Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-20-2017, 12:04 AM   #1
Newbie
 
City: Springfield,or
Country: USA
Join Date: May 2017
Posts: 2
twin with single screw

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.
__________________
Advertisement

VW Tolly is offline   Reply With Quote
Old 05-20-2017, 12:43 AM   #2
TF Site Team
 
Insequent's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Insequent
Vessel Model: Ocean Alexander 50 Mk I
Join Date: Mar 2012
Posts: 2,332
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.
__________________

__________________
Brian
Insequent is offline   Reply With Quote
Old 05-20-2017, 12:50 AM   #3
Guru
 
HopCar's Avatar
 
City: Miami Florida
Vessel Name: Possum
Vessel Model: Ellis 28
Join Date: Aug 2011
Posts: 4,361
Welcome aboard! Interesting first post. Wish I had something useful to add but I'd like to follow this conversation.
__________________
Parks Masterson
HopCar is online now   Reply With Quote
Old 05-20-2017, 01:30 AM   #4
Veteran Member
 
theTopsail's Avatar
 
City: Southampton / Los Angeles
Country: UK / USA
Join Date: May 2017
Posts: 68
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?
theTopsail is offline   Reply With Quote
Old 05-20-2017, 01:58 AM   #5
Guru
 
BandB's Avatar
 
City: Fort Lauderdale
Country: USA
Join Date: Jan 2014
Posts: 17,251
Quote:
Originally Posted by VW Tolly View Post
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.
Why?
BandB is online now   Reply With Quote
Old 05-20-2017, 02:06 AM   #6
Senior Member
 
City: Maple Bay BC
Country: Canada
Join Date: Dec 2016
Posts: 127
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.
Greg S is offline   Reply With Quote
Old 05-20-2017, 02:25 AM   #7
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler(extended to 30 feet) Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,983
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 is offline   Reply With Quote
Old 05-20-2017, 02:34 AM   #8
Veteran Member
 
theTopsail's Avatar
 
City: Southampton / Los Angeles
Country: UK / USA
Join Date: May 2017
Posts: 68
Quote:
Originally Posted by Al View Post
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.
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.
__________________
Aaron
theTopsail is offline   Reply With Quote
Old 05-20-2017, 03:31 AM   #9
Al
Guru
 
Al's Avatar
 
City: ketchikan, Alaska
Country: usa
Vessel Name: 'SLO'~BELLE
Vessel Model: 1978 Marben-27' Flybridge Trawler(extended to 30 feet) Pilothouse Pocket Cruiser[
Join Date: Apr 2012
Posts: 1,983
Quote:
Originally Posted by theTopsail View Post
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.
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,
Al is offline   Reply With Quote
Old 05-20-2017, 03:35 AM   #10
TF Site Team
 
City: Brisbane
Country: Australia
Vessel Name: Now boatless - sold 6/2018
Vessel Model: Had a Clipper (CHB) 34
Join Date: Jun 2008
Posts: 7,283
Send a message via Skype™ to Peter B
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.
__________________
Pete
Peter B is offline   Reply With Quote
Old 05-20-2017, 03:47 AM   #11
Senior Member
 
knotheadcharters's Avatar
 
City: Jacksonville, FL
Vessel Name: Amar la Vida
Vessel Model: 1989 Carver Californian 48' MY
Join Date: Jan 2011
Posts: 338
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?
knotheadcharters is offline   Reply With Quote
Old 05-20-2017, 03:57 AM   #12
Guru
 
City: Sydney
Country: Australia
Join Date: Jul 2015
Posts: 1,646
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
gaston is offline   Reply With Quote
Old 05-20-2017, 03:58 AM   #13
Guru
 
City: Satsuma FL/Daytona Beach Shores
Country: United States
Vessel Name: No Mo Trawla
Vessel Model: Hurricane SS188
Join Date: Jul 2014
Posts: 2,175
Welcome.

As far as I know, VW diesels have not been marinized. Have you given any thought to how you will cool the engines?
__________________
Buffalo Bluff Light 28
Donsan is offline   Reply With Quote
Old 05-20-2017, 04:09 AM   #14
Veteran Member
 
theTopsail's Avatar
 
City: Southampton / Los Angeles
Country: UK / USA
Join Date: May 2017
Posts: 68
Quote:
Originally Posted by Donsan View Post
Welcome.

As far as I know, VW diesels have not been marinized. Have you given any thought to how you will cool the engines?
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/uploa...ning_boats.pdf if you are interested
__________________
Aaron
theTopsail is offline   Reply With Quote
Old 05-20-2017, 04:34 AM   #15
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 12,592
Greetings,
Welcome aboard.
__________________
RTF
RT Firefly is offline   Reply With Quote
Old 05-20-2017, 07:53 AM   #16
Guru
 
ranger42c's Avatar
 
City: Maryland
Country: USA
Vessel Model: 42' Sportfish
Join Date: Aug 2013
Posts: 4,561
Quote:
Originally Posted by VW Tolly View Post
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.

Welcome. Interesting question.

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

What disadvantages?

-Chris
__________________
South River, Chesapeake Bay
ranger42c is offline   Reply With Quote
Old 05-20-2017, 07:58 AM   #17
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 19,622
What is "Plan B" , go for it.
FF is offline   Reply With Quote
Old 05-20-2017, 08:09 AM   #18
Guru
 
City: Fairport
Country: United States
Join Date: Jan 2017
Posts: 1,613
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).
diver dave is offline   Reply With Quote
Old 05-20-2017, 08:17 AM   #19
Newbie
 
City: Springfield,or
Country: USA
Join Date: May 2017
Posts: 2
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.
VW Tolly is offline   Reply With Quote
Old 05-20-2017, 08:37 AM   #20
Guru
 
City: Hotel, CA
Country: Fried
Join Date: Sep 2011
Posts: 8,324
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?
__________________

__________________
Craig

It's easier to fool people than to convince them that they've been fooled - Mark Twain
CPseudonym is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 01:38 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×