Belt Drive

Abel Tasman Sea Shuttle working in the Abel Tasman National Park uses belt drives on some of their larger aluminum catamaran passenger ferries.
Basically they take passengers around the coastline of the park and drop them off on SHALLOW sandy beaches by beaching the boat.

Their problem was to be able to get their ferries close enough to shore to allow the passenger to disembark but not have the propellers digging up the sand.

They designed a belt drive system to be able to lift the props partially out of the water for shallow water operation.

Actually they designed and built two different types of drives, As this was several years ago there is a chance that some of what I put into this comment might pertain to one or the other type of drive as to length of boat etc but will get this information into the thread as to the viability of a belt drive system.

I rode on both of these taxis, one out and one back several years ago

Belt drive
25 meter aluminum catamaran, 150 passenger, twin Scania 485kw/600 hp diesels
The motors were above the prop shafts in an engine compartment that hinges just ahead of the front of the engines. When coming to shore the engine compartments were pivoted UP by hydraulic rams lifting the props partially out of the water.Ie the motor and props lifted up

I spoke to the captain about this unique drive and he put in a dvd on the in cabin screen that showed the entire build process of the boat and drive system.

Again from memory, I would expect that the ferry cruised at maybe 20 knots and the captain said that they had several thousands of hours on a set of Kevlar belts

Side pivot taxi
Not sure on the size of this boat ( maybe 15 meters) the engines were fixed but their outdrives which were designed by the owners, actually rotated outward on the axis of the input shaft to lift the props partially clear of the water

Two rather unique drives

 

DVD on Belt Driven Prop System

I wonder if there is anyway to come up with a copy of that DVD :!::idea:

 

I have been all over the net trying to find this hoping that it was posted somewhere.
I guess you could contact them to see if they would send you a copy.
There was also a reference that I found that mentioned KNS Marine or Drives that had a hand in either the boat build or the drive build
good luck and if you are able to obtain a copy, could you drop me a note

 

I sent them an email asking for details. We'll see what comes of it.

 

Never got an answer to my inquiry.

Shame to let this subject thread fade away. I just referenced it (link) from another forum discussion pertaining to some sort of outboard or outdrive
power system for pleasure catamarans.

 

New 'Rudder Drive'

This news just in...
https://www.maritimepropulsion.com/news/torqeedo-and-hanse-yachts-517058

Torqeedo and Hanse Yachts Launch Rudder Drive

...actually this probably should be placed under 'electric drive subject'

 

4000 watts is only 5.36 HP!! not 8 hp.

 

Sliding Motions at Tooth Interfaces

This was another reason I chose the chain drive vs belt drive option. Look closely at the interface of the chain with the teeth of the sproket compared to the sliding action you would experience withe the fiber belt arrangement. And look at the size of the contact patch.

 

The USN's test SWATH vessel "Kaimalino" used chain drives between her 2230 HP turbines and CP props.

 

wow :!:

 

Some chain drive technology I'm familiar with, referred to as 'silent chains'.

Fundamentals
Ramsey Products | Silent Chain Fundamentals

Advantages
Ramsey Products | Advantages of Ramsey Silent Chain


....some chain efficiency discussions
Transmission, Driveline, Hybrid Drive engineering - roller chain efficiency[/QUOTE]

...more discussions here:
http://www.yachtforums.com/threads/diesel-electric-propulsion.2229/page-9

 

I understand that a ribbed synthetic belt can attain efficiencies of near 98%.

Your pictures states no interference in the chain, ie sliding along the tooth to link interface. But this might only be where you are not running through a gear reduction where the Beta angle (the angle the chain is in contact with the sprocket) is 180 degree. Ie a one to one ratio but say a two to one the situation might change.

Re no sliding, there will be significant sliding in the pins of the link and normally if you use a chain, a lubrication systems, oil feed, pump, reservoir enclosed chain case, seals etc MIGHT be required especially in high horsepower applications

Of course there are many examples of dry chain power transmissions

For a wet lubricated chain drive system, there were literally millions manufactured by a company called New Process Gear for installation in 4 wheel drive trucks in the 70's 90's and perhaps even today. These would be coupled to engines up to 350 horsepower and were splash lubricated.
NP 203 was the chain transfer case and NP205 was the gear to gear transfer case.
This chain drive did not offer much of a gear reduction if any and the entire unit was quite heavy.
The weakness would show over time as chain and sprocket wear. The chain had several parallel rows of links, ie like a link belt about 2 inches wide to carry the load.

Regarding your comment, "look at the size of the contact patch" If you have a surface that has a convex curve touching either a straight or another convex curve, you will have only a linear contact line. Ie one thin contact line running at 90 degrees to the sprocket face. Much like a spur gear

 

NP203 chain

 

Interesting questions you ask, and I am not sure i can answer them thoroughly at this time.

Possible, but because of cordial actions I think the chain outlast the synthetic belt.

The vertical drive leg configuration I would be utilizing would be more of a one-to-one application rather than any sizable 'gear reduction'. Any gear reductions would take place in the gear box & reverser attached to the engine.

I had thought that some lubrication fluid would be needed for both the chain and the bearings in the opposing shafts. That could occur with a slight splash type lub, whereas synthetic belts might not like those lubs being supplied to the shaft bearings.

I believe the PYI units utilized chains that were greater than 4 inches wide.
"Width?
Silent chain widths can range from less than 1 inch to over 20 inches. As width increases, so does cost, so it is most economical to choose the smallest width suitable for the application at hand. Whenever possible it is also advisable to choose from stock or standard widths rather than specifying a width that must be specially ordered."

"Two Pin or Single Pin Joints?
Two pin joints have pins that roll or rock on one another when the chain flexes. This type of joint minimizes friction, vibration, and wear while maximizing efficiency. Single pin chains contain a single round or oval pin in each joint. These are very simple to connect, resist fouling, and can be more economical for conveying or less rigorous PT applications.
http://www.ramseychain.com/eng_fundamentals.asp?id=3"

Somewhere doing my research I found an engineering site that discussed this 'gear/sproket engagment' issue but I can't find it right now.

Barry, you appear to be extremely interested in this subject. have you had any other dealings with belt or chain drives?

 

https://www.myodesie.com/wiki/index/returnEntry/id/3058#Chain Drive Advantages