Belt Drive

I've look everywhere... Can't seem to find much information about belt drives (i.e. having an engine turn a toothed sprocket and connecting to a toothed sprocket on the prop shaft with a Kevlar belt similar to that on a motorcycle.) So I figured asking here would be the easiest way to get some leads.

1) Can it be done? Has anyone done it?

2) What are the problems? How would one solve these problems?
I see that fact that marine engine installation is designed to take torsional loading and fore-aft thrust loading not side trust loading being a problem.

3) Would a dedication thrust bearing be a necessity? If so who makes them? (besides aquadrive)

4) Is there such a thing as a remote 8 degree transmission.

Would it be worth while to develop such a system? I see being able to place twin motors in series a huge advantage... but maybe I am the other one. Would you buy a boat with such a system?

 

Check out the electric drive websites. They almost all use a belt drive with a double thrust bearing setup.

 

Belt drive is complicated...extra parts ..and it forces you to raise or offest the engine up on its beds to compensate for the belting gear.

Why belt ? Perhaps OK on small workboat . When I was a kid I had a lawnmower engine powered skiff that was belted.

Two rubber tires, one on the shaft and one on the engine will work on a small lawnmower craft

 

Why belt?

I am a fisherman so i see a few reasons. True fishing boats rarely have raised engine hatches, because cockpit space is a precious comodody. And with twin engine instalation the deeper in the hull the lower the deck can be (since no one wants to be in a boat that is 16 inches self bailing. Ie you cant touch the water over the gunnel unless someone holds your feet.) Also the deeper the engines the more stable the boat, which is also very important for drift fishing. I see putting one engine fore and belted to port, and one engine aft belted starboard very useful for solving these problems. Also would be better than one larger single reduced draft, lower deck, two engines.... but there must be a reason why most builders do not do this.

 

in ww2 the type 21 uboat had belted drive, for noise reduction

 

Toothed belt drives are noisy, and aren't very efficient. A chain is more efficient, but requires more maintenance. A gear drive does it best, efficient, quiet, long lasting and clean. Yes it costs a bit more, but if you don't want to be stuck out on the water somewhere you want reliability. Spend the money for a gear drive and don't look back.

 

How much hp? Belts are great for low hp applications.

C.O.
http://whatsintheshop.blogspot.com/

 

Toothed drive belts can handle hundreds of horsepower. Problem is when they do they get wide and make more noise.

 

Try the 'search function' button above. Search for chain drive and belt drive. I've posted a number of items on the subject.

...also have a look thru some propulsion ideas here:
http://www.runningtideyachts.com/dynarig/

 

I really like the idea of belt or chain drives because its so much lighter and could with a bit of ingenuity be reversible. It also could be extremely simple so maintenance would be a cinch as well

I've never tried one on a boat but as a kid just about everything I owned was belt drive

 

Just for fun ...

How do you handle clutching and reversing with your belt system ?

Once you have solved these two issues, adding gears will be simpler than adding belts.

BTW, belt systems for electric engines have no clutch and no reverse.

 

on an electric system revers is in the motor itself

on a clutch system it would be the same as in a motorcycle

 

With out knowing the hp requirements it is hard to know what is needed for reversing and clutching. For low power use you can get away with using a loose belt for clutching, this may not work as well on high hp applications. Cogged or toothed belts will obviously not allow this.

For a low power setup look at Rob White's in his Rescue minor. It uses the loose belt nuetral and a set off rubber wheels on the shafts for reverse.

C.O.
http://whatsintheshop.blogspot.com/

 

I'm considering of matching with something rather light in hp (with a toothed belt.) Yanmar 4JH#, VW TD75-4, Nanni 4.340 TDI, FNM HPE 110, Weber 750TC, or Rotax 1503 SC IC. All in the 100-200hp range. The system would likely be set up with a standard ZF reduction gear with reverse. The sole purpose would be to use center installation to allow below deck engines, and lower center of mass. The belts would transmit power to the remote transmission outboard of the motor itself.

 

These posts seem to contradict each other. While cruising the web, I came across this http://www.aermarine.com/tubolari_eng.htm A Rotary 40hp 4 Stroke powered jet tender. And it uses a toothed belt.
http://www.youtube.com/watch?v=aDptlPPAwx4 Doesn't seem very loud to me. Seems as though the motor itself is much louder than the belt. Rotary... Why? I have no idea.