Jackable Inboard/Outboard why not

A jackable I/O is much easier to use in shallows because it can be lifted straight up and down with out tilting backwards and the thrust angle is better and does not push the back of the boat down with more power applied.On a trailer boat the drive is more compact on the road.A better depth control is possible for different props.The drive can still tilt backwards when going aground and a shallower draught can be achieved lifting the drive straight up.

 

Hmmm, I've never seen a jackable I/O - who makes them?

 

Jackable inboard

Rings a bell Tom...but can't place the origins- but I remember seeing an illustration of an Indonesian fishing boat with a prop shaft that could be wound up on an inboard 'jack handle' to 'jump reefs'. It was attached to the drive by a pair of couplings and could be raised by at least a metre - level with the boat sole - or dropped for 'better grip' well below the rudder. Only an illustration - no technical notes. And I believe Yorkshire Cobbles have a similar arrangement. But now you've reminded me I'll start agoogling.

 

hi Tom, as we talked about before
http://www.boatdesign.net/forums/showthread.php?t=1831&highlight=mercury
when i thought the new sterdrives were adjustable in flight
did i say i like those rudder sterdrives you showed as well?

 

1960's to 80's OMC.

 

Albemarle. They've been doinf this for awhile - nice setup.


http://www.albemarleboats.com/trailerable/index.html

 

Ah... jackable..... not jackshaft.....

 

CV joints that are cheap and can take the horsepower is always the issue. Universal joints at more than six degree shaft angle CAN vibrate.

 

I see no reason why you couldn't use CV joints from (say) a BMW M3 or M5. Couple hundred bucks US and widely available, with a range of motion of about 13 degrees, give or take. The e46-body M3 puts out 340HP, say 285 at the rear wheels, and I've never heard of one of them failing due to stress.

Look in any 'tuner' catalog and you can find CV joints for hot-rodded Hondas that will most certainly take any strain thrown at them.

 

Other places to look.

http://cvcoupling.com/

http://www.schottel.de/eng/r_produkte/produkte.htm

Pericles

 

Automobile drive trains are not under the same stress that boat or aircraft drive trains get. An automobile drive train may be transmitting the full power of the engine for seconds at a time, never constant, hour after hour of full or near full power. An automobile only uses a small fraction of the maximum engine power when traveling at a constant speed, as when cruising on a highway. Conversely, a boat drivetrain is usually run at something over 1/2 rated maximum power for hour after hour at a time.

So, you may see that automotive parts may work for a while, but their life span may be very short. Like some dragstrip race car engines, whose lifespan before overhaul is measured in seconds.

 

Conventional I/O`s run u/v`s in line which does not lubricate and wear over a big area of the bearing surfaces,so they wear in one spot and rattle and soon fail.U/V`s run on an angle run quieter and wear better,like automative drives and conventional fixed inboard`s run at an angle.
I/O`s stress U/V`s if run at full power on turns unless the angle is limited.So a jackable I/O should have advantages of quiter running and wear.And you could run your drive in surface piercing mode or subsurface drive.