Cobalt. Yeah, That’s The Ticket.

Our bimini (the fabric awning that shades Eagle Too’s cockpit) is big enough to play tennis on. Well OK, that’s probably an exaggeration. But I’ll bet you could play badminton on it. It’s definitely big enough for badminton. Anyway, it’s pretty large, and it’s supported by four stainless steel frames, or bows. Now the fittings that hold these bows in place are the type that use small Allen screws to pinch the end of the tubes and keep them from pulling loose. I’ll bet you probably have some on your boat as well.

BiminiRivet1So the only thing holding the bimini frame bow in place is the pressure of that little Allen screw against the frame tube. Interesting thing about that little screw. It can’t handle the force of a 50 knot wind. At least, not when you have a bimini big enough to play badminton on.

How do we know? Because as we described in Our Perfect Storm, we actually had the chance to try it out and see what happens. And what happened is that as the wind topped 50 knots, the bimini frames started pulling out of those fittings. If it hadn’t been for Rhonda holding on to it for dear life, it would have probably become our dear departed bimini.

I knew I could improve the strength of that connection. My plan was to remove those little Allen screws, drill holes though the frame tubes, and insert stainless steel rivets to replace the little screws. There’s no way they would pull loose. I figured the fabric would be blown to tatters before the rivets would shear off.

So one recent blistering hot afternoon, I pulled out my DeWalt cordless drill (love that thing a lot!) and my Craftsman drill bit set. The set that was clearly labeled “Suitable for all metals.”

Removing the first Allen screw, I shot some Boeshield T-9 (my lubricant of choice) into the hole and then started to drill. And drill. And drill some more. And sweat a lot. And then drill a bit more, while sweating profusely. And then alternate drilling and sweating, with just a touch of swearing.

After about 10 minutes, I stopped to check my progress. If I looked really close, I could just make out where my “suitable for all metals” Craftsman drill bit had scratched the surface of the stainless steel frame tube. Maybe. Just a little.

This obviously wasn’t going to work. Such is often the way of things when it comes to boat jobs.

After laying below, cooling off, and putting on a dry shirt, I started doing some research on how in the hell you drill a hole in stainless steel. What I basically discovered is that your only hope of accomplishing it without industrial tools is to use cobalt steel drill bits, along with a good lubricant and lots of pressure. Not having any cobalt steel drill bits handy, I moved this job back to the bottom of my “to do” list.

So I happened to find myself at Lowe’s the other day, and I actually remembered that I had this job hanging out there that I had started and had given up on for lack of cobalt drill bits. So I popped into the tool section, and sure enough, they had a nice fourteen piece cobalt drill bit set for $29.98 made by Rigid, which is one of the better names in cheap Chinese tools.

And you know what? They worked. I switched to WD-40 rather than Boeshield T-9 to lubricate the bit, and with steady pressure and a moderate speed, I was rewarded with the sight of shiny little metal spirals falling from the hole as I bored through the first frame bow in a couple of minutes. The rest fell quickly into line. I then inserted the 5/16ths stainless steel rivets I’d picked up some time back at West Marine (stainless and not aluminum to reduce the chance of corrosion from dissimilar metals) and with the help of my handy rivet tool:

BiminiRivet3I “popped” rivets into each of the frame bow fittings.

BiminiRivet2Now truthfully, I hope we’ve crossed “ride out 60 mile per hour winds at anchor” off our list of life experiences and don’t ever have to test these fittings. But if a next time ever comes, well, I feel pretty confident that a flying flailing bimini will be one thing we won’t have to deal with.

3 thoughts on “Cobalt. Yeah, That’s The Ticket.

      1. Deb

        We completely converted our bimini to rigid frame and got rid of all of the straps. When we did that we put stainless rivets in every end fitting – and there were a lot! We did also use it when we built the solar panel frame. We sometimes also make a little extra $$$ sharpening drill bits for fellow cruisers at anchorage.

        S/V Kintala


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