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Hit anything lately ?

Discussion in 'Technical Discussion' started by theav8r, Feb 3, 2009.

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  1. theav8r

    theav8r New Member

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    ok, with all these new pod systems being built there is much talk about damage to these drive systems from hitting some unseen object / running aground or ??? ......

    is this a real concern ??

    with my 20 years of go fast boats , I have never damaged my drive system from hitting something or running aground .....
  2. Capt J

    Capt J Senior Member

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    Any drive system will be damaged if you hit anything or run aground with any speed behind you. I would say that hitting an object with any type of drive system would be a concern if you're going over 8 knots and running aground at any speed. The pod systems are designed to break away in an extreme case of hitting something and leaving the hull without a hole in it from the drive system. I have not seen any damaged units to testify to this at all.
  3. m2m

    m2m Senior Member

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    I agree that hitting something with these pods could become extremely expensive. On of the worst drawbacks to these systems (other than grounding damage) is damaging the seals which is often caused by fishing line-once water gets in the trouble begins.
  4. Capt Bill11

    Capt Bill11 Senior Member

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    Have you seen this first hand? Which seal are you speaking of?
  5. NYCAP123

    NYCAP123 Senior Member

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    Can't see fishing line being any more problem than on any outdrive. As far as the upper seals are concerned it's not like they're spinning so the line would just drape until it washes off. The prop sears would represent the same problems with the same results. One major plus with the pod would be that they break off and seal. Hit that hard with an I/O and it could rip your transom.
  6. AMG

    AMG YF Moderator

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    Have you ever seen this happening to an I/O? I have seen many drives missing but no damage to the transom. Normally it just bumps up and then down again, with or without damage from the grounding.
  7. m2m

    m2m Senior Member

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    I have seen this first hand. the seal that was damaged was a lower seal on the Volvo IPS drive.
  8. NYCAP123

    NYCAP123 Senior Member

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    I've seen damage of all sorts to transoms from all sorts of causes. However I meant to write 'rip out of your'. Thanks.
  9. Capt Bill11

    Capt Bill11 Senior Member

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    By lower seal I assume you to mean the seal at the hull?

    So fishing line cut the seal?

    What diameter/test would you say the line was?

    What was damaged besides the seal?

    Did it let water in to the boat, drive unit or both?

    Isn't there a seal on the inside of the hull as well?

    Seems like a major weakness in this system if fishing line alone can mess up one of the main seals.
  10. NYCAP123

    NYCAP123 Senior Member

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    The lower seal is behind the prop and is vulnerable to damage by fishing line on every option with a lower unit.
  11. Marmot

    Marmot Senior Member

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    "Seems like a major weakness in this system if fishing line alone can mess up one of the main seals."

    Does it to very large ships all the time. It doesn't take much monofilament to destroy a lip seal.
  12. Capt Bill11

    Capt Bill11 Senior Member

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    Yes I understand that. But on a new system like this one would think that had been taken into consideration and perhaps over come.
  13. NYCAP123

    NYCAP123 Senior Member

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    Simple. Just invent a product that is hard enough not to cut with a razor but soft and pliable enough to stop water migration while not costing enough to break NASA's budget.
  14. Capt Bill11

    Capt Bill11 Senior Member

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    See, I knew there was an answer. :D

    But seriously, if the damage happens at the pivot point of the drive, I would think there would be a way to shield the seal in a way that would preclude line from getting in and doing damage to the seal.

    I guess I need to take a closer look at the drives at the Miami show.
  15. NYCAP123

    NYCAP123 Senior Member

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    One of us is misunderstanding m2m. Is it the lower seal behind the prop or the hull seal? Don't see how the later would be possible. Don't see how there would be enough movement to work the line in or to cause a cut. The pods on tugs spin 360* and get a lot of work but I haven't heard of that problem there either.
  16. Capt J

    Capt J Senior Member

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    5200!!!!!!!!!!!!!!!!!!!! hehehe
  17. NYCAP123

    NYCAP123 Senior Member

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    Capt J, thank goodness you're not an engineer.:D
  18. Capt J

    Capt J Senior Member

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    hehehehe well 5200 does meet all of your qualifications. Hard enough not to cut with a razor (well you can but it takes a lot of work), pliable, and doesn't cost an arm and a leg. hehehe
  19. Capt Bill11

    Capt Bill11 Senior Member

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    Either have I. And that's way I asked those questions. I was trying to find out which seal he meant. If it was a prop shaft seal that failed that would be no different than what can happen on most any type of drive. Or even to a shaft bearing.

    But if it was the pivot point seal that would be a big design flaw IMO.
  20. Capt Bill11

    Capt Bill11 Senior Member

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    Yeah, but it always seems to end up on you arm and leg. :D