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Old 12-24-2016, 08:31 PM   #21
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Some more good info here, and another reason I favor silent chain drive...

Belt Drive - Page 5 - Boat Design Forums

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Old 12-25-2016, 12:27 AM   #22
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Anyone willing to wager what the life of the belts are? Why not chains?
Belts are the way to go. Chains have seen their day in this kind of application, IMO.
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Old 12-25-2016, 09:32 AM   #23
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Belts are the way to go. Chains have seen their day in this kind of application, IMO.
Not sure how popular belts are for engine timing in autos nowadays but once they were the rage to get weight savings and reduce noise. I think most manufacturers have gone back to chains at least for diesel engines. In diesel Rabbits circa 1980, the timing belts were supposed to be replaced at 50K miles at considerable expense and if you threw one, well, bye bye engine. When I lived Japan, our Toyota Chaser threw a belt on a gas car with under 50K kms but gas engines go on. I have no use for belts.
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Old 12-25-2016, 09:44 AM   #24
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Not sure how popular belts are for engine timing in autos nowadays but once they were the rage to get weight savings and reduce noise. I think most manufacturers have gone back to chains at least for diesel engines. In diesel Rabbits circa 1980, the timing belts were supposed to be replaced at 50K miles at considerable expense and if you threw one, well, bye bye engine. When I lived Japan, our Toyota Chaser threw a belt on a gas car with under 50K kms but gas engines go on. I have no use for belts.
No difference in the results if a timing belt or chain fails. As to failing to follow manufacturer's recommended service intervals, bad things happen if you don't change the oil either.

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Old 12-25-2016, 10:07 AM   #25
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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.


...also
https://www.myodesie.com/wiki/index/...e%20Advantages
Quote:
Concentric Pin and Rocket Joint on Silent Chain

The concentric pin and rocker joint is used in some designs of silent chain. This joint, together with the involute sprocket tooth reduces chordal action to a minimum. The joint consists of a pin and rocker, each with identical cross-sections and concentric radii. When the chain engages the sprocket, the curved surfaces roll on one another, thus eliminating sliding friction and joint galling.

Before the chain engages the sprocket, the contact point of the pin and rocker remains below the pitch line as shown in Figure 18 Top . As the chain engages the sprocket, the contact point moves upward and the pitch of the chain elongates as shown in Figure 18 Bottom.
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Old 12-25-2016, 10:28 AM   #26
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If you hit something with the propeller, I would rather have a belt absorbing some of the shock as opposed to a chain transfering all of it to other parts of the outboard.

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Old 12-25-2016, 10:31 AM   #27
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I find the mechanics of it interesting in a stimulating way. New mechanical things are great.

But I'm thinking this far aft engine system dosn't marry well on trawlers. There's enough trawlers out of trim as it is. Most all of them bow down. Trawlers in big water should have their propellers as deep in the water as practical. OB and IO units fail in that way and on big waves could find their prop out of the water just when it's needed for some propwash over the too small rudder.

If I had a choice of an Oxe powered NT32 or what's offered now I definitely go for the conventional powered boat.
Hi Eric,

belt-driven is a very old invention, in this picture of two large diesel and one shaft. Swedish picture old ship. oxe is also from Sweden. Many things have already been invented now reuse use. a good example of Volvo Penta IPS, translate Advanced transmissions and front-facing propellers were invented in about 60-70 yars then


2 engine powering one shaft. Variable pitch propeller. New fire pump 2012 and new bilge pump in 2011.






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Old 12-25-2016, 10:35 AM   #28
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My late model Honda and Jettas had/have timing chains.
Interestingly my present 5 cyl 13 Jetta has the timing chain on the flywheel end of the engine.
Don't know for sure but I think timing belts are a thing of the past.

Baltic Sea,
The drive systen in the above picture would not have counter rotating props.
The cog belts are more efficient than the old deep V belts and require far less tension.
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Old 12-25-2016, 10:37 AM   #29
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The problem with any chain, including the above, is that each pin-to-link interface wears. Not much wear, but it changes the pitch slightly. And now you have sliding contact on the link to wheel interface. And add up all the pin to link wear and you get a considerable change in total length, aka "stretch". This forces the need of a tensioner mechanism that can gradually compensate fro the stretch.

I have no problem using chains in certain apps, but do have a problem with the tensioners presently in use. Little plastic guides of doubtful chemical stability, springs, hydraulic pistons, little springs and clips.

Belts need some sort of tensioner in most apps, mostly due to thermal expansion, but at least pitch remains much more constant than on a chain. The wear and thermal expansion dimensional changes less than chains. And quieter.

Neither is a silver bullet for all apps.

On the OXE I am real curious how the are guiding the outer surface of the belt as it courses down into the lower unit. Seems they would need some guides or rollers to squeeze the belt together to get a slim profile above the "torpedo" shaft housing. Can't yet imagine an easy way to do that.
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Old 12-25-2016, 12:50 PM   #30
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Diesel Outboards

Two things that caught my attention:

1) Not less that 33% of the fuel used turns into heat that goes out the exhaust as unused energy. Dry Manifolds & Turbo's start to glow red at at about 25 HP per liter and are get bright red at 50HP per liter and up...........Just how to they deal with the heat at those HP levels? Certainly Cummins, JD, Yanmar and Detroit never figured it out in marine applications in an open engine room.. Now, it is in a very small enclosure?

2) Curious how they deal with belt tension on the lower belt with fixed shaft centers over time? The upper belt is easy as it always has a "slack side", but the lower belt can run opposite directions with means a spring tensioner would not work.

For sure toothed belt technology has come along ways. Harley converted over to it over 25 yrs ago

The first Helicopter I flew had 5 v-belts (1968) that connected the Lycoming engines crankshaft to the transmission and using a "Lawn-mower" type belt tensioner on a linear actuator to make it engage so the main rotor would turn. Neutral, so you could start the engine, was "slack" belts. You just engaged slowly with controlled belt slippage to get the rotor turning, then it it "lock-up" so to say.

I am a fan on new technology, but it also has to prove itself "Long Term" in the right application. Of course, the military does not really care about that anyway. Just look at the condition of the 10-12 year old RIB's and QSB 5.9's that are coming on the used engine market these days. All run hard and put away wet.Love the business though that comes our way because of it.

To me, the jury is still out on POD drives. All I see is very high maintenance costs vs. very low hour annual use. Plus, if used in heavier boats that run at hull speeds for long distances (called "cruising") , MPG seems dismal at best compared to convention running gear w/ big props.


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Old 12-25-2016, 01:45 PM   #31
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I am a fan on new technology, but it also has to prove itself "Long Term" in the right application. Of course, the military does not really care about that anyway. Just look at the condition of the 10-12 year old RIB's and QSB 5.9's that are coming on the used engine market these days. All run hard and put away wet.Love the business though that comes our way because of it.

To me, the jury is still out on POD drives. All I see is very high maintenance costs vs. very low hour annual use. Plus, if used in heavier boats that run at hull speeds for long distances (called "cruising") , MPG seems dismal at best compared to convention running gear w/ big props.


Tony
I am never a first generation adopter. I want it proven. Show it to me in real use over a long trial period. Whether it's computer technology, engines or boat designs, I feel the same. Someone else can work through the initial problems. Show me some diesel outboards on utility boats that I can see and touch, getting heavy use for the last two years and then I might listen.

Now, as to pods, I don't personally want them but don't share your "jury still out". Pods are a long established technology. They've been in the commercial market for decades and now IPS and Zeus have been around in the recreational market for a long time. Some builders I respect greatly, such as Delta Powerboats, use them very successfully.

As to heavier boats that run at hull speeds for long periods of time (called "slow cruising"), that is clearly not the pod market and not the appropriate application. I'm personally not aware of much of that being done.

Then as to pods in the lighter recreational boat market, I think much of what I've seen is pods being sold to inexperienced boaters and, therefore, the maintenance issues being greatly increased. I see a lot of pods damaged but with the lack of experience by the operator they would have damaged any type of propulsion system. Pods are going to have worse records when sold to first time boaters and cruisers. Now, I think many of their sales are strictly gimmick sales. Joysticks have sold more pods than anything else, because docking fears prevail. The problem is there is more to boating than docking, much more, plus joysticks are available now for any type propulsion system.

Our most recent purchased boat offered pods or conventional. The first negative then I saw toward the pods was that the boat wasn't really designed for them. The best pod applications are boats build for them from the ground up. Now, we intended to use this boat on the loop and I just saw the risk of damage to the pods greater (draft slightly greater) plus the available expertise along the route to quickly make repairs or replace pods. In terms of performance, the pods had a slight speed advantage, but we upgraded engines to mostly offset that. At cruising speed (not hull speed but 20-26 knots) the pods were far more efficient. That just didn't excite me. Then also, the pods offer the potential of space savings and added space for other things, but in this boat, that was not realized. In fact, they came with a smaller fuel capacity and no greater space benefit, since the engine room dimensions were already fixed. As to your findings on fuel, even at 10 knots and less, the pods on this boat used less fuel than the conventional drives. Now, they didn't match a small diesel with big props but that's not the nature of the boat or their intended use.

So, I don't think the verdict on pods is still out. I think they are what they are and proven over time. They are not the failures some predicted, but they haven't taken over the world as others predicted. A huge limiting factor in market share has been that Zeus is limited by Cummins engine sizes and, therefore, has to keep adding engines to compete in even the 60' range. IPS goes further but with Sea Ray the largest builder of boats in that range, and their Zeus marriage, it has limited pods in the Express boat and day cruiser market. I think Zeus for Brunswick was strictly a defensive measure as competitors were offering IPS. I know people with vast amounts of experience with pods on many different boats who are totally sold on them. I also know novice boaters who have been through several pods on their two year old boat. Then I know some builders who were early into the pod world and are IPS all the way.

One thing that has impacted pods negatively in market share is that as they were gaining popularity and perhaps had potential in many cases in lieu of inboard outboards and not just inboards, the I/O market was shrinking while the outboard market was growing. Small SF's and CC's were initially targeted as pod applications. Well, small SF's have shrunk as to their size of the market and the growing share has gone to outboard powered CC's increasing in size.
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Old 12-25-2016, 03:22 PM   #32
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I think three things account for pod market share particularly IPS success. Builders and architects like them for installation and design purposes. Joy stick control and precise docking really appeals to many boaters. Volvo's advertising sold the public the idea of fuel economy without pointing out it is only so at certain higher speeds on certain boats,not slower cruising boats or even SD at moderate speeds.
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Old 12-25-2016, 06:38 PM   #33
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Originally Posted by Nomad Willy View Post
My late model Honda and Jettas had/have timing chains.
Interestingly my present 5 cyl 13 Jetta has the timing chain on the flywheel end of the engine.
Don't know for sure but I think timing belts are a thing of the past.

Baltic Sea,
The drive systen in the above picture would not have counter rotating props.
The cog belts are more efficient than the old deep V belts and require far less tension.

Eric,
The picture from Baltic is 2 engines onto 1 shaft; ergo, only 1 prop.
Likely has controllable pitch for reverse

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Old 12-25-2016, 07:03 PM   #34
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Mercury has a pretty interesting diesel fueled outboard that is spark ignited. Shouldn't need the same high compression as a tradition diesel. This would aid in bringing the weight down.
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Old 12-25-2016, 07:30 PM   #35
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Mercury has a pretty interesting diesel fueled outboard that is spark ignited. Shouldn't need the same high compression as a tradition diesel. This would aid in bringing the weight down.


Why do I have cold sweats whenever the word Mercury is mentioned
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Old 12-26-2016, 01:03 AM   #36
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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
I am still trying to get more info on these 2 systems,...and a copy of that DVD that's mentioned.
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Old 12-26-2016, 01:21 AM   #37
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I am never a first generation adopter. I want it proven. Show it to me in real use over a long trial period. Whether it's computer technology, engines or boat designs, I feel the same. Someone else can work through the initial problems. Show me some diesel outboards on utility boats that I can see and touch, getting heavy use for the last two years and then I might listen.

Now, as to pods, I don't personally want them but don't share your "jury still out". Pods are a long established technology. They've been in the commercial market for decades and now IPS and Zeus have been around in the recreational market for a long time. Some builders I respect greatly, such as Delta Powerboats, use them very successfully.

As to heavier boats that run at hull speeds for long periods of time (called "slow cruising"), that is clearly not the pod market and not the appropriate application. I'm personally not aware of much of that being done.

Then as to pods in the lighter recreational boat market, I think much of what I've seen is pods being sold to inexperienced boaters and, therefore, the maintenance issues being greatly increased. I see a lot of pods damaged but with the lack of experience by the operator they would have damaged any type of propulsion system. Pods are going to have worse records when sold to first time boaters and cruisers. Now, I think many of their sales are strictly gimmick sales. Joysticks have sold more pods than anything else, because docking fears prevail. The problem is there is more to boating than docking, much more, plus joysticks are available now for any type propulsion system.

Our most recent purchased boat offered pods or conventional. The first negative then I saw toward the pods was that the boat wasn't really designed for them. The best pod applications are boats build for them from the ground up. Now, we intended to use this boat on the loop and I just saw the risk of damage to the pods greater (draft slightly greater) plus the available expertise along the route to quickly make repairs or replace pods. In terms of performance, the pods had a slight speed advantage, but we upgraded engines to mostly offset that. At cruising speed (not hull speed but 20-26 knots) the pods were far more efficient. That just didn't excite me. Then also, the pods offer the potential of space savings and added space for other things, but in this boat, that was not realized. In fact, they came with a smaller fuel capacity and no greater space benefit, since the engine room dimensions were already fixed. As to your findings on fuel, even at 10 knots and less, the pods on this boat used less fuel than the conventional drives. Now, they didn't match a small diesel with big props but that's not the nature of the boat or their intended use.

So, I don't think the verdict on pods is still out. I think they are what they are and proven over time. They are not the failures some predicted, but they haven't taken over the world as others predicted. A huge limiting factor in market share has been that Zeus is limited by Cummins engine sizes and, therefore, has to keep adding engines to compete in even the 60' range. IPS goes further but with Sea Ray the largest builder of boats in that range, and their Zeus marriage, it has limited pods in the Express boat and day cruiser market. I think Zeus for Brunswick was strictly a defensive measure as competitors were offering IPS. I know people with vast amounts of experience with pods on many different boats who are totally sold on them. I also know novice boaters who have been through several pods on their two year old boat. Then I know some builders who were early into the pod world and are IPS all the way.

One thing that has impacted pods negatively in market share is that as they were gaining popularity and perhaps had potential in many cases in lieu of inboard outboards and not just inboards, the I/O market was shrinking while the outboard market was growing. Small SF's and CC's were initially targeted as pod applications. Well, small SF's have shrunk as to their size of the market and the growing share has gone to outboard powered CC's increasing in size.

Volvo IPS has failed in many situations when a boat ride on the rocks. Volvo has designed the IPS released "cut" and the water will not leak in hard. the truth was the entire unit is torn loose and makes a big hole in the bottom of the vessel sink quickly. of course, been reasons other than a Volvo.

A lot of it was necessary to also careless and sloppy installation Jeanneau laminating

Official accident investigation Jeanneau prestige and ips. stern was torn from the bottom part, the ips will not cut. browse through a lot of pictures and at the end of starting on page 57 in English, too.


⭐JEANNEAU PRESTIGE 42S, A (FIN), uppoaminen Inkoon edustalla
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Old 12-26-2016, 06:22 AM   #38
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It's a great idea but I foresee two problems.
To meet Euro 5/6 emissions the engine must be electronically controlled, sea water and engine electronics do not make great bedfellows.
The Opel base engine is not the most durable engine in terms of camshaft reliability.
The European Union has pushed unrealistic rules for engineers to meet on engine emissions and the only way to achieve it is now by electronics. The tendency for small highly tuned engines to control emissions and save weight has reach such a stage (VW emissions scandal) that the thinking is now swinging back to big block motors.


Meanwhile wood fired (eco )home/factory heating and China commissioning a coal fired power station every day produces more pollution.
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Old 12-26-2016, 08:09 AM   #39
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Mercury has a pretty interesting diesel fueled outboard that is spark ignited. Shouldn't need the same high compression as a tradition diesel. This would aid in bringing the weight down.
http://www.trawlerforum.com/forums/s...ard-29396.html

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Old 12-26-2016, 08:50 AM   #40
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Volvo IPS has failed in many situations when a boat ride on the rocks. Volvo has designed the IPS released "cut" and the water will not leak in hard. the truth was the entire unit is torn loose and makes a big hole in the bottom of the vessel sink quickly. of course, been reasons other than a Volvo.

A lot of it was necessary to also careless and sloppy installation Jeanneau laminating

Official accident investigation Jeanneau prestige and ips. stern was torn from the bottom part, the ips will not cut. browse through a lot of pictures and at the end of starting on page 57 in English, too.
And the point is? That if you run your boat on the rocks, you're going to have a lot of damage? That's not exactly limited to one form of propulsion. Now, overzealous sales people may be representing it to magically overcome, but I certainly didn't represent pods in that way in my post. Jeanneau and Prestige are also at the bottom end of the price and quality scale and attract a lot of first time boaters.
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