuts on the underside. Good luck. Post pics when done! It is always hard to get your courage up to drill a hole in a boat. lol.
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