Jet boat not performing

Discussion in 'Jet Drives' started by Truls, Apr 22, 2010.

  1. Truls
    Joined: Dec 2007
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    Location: Seattle

    Truls Commercial Fisherman

    And yes, these jets were supposedly purchased directly from Hamilton Hough for this boat. Again, these are early hamilton jets for the US fishing fleet and this boat is probably one of the reasons they are so picky with hull design now.

  2. Truls
    Joined: Dec 2007
    Posts: 24
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    Location: Seattle

    Truls Commercial Fisherman

    Just an update to an old thread. I have spent a lot of time on this forum and other places trying to better understand jets and how to make an improvement to my boat's performance. By performance I mainly refer to fuel economy at this point. I have pretty much given up on getting it up on step.

    I have built a couple of intake grates with about 25% more surface area out of stainless and increased the surface area of the nozzles about 15%. I am basically trying to flow more water at low speed, my only speed with this boat. I have also increased the KW rating on the impellers from 17 to 18 KW.

    I came across videos on youtube of my boat from this last summer and remembered that there had been a request for video of the boat.

    There is a lot of action in the fishery as far as new boats. Here is what looks to me to be a very similar hull with a single traktor jet and great performance. It sea trialed at 25 knots with 5000 pounds in the fish holds making it similar in weight to the Net Profit.

    There has been a lot of concerns about the hull shape of my boat, but this shows that similar boats can perform very well in all respects. Mine was just one of the very first, and too heavy. In my opinion All American Marine has done a great job with this boat. But I think it will take about $500k to get one.

    Hopefully I will gain some efficiency from my jets this summer, as I expect fuel to cost around 5 bucks per gallon on the fishing grounds.


    Last edited: May 8, 2011
  3. anthony goodson
    Joined: Mar 2007
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    Location: Dorset UK & Murcia Spain

    anthony goodson Senior Member

    Thanks for the update Truls ,hope your modifications pay off.
  4. sp@hamjet
    Joined: Jun 2011
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    Location: Seattle,Wa

    sp@hamjet New Member

    I was there when this boat was built. Long story short, boat is heavier than it should have been, the original owner (not the current owner) was advised to reduce the weight, redo the keel coolers, shift weight (modify the LCG) and use a reduction gear to get on coarse impellers rather than a 1:1 electric clutch. All the things that were not just right added together unfortunitly resulted in a boat that probably cannot be made to plane without significant surgery. Point being this isn’t a jet issue, HJ offered advice, lots of it. It was just never translated into the needed changes. There are lots of jet powered Bristol Bay Boats, many run 321 jets and Cummins, Cat or Volvo engines of about the same power that work very well.

  5. Truls
    Joined: Dec 2007
    Posts: 24
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    Location: Seattle

    Truls Commercial Fisherman

    Update since modyfying intakes and nozzles

    Thanks for input and extending my knowledge. I am happy with the results of my previously discussed modifications. Nothing dramatic, but I gained about two knots. Significant when you consider an increase from about 8 to 10 knots.

    Realistically an increase from 6 to 8 since it is just not worth using full power for a marginal increase in speed. Though at times it makes sense when bucking a hard tide or when lots of money is on the line. Now I get about 8 knots at 2000 RPM, versus at 2600 RPM before.

    It also seemed I burn less fuel at lower speeds, though I ended up using a bit more horsepower than normal since I saw a gain in speed. As it was I used less over the season than last year, but I kept up with most of the fleet in speed.

    I have never won a race to the tenderer to deliver before, unless I was clearly ahead. This year it happened frequently. Well worth the extra 20 bucks in fuel in order to catch an extra 30 minutes of sleep.

    I was not looking to get up on plane at this point. I was content with gaining some speed and fuel economy. At about a cost of $500 and some of my own labor I built two new intakes and opened up the nozzles. Can't remember exactly how it broke down, but I had about $2k into pitching and building up the impellers. Previously building up the impellers had no noticable effect on performance.

    Hamilton Jet - You have always provided excellent service when it comes to parts, and support when I've needed repair advice. And you build a depenable and durable product. However, this information would have been great years ago when I first got the boat.

    You were consulted when I spent about $20k to lighten the boat and shift the LCG to within 6 inches of your specs. It made the boat better handling, and I do not regret doing the work, but I would have appreciated some outside the box thinking as well. And solutions that do not come in increments of tens of thousands of dollars.

    Forum participants - I appreciate all the input. The comments on the intakes came from this thread. I believe I chose to open the nozzles based on information I found elsewhere. The pitch issue is from Cordova and Bristol Bay guys with hamilton jets. A lot of them end up with higher KW ratings than specified from Hamilton Jet, combined with pyrometers.
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