CC247

I want to change my thru-prop exaust over to silent choice. Any tips on drilling the 4" holes,type of sealer, is there a special jig or something? Thanks

Wally

iTrader: (1)

Easiest way to figure out where to cut the holes is to get some of the 4" exhaust hose and install it on the manifolds.....the hose will naturaly line up where it needs to be on the boat. You can outline that with a marker and drill yourself a small pilot hole from the inside of the boat. Then on the outside you get a bunch of the painters blue masking tape and mask it up around where you will be cutting to keep the gel from chipping. When you have cut your hole, insert the tips loosely to drill any screw holes you may need. Then peel the tape from the outside into the hole to keep from pulling any gel away. Mix yourself up some fiberglass resin and get a disposable small paint brush and seal up any of the freshly cut glass that you see there. As for sealing the tips......best bet would probably be the 3m 4200 fast cure. The 5200 is way to strong and if you need to remove the tip in the future you will rip gel/glass along with the tips!
Good luck. Measure twice and take your time

hillbilly24

Use a hole saw to drill the wholes, make sure it is deep enough to go all the way through. If not after you get part way through you can pop the piece out carefully with a screw driver and then drill through the rest of the way, dont try and drill from both sides it doesnt work very well at all. start with the drill in reverse until you get through the gelcoat (this prevents cracking the gelcoat) then switch the drill to foward for the rest of the way through. the silent choice setup should coem with a template but dont just pop it on drill you need to make sure you can route the exhuast to where you want to mount the tips, some custom pipes or flex tube may be neccesary to get it all lined up. make sure you thouroughly think the routing out though before you drill cuase there aint no turning back you may need to spread the tips further apart then shown on the template to clear everything depending on your setup. Baot life makes a sealant called life seal that works great and comes in clear white and black and you can get it as west marine or boat us stores. I think that answers all of your questions if not let me know.

hillbilly24

And what wally said about sealing the transom inside the holes is very important too. I have found the drill in reverse mthod to work better then tape but doing both wouldn't be a bad idea.

Wally

iTrader: (1)

Yes i forgot the drill in reverse thing........its second nature to me now so i tend to forget little things like that! Good catch there hillbilly24!!

CC247

Thanks, great info. Great site!!!