[Kartbuilding] Fwd: A little off the subject. - boats

Stephen Burke kartbuilding at gmail.com
Fri Oct 6 19:29:32 IST 2006

Thanks for the input.  The boats on my web site are all designed for
outboard use.  The application I was asking about was for a series of
designs that I have not published yet because I have not figured out the
drive issue.  Specifically they are small launches that used to take small
make and break (one lung) engines that developed about 3 to 5 HP.  These
boats are for cruising around the inner harbor and in times past had awnings
over them for a leisurely cruise.
Well, they don't make one lung engines anymore and steam is out of the
question.  I could spec in a sailboat auxiliary engine but that is a $5000
price tag.  So All I need is 3000 rpm or so at the shaft with one forward
gear, but reverse would be nice.  I thought about the pulley idea, but would
need to engage and disengage the engine as it was spinning.  I guess that
this could most easily be accomplished by being able to shift the spinning
engine pulley into the path of the drive belt in order to engage the
propeller.  That is how they used to power band saws and other shop tools.
A tricky bit of fitting, but it could be done.  I have also been looking at
centrifugal clutches which might be a good way to go but will require
precise alignment of the shaft with the stuffing box.

If a creative Idea comes to you, keep me in mind.

Thanks for your help.

Best Regards

Jack Battersby
Sandy Point Boat Works LLC


I saw your website and I get exactly the idea that you are on about.

Putting together a drive chain all depends on the type of engines you are
Would you not just specify an outboard engine? All that would have to
be done is the mounting part. This would save a load of work on
everyones part.

Fail that, and you are going to go down a cheap route with your drive
chain, looking at lawnmower engines, then you will have a lot of work
in store. A welder would nearly be compulsory to putting together a
drive chain.

Here is what I would do:
Outside of the boat: mount an axle (spinning bar on bearings).
Put the propeller at one end which will be in the water. Put a pulley
wheel at the other end.
Connect up an engine from inside the boat to this pulley via a drive belt.

For the larger boats, you can simply get a bigger prop and use the
same drive connection. Hopefully the large engine may have its own
reverse gear built in. Fail that, you could hook it up via drive

But if you ask me: - if you are looking for people to get a 30 hp
engine and then to go messing with drive and stuff - I would tell them
to go to website xwhateverz and to get the specific engine.

Best of Luck

> Hi,
> I wonder if you couldn't help me with a project I am working on.  I am a
> designer of boats and I sell designs, plans and how to videos for
> boatbuilding.  I have a number of designs that require anywhere from 5 to
> hp that I am sure could be powered by standard lawn mower type engines.
> problem is I don't know as much as I need to about putting together a
> train.
> In its simplest configuration, I could use a 5hp engine with a way to put
> in neutral for starting and stopping and some kind of clutch to engage the
> engine.  Reverse would be nice, but this configuration would work for
> launches.  At the other end of the spectrum, I have designed a number of
> small racing boats that would fly with a 20 to 30 HP engine.  This would
> definitely need a reverse gear though.
> I am well versed in electronics, different types of fabrication and
> and boat design, but I simply do not have a lot of experience in putting
> small drive trains together.  The other issue is whatever I do must be
> reproducible by the home builder.
> Any ideas.
> Best Regards
> Jack Battersby
> Sandy Point Boat Works LLC
> WWW.SandyPointBoatWorks.com

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