How to not crack gelcoat

[nipper]

I need to put some stainless steel snaps into my gelcoat area. I thought I remembered a thread where someone gave advice on how to do so without causing any cracks in the gelcoat. Any help would be appreciated.

[NOTHING ELSE MATTERS]

Make you hole as normal, then counter sink the hole, you can use the phillips screw bit on your screw gun.

[spareparts]

I have a counter sink bit I use, but as NEM said, just cram the screw bit in the hole, spin it for a few, them put the screw in the hole. Ive run the screw backwards for a few and had it work as well

[nipper]

Thanks Spare and NEM. Another question. What I am doing is putting curtains made of sunbrella over the cutouts where my rodboxes were--basically making that area a storage area for skis, life vests, etc. I have lined the area with indoor outdoor carpet to protect the hull and reduce noise from vibration. About how far apart should I have the snaps?

[reelapeelin]

Originally Posted by nipper

Thanks Spare and NEM. Another question. What I am doing is putting curtains made of sunbrella over the cutouts where my rodboxes were--basically making that area a storage area for skis, life vests, etc. I have lined the area with indoor outdoor carpet to protect the hull and reduce noise from vibration. About how far apart should I have the snaps?

Snaps on my top are about 8-9" apart...

and on the screw thing, they're right on the money on use of the counter-sink or phillips-head bit!!...and another thing is bit selection when drilling the hole...doesn't take much glass to get a strong bite, so size the hole you drill accordingly...I hold up a bit shank to a screw when determining hole size...showing about 1/2 the thread looking past the bit is about right...

[nipper]

Thanks guys. I have rod boxes from a 1991 V 20 cuddy that need some slight repairs that I might just let go after I complete this. They are not the nicest rod boxes (i.e. no teak or anything), but for someone in need who has a hull in that year range, they would work.

[Destroyer]

Originally Posted by reelapeelin

Snaps on my top are about 8-9" apart...

and on the screw thing, they're right on the money on use of the counter-sink or phillips-head bit!!...and another thing is bit selection when drilling the hole...doesn't take much glass to get a strong bite, so size the hole you drill accordingly...I hold up a bit shank to a screw when determining hole size...showing about 1/2 the thread looking past the bit is about right...

I've found (through a lot of trial and pain) that when drilling holes I just use whatever size drill it would be if I was going to tap the hole instead of put a screw in it.. So (for instance) a 1/4" screw gets a #7 drillbit which gives you (roughly) 75% thread in plastic, copper, brass etc. A 1/8" screw (snap thread size?) would use a #38 drillbit for that same 75% thread in plastic, brass or copper. Just use a 1" micrometer or a good set of verneer calipers to determine what the size is of the screw you are installing, then size your drillbit accordingly. You can find several charts on the internet for determining what drill to use for what size. This is a good source:

http://www.shender4.com/thread_chart.htm