| Author |
Message |
    
William Vlies
Member
Username: billv
Post Number: 7
Registered: 06-2007
| | Posted on Tuesday, March 02, 2010 - 01:41 am: | 
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Call me silly but. About to fit aa old single cylinder diesel to my 14 ft glass clinker style boat. Clutches are hard to find and props cost lots. So motor mounted a little higher with pulley on output. Prop shaft suitably supported fitted with pulley below. loose v belt belt tightened with clutch lever and idler wheel (will be the clutch). Similar to ride on mower . No prop shaft alignment problem, able to select gear ratio to suit availabe prop and change for performance.
Must keep all dry. Has anyone tried this and what problems do you forsee.
Bill V |
jerome blumberg
Member
Username: jerome
Post Number: 4
Registered: 11-2008
| | Posted on Tuesday, March 02, 2010 - 03:33 am: |
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careful with your fingers... |
Todd Vidgen
Senior Member
Username: todd_vidgen
Post Number: 160
Registered: 03-2008
| | Posted on Tuesday, March 02, 2010 - 03:53 pm: |
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I think you wont have enough surface area on
a belt/pulley system to achieve enough friction
to drive a prop at any great speed without having
multiple belts and pulleys and a fair amount of belt tension.This in turn would require additional
plummer blocks to support the shaft,a moderately
more complex tension release assembly.All of which would take up space and probably cost more.
It would also raise the engine height,making
your boat more unstable |
Frank Petran
Senior Member
Username: frank_petran
Post Number: 87
Registered: 05-2009
| | Posted on Tuesday, March 02, 2010 - 08:51 pm: |
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I have to agree with Todd. A rule of thumb. To increase the speed of the prop the horsepower will increase expediently along with the torque requirements. Single V-belts do not have enough surface area per belt for your application and multiple belts will become a nightmare. Look into a regular prop shaft installation it will be the best and safeist way to go. |
J.B. Castagnos
Senior Member
Username: jb_castagnos
Post Number: 513
Registered: 07-2002
| | Posted on Tuesday, March 02, 2010 - 10:58 pm: |
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Faegol used a V drive with belts, one of the pulleys had a rubber liner, for reverse you would bring the pulleys together, loosening the belts and when the pulleys touched you had reverse rotation. Airboats use a large belt with toothed sprockets similar to timing belts, these are on 504 cu in Chevys, I'm sure you could use a smaller version, no slipping even when wet, don't have to be over tightened, less power loss. |
William Vlies
Member
Username: billv
Post Number: 8
Registered: 06-2007
| | Posted on Wednesday, March 03, 2010 - 12:28 am: |
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Thanks for the input
This is a single cylinder motor estimated 5-7 hp. Clutch and belt will be inside the engine box. As a school maintainance guy I use ride on mowers up to 24 hp, single A section belt drives to both wheels and 50 inch cutter deck. I have mounted the motor and at this stage and Im not to concerned about center of gravity. Motor is only about 4inchs higher than usual (lowered the prop shaft 2 inches. Motor also is offset slightly and this is okay as output shaft is not centered to motor body Therefore the fore and aft center of gravity should be okay. Frank, I didnt mention the motor has an inbuilt reduction box which I cant remove so the output rmp is lower than Id like. Motor is to good not to use.
Drive puuley at first will be 6inches with a 4 inch pulley on prop shaft
Its not that much trouble to try the system and if it aint good it will come out. Get back to with reults in a few weeks |
Todd Vidgen
Senior Member
Username: todd_vidgen
Post Number: 161
Registered: 03-2008
| | Posted on Wednesday, March 03, 2010 - 02:46 am: |
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Knock yourself out
A propeller is not the same as a lawnmower blade
The loads are consistent and huge in a boat |
Todd Vidgen
Senior Member
Username: todd_vidgen
Post Number: 162
Registered: 03-2008
| | Posted on Wednesday, March 03, 2010 - 07:50 pm: |
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You might give some thought to rigging a thrust
bearing while your at it |
Laurie Derwent
Member
Username: laurie_d
Post Number: 26
Registered: 10-2009
| | Posted on Wednesday, March 03, 2010 - 09:09 pm: |
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Gents,
I saw a 'simplex' gearbox on ebay that may well solve the need for the pulleys.
Otherwise, from my experience with circlar saw I'd suggest twin or triple belts may be enough to hand the load of a prop. I cannot imagine a toothed belt woking so well with a slip clutch arrangement.
Give or take the gearing of the pulleys, tThe reduction gearing that's on the motor will need to be considered when deciding the prop size and should help reduce wear on the belts.
Cheers Laurie |
jerome blumberg
Member
Username: jerome
Post Number: 5
Registered: 11-2008
| | Posted on Thursday, March 04, 2010 - 02:12 am: |
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I would just not advise you to do this. You should better put your energy in installing a well-known simple reliable system : there is so much to enjoy with a boat elsewhere. You will enjoy your boat more with a reliable system. You better not rely on something that might fail under unforeseen conditions like a belt because it can also be dangerous. It is always going to happen with a boat(strong wind, person falling overboard, etc) even on a little lake. All the best anyway |
Boyd Guard
Member
Username: boyd_guard
Post Number: 19
Registered: 06-2005
| | Posted on Thursday, March 04, 2010 - 03:15 am: |
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Vee belts drive the world |
John Davis
Senior Member
Username: johnny
Post Number: 270
Registered: 03-2006
| | Posted on Friday, March 05, 2010 - 10:38 am: |
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William,
I have a little 14ft boat that has this type of V-belt setup with a lawn mower type engine. This is the way the boat was when I purchased it and I have not tried the system myself and do not plan on trying it. I will install a old one lunger engine probably with direct drive. However the older gentleman that use to operate this little boat told me that the system works great! It has a 12" two blade brass prop. I do not recall the pitch at this time but I can find out if needed. This has the rubber pulleys for reverse just like J.B. was talking about. The large diameter pulley in the back had a rubber V-belt that fit tite around the pulley. It may have been glued to the pulley. There was a small rubber disk up on the top next to the small pulley. The whole engine is mounted on a frame that hinged up and down. You pull up on a flat bar lever to engage and go forward. The linkage was adjustable so when you pulled the lever up it would just go over top dead center and knuckle in or sort of lock in place. Push lever down and hold pressure on wheel to go in reverse. For nuetral you would just have to hold the lever in the middle or where the belt was loose but not touch the rubber wheels together. A little bit of a crude system but I guess it worked.
See photo below, also link has more photos of boat if interested.
http://www.oldmarineengine.com/discus/messages/4/108212.html
 |
Frank Petran
Senior Member
Username: frank_petran
Post Number: 89
Registered: 05-2009
| | Posted on Friday, March 05, 2010 - 12:13 pm: |
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I have to admit, the set up will work. With a small 2 blade prop with a low pitch it should work OK. If I were you I would just modify the set up to work with your new engine. Put in a detent on the shifting lever for neutral, forward and reverse. It will be hard to have to do hold the engine in the proper position when docking with the wind and current against you. Murhpy's Law will apply |
John Davis
Senior Member
Username: johnny
Post Number: 272
Registered: 03-2006
| | Posted on Friday, March 05, 2010 - 04:18 pm: |
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I looked at the prop and it has stamped into it (12 RH 10) So that would be 12" diameter right hand, 10 pitch correct? I'm no boat or prop expert but I think that is what it is. Also looked at the engine and mounts a little closer. There are two retangle frams made out of 1" angle iron that are hinged on one end and linkage and lever on the other end. The engine is bolted to the top frame and the bottom frame is mounted to the boat. Bottom frame has a large bearing and housing bolted to the frame that the prop shaft comes through with a heavy collar that sets against the face the inner bearing race. So I guess this shaft and pulley bearing is also acting as the thrust bearing. Large pulleys also attach to this same shaft. |
Scott Hunter
Visitor
| | Posted on Tuesday, March 15, 2011 - 04:11 pm: |
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Check out Rob White's website http://www.robbwhite.com/index.html
20 odd HP Kubota in a Atkin Rescue Minor. Works for him.
Don't say it can't be done if you haven't either tried it or done it. |
Todd Vidgen
Senior Member
Username: todd_vidgen
Post Number: 206
Registered: 03-2008
| | Posted on Tuesday, March 15, 2011 - 04:50 pm: |
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Nobody said it couldn't be done.
Some of us just think their are more reliable,safer,
less complicated ways of connecting an engine to a
prop shaft,without having to move engines up and down etc to engage drive.I personally prefer my motor to be firmly secured in the boat as I have
taken it out to sea in 1.5 meter swells with 1.5 meter waves,and the thought of a couple of hundred
pound of cast iron with exposed flywheel coming
adrift does not thrill me.
Cheers Todd |
Laurie Derwent
Senior Member
Username: laurie_d
Post Number: 91
Registered: 10-2009
| | Posted on Tuesday, March 15, 2011 - 07:13 pm: |
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We could discuss the pros and cons of the mechanical aspects of a belt drive system until the Hesperus is refloated. I haven't had a chance to look at Rob White's set up, but for me, sitting at the tiller behind the lawn mower engine (with standard exhaust set up)on anything but the windiest of days would fill my system with so much exhaust fumes that I probably wouldn't even know if the motor lept off it's mounting or not. Having spent many hours in a boat on calm days with a stationary pump motor running I won't even mention the OH&S issues. Cheers. |
