diy surface drive?

Thanks for posing the photos and descriptions of your setup above.
I like the notion of engineering something like that for yourself.
Kudos.

 

I've been thinking and redesigned the drive. It will now be TRIMMABLE. This won't work for a lot of you guys, but for my small 11 foot boat, it sounds easy enough.
Instead of U joints, I thought I'd trim the whole drive train. The engine bed will share the same mount as the shaft tube and trim bars.
To increase the depth of the prop, lift the engine up at the forword end. The cradle is pivoted at the rear of the engine compartment. To increase speed, lower the engine in order to put the prop up near the surface.
I first made a wood mock-up of the cradle and then of steel.
Raising and lowering will be done by an acme screw and an automotive power window motor. Shifting the transmission will be done by a power door lock acuator.

Dave

 

I've been thinking and redesigned the drive. It will now be TRIMMABLE. This won't work for a lot of you guys, but for my small 11 foot boat, it sounds easy enough.
Instead of U joints, I thought I'd trim the whole drive train. The engine bed will share the same mount as the shaft tube and trim bars.
To increase the depth of the prop, lift the engine up at the forword end. The cradle is pivoted at the rear of the engine compartment. To increase speed, lower the engine in order to put the prop up near the surface.
I first made a wood mock-up of the cradle and then of steel.
Raising and lowering will be done by an acme screw and an automotive power window motor. Shifting the transmission will be done by a power door lock acuator.

Dave

 

The image shows the first outboard supplied to the public.The first long-tail boat in the Paris Exhibition c 1900`s. french colonies adopted them every where.

 

Here's some more pictures of my progress. The cradle pivots just fine for trimming. The rudder is still being milled along with the jack shaft. Now the wiring needs to be done.

 

Nice work! Keep us posted.

 

Trimming a surface drive can be a really bad idea. It can make the boat get out of control. A proper setup should be able to be trimmed with the throttle. Also, it is really important to work the throttle properly when you go airborne so as not to lose control.

 

Why do they make them trimmable then?

 

Where do you come up with this stuff? Do you actually have experience or ?

If your idea is correct, then every I/O and Outboard should be fixed with no trim capability due to fear of the operator's thumb making the boat get out of control. Unfortunately no one would buy an I/O nor outboard without trim. Why do these matter? B/C they too can be configured as a surface drive, it is all a matter of the installed height. Likewise the same can be said of surface drives. The ability to trim has added benefits over the inability to trim.

 

Once you have the trim set up, it doesn't need to be changed continuosly. Surface drives, with their long leverage, make changes more drastic. It should be possible to control the boat with throttle changes when you are goind downwind, for example. An outboard installed for surface propellers and an surface drives are quite different, because of the distance the propeller is from the boat. Early surface drives use to trim up to ventilate the propeller and unload it for the "hole shot". Now they are usually left down and ventilated with the exhaust or other means.

 

The reason for a trimable surface drive, at least on THIS boat, is this is a Hal Kelly design that glups in mass amounts of air at the front and compresses it to a point of lifting the transom considerably up. If the trim is fixed for one speed, it may not be right for a different speed, like comming out of a turn or heading into the wind.

 

So the intricate hydraulics of the Arneson are no longer needed and the fixed type such as the Levi drive is preferable that accomodates for ventilation in its design,-- disregarding the financial savings?

 

Yes, the Arneson is a complicated design. As with all technology, things get improved with experimentation.

 

Once again, where do you get this stuff? So the throttle will change the boats attitude and engine load as well as speed regardless of everything else? You are stepping back in time and are tied to the problems of the past with this thinking.

 

Arnesons dominate on fast poker run boats. Only reason I don't own a pair of arneson bravo conversions is the $$,$$$.

Kudos again on your DIY stupidbaker57.