Installing Perko Fender Locks - Drilling Suggestions

[04select200]

I was wondering if any one has ever installed these. They say then take #8 screws, but dont say how long they need to be. Any ideas? I was thinking 1/2 to 3/4. Also, what size hole do I need to predrill in the gellcoat for these #8 screws. Any suggestions for drilling into gellcoat, I have never done it?

 

[jason78]

Just measure twice and drill once. After drilling the hole, get a bit several sizes larger and by hand twist the bit in the top of the hole to wear down the Gelcoat a bit. This reduces the likelyhood that the Gelcoat will crack when you screw in. Remember the gelcoat is not thick at all, most of what you will drilling in to is fiberglass. Be sure and squeeze some caulk in the hole before you put the screw in.

 

[Big Island Lifer]

http://www.youtube.com/watch?v=akIYW4yMDZc&feature=player_embedded

This guy know his sh*t!

 

[spfortjohn]

When attaching anything to my boats I always drill and tap the hole and use 4200 marine sealant on the holes. Never had any pull out or spyder crack the gelcoat.

Try it it works great.

John

 

[MLauman]

I always run the drill bit backwards thru the gelcoat layer. Then forwards thru the fiberglass. This minimizes chipping gelcoat. Masking tape helps also.

 

[04select200]

Any ideas on what length screw, or what size hole to predrill for #8 screw?

 

[1stSeaRay]

http://www.engineershandbook.com/Tables/woodscrewpilotholes.htm

check out this link....plan on using the the size listed in the hardwood column, and possibly one bigger.

 

[wish2fish]

http://www.youtube.com/watch?v=akIYW4yMDZc&feature=player_embedded

This guy know his sh*t!

No, Jay is just stupid enough to try anything! :grin:

 

[HUMPH]

Any ideas on what length screw, or what size hole to predrill for #8 screw?

You may want to consider through bolting this if you can access the back side of the space. It is always a much better installation. Fenders don't have much weight but when you leave a dock and one gets stuck it can rip wood screws right out of the glass...

 

[Pachanga Boy]

just to add on to what others have said, one tip I've learned is when your installing the screws don't use a drill with a bit, use a hand screw driver. That way when you're driving the screw if you start to get too much resistance or hear any sort of "crack" noise you can instantly stop and back out before you crack the gelcoat. although don't wait for the noise haha. then just clean up the hole with a drill (wiggle the bit back and forth in the hole along a single axis) to enlarge the hole just a bit.
as far as picking out a drill bit, I usually just line up a bit with the shaft size of the screw (width between the threads not outside-outside of the threads)

 

[CliffA]

You may want to consider through bolting this if you can access the back side of the space. It is always a much better installation. Fenders don't have much weight but when you leave a dock and one gets stuck it can rip wood screws right out of the glass...

my thoughts exactly.....if you get any significant waves from nearby boats while your boat is tied up the up and down wave action can cause the fender to get trapped below the dock edge when the boat tilts down...then when the boat tilts up with the next wave and the fender is trapped under the dock edge there will be a lot of stress put on the fender line and the fender line hanger...i would go as far as using a backing plate of some sort along with the through bolts, or at least use some large fender washers...