I have a Slingshot Glide and want to drill a couple of new holes in it to change the fins,by doing this will I damage the board, will the board take in water,do I need to waterproof the holes ?

Just drill it, what have you got to loose? its only a board.

dunno about drilling and tapping your fins, the side wall of a lot of fins is very thin once the holes have been drilled. I know the center of a 2 bolt fin could handle that but you would have to be so damn carefull to get it perfect so as to not bust through the side wall.

As for the holes in the board. It would depend entirely on the construction as to whether or not this can be done without letting water in (i have no idea what the construction on a glide is). I would guess that if you have 2 holes and you drill right between them you would be okay but would end up with a pretty weak area. and if it was anywhere else you could potentiall seal it up by screwing in the fins and then very carefully sealing the contact points between the fin/deck and screw/deck with Sikaflex.

What is wrong with simply buying the correct mount fins simular to the ones you are thinnking of installing, bound to be cheaper that risking a whole board.

why risk breaking a board just for new fins

my advice is find some other similar fins that fit.

ewan

What sort of fins do you want, I make 40 and 50mm fins in various lengths with one screw and 2 molded in locating lugs or 2 screws with no lugs.

I wouldn't drill my board.

Board: $100 upwards for a second hand board
Fins: $35.00 a set of 4 + postage

If you stuff the board it takes a long time to dry out or it's a costly repair

I don't know if it is a good idea. Have never done and wouldn't recommend anyone doing it, it just doesn't sound right.
Don't know how old the board is but you may loose warrantee on it if it is still in warrantee.
Don't do it mate!