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Volvo IPS - CMD Zeus

Discussion in 'Technical Discussion' started by orion, Oct 21, 2006.

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  1. brian eiland

    brian eiland Senior Member

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    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)
  2. Blair

    Blair New Member

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    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?
  3. denizci

    denizci New Member

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    Should we say IPS has a problem now?

    I just saw this thread earlier:

    http://www.yachtforums.com/forums/g...appens-ips-propelled-boat-when-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.
  4. AMG

    AMG YF Moderator

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    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!
  5. denizci

    denizci New Member

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    I couldn't agree more!!

    P.S. I still like' em...
  6. K1W1

    K1W1 Senior Member

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    Hi,

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

  7. NoRudder

    NoRudder New Member

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    True Pod drive

    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.
  8. Blair

    Blair New Member

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    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.
  9. NYCAP123

    NYCAP123 Senior Member

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    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.
  10. NoRudder

    NoRudder New Member

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    Grounding is never a good thing!

    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?
  11. Marmot

    Marmot Senior Member

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    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.
  12. NYCAP123

    NYCAP123 Senior Member

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    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.:rolleyes: Besides you're talking about a "podded propulsors" .....Pod for short.;)
  13. Marmot

    Marmot Senior Member

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    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.
  14. NYCAP123

    NYCAP123 Senior Member

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    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.
  15. K1W1

    K1W1 Senior Member

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  16. NYCAP123

    NYCAP123 Senior Member

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    I know what a "real" pod system looks like. Now you just have to convince Volvo, Cummins, Caterpillar, ZF and a few boat manufacturers.;) Let me know how that works out.
  17. Marmot

    Marmot Senior Member

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    Sure you do, but like most other people, you don't know what one is.

    The marketing folks at the companies jumping on the bandwagon are counting on people like you to think the same way. They use the term because it makes uniformed buyers think it is the same system introduced to provide great benefits (after a few years of costly screwups) to cruise ships and now ice-breaking tankers among other applications.

    It just wouldn't attract as much attention if they called it a non-tilting-through-the-bottom-inboard-outboard would it? Or like the workboat crowd call them, Z-drives or tractor drives. The folks they are aiming at want to pretend they are buying into a more technologically sophisticated class of shipowners.

    It appears that in this case marketing has once again trumped engineering and will probably continue to do so until enough of the things fall off or sink boats that would have been cheaper and just as effective with transom mounted outdrives. The only thing they offer is a control system that lets prop drivers almost match the maneuverability of jet boats without having to know how to drive ... until the things break off.
  18. NYCAP123

    NYCAP123 Senior Member

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    Let us know how your campaign works out.:D BTW, don't ever presume to know what anyone else does or doesn't know. It makes you look more foolish. I've been on a few tugs with it. I'm no expert and don't profess to be one, but YES I do know what one is.
  19. K1W1

    K1W1 Senior Member

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    Hi,

    What have you been on a few Tugs with NYCAP?

    I seriously doubt you would find a tug sporting full pods, they tend to use these:

    http://en.wikipedia.org/wiki/Voith-Schneider
  20. Marmot

    Marmot Senior Member

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    Sorry Cap, I don't have a "campaign." I could care less who buys the stuff, I just pointed out that marketing has more power over people in the boat business than engineering and this is a great example.

    And if you knew what a pod was, where they came from, and how they worked, you wouldn't call an outdrive a pod, that's not an assumption, that's a fact. I also doubt if you have ever been on a tug with a pod drive. A Z-drive or a tractor maybe, but not a pod drive. But, who knows, I haven't seen everything, maybe your sportsfish has a couple too.