Boat Speaker Installation

[TBradley]

Could use some advice. I am replacing my old 6.5" flush mount speakers in my boat. The new speakers are slightly larger in diameter which will require me to increase the size of the exisiting holes in fiberglass sidewall in the cockpit area. The previous holes were cut quite nicley and I don't think increasing the hole diameter will be all that hard.

However - I have never cut fiberglass like this and am wondering what is best tool and blade type to do the job. Want to make sure I don't fracture the fiberglass by using the wrong device or method.

Thanks in advance for any advice.
TB

[ozzgood2001]

dremel with a nice sharp spiral blade would be nice move it around good and slow. nothing worse than a rough cut creating stress cracks. pick up a multi pack of spiral blades they dont seem to keep a edge very long thet burn up quick.

[Jason Adam]

For drilling, reverse drill your holes first and countersink them a bit before you screw into them or bolt through. For cutting new holes, I always use a standard hole cutter. To widen, I guess it would depend on how much you need to bore the hole out..

[dtg]

Should he, put some tape down on the glass, before he goes cutting it?

[wild bill]

how much bigger are you talking? is it wood covered with glass or all glass?

if it just a little bit i would just grind it larger. if its a lot use a jig saw with a finer blade or a rotozip.

[ScottC]

Should he, put some tape down on the glass, before he goes cutting it?
Yes, the blue tape by 3M works very well for this job. As for cutting...what wild bill said should work just fine.

[SabikiRig]

Tbradley,

Is the fiberglass you are planning to cut cored with Plywood on the inside? If so a Dremel is not going to cut the mustard. A Dremel may work if your just cutting the gelcoat and laminate.

I would suggest using a Variable Speed Jig saw with a fiberglass blade. (Bosch 10 TPI)

Lay the blue 3m tape down on the area you are going to cut and draw your layout on the tape. The tape will prevent the gelcoat from chipping as you cut.

[MGV]

Reverse drill is what bass pro said to do.

[TBradley]

Many Thanks on all the advice. I think the dremel solution will work best for this application. The problem I have is that the magnet on the backside of the speaker is slightly larger and by extension the casing on the back side of the speaker is maybe 1/4" larger in diameter than the previous speakers which require me to "open up" the exisiting holes a liitle bit.

Not being an expert in fiberglass repair...the fiberglass it'self look to be 1/4" thick with no wood core. Its a partition on the inner cockpit area near the cuddy.