Installing bimini hardware - best method?

[scoutabout]

I want to transfer the bimini from my previous boat to the Scout as I think the beam of both boats is within a couple of inches.

The bimini was secured on the SeaRay in six places -- four metal hoops (2 fore and 2 aft) for the straps to clip to, and two saddle type mounts with the quick-pull pins screwed into the windshield frame left and right for the rigid poles.

So, the question is, what's the smart way to drill similar holes in the new boat? My concern with the fibreglass is I'm going to start spider cracks in the gel coat or the drill bit will start walking around and with the window frames I'm concerned I will crack the glass drilling into the aluminum. I wasn't around for the first install and want to do it right.

Suggestions on method and screw types anyone? The current screws look like plain old wood screws and were starting to rust.

 

[studlymandingo]

Re: Installing bimini hardware - best method?

Drill a pilot hole with a good sharp drill bit first. DO NOT use wood screws when going back; use only stainless steel screws when you go back. When you put the screws in the fiberglass, use 3M 4200 to keep them from moving; that in combination with pilot holes will reduce the chance of spider-cracks.

Be cautious drilling around the glass, don't use a lot of pressure and verify you don't have glass behind the frame before the screw goes in.​

 

[Nova II 260]

Re: Installing bimini hardware - best method?

Mask of your hole location, use sharp drill bits, and drill pilot holes. Let the drill bit do the cutting, don't force it. Use stainless screws.

 

[bruceb58]

Re: Installing bimini hardware - best method?

After drilling holes, I always follow with a counter-sink bit to keep the gelcoat from cracking when I put in the screw.

 

[Reel Poor]

Re: Installing bimini hardware - best method?

Different size screws require different size pilot holes. Very important when dealing with fiberglass with a gelcoat finish. If your pilot hole is to small and you try to force the scew you can/will twist the head off. Once you have your pilot hole you will NEED to chamfer the pilot hole. Chamfering should be done all the way thru the gelcoat finish. The idea is to remove enough gelcoat so that none of the screw threads contact the gelcoat. CAUTION: DO NOT chamfer with a larger sized drill bit, it can/will pop out large pieces of the gelcoat. Use a burr too or a chamfering bit.

 

[scoutabout]

Re: Installing bimini hardware - best method?

Beautiful -- thanks guys!

And so, if I understand you right, the chamfer should be the depth of the gelcoat (which should match the thickness of the screw head) and the threads are biting into the matting only? How thick is gelcoat anyway?

 

[bruceb58]

Re: Installing bimini hardware - best method?

I just drill the countersink in so that the width of the opening in the gelcoat is wider than the threads...doesn't take much because the gelcoat is pretty thin.

You will see.