[brian eiland]

Originally Posted by denizci

What I see so far is, even though there are few examples of successful application of these systems, they seem like they are somehow still in their experimenting or proving themselves stage and couldn't make it out to the mainstream market yet. Maybe just because of financial or marketing reasons, but for some reason they are not there yet.

This brings me to Blair's point where he mentions a well designed conventional shaft propolsion is still the most accepted system in place.

I am still optimistic though. There will be well accepted alternative (to shaft drive) systems for trawler boats in the future..

Thanks ya'll...

Sorry Denizci, I am a bit of a 'futurist. But look HERE, big yacht just launched with hubless thrusters.

I was hoping this rim drive technology would move along quickly, but I'm affraid the current economies may slow some of this new development down. I just imagine the uphill battle IPS has had to endure to bring their 'unconventional idea' forward to where it is today.

(ck the private message I sent you Denizci)

[Blair]

Good point Brian - I think Ethereal still has a conventional shaft mounted propellor set up but of course a sailing hull shape allows for optimisation of the drive train and alignment.

Presumably rim driven thrusters are more easily accomodated as the drive can be retained within the hull which I think would be somewhat harder to achieve effectively with a steerable rim-driven pod - at a competitive price anyway. You might have also seen the website powersail.co.nz for their Z drive concept - a retracting pod like some thrusters for the main drive to avoid loss of sailing performance. 20m sailing yacht does 18 knots under power!

Nothing is new though. Despite the excitment about IPS and forward facing props for pleasure craft there was an example here about 40 or so years ago. It was called Argonaut and was a stern drive pod configuration with a forward facing prop. Worked OK it seems but then even conventional stern drives were viewed as problematical beasts so it suffered an probably underserved death due to market reluctance.

Battery advances have been amazing - a floating hotel like Ethereal being able to motor and function for a day on stored juice! Not sure how 'green' that is though as the energy has to be generated and the whole system has eaten an awful amount of carbon to produce and to maintain?

[denizci]

I just saw this thread earlier:

http://www.yachtforums.com/forums/ge...hits-rock.html

Apparently, a boat with IPS drives has stricken an object and damaged badly. You can read all the details from the link above.

I wonder what kind of impact (and therefore damage) would occur to the Zeus drives under similar circumstances...

Too bad for Volvo...

Cheers,
Denizci.

Note for Brian Eiland: I am finally catching up with all those info (and leads) you have posted here and boatdesign. They are very interesting and learned a lot, thank you.

[AMG]

Originally Posted by denizci

Should we say IPS has a problem now?

Any boat owner that hits a rock or the sea bottom has a problem and each incident is different from the other. I once hit a small rock 40 years ago and bent the prop on my Volvo Aquamatic. I was not blaming Volvo for not having charted that rock and since then I have been lucky.

The difference between IPS and Zeus is there and hitting a rock will be expensive with both systems. Both have tried to avoid water intrusion at such events, but if you want to feel completely safe: - Never hit a rock!

[denizci]

Originally Posted by AMG

if you want to feel completely safe: - Never hit a rock!

I couldn't agree more!!

P.S. I still like' em...

[K1W1]

Hi,

It looks like the IPS Units have been a good sales item for Volvo...

Volvo Penta delivers 10,000th IPS unit

It was designed to be a revolution in boating. And it became one.
This spring, Volvo Penta has delivered the 10,000th IPS system
since the start in 2005.

Introduction of the Volvo Penta IPS (Inboard Performance System) – the world’s first pod system – meant a fundamental change in the marine industry.

With unique technical solutions, Volvo Penta developed a propulsion system that created totally new conditions for boats that until then were equipped with traditional straight shafts.

The key to success is the forward-facing propellers and the individually steerable drive units. These, combined with the system’s other advantages, provide the boat superior efficiency and improved features in virtually all areas: fuel consumption, performance, comfort, onboard space, maneuverability and installation. And with the joystick, which makes docking and close quarter maneuvering much easier, boating has become accessible to entirely new customer groups.

Most of the world’s leading boat builders quickly adopted the new propulsion system and currently IPS is featured in more than 250 boat models from builders around the world.

In many segments, the traditional straight shaft has entirely disappeared and been replaced by IPS. And this spring, Volvo Penta has delivered the 10,000th IPS system since the start in 2005.

“This is more than the most optimistic calculations we had at launch,” says Göran Gummeson, President and CEO of Volvo Penta. “But the advantages with the new system, particularly environmentally, are overwhelming and the industry quickly realized it.”

Precisely as with Volvo Penta’s other world-unique innovations in the marine industry, such as the Aquamatic sterndrive and Duoprop counter-rotating propellers, other manufacturers have copied Volvo Penta by launching systems similar to IPS - but with lower efficiency.

“When we introduced the IPS system, our assessment was that we had secured a lead of at least five years on our competitors. The actual market scenario to date indicates that this assessment is probably fairly accurate,” says Göran Gummeson.

Volvo Penta has continued to develop the IPS concept and this year is unveiling a new and more powerful unit linked to Volvo’s 11-liter engine, which means that increasingly more and larger boats can now gain access to all the advantages of the IPS system.

IPS was introduced initially as a twin installation, that is, two drive systems in each boat. However, it quickly became apparent that the system’s great flexibility facilitates multi-installations (three and four systems), which consequently means that Volvo Penta can currently offer the IPS system for boats from about 40 feet.

May 29, 2009

[rip728]

K1W1,

You obviously show great experience in all your posts here on this site and I respect your thoughts and opinions here. I do not have the large yacht and ship experience you have.
But you have stated the ZEUS and IPS are not "true pods" like the diesel electric ones on ships, tugs and so forth like AZIPOD.
But are they not a new class of pod designed for the mainstream yacht industry below the megayacht and ship class? Maybe "Econopod" or "class 1" for the rest of us so to speak? It can't swing 360 degrees and there are other limitations of course, but at a much more affordable price at least! I don't want to debate the definition, just offer it as a thought it could sort of be looked at as a pod system maybe?
As you posted, IPS has been a really good thing for Volvo Penta. IPS 2 is releasing now and IPS 3 will have the D13 power I think next year. That engine is released now at 900HP as an inboard power option. But they showed the IPS 1, 2 and 3 series props at Miami. The D13 must be the IPS 3 version I would think, since the D11 is IPS 2?
ZEUS (the ZF ZEUS or CMD ZEUS) is stating horsepower ranges up to 715HP I understand. Various engine brands supported with a range of top RPM from 2300 to 3900 I am told. The current prop sizes and ratios might make this a little challenging I would think (as in how much load a given diameter set of props can handle). But in either case this new breed of "pod drives" as they have been called seem to be making progress in the marketplace. I hope you see a little of my humor mixed in here for you. I just think they should be considered by yacht designers when they might provide the best propulsion option for the smaller yacht class up to 100 feet maybe.

[Blair]

Perhaps the suggestion can be made that although the new systems are designed to shear off when hitting a solid object (a unidirectional force generally), maybe the more threatening damage that can occur perhaps is when the unit (and craft) does not have the inertia to shear the unit off and the boat settles from its previous level of draft (assuming it was planing beforehand for example). In such cases as the craft slows to a stop (and the rock/reef is still there) the force is then transmitted more upwards on the pod and that force is a significant proportion of the gross weight of the vessel reducing of course until it reaches its normal bouyancy draft (when not underway). When you apply perhaps many tons of compression upwards at a point that is not large in area then it seems to me that it could force the unit through the hull and therefore cause significant ingress of water. It is not different from the damage that sometimes can be seen when a shaft strut (or rudder stock) is forced through the hull when a normal drive system has suffered a rock attack.

I guess the trick for pod designers is to find a balance between the shear point and serviceable rigidity but if the shear point is high, the alternative risk of compression damage becomes more apparent if a boat settles on the unit itself. The trick for the boat designers is to ensure that adequate calculation of the scantlings is made to accommodate the likely weight of the boat squatting like a duck on the unit that is mounted on a rock!

Forget all that, avoid rocks whatever the system is as you can't win in any case.

[NYCAP123]

I would guess that having a boat with IPS/Zeus rest on a rock (maybe when the tide goes out) would have much the same effect as you'd have on rudders. They just have to work on the sealing mechanism so it reacts properly to a partial separation as well as when the drive is completely knocked off.
RIP728, I think you are absolutely right about the terminology. No it is not the same type of pod used on ships and tugs etc. but these are indeed pods. They are not outdrives, shafts, jets or outboards. They are pods that mount under the boat. They just don't swing 360* and use totally different mechanical systems and actions. A Tata is a car and so is a Bentley. You want to be specific when ordering a new car or pod. Semantics.

[rip728]

There is plenty of talk about grounding in the other thread in YachtForums and I really don't want to bring that into this thread. One of the last jobs I had to do working for a marina was to rebuild all the running gear on a Hatteras 60 that cleaned everything off, after our glass guy was done. I think I still have certain aches and pains from this 16 years later. Grounding a nice yacht is not a good thing, but it can happen to even the very best captains under certain conditions (is your chart really correct?).
One point here is new struts, shafts, custom props are not off the shelf standard parts typically, but now "production" pods can maybe offer this.
The interface between propulsion unit and hull is a really important area as Blair was eluding to. FRP can be tricky and typically is applied by some of the newest members to join a boat company maybe? And yes direct impact at the front, side, backing into something or coming to rest on it all must be considered. I watched the videos CMD placed on their web site taking the drives off and the "high speed" grounding (Looked to me like the throttled back a bit). I know a bunch of posts asked to see this type of video. I am of the understanding that CMD uses bolts that shear off. Volvo Penta IPS has a part designed to shear that the drive pivots on. These manufacturers will continue to monitor what goes on and keep improving as the systems mature. A better product is what everyone wants, right?
Keep your charts up to date and the beer in the fridge until the lines are secure. Please?

[Marmot]

Originally Posted by NYCAP123

No it is not the same type of pod used on ships and tugs etc. but these are indeed pods.

No way are these things "pods." They are simply another version of an outdrive or a lightweight Z-drive. A podded propulsor contains the drive motor within its housing and is a specific type of propulsion unit.

Calling them "pods" is just a marketing gimmick to make people think the technology that drives modern cruise ships and tankers has filtered down to recreational vessels. It just ain't so. These things, as they stand now, are just an outdrive without the ability to kick up and protect itself from the inevitable.

[NYCAP123]

Originally Posted by Marmot

No way are these things "pods." They are simply another version of an outdrive or a lightweight Z-drive. A podded propulsor contains the drive motor within its housing and is a specific type of propulsion unit.

Calling them "pods" is just a marketing gimmick to make people think the technology that drives modern cruise ships and tankers has filtered down to recreational vessels. It just ain't so. These things, as they stand now, are just an outdrive without the ability to kick up and protect itself from the inevitable.

It's semantics. An object is what it is regardless of what you call it. According to one dictionary Pod: "a detachable container or housing". Calling IPS or Zeus a pod is technically correct and makes it easier to visualize and relate to than the boat I'm selling has the new 'outdrive that goes under the boat instead of in the back and is totally different but the same' or we could simplify that by using the acronym 'OTGUTBIOITBAITDBTS'. It's just time to be specific when ordering a pod drive system. I don't think anybody will get confused and put IPS under a cruise ship. Besides you're talking about a "podded propulsors" .....Pod for short.

[Marmot]

Originally Posted by NYCAP123

It's semantics.

No, it's an outdrive or a Z-drive. There is no drive motor in the underwater part of those things. There is no more a "pod" to them than there is with an outboard motor. It is nothing more than a housing for a drive shaft and a couple of gears, just like any other outdrive.

A pod drive or podded propulsor has a "pod" that contains the drive motor. These things are not podded propulsors, they are not pod drives.

You dismissing this as semantics is like someone saying a Bayliner is a sportsfish just because sportsmen fish from them ... the term is very specific as to the design and function.

[NYCAP123]

Yes it is semantics. Have you Googled "Pod Drives For Boats" lately? Unless you have a new dictionary about to be published you're tilting at windmills. Even CAT is calling it that.

[K1W1]

Hi,

Take a look here to see what a real pod system looks like.

http://lmgtfy.com/?q=pod+propulsion+system