Jet Drive for 10m tour boat - weed and shallow water solution needed

Discussion in 'Jet Drives' started by yodani, Nov 29, 2010.

  1. SKR
    Joined: Nov 2010
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    SKR Alexander

    I apologize for the long absence.

    I can say straight away that used waterjets in your conditions is impossible. Even the waterjets that can operate in such conditions will be blocked by vegetation. Need a drive that is not afraid of vegetation. Such drives have only a small capacity. Over 40 hp I have never met.
    So he is working on vegetation:

    http://www.youtube.com/watch?v=nmLimrdKaBo
     
  2. yodani
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    yodani Senior Member

    Hi SKR

    I am aware of these mud motors and boats with mud weedless propellers and I have mentioned them in the previous posts. This would not work for me as the conditions are not as extreme here in the Delta ... not most of the time and at such boat size - 10x3m it will be inefficient, loud and impossible to handle. Plus the noise of these air cooled motors is too much for nature lovers.

    I will probably go with the traditional prop with rope and weed cutter with keel cooling too. Jet drives are appealing for their shallow draft and low drag. The guys at Phantom must have done something rite.. ;)
     
  3. CDK
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    CDK retired engineer

    The only jet designed for such an environment is the Italian Castoldi. They have a unique intake grate design that lets you cut weeds and plastic by moving a lever.
    The Italian coast guard and navy successfully use these jets for pursuit in very shallow waters.

    Another feature is that they are geared, so engine and jet pump can be matched and the input shaft is located above the pump shaft, allowing the engine to be mounted horizontally with good access for service.
     
  4. anthony goodson
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    anthony goodson Senior Member

    Good morning CDK you've been reading those brochures again ,haven't you ,now just remember how much trouble that got you in the last time.
     
  5. SKR
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    SKR Alexander

    2 yodani:

    Since the noise is not difficult to manage. Waterjet use is very problematic.
    Phantom familiar to me. I brought him the owner of a consultation. This boat is designed to Alaska, where the stones, rather than vegetation. You had better ask those who make boats for Florida.




    2 CDK:

    Castoldi can only try to clean the grill, clean the nozzle and the rectifying device can not.
     
  6. yodani
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    yodani Senior Member

    Thanks CDK,

    That is a good thing to know. On Castoldi website I found some good information and some boat models that would be close to my needs.

    I know you have had problems with your jet boat and I read you are not a fan of them any more. How is your tunnel prop project going?
     
  7. anthony goodson
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    anthony goodson Senior Member

    Yodani, glossy brochures are the main reason that water jets have a bad reputation ,it all looks good on paper and in theory but then when things go wrong it's always a bad customer that's the reason ,never the manufacturer. Hamilton are one exception to this ,put your questions to them ,and then post here what they say. Include plenty of detail and they will treat it as a serious enquiry. Personally I think you have the answer already.
     
  8. CDK
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    CDK retired engineer

    Yes Anthony, the scars on my soul are still there.
    BUT..... I fell for the smooth talk and bargain prices from Berkeley Jet, not knowing I dealt with cowboys. Had I bought the much more expensive Castoldis there would still have been technical issues, but at least they would not have dissolved like lumps of sugar.

    The fast public transport here are 250+ seats catamarans, powered by twin turbines with jets, running almost 50 knots, so it is incorrect to think jets are only suitable for small, light craft.
     
  9. CDK
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    CDK retired engineer

    Except for the lack of speed, I am fairly satisfied with the tunnel drives, especially the extremely low fuel consumption.
    Your speed demand is quite different, so it is no solution for you.

    As I said in my previous post, the Italian government uses Castoldi powered boats to chase smugglers. I know one guy who earns money by crossing the Adriatic from Montenegro in a 39 ft. RIB. Until last year he did that with twin Mercruisers, which made him an easy prey in the shallow waters near the Italian coast.
    This summer he showed up with a new boat, again with two V-8s, but now equipped with enormous 5-blade surface piercing props....
     
  10. anthony goodson
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    anthony goodson Senior Member

    Completely agree with you CDK ,couldn't resist pulling your leg a little though .Weed growing in shallow water will always be a problem to a slow moving jet, a weed grill, although useful , won't deal with large amounts ,and once it's wrapped around the shaft and jammed in between the impeller and stator vanes there is very little you can do. So it does depend ,I suppose on how serious the infestation is ,but from Yodani's description it sounds quite bad. A separate cooling water intake and pump ,rather than a tapping from the wear ring can mitigate the problem sometimes ,in that the engine can still run without overheating even with a partly blocked jet and I have used this with some success in the past but even this will tend to block in thick weed. The advantage of the jets in your ferries ,is that the turbines are seeing a more or less constant and predetermined load ,and you are quite correct, this works very well.
     
  11. scotch&water
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    scotch&water Junior Member

    Hi Matthew DS For your information Bentz Boats Has completed construction af a 60ft x18.5ft x3ft Aluminum Tour Boat with twin Cummins for power, with Konrad Prop Drives. Since the operation is at times is faced with weed choking and speeds are mostly under 10k,with stops for sight seeing. The Quality of construction is First class and beefy, with Air cond. and heat it will extend the usage season for us. The Canyon Voyager was launched in mid Oct. 2010 .WE are thrilled to have this vessel in our fleet and when things warm up and the Ice is gone The Canyon Voyager will be on the water taking Tourist for a trip through the canyon. Fritz
     
  12. michael pierzga
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    michael pierzga Senior Member

    protected Props via tunnel drive are cheap, well proven, easy to fix and effective. Jets are problematic. I couldnt imagine running a profitable buisness in weed, garbage , shallow harbors with jets. Perhaps there is some new break thru in jet technolgy...I just have never seen it.
     
  13. apex1

    apex1 Guest

    Would you enlighten us what "protected Props via tunnel drive" means?

    Yodani


    If the lower end of the speed required is sufficient, I would think about "Schottel Pump Jets"
    they do not suck ropes, sand or weed, and operate on a wet rag.
    Some of the passenger cruisers in your area use them as main propulsion.

    Regards
    Richard
     
  14. yodani
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    yodani Senior Member

    Yes Schottel Pump Jets are interesting but not for such application as they are heavy 380kg pump only and as you said they are for slow travelling boats not for planing boats. The SPJ 15 model is the smallest of all and weighs 360 kg with max power of 75 hp. I have seen some of the Danube Cruisers here with such propulsion but never had the chance to go on board.

    Tunnels?

    Just to give you an idea of what kind of vegetation I talk about I have attached some pictures
     

    Attached Files:


  15. marshmat
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    marshmat Senior Member

    Yodani,

    In vegetation that thick, if decent speed is desired, I would likely be looking at a hovercraft. The next choice might be a flat bottom hull with an air propeller and air rudders. In either case, you'd have to put up with the noise. If you're willing to stick to no more than six knots or so, a displacement hull with very well-protected props might suffice, but you'd have to be very careful in shaping the skegs, props and rudders so that they shed anything that gets picked up.

    Weed and rope cutters on a prop shaft work great when you have one or two things at a time that need to be cut. Get a 10" mat of vegetation wrapped around the shaft, and even fairly big cutting blades will be overwhelmed.
     
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