September 6,
Well, it is Labor Day here in the U.S. where we celebrate working our ass off. I celebrated by working on the boat and grilling out with my sister and wife.
I decided to get back to work on the tanks after finishing up the main deckhouse framing last month. That means drilling a whole lot of holes for the inspection ports. The backing ring also has to be threaded to retain the 316 SS bolts that hold the port on. There are 16 1.5 inch #20 bolts per port and four ports. The ring has to be threaded, the port cap has to be drilled and the top of the tank also must be drilled and all those holes had better line up. This means making an accurate jig out of some aluminum I have lying around. A circle may be accurately divided into equal parts using a compass. A simple Google search will tell you how; https://www.youtube.com/watch?v=5TXnDbyApAM. My advice is to always mark the lines dividing the circle with three points i.e. double the points in the video above. Two measured points with the compass (each take two sweeps of the compass) and the center mark.
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| Aluminum pattern in the rear. backing ring on top of port covers are below/ |
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| Drilling the holes that will be threaded in the backing rings or bolt retaining rings. |
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| This is how we drill. I'm using a small drill press donated by Mark Finger who is a cherished ex-boss of mine. He has since moved to Colorado to retire. |
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| One of the tank tops drilled to match the bolt retaining ring. |
