Drilling into the Gelcoat

[Mike G]

I am about to take on the task of wiring my tower speakers and I have a question about drilling through the gel coat. It seems that from the posts I have read everyone has removed the tower and drilled from the top side. I have access to the base of the tower from underneath - are there any issues with drilling from underneath as opposed to removing the tower and drillling topside?

[kaneboats]

Never tried it but I know the SOP is to lay a piece of tape and then drill (in reverse) through the gelcoat and then forward through the glass. I imagine going from the back side has the potential to cause a crack or chip in the gel coat.

[sandm]

I, too, have not done the underside, but having done the topside and I'd do that again every time when possible as I know that it does work as kane has described..

guess if it works, use it

[Razzman]

The fault with that is that when you break through the gelcoat on top it will more than likely crack the gel and cause spider cracks to eminate outwards from the hole over time. Granted removing the tower is a pain but well worth doing it correctly in the long run.

If it were mine i would dril a very small pilot hole from underneath then unbolt it and just move it slightly to allow drilling. Reverse drill the hole until through the gel then forward, then countersink to prevent cracks.

[Mike G]

Thanks for all of the feedback. This is obviously the first time I have had to drill into the gelcoat of a boat and I don't want to screw it up.

[mmandley]

Are you refering to drilling from the tower foot into the boat for your cubby area? I did this on my boat and i drilled from the inside threw the boat into the center of the front foot on my tower.

Mine has a plate on the inside, heavly reinforced with a 1inch fiberglass or some material, then the hull, and the tower front foot is bolted right at that spot. It also has a pre cut hole in the center of all the mounting bolts in that plate. Id post some pics but im not at home this week. I might have some old pics of my amps and how i wired the tower.

If this is the place you are talking about then yes you can drill threw it. I ran my drill in reverse the whole way threw it though. Drilling in forward from the back will absolutly thrash the gell coating. Think of what a drill bit does when you drill threw wood on the back side. It generaly blows out.

I measured a ton of times. Then i took a very small bit and drilled a pilot whole in forward, it was a very very small bit, i wanted to double check my drill location so if i missed my tower leg i only had a tiny hole to fix. Then i progressivly got bigger and bigger till i reaced a 1/2 hole.

The hardest part of drilling threw the bottom of the boat up into the tower leg is the angle. You have to drill it straight up or you realy risk missing the tower foot. This area of the boat is incredably thick. Once i fished the live threw there and pulled speaker wire it was a long task. The speaker wire didnt want to make the bend into the hole i drilled and it took a lont time. I finaly got it and it created a truly seamly wire effect that matched the factory side for the nav light on the top of the tower.

If you have questions ro want to see some pics Pm me

[Mike G]

mmandley,
that is exactly where I am tring to drill. I am not real sure about the plate but I think mine is the same as what you are referring to on your boat. Unfortunately I keep my boat in storage near the lake which is about an hour away so I am going to make a trip this weekend to check on her and see what I have. I may get back with you next week for some pics as that may really help.

[Mikey]

As a plumber,when we drill fibreglass or acrylic tubs and showers we always drill from the finished side. If you don't as mentioned above it will blow out and splinter at the very least. Unless you have a area with lots of coverage i wouldn't recommend doing it.Also the bit backwards to start also helps,as does a Sharp bit pushing and or rocking bit around gently.

[Suprahunter]

You have to countersink the hole as Razzman said or you will most likely get spider cracks. There is a lot of strain on that part of the hull. When I installed my tower the directions specifically said to counter sink the holes.

[mmandley]

Mikey and Suprahunter i agree with you both 100% you should drill from the Gel Coat side and counter sink holes.

The front legs of the tower are actualy not under that much stress when pulling a boarder. The Rear legs are taking the brint of the force.

As i said before if you use small bits and progresivly get bigger you wont have any issues.

I can say i have drilled about 13 new holes in my boat in the gell coat. I have seen exactly what happens when you drill, cut, heat, sand and file gel coat on these boats. As long as your going small and getting bigger, going in reverse so the bit doesnt bite into the gell you can go threw from the back side and not cause splinter cracks.

Its never recomended but it is possible. Taking the tower off is the best option but it wasnt and isnt always an option for everyone. I can also tell you stereo shops Do Not remove your tower when they run speaker wires as a normal practise. They drill it from the inside out and i would bet money they dont step up the bits from small to large.