Best Drill bit for Fiberglass?

[mf01]

I'm putting some pop-up cleats on the back for my Sport Nautique and they require a 1" hole to be cut through the gelcoat/fiberglass. What is the best bit to use? I have read in other forums to use a forstner bit. Also, I've seen a bullet bit recommended. Any thoughts?

[NCH2oSki]

I used a hole saw, in reverse through the gel, then forward to finish. Cover the area with blue tape before hand, and Sand the edges of the gel afterwards.

[scottb7]

I think the reverse first is super helpful.

[nyryan2001]

yep reverse... regular new sharp Dewalt style bits will work well...

With such a big hole a smaller pilot hole first may help, both in reverse.... and chamfer/taper the holes afterwards so the load on the bolt is solely on fiberglass and not at all on gel... failure to do that puts load on the gel when those cleats are pulled on ...THAT will give you cracks.

[swankster]

Thank for asking and posting this. I'll use this when I put the FAE on the G this weekend. Won't be one inch holes but still like the idea of reverse and taper.

[mf01]

Another question on the topic. Is the gunwale strong enough for the cleats?

This is the cleat I plan to use. http://ecx.images-amazon.com/images/...oL._SX300_.jpg

[s_kelley2000]

Does your boat have any existing cleats? If so I would look at the backside of those if you can to determine if they used any backing plates or beefed up the fiberglass. To be safe it might be a good idea to use an aluminum backing plate or beef up the area with some mat and glass like you would for tower supports.

Do you have a link for those cleats? I have been contemplating replacing my midship cleats with pull up ones and also adding a set near the stern of my boat.

[nyryan2001]

generally the strongest fiberglass will not be a big open panel of fiberglass... but near a corner, or near a bend... or perhaps 2 coners or bends like the top of a gunwhale, perhaps only 3-4" wide. Those corners and bends reinforce, and reduce flex.

Those smaller spans of fiberglass will be stronger and have less flex under extreme loads... as compared to a huge wide open panel of FG, like the broadside of your boat for example.

When you get into extreme applications... like adding an aftermarket tower, or lifting rings..... they are almost always near corner to reduce flex AND the backsides are reinforced with some type of backing plate to distribute the load over the largest area possible.

[mf01]

Does your boat have any existing cleats? If so I would look at the backside of those if you can to determine if they used any backing plates or beefed up the fiberglass. To be safe it might be a good idea to use an aluminum backing plate or beef up the area with some mat and glass like you would for tower supports.

Do you have a link for those cleats? I have been contemplating replacing my midship cleats with pull up ones and also adding a set near the stern of my boat.

http://www.amazon.com/attwood-AT-20-.../dp/B001O0DKMA

[TxJole]

I used oem Nautique cleat last year and they have a MUCH larger backing plate then Attwoods. I also use a new step bit to drill the holes, it bevels the gel coat for you.

[Pjoachim]

What is a "Step bit"?

[Chexi]

Think of a step pyramid, just circular. Your local hardware store has them. They are not cheap, but they are worth it, especially when going through metal.

[TxJole]

Step bit, my "go to" tool now.

http://www.lenoxtools.com/pages/Prod...tStepDrillBits

[mf01]

Did you run the step bit in reverse?

You can get them at Harbor Freight. I have a few, but the largest is 3/4".

[TxJole]

I start it in reverse then flip to forward. Key is slow and steady and let the bit cut.