Gear box question

[Steve in SoCal]

Stian,

It is kind of the reverse of that where one engine can drive two prop shafts, I am thinking of timming belts with a transmission the ties both shafts together when it is engaged. On a boat where the shafts turn CW and CCW you need a transmission to reverse the rotation from one shaft to the other.

Steve

[StianM]

Originally Posted by Steve in SoCal

Jack,


The unknown is, do the output shafts on the transmissions need the engine running to lube the output stage?

The lube oil pump is normaly fitted on the gear so if the gear is turning also the pump will be turning.

Originally Posted by Steve in SoCal

Stian,

It is kind of the reverse of that where one engine can drive two prop shafts, I am thinking of timming belts with a transmission the ties both shafts together when it is engaged. On a boat where the shafts turn CW and CCW you need a transmission to reverse the rotation from one shaft to the other.

Steve

You defently will nead a custom buildt gerbox. Contact some local workshop making gearboxes for industry.

[Steve in SoCal]

Stian,

Thanks,

I tried to add a drawing but the file would not attach? I think you understand what I want to do?

Steve

[Pericles]

Steve,

A triple screw installation would offer low speeds with easier handling at low cruising speeds using low powered Ossa electric motors, wing mounted.

When greater speeds are wanted, engage the 800hp centre shaft. The two wing props could be left to freewheel and generate some useful current for the main motor.

Pericles

[Steve in SoCal]

Pericles,

I have still not received and of the info from Ossa about fuel flow and details about their system. I have been looking at BLDC motors and generators and Audi V-8 and V-12 diesel engines. A couple of Audi V-12's tuned up with Yellowfin drives could be interesting

Steve

[Steve in SoCal]

I have been thinking about non traditional engines lately and aside from the Audi's I have looked at the GM/Isuzu DuraMax. I have a friend that worked on a Chevy Impala for MTV that had a DuraMax that made over 900 HP and 1400 pounds of torque. I know these are not duty rated for this type of use but they are so light and make so much power it is hard not to ponder their use. In a car they are power limited by how much heat the intercooler can absorb in a boat I would guess that they could live longer and make more power. The Audi and Mercedes V-8s would be great wing motors

Steve

[StianM]

If you want to go not traditional why not just go for a gasturbine? They are less fuel effician't but the weigh saving would propartly save the lower effycensy once your planing.

3 engines and 3 proppeles seam like a waste to me. Eatch proppeler shaft will add weight and increase instalation and operational cost.

For your neads in speed's diesel electric is the way to go, but your choice off hull eliminate that because off the extra weigh diesel electric add.

Two engines running one proppeler would be perfect if you where able to find gears and proppelers matching engines that are optional for this kind off boat, but you want two proppeler.

Using two engines and two proppelers and just stop one engine while runnning slop and leave the proppler just spinning in the water would solve all problems, but would make your boat want to runn in circles.

3 waterjets could be installed having a center one with a output off 600hp and two on the wings at 1000hp eatch, but again that would increase instalation cost and operational cost + waterjets are not as efficiant as proppelers. The senter engine could then also serve as generator.

You have a problem with no perfect sulution

[mindbender]

just an fyi for comparison:

new here so be patient..pahlease...when i was in the AF as a firefighter I operated a big flightline rig that was powered by two, side-by-side detroit diesles, 2-cycle blown, v8's. Incredible power...one was primary drive and could run the truck alone but the second was also used to drive but was also in charge of running the pump which it could do while helping drive. I was told the truck empty could do a 14.5 1/4mile...it was very very fast for over 40tons-8 wheel drive and could burn all 8.

This was 25 years ago but the transmission had a similar design as to what you might be looking for...and looked like a marine tranny....made by oshkosh i think.

[Steve in SoCal]

Mindbender,

I am not looking for a transmission but if the idea is worth developing and it seems to be a moot point.

As an aside I know how well crash trucks can move and squirt. I Know the 8 wheel Oshkosh and it's little sisters the 6 and four wheel versions. It is amazing to see these trucks in action on fire drills. If I recall loaded with water the big ones were over a 100000 pounds? The big ones at Edwards in the early 1990's had two V-12 as I recall.

Thanks to all who replied, it seems that this is not worth researching further for the masses. I guess the average boater uses their boat infrequently enough that this would not be a viable idea.

Steve

[alan white]

Originally Posted by Steve in SoCal

Hi all,

I am thinking about a concept I have to drive two props from one engine only in a twin engine design. I have a good idea of what I need to do but, I need some information on marine gear boxes. Typically you have a forward neutral and reverse and one gear box is set to counter rotate. When the gear box is in neutral what effect would providing power from the other engine to the dead engines shaft have on the gear box.

Instead of using diesel electric I am thinking of splitting power between shafts from one engine at low power cruise speeds. This keeps the engine running under a good load and in a range where it is near minimum BSFC. This would not be a hydraulic or electric load sharing but a mechanical connection between the driven shaft below the gear box and the driving shaft.

Steve

Ideally, and I'm sure this doesn't exist------- would be to run both engines direct to respective prop shafts through the equivilant of 2 four cylinder crankshafts. Connecting rods (4) would be straight-line between. Would be balanced, very efficient, never wear out, silent. The con rods could be tubular rather than I-beam, Distance between only a matter of con rod length. Just noodling, carry on.

Alan

[Steve in SoCal]

Alan,

That could work on a boat where both shafts turn in the same direction and the shafts had enough clearance to swing that. You couldn't disconnect them very easily, the idea is to use either one or two engines as needed. The gyroscopic force could be quite high though. The use of belts or chains give you the flexibility to offset the drive to clear obstructions and minimize gyroscopic precession.

The idea I have in mind is something I would like to play with but it seems to be of little value to anyone else.

Steve

[alan white]

Originally Posted by Steve in SoCal

Alan,

That could work on a boat where both shafts turn in the same direction and the shafts had enough clearance to swing that. You couldn't disconnect them very easily, the idea is to use either one or two engines as needed. The gyroscopic force could be quite high though. The use of belts or chains give you the flexibility to offset the drive to clear obstructions and minimize gyroscopic precession.

The idea I have in mind is something I would like to play with but it seems to be of little value to anyone else.

Steve

What's the distance between the prop shafts?

[Steve in SoCal]

Alan,

The distance is about 9 feet and the shafts are on a 7 degree down angle.

Steve

[alan white]

Could the two shafts be carried on inside bearings, and then shafts with universal joints be swung from them? The distance to the engines forward matters too. All this allows a very simple gearbox having only four gears. This would lock the engines in reversed rotation, allow one engine or both to power both props, disconnevt the idle engine, just one lever, allow angle change for props if desired.

A.

[StianM]

Don't know if annyone here know wichmann.

I just remember there turbocharging system.

They use a two stage system with root's blower and a turbo.

The root's blower had a hydraulic regulation system that would make it charge at high boost, but once the turbo started to charge it would slowly let the turbo take over the work. On max bost the turbo would charge trough the blower and the blower itself would only add 0,1bar extra bost.

They where operating good on low loads unlike the normal turbocharged diesel.