Building an Aligator

Yup my dad is 90 and he still got with it up till last year. His age finally caught up with him and slowed him way down, I took my son to see his Pop Pop and we all had a great visit at the retirement condo's, Tom and I were probably the youngest visitors in a while. All the oldsters sitting in front of the building in their power scooter at the allowed distance away from the door to smoke. I said they were all definitely old men and women so let them smoke if they want to. It was kind of eerie watching all of them sitting out there like a bunch of vulture's on a phone line. And the boat is coming together pretty darn quick it wont be long before you start fitting the engine and boats internals. I love watching how fast it is coming together by a crew of guys who have never probably worked together as a team. So the speed of the progress is amazing really.

Bob
 
Been working on this a morning or so a week, coming along slowly. Brought down my magnetic drill this morn and drilled the flat bar that protects the skids an the angle for the edges.

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Greg

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Need to do some actual engineering design work now, and would like some input on paddle size.
My thought is paddle size would be based on the boat sitting stationary and applying steam pressure to the engine to get it moving. Too much paddle area and you won't move the paddle through the water, too small and you won't get enough thrust to move the boat at a reasonable acceleration.
The dia of the paddles will be 8 feet. That gets the shaft at deck level and the bottom of the paddles even with the bottom of the boat.
Rotational speed would be set to give hull speed plus a certain amount for slip. How much slip?
Once the speed is determined I can calculate the torque available at the paddle shaft based on the bore and stoke of the steam engine and boiler pressure.
So for a given torque and a 4 foot arm how do I determine how much area on the blades can be moved through still water at startup?

Any thoughts would be appreciated, there's not much in the way of engineering formulas out there on the net for paddle wheelers, wonder why?
 
The basic hull is finished. The rest of the crew (I don't paint) brushed on a coat of some aluminum rich urethane for an undercoat then a rubberized top coat. Was slow drying in the shed so we pulled it out yesterday. Used log rollers under it and the tractor to hold up the front as we pulled. Worked quite well. Going to let the rubber cure for a few days then flip it over to start the machinery install.

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Based on the wood volumes it weighs about 4000 pounds now.

Greg
 
Haven't found a suitable winch yet, but have installed the rigging they attached the block and tackle to at the rear and the front is ready to go on.

Greg
 
Sounds good. Where will you keep it docked? I see your not really to far from Ottawa. My brother lives there so I may get out and come see your "Aligator" once it is done!
 
The museum at White Lake wants us to dock it there. The curator has been coming around to photograph the progress, had to shoe him away a few times yesterday while we were moving it.
 
A couple of updates.
Tried alligator wrestling and won. With the help of a couple of tractors and some big slings managed to get it flipped right side up. Went over smooth as could be.
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Today I did some light machining. Started the main shaft that carries the two paddle wheels. Thinking this is probably the first one made for an alligator in about 100 years.
The shaft is 3 inch dia and 124 inches long, definitely needed the crane to feed it through the headstock. Used the steady rest to hold up the end while I centre drilled it. then switched to the tailstock for machining.

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The shaft will run on babbitt bearings so needed as smooth a surface as possible where they ride. The shaft is I think just mild steel, salvaged from a sawmill. Used a shear tool for the final finish.

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Found a couple of 1 7/8 x 8 tpi nuts, so thats what we cut to hold the paddle wheels on.

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Greg

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Dang... that's a heck of a boat! Nice use of a shear tool, too. That is one application that it really shines in. Do you plan to cross drill the end of the shaft for a pin to secure the nut from falling off? On the water is no place for a chance for something important like that nut to decide it wants a swim.

Excellent work!
 
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