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Repower convert from shafts to pods?

Discussion in 'General Yachting Discussion' started by TeKeela, Aug 12, 2015.

  1. TeKeela, Aug 12, 2015
    #1
    TeKeela

    TeKeela Member

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    Let's say you have an old Broward or Hatteras MY, it has 92s or 71s in there 8 or 12s under 900hp each and time for a repower. Let's say its a 12-16kt boat. So under 900 Cats or Cummins could be a good substitute.

    Why wouldn't going with pods be a good choice? You gain maneuverability, more space in the engine room, less drag, less weight, underwater exhaust, more space from removing traditional exhaust modern gauge display (that's 4 sq ft of helm space!) and joystick control.

    Pros Cons?
  2. Maxwell, Aug 12, 2015
    #2
    Maxwell

    Maxwell Senior Member

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    From a maneuverability and efficiency perspective you are correct. However I would think it could be cost prohibitive (if it can even be done) due to the modifications that would be needed on the hull etc. The reinforcement needed etc to ensure the pods would shear etc if needed would likely be difficult.

    We had IPS in the last boat that I owned and I'm not sure that I'd get another one. Loved the ability to bail out to the joystick if things got a little interesting around the dock etc, but there's something to be said about the simplicity of shafts from a maintenance perspective as well as not worrying about my forward facing propellers striking something...
  3. NYCAP123, Aug 12, 2015
    #3
    NYCAP123

    NYCAP123 Senior Member

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    Most boats are designed for their propulsion systems. Certainly IPS & Zeus. I guess anything can be converted to anything, but it's a matter of whether the benefit would be worth the cost.
  4. olderboater, Aug 12, 2015
    #4
    olderboater

    olderboater Senior Member

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    I think that's the main point I would make too. You're talking about putting a propulsion system in a boat that's not designed for it and that you have no history or previous installations to know how it will work and perform. Both IPS and Zeus work best when certain design features are there.
  5. Capt J, Aug 12, 2015
    #5
    Capt J

    Capt J Senior Member

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    What they said. Both ZUES and IPS need to be mounted verticle to the waterline, they cannot be mounted at an angle on the V. They also need a hull and engine bed that is designed for them. Although I've seen a few retrofitted. The Broward would be a FAR easier deal because you could just weld what you need right into the hull and I'm sure a naval architect could get it right. ZF can but the boat handles REALLY ODD when you mount them on the same angle as the V. Most big browards and Hatteras cruised at 20 knots. A set of C18 CATS to replace 12v71's or 12v92's would get you more speed, fuel efficiency, and engine room space.
  6. Capt Ralph, Aug 12, 2015
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Think were missing another view. Your going to need to jack shaft back a ways to the pods. Somewhere around your last strut or just before. Above that point your going to need access and at least 3 feet of vertical clearance. 2 feet up and parallel to the main engine, a direct (straight) shaft.
    Just the physical placement of the inboard drive line will eat up a lot of interior bilges.
    If the pods go down in the after ER, they won't have the leverage against the hull to maneuver.

    Now, keep conventional drive line and a pair of QSMs or taller and your hp requirements go down since your not lugging around that old designed 4000+ pounds of Detroit cast iron.

    It's a new power plant either way, stay conventional and lighten up the HP.
    Last edited: Aug 12, 2015
  7. TeKeela, Aug 12, 2015
    #7
    TeKeela

    TeKeela Member

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    Note this is out of curiosity, I have neither boat to deal with this issue but as I view them, I think how would one get rid of DD and what could be upgraded.

    My last calculation if correctly recalled were around 28" of vertical height above the hull for the pod. I think that was a ZF4000. And yes they would need to be a vertical mount, unlike a Volvo which confound me as to why that would work properly tilted sideways.

    It still looks like if you have the clearance from the hull to the deck, or can make it, and can penetrate any cofferdams or bulkheads for the jackshafts there are no other issues. No, not designed for it, but it should function whether there is a shaft above or below the hull. Yes Broward gets welded and mods would be easier, but the Hatt has a 2" think bottom so it has the strength, just needs the mods in glass.

    If the efficiency can't make up for the cost, then ZF quickshift could be an answer.

    I am just wondering why I see so many "just majored" on these 92s and 71s. Especially the older Hatts that have the double engine room. Absolutely no space in there with those motors.

    The person who decides a rebuild must not like their engineers/captains. I would rather make some room and keep things easily serviceable and clean.
  8. Capt J, Aug 12, 2015
    #8
    Capt J

    Capt J Senior Member

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    Because it's 1/3 of the price to rebuild a detroit instead of repowering and many times they're just rebuilding one and not both. Also, you don't have to cut a hole in the side of the boat or do other major surgery to get them out of the boat and new engines installed. 95%+ of the time the Detroits can and are rebuilt in place.
  9. TeKeela, Aug 12, 2015
    #9
    TeKeela

    TeKeela Member

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    I know its cheaper of course and each time I look at a salon I wonder where the engine room is, I've pulled out a set from above not from the side. It is a big job but oh so good of a feeling once those things are out and the others in.
  10. Bamboo, Aug 13, 2015
    #10
    Bamboo

    Bamboo Senior Member

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    Anything can be done with enough money, time or knowledge. Deciding if it's a worthwhile endeavor is another matter...
  11. K1W1, Aug 13, 2015
    #11
    K1W1

    K1W1 Senior Member

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    There in lies the key to going ahead or not, a good part of what should be considered during the decision process is the amount of cash available to be used that will never really be recovered in anything other than the joy of using the vessel.
  12. MYTraveler, Aug 14, 2015
    #12
    MYTraveler

    MYTraveler Member

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    When I had my boat built, I considered pods. I was convinced that it wasn't a good choice for my needs since my boats mission is to go to remote areas where high tech stuff isn't easily serviced.
  13. TeKeela, Aug 15, 2015
    #13
    TeKeela

    TeKeela Member

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    I think that would have to be the way to go, mechanical engines and shafts.

    When I posed the question I had been eyeing <sp?> vessels more appropriate for the Bahamas but anywhere remote would definitely not be a good choice for pods.