Welcome! Need support, you got it. Or share you ideas and experiences.
In Reply to: motorcycle engine inboard posted by firstname.lastname@example.org on September 09, 2003 at 06:43:54:
Interesting project...but remember, the spinning prop pushes on the shaft which pushes on a thrust bearing (usually in the gearbox). You can't just hook the shaft to the side of the motorcycle motor...I don't know of any motorcycle motors that are designed to accept thrust from the exterior. You'll need a separate gearbox or simply at thrust bearing mounting in fron of a shoulder on the prop shaft, to take the thrust and drive the boat. Naturally, that gearbox or thrust bearing block will have to be very well secured to the stiff structure of the boat.
What if I put a sprocket on the shaft and then ran a chain to the motor. Or could I put a collar on the prop side of one of the pillow block bearings to keep thrust off of the motor/gearbox shaft? would it be a good idea to remove the gearbox/transmission from the motor or will I need the different speeds? I suppose reverse is out of the question. Do you have any suggestions for mounting the motor?
Thank you so much for your reply!!
Reverse gear is not out of the question, but more than one forward gear is not doable. On a boat, you don't get much credit for forward momentum. The forces on the propeller are practically static, meaning that, if you get going in first gear and then shift to second, the torque requirements haven't changed, and the motor will lug down and die. The only way to get around this, I think, would be to simultaneously switch down to a smaller propeller with each increase in gear. Of course, you wouldn't go any faster, so why bother...I may be a little foggy on the science of all this, but if you ever see a boat with more than one forward gear, let me know. Better yet, race the inventor to the patent office!
It sounds like I may as well pull the gearbox off of the motor and use the direct shaft. How could I go about having reverse, any other suggestions about the driveshaft? Is there a science on what angle the shaft/prop should be? If there is something else I need to consider please advise.
Maybe dont pull off the transmission, just use the gear that best matches the prop and horsepower specs. alot of outboards use 1.57 as the motor prop ratio. Maybe you can have a reverse if you use an ATC (3 wheeler or similar) motor.
I think I might have a change of plans. I have a 12 horse briggs motor that I think may be easier to install. Can someone tell me what angle I need to set the prop shaft at when it protrudes out of the boat, I also could use some input on a stuffing box or shaft seal. Do inboard motor boats use some type of biscuit or vibration damper such as an automobile on the engine mounts?
i live near the shore and have been thinking about the same thing for awhile. the idea of paying for an outboard engine that essentially is the same thing the wright bros. used at kittyhawk for thousands of dollars and needs to be fixed every year seems rediculous
please post another message or email and let me know how you made out. the idea has a lot of merit.
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