twin with single screw

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VW Tolly

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I am proposing to re power from a single gas to twin vw diesels by way of v belts to a common shaft to input a v drive transmission. Does anyone know of this being done?
I hope that I'm posting this in the right place. This is all new to me.
 
I assume the Tolly is not all that large? If you are only using one engine at a time, and use enough belts for the power being delivered then it could work. If you want to use both engines at once then you would need accurate engine rpm synchronisation to avoid belt slippage on one of them.. You would need clutches for each engine also.

Doable, but a fair bit of custom work required. If you already have the VW diesels then it might be worthwhile. If you are buying engines, just get one a bit larger.
 
Welcome aboard! Interesting first post. Wish I had something useful to add but I'd like to follow this conversation.
 
Using two engines on the same shaft has been done before however it is not too common. I would be worried about synchronization. If the engines are out of line with each other, your fuel burn will be bad due to one engine trying to spin the other one.

Are you going with the twin engines on a single driveshaft for redundancy purposes?

I assume this could also be a case of trying not to cut new holes for twin prop shafts?
 
VW Tolly said:
I am proposing to re power from a single gas to twin vw diesels by way of v belts to a common shaft to input a v drive transmission. Does anyone know of this being done?
I hope that I'm posting this in the right place. This is all new to me.
Click to expand...

Why?
 
Powerbands would be better than V belts. A flat, ribbed belt like the type used on modern autos for waterpump and alternators only much larger of course.
 
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Slips the mind but there is a company 'Floke' [sp]during the ww11 that manufactured gears that incoporated up to 4 engines to a single shaft. There is a ex Army tug of ww11 vintage floating about here that has this gear and four 671 jimmies mated up to it. Funny story- The tug was employed to shove a lumber carrier from the dock. I was the Super Cargo and in charge of arrival/departure in conjunction with the actual cargo loading. My employer happened to be on site when the sea pilot called to the tug for 1/2 ahead. the tug reacted and the ship didn't. The pilot then asked for 3/4 ahead, the tug responded but the ship didn't. so the pilot asked for 'Full Power" the tug reacted but the ship remained laying to the dock. My employer took my radio and asked the captain of the tug " How many engines do you have running?" "One" the response came back. After a dead silence from the sea pilot, my employer said " G-D it !!! I pay you for four GD engines, give the pilot four engines!!!"
So yes there is a process of mating more than one shaft to several engines.
The better discussion, is that of mating a single diesel mounted using the respective engine bed stringers of a duel engine set up and employing hydralic motors one counter clockwise, to each shaft and engage these with a main hydralic pump off the single main engine. There is one of these in Ketchikan as well. Two low block 671s removed, a single high block 671 employed. Went by the house day before yesterday doing 8 plus knots. 55' boat, steel trawler hull, pleasure boat.
Didn't mean to mess with the thread, hope it is found interesting.

Welcome to the forum Tolly, great place for information.

Alk-Ketchikan
 
Al said:
The better discussion, is that of mating a single diesel mounted using the respective engine bed stringers of a duel engine set up and employing hydralic motors one counter clockwise, to each shaft and engage these with a main hydralic pump off the single main engine.
Click to expand...

That would be an interesting discussion. I suppose you could use a PTO on the main engine to run the hydraulic motors. In essence the main engine would be turned into a generator just for the hydraulic motors.
 
theTopsail said:
That would be an interesting discussion. I suppose you could use a PTO on the main engine to run the hydraulic motors. In essence the main engine would be turned into a generator just for the hydraulic motors.
Click to expand...

yep, the fellow employed valves on the individual shafts to make forward and reverse. The nice part is you have flexibility with location of components to a degree,
 
I'm with BandB...you could do it, going to a heap of trouble...but why would you want to. You would be entering tiger country, with all the potential trouble associated with a non-standard set-up, with cost of two engines, counter-rotating being necessary I would think, not to forget syncronisation issues, and the probably negatives come re-sale time. You would not even end up with the get-home redundancy normally had with twins, because one of the commonest causes of the need for that is damage by something like a grounding or picking up a pot float, etc, to the drive train and/or prop.
 
How about just repower with one Diesel? Keep the second for spares. Why may I ask do you want to install both? It seems like an engineering nightmare. Engine mounts for one plus do you have enough room for 2 engines and the pieced together driveline that will have to be created?
 
Wouldn't 2 x. VW diesels be twice as bad as a single VW diesel .


Sorry Im not a fan of VW Diesels they work so hard to get the HP and Torque numbers .

Bit like 2 chainsaw motors in a Harley Davidson
 
Welcome.

As far as I know, VW diesels have not been marinized. Have you given any thought to how you will cool the engines?
 
Donsan said:
Welcome.

As far as I know, VW diesels have not been marinized. Have you given any thought to how you will cool the engines?
Click to expand...

Little known fact in the States but VW makes lots of marine engines. From my limited experience with them however they are mostly used in planing boats which use high speed diesels.

I don't know why they haven't been popular in the states.

Take a look at http://www.volkswagenmarine.nl/uploads/engines_for_planing_boats.pdf if you are interested
 
VW Tolly said:
I am proposing to re power from a single gas to twin vw diesels by way of v belts to a common shaft to input a v drive transmission. Does anyone know of this being done?
I hope that I'm posting this in the right place. This is all new to me.
Click to expand...


Welcome. Interesting question.

What end goal(s) are you trying to accomplish? What advantages do you see with your proposed system?

What disadvantages?

-Chris
 
There is at least one ocean dredge that uses 4 large diesels in tandem/dual. Eventually driving 2 shafts, though either hydraulic or mechanical gearboxes. There was a 5th identical diesel in the engine room running the generator. I would tend to think diesel/electric would be more common now, with the advent of high efficiency power controls.
Again, to what advantage? Simply that VW doesn't make a large enough single? Or, reliability? One thing to consider, I"ve seen a single thrown belt get wound up in the remaining belt(s).
 
I do have the engines and I have the machining, welding, mechanical experience but know nothing about synchronization. I theorize finding the best ratio for economy with one engine and use the second engine for redundancy and extra power ie. crossing the bar etc. I would mount the engines on air bags to dampen vibration and tension/clutch v belts - four 5/8" belts per engine. I don't even know if I can drive the belts of the end of the crank or need carrier bearings.

These diesel engines are very small and light and put out about 65 hp each.
 
Carrier bearings will almost be a given as those engines will not hold up to that side load long term. HP is not as important as the torque curve. I've only seen a handful of Tollycraft singles, which one do you have?
 
VW, consider a differential to solve the sync issue. Use a locker and belt slack for single engine capable operation. Have fun!
 
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Peter B said:
I'm with BandB...you could do it, going to a heap of trouble...but why would you want to. You would be entering tiger country, with all the potential trouble associated with a non-standard set-up, with cost of two engines, counter-rotating being necessary I would think, not to forget syncronisation issues, and the probably negatives come re-sale time. You would not even end up with the get-home redundancy normally had with twins, because one of the commonest causes of the need for that is damage by something like a grounding or picking up a pot float, etc, to the drive train and/or prop.
Click to expand...

Sorry to see a newbie getting beat up just for offering some not bad original thinking. Tiger country w nonstandard stuff. End of the world. Come-on guys stop being a slave to what industry produces. They almost always make stuff for the average guy. Except when they make stuff (like car seats) for little tiny guys. But they also made those seats for really big guys. Not the ideal seat.

You're right Peter the guy will have problems to solve and some will never get really solved. But his power system can/could be made just for him. May even be better than what is usually found because that's what is usually offered is to please and accomodate everyone.

But perhaps most importantly this may be just a fun experiment. And a golden experience. Or it may be the nightmare portrayed by my friend Peter B. The downside to my anchoring experiments is small, if I'm lucky (and I have been) I'll just throw the wacked up anchors in the scap metal bin and enjoy the memories and what I've learned. A multi-engine power system installation has far greater potential chances for loss.

If the newbie just wants a cheap power system I'll agree w PeterB but if the newbie can hardly wait to see if this works or that and sees his effort as an experiment w much to learn and is prepared for whatever could happen .... it would be a shame to discourage him.

No,
VW Tolly this thread should have gone on "Power Systems".
 
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VW Tolly said:
I would mount the engines on air bags to dampen vibration and tension/clutch v belts - four 5/8" belts per engine. I don't even know if I can drive the belts of the end of the crank or need carrier bearings.
Click to expand...

The airbags should work well to dampen vibrations. While running the belts to the shaft would be the most efficient and easiest way to get the job done (imo), the bearings could add some extra protection if anything hits the prop.
 
I can see an advantage for a boat like mine to have twins turning one prop.
My single propeller is very well protected by a heavy skeg. Two props would be much more likely to be damaged by grounding.
 
I forget which marine transmission has PTI (Power take in) options so you can power the prop from alternate power source...

I believe I am with Gaston on this one... two VW's are two too many.

Stu
 
Falk had tandem gear boxes that were common in WW2 era equipment. Some of the CG Lightships even had a Quad box turning 4 6-71's onto 1 shaft. Many older military craft were equipped. The quad box had the 6-71's perpendicular to the shaft 2 on each side.

Belt drives were used to turn prop shafts as well. HY vo drive setup mentioned in VUP 1 by Robert Beebe shows some examples. Blount Marine in Rhode Island Built the " Walter E Phipps" for Don Phipps in the early 70's. I was on that boat many times,although never underway. It was used as a Marine electronics test boat for lots of the Raytheon Marine gear in the 70's and 80's. It didn't have multiple engines but a single 6-71 mounted over the shaft and an industrial cogged belt driving it.
 
VW, I have prototyped airbags for my portable genny running topside, worked OK. You will have to design some restraints to keep engines from moving around.

Consider rigging all this up on the bench first vs bilge work to improve your labor factor, sorting of detail routing of wires, hoses, mechanical, service access, etc.
 
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I can't see why anyone would do this...but its not high tech, been done in the past. What is he trying to accomplish? ....
 
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