More Airboat Updates

The mini airboat recently suffered a temporary setback, resulting from a high-speed collision on the safety cage.

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The plastic safety cage I had built around the engine was pushed into the spinning propeller, which ripped through the hardware cloth and aluminum braces. The propeller itself shattered from the impact.

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A word of advice, DONT BREAK YOUR PROP! These things are stupidly expensive. I ended up paying more than twice what the hull cost for a new propeller!

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I decided (with some coaxing) that the plastic hoops weren’t strong enough, and that I should go with metal. After acquiring some aluminum tubing of sufficient length to make a suitable-diameter hoop, I was then faced with the problem of bending it. I considered multiple options including hand-bending with sand, heating it, buying a conduit bender, and renting a roller bender, but couldn’t come up with a reasonable-cost way of doing it without kinking. Then I finally stumbled across this wonderful website, which explained how to make bending jigs.

Below is my basic jig, made by tracing out a line of slightly smaller diameter than my desired hoop (because the bent metal wants to spring out larger). I then screwed down blocks aligned with the curve, and bent a piece of flat stock to conform to the arc. The last steps were a stop to hold the tube against the curve, and a cross brace over the blocks to help resist the force on the tube.

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My pipe sections were so long that I could not find space inside the garage to secure the jig AND move around it during the bending process. I solved this by securing the jig vertically to a tree, and pulling the tubing down around the curve a little at a time.

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Eventually, I had my aluminum hoops! I made two of the same diameter, for the front and back of the safety cage.

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Below are the new hoops sitting next to the airboat, prior to removing the old plastic hoops. As a side note there are 3 other boats visible in this photo, with oars and gas tank for a 4th, two more are off-camera, and I’ve since acquired an 8th small boat (not counting barrel rafts or inflatables). I may have a problem.

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One Response to More Airboat Updates

  1. Sharon Skarda says:

    How long did it take u to complete this project? Greg and I do enjoy your postings.

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