A Brutal Reminder

February 17, 2019

 

 

So a couple of recent reminders of the Route du Rhum.

 

As you may recall, I had a bit of a rough patch. Those 10

or 11 days of wind in the mid 30's and gusts to 50? Yeah... so at the time I thought all that "flying off waves and slamming to a sudden and violent stop" only caused psychic damage. Nope. Not so.

 

These pics are of Dragon's engine mounts. Your car has them, boats have them... every mounted engine has them. Typically four of them, one on each corner of the engine. 


The boxy silver bit actually is bonded to a big rubber block which in turn is bonded to the plate that is bolted to the boat. Then your engine has a flange with a hole in it that sits on that stud that that screws into the top of the boxy silver bit. As the engine is running, the vibration of the engine is dampened by the rubber block.

 

As you can see in the pictures, something ain't so good with Dragon's engine mounts. The studs are sheared right off, the engine no longer connected to the mount. Those are 12 millimeter studs, Rockwell hardness B70 with a tensile strength of 70,000 psi. And before my engineering friends jump in and explain in their cute geeky way that tensile strength is not relevant to shear loads, the reality is that it it still means they are beefy as fu#$. But when you slam off of a wave and your boat comes to a sudden halt, everything in your boat still wants to move forward. Some dude Newton figured that one out. And when your engine still wants to fly like a bird and the only thing holding it back are four 12 mm studs... well, apparently "beefy as fu*#" is not beefy enough. The circled bits on each picture are the studs and they are supposed to be one piece. Oops.

 

Strangely enough, we did not figure it out until the Pineapple Cup. I charge the batteries with an Efoy fuel cell these days and the engine frankly does not get much use. But delivering home from the Pineapple Cup there was finally enough movement in the engine that it killed the transmission, and that was that. So the studs are being replaced with 12.9 grade steel (170,000 psi of tensile strength), and a new tranny is going into the boat. 

 

More on that second reminder of the Route du Rhum tomorrow. It's a good one.

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