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Re: [AtkinBoats] Digest Number 364

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  • Rob Rohde-Szudy
    Robb White covered his homemade version for his version of Rescue Minor in back issues of Messing About in Boats. I am not sure which ones since I wasn t a
    Message 1 of 1 , Feb 24, 2006
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      Robb White covered his homemade version for his version of Rescue Minor in back issues of Messing About in Boats. I am not sure which ones since I wasn't a subscriber at the time. Maybe Robb will chime in when he gets around to reading this. He was kind enough to share the details with me.

      In brief, he set up like an old-school riding mower. The engine hinges so the aft end can pivot up and down. When jacked up, a grooved V belt is tensioned to provide forward, when slackened it's neutral, and when dropped all the way a rubber wheel on the engine's shaft contacts a phenolic plastic wheel on the prop shaft for reverse. The prop shaft is regualr stainless rod, machined for the prop end, and farm type thrust bearings are used with a traditional stuffing box and cutless bearings. The tensioning is done with a truck type air spring fitted between bearings on the end of the engine shaft and across from it on the prop shaft. Those are kind of expensive and there's nothing to say you can't tension it with threaded rod or for that matter a wedge and mallet. Even a bigass lever would probably work if you use V-belts rather than grooved V belts (Vs need less tension).

      His shaft is very short and the engine's vibration is not coupled to it, so it's rock-solid and the stuffing never wears out. You can also mount the shaft damned near horizontal, which is good for efficiency and handling. The belting runs quiet and cool compared to gears, and of course it's relatively cheap. The only trouble is that you're stuck with left-handed props. This can be addressed by running the shaft fully under the engine and mounting the engine backwards, but this makes you mount the engine higher - bad if it's very heavy. Probably OK for an air-cooled engine, though.

      I assume you're talking about a horizontal shaft engine, by the way. If you're talking about a vertical shaft engine from a big lawnmower, just use the lower unit gearing from a 25hp outboard. You'd probably need to pump the oil through a cooler, though. Gears get hot fast!

      Best of luck,

      Rob Rohde-Szudy
      Madison, WI

      AtkinBoats@yahoogroups.com wrote:
      There is 1 message in this issue.

      Topics in this digest:

      1. gearbox for air-cooled inboard
      From: "michaelparkeroysterville"


      Message: 1
      Date: Fri, 24 Feb 2006 01:03:13 -0000
      From: "michaelparkeroysterville"
      Subject: gearbox for air-cooled inboard

      Does anyone know of a simple transmission with forward-neutral-reverse
      that can be used with a 10-16 hp air-cooled inboard engine? These units
      were common in the 1950s and before, but I want one that is of current
      manufacturer. Thanks for your help.


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