Specific drill bit for drilling through gelcoat?

[iamthunderman]

I am installing my tower tomorrow, was wondering if anyone has any reccomendations on a brand and type of bit to use for drilling through the gelcoat?

Thanks!

 

[Silverbullet555]

Re: Specific drill bit for drilling through gelcoat?

Run it in reverse to break through the gelcoat. I also like to use a countersink before drilling so the hole in the gel is larger than the hole you are drilling.

What are you using for backer plate behind the mounts?

 

[ThreeMileBayWaker]

Re: Specific drill bit for drilling through gelcoat?

Carbide/ diamond tip... drill in reverse through gel coat as mentioned above. Counter sink the hole with a round ball tip sand bit to prevent the gel coat from cracking.


vist www.samsonsports.com for a how-to video. Shows many good tips.

 

[iamthunderman]

Re: Specific drill bit for drilling through gelcoat?

I am going to use some marine grade plywood and marine grade epoxy. Any different advice?

 

[iamthunderman]

Re: Specific drill bit for drilling through gelcoat?

I need a 3/8 bit for the drilling part, what size ball tip sand bit should I use?

Also, I am going to use marine grade plywood for backing. Should I use liquid nails or some supermend epoxy?

Carbide/ diamond tip... drill in reverse through gel coat as mentioned above. Counter sink the hole with a round ball tip sand bit to prevent the gel coat from cracking.


vist www.samsonsports.com for a how-to video. Shows many good tips.

 

[Silverbullet555]

Re: Specific drill bit for drilling through gelcoat?

I am going to use some marine grade plywood and marine grade epoxy. Any different advice?

Use a big enough piece to really distirbute the load. Also, I would mix the epoxy with a filler to a PB consistency and and bond it to the back filling ALL voids in between the board and the hull. The hull will likely have high and low spots and will probably be curved. Your goal is not to squish out all the epoxy behind the board but rather to fill the gaps to distribute the load. You want not stress on the hull when in a resting state as it will lead to cracks. I hope I am maxing sense.

You can do all the drilling and prep first, then PB the boards and mount the tower tightening everything just enough to squeeze some of the epoxy out. Then when FULLY cured you can tighten everything to spec. Or you can mount the board first and let it cure then drill through it. The advantage of the first way is that you can position the backer so that the bolts are truly perpendicular to the board relieving some of the stress.

 

[iamthunderman]

Re: Specific drill bit for drilling through gelcoat?

Thanmks for the tips guys. I got a brad tip with a ball sander, but I think I might take the brad tip back for a diamond tipped bit. For the epoxy I got 3m 5200 marine adhesive sealant, it has a very thick consistency. I am going to cut out 4x6 backings from 3/8 inch plywood.

I'll take pics. Thanks for the advice.

 

[pigrge]

Re: Specific drill bit for drilling through gelcoat?

hey man,
I would suggest taking the 5200 back in lieu of AT LEAST some PL Premium Construction adhesive. That stuff is just about as good as epoxy and half the cost of the 5200. It is my unserstanding that the 5200 is flexible, which is NOT what you want. The PL is not flexible and provides a MONSTER grip!
Just my .02 tho!

 

[250Gimp]

Re: Specific drill bit for drilling through gelcoat?

I agree with pigrge above. The 5200 will not dry hard like an epoxy or PL. I would recommend an epoxy as it dries harder than PL in my opinion, but use PL as a minimum.

You can keep the 5200 to seal around any holes you may have in your hull, even below the water line.

Cheers

 

[Silverbullet555]

Re: Specific drill bit for drilling through gelcoat?

I agree with pigrge above. The 5200 will not dry hard like an epoxy or PL. I would recommend an epoxy as it dries harder than PL in my opinion, but use PL as a minimum.

You can keep the 5200 to seal around any holes you may have in your hull, even below the water line.

Cheers

X3

You want the epoxy for the filler between the backing plates. I would use 4200 for the sealant instead of 5200 so you can remove in the future if you need to. Hope we're not too late.

 

[iamthunderman]

Re: Specific drill bit for drilling through gelcoat?

Ughhhhhh, I used the 5200....... I had some issues, but resolved them pretty quickly. The instructions that came with the kit said drill with a 3/8 bit but I actually needed a 5/8 bit..... so after countersinking with a ball sander (thanks to threemilebay for the link) and prepping my holes for a 3/8 screw I quickly found out I needed a bigger hole. SO I just did the reverse process by ball sanding to a 3/4 inch sountersink type hole at the top of the gelcoat, then bought a 5/8 bit and reverse drilled the rest of the hole, no chips or cracks I did do something a bit different, I cut four 4x3 pieces of plywood and covered both sides with some think PB marine epoxy and let it cure, then used the 5200 on the underside to fit up against the underside of the boat. There were no major curves where I put the legs of the tower.

The rest will take place theis afternoon. Should I drill and pull speaker wires before I put the rest of the tower up?

Thunder

 

[Silverbullet555]

Re: Specific drill bit for drilling through gelcoat?

Everything is easier to drill when it is not over your head. At a minimum I would drill holes and put in string to make it easier to pull wires when complete.

How are you getting the wires out of the boat? In other words are you drilling through the hull and jumping to the lower support then out of the lower support into the tower?

Either way, the more prep work you do before the tower goes on the easier it is. I have done two towers after they were installed and drilling, soldering, etc over your head gets old after a while. The more you can do before you put it up the better when it comes to drilling, etc.