Does anyone have experiences with different jet manufacturers for large vessels?

Discussion in 'Jet Drives' started by BIGBOATBUILDER, Oct 25, 2007.

  1. BIGBOATBUILDER
    Joined: Sep 2007
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    BIGBOATBUILDER Junior Member

    Hi,

    I would be interested to hear of experiences regarding waterjets used on big high speed vessels (LOA about 37m = 122ft).

    Has anyone found certain manufacturers particularly good in terms of quality, service, reliability, price?
    Has anyone had particullarly bad experiences?

    Thanks for your input.

    Charlie
     
  2. yipster
    Joined: Oct 2002
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    yipster designer

    no experience and only very little knowledge on big jets here...
    but i did like the pics i once saw of a small cat taking jet sterns out of a big cat in the water
     
  3. RANCHI OTTO
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    RANCHI OTTO Naval Architect

    The best thrust for 35 knots have the Kamewa and MJP waterjets.

    The MJP has lower price...

    Send the resistance curve to them and compare the results...

    Once the model selected compare the weight of the installation too...
     
  4. BIGBOATBUILDER
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    BIGBOATBUILDER Junior Member

    Thanks!

    Thanks Otto,

    fabulous to have someone around here with a lot of experience who is not scared to share some thoughts.

    Great!

    best regards,

    Charlie
     
  5. RANCHI OTTO
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    RANCHI OTTO Naval Architect

    Bitte schoen Charlie, you are welcome!
     
  6. lazeyjack

    lazeyjack Guest

    Hamilton jet in new zealand
    the thing I have against jets is that they track the vessel poorly, I built a 18m with a box keel 400mm deep but it was still all over the sea, so now they go everywhere on autopilot
    You dont see many jets around, and that is because there never was anything invented that is better than the screw propeller, I also find them to be prohibively expensive and therefore only an option when the situation allows nothing else( shallow river work, marine farming) cheers Stu
     
  7. RANCHI OTTO
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    RANCHI OTTO Naval Architect

    We are speaking about waterjets for large passenger vessel over 35 m length o.a. (no problems of air intake in waterducts)

    The OPC defined (EHPbh/DHP) is much better with a waterjet than with a submerged propeller at 35 knots.

    EHPbh = effective horspower bare hull (Rt*v/75)
    DHP = delivered horspower (BHP*Etamech.)

    The appendages resistance with submerged propellers is of 10% abt. (rudders, shafts, propeller brackets, strut palms, bossings..)

    Installing Kamewa waterjet instead standard models at 35 knots you save 10% power abt.

    Even if the Kamewa waterjet are more expensive, 10% less power at 35 knots constant speed means:
    - Smaller engine model (less expensive and less weight)
    - Smaller gear box (less expensive and less weight)

    and 10% less fuel oil consumption!

    The Hamilton waterjets have low thrust for such size of ship...


    Anyway try to ask Hamilton for a thrust vs speed forecast and than compare with Kamewa....

    Designing military high speed craft, all clients are asking for waterjets because easy to manoeuvring in harbor and less problems to employ them.
    Only for very "special" designs I convince them to install surface propellers.
     
  8. StianM
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    StianM Senior Member

    Hamilton jets have a design on it's cower that allow for bether reversing.

    MJP waterjets are used moust Taiwan coust guard vessels and I have seen no significant problems using them.

    Unlike our friend here I disagree that waterjet is crap.

    It's more reabile if you drive in water with mutch debrise floating around.

    It allow for driving in shalow water.

    You can do the moust amasing things if you KNOW! how to handle it.
    I had a course in fast MOB boat driving and I had not had that mutch funn in a boat all my life.
     
  9. RANCHI OTTO
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    RANCHI OTTO Naval Architect

    Here you have a reference list of MJP waterjets.
     

    Attached Files:

  10. huntress
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    huntress New Member

    jet drive?

    we are looking at purchasing a boat with MTU's with 2000 hrs engine's are kamewa model 16v-396te84 _ hp is 3000 my question is how reliable are they? If anyone has spent any time around this type of jet drive I would like your imput. Thanks Jim
     
  11. tkinak
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    tkinak Junior Member

    Charlie,

    I have mostly Hamilton experience the largest a 105' quad 422 Hamilton with 825hp each 35 knot top speed. I've been maintaining them for 18 years and can't say enough about how simple and easy they are to work on. We rarely have any type of major failure that wasn't caused by us. We currently operate close to 60 Hamilton jets in our fleet and two Doen.

    Speaking with a former long time Hamilton salesman after we unsuccessfully tried other manufacturers I asked who were the main players and he stated Kamewa and Hamilton. Service and parts are great.

    I would be Leary of Ultra Jet or Doen unless they have improved in the last 8-10 years, which they most certainly must have. During sea trial the Doen tech used a pipe wrench to adjust pitch to match the engine max rpm. Hamilton always comes out dead on with correct impeller and nozzles and with boat speed estimates. They have a database with every hull launched and compare your specs and can predict boat speed incredibly accurately.

    Performance wise the Hamilton's have always performed much better. So much better we cut four Ultrajets out and replaced them with Hamilton's, a spendy refit. Full load cruise into a little weather increased from 17 knots to 25 using less RPM. The Doen vessel is about three knots slower than it's Hamilton driven sister ship.

    TK
     
  12. CTMD
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    CTMD Naval Architect

    Thats basically the default engine/jet package for every catamaran ferry in Hong Kong. You'll be fine.
     
  13. Multi600
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    Multi600 Junior Member

    Hi
    I have around 10 years experience with Kamewa and Lips units on 74m to 100m fast aluminium ferries. They both were fine mechanically, any problems we had tended to be due to corrosion or cavitation.
     

  14. BMcF
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    BMcF Senior Member

    x2. I lost count how many 35-42m cats (displacement and surface-effect both..largely built in Norway and Oz) that we used that combination in since the late 80s..more than 50 at least). The SESs had more problems with the main engines due to air ingestion in the jets causing large load fluctuations on the engines that the governors could not cope with. However, the newer engines have better controls all around and the conventional cats did not have that problem to such a degree in any event. The KaMeWa 63/72 jets that were used behind those engines were always very reliable after some early problems with input shaft seal and internal shaft oil seals were resolved.
     
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