OK, that headline was a test of how clean your mind is. If you didn’t immediately assume that I was writing about my current fixation, bolted joints, you failed.
Anyway, one of the things that never ceases to amaze me is how common sense can fail us non-engineers.
In that vein, here’s something I only learned in 2019 when I hired an engineer to advise on what I needed to do to solve the excessive flexing in the plate that takes the thrust from the Aquadrive on the McCurdy and Rhodes 56 (M&R 56) that had been installed by a welder and machinist some years before.
Common sense would say that if we want to double the resistance to bending of that plate (engineers call this stiffness) we should double the thickness.
Interesting. Over 15 years ago I specified 25mm marine ply for my Aquadrive 15 thrust plate. The company wanted to fit 15mm but I thought that was too light. In my case, the plate fully bridges the narrow bilge so it is a very stiff installation being supported on all three sides once glassed in. It had stood the test of time.
Also, a history of penny washers (fender washers) deforming, resulted in me only using thick large diameter washers at 3mm or 5mm thickness, depending on bolt size. I have never experienced washer deforming since changing. Of course, large diameter washers are not always needed and standard washers on a stiff surface should suffice.
Hi Alastair,
Sounds like a good call and one with pretty much no down side given that the minimal added weight was down low.
“One more tip. Don’t trust welders and machinists to make engineering decisions, no matter how confident they sound.”
As an engineer I must add, don’t ignore them either. They may have a reason they can’t put into engineering terms. This is quite common. Ask questions and you may tease out an explanation or part of one. Engineers don’t always know that much about welding or machining.
Hi Drew,
Good point. The same two guys helped me improve many things over the years.
Agree wholeheartedly with Drew Frye.
BTW I am a mechanical engineer