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Thread: Bolt on jet/engine unit

  1. #1
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    Default Bolt on jet/engine unit

    Found this by accident when surfing around....

    http://www.swordmarine.com/Products/jetpac.htm

    Does this concept make any sense?

  2. #2
    Moderator AKmud's Avatar
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    Looks like it has potential.... A 275hp engine with a 10" jet would put out some thrust for sure. I'd be a little worried about the 1000#'s sitting on the transom though.
    AKmud
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    The porcupine is a peacful animal yet God still thought it necessary to give him quills....

  3. #3

    Default Did you see the pic of this unit on the sailboat?

    Another one of those things that just strike me as - Wrong.
    I think AKMud is right though, hope you don't have to cross any RR tracks on your way to the launch. Frost heaves would be deadly.
    Mike
    Mike
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    There is a faster way off the mountain, might hurt a little though.

  4. #4
    Member Rod in Wasilla's Avatar
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    I don't think that is such a big issue. There are plenty of boats out there hanging that much off the transom now. A pair of Honda 135's (270 total hp) is 956 pounds. Although you may need to modify the trailer to properly support it.
    Quote Originally Posted by northwestalska
    ... you canít tell stories about the adventures you wished you had done!

  5. #5

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    I don't know. The weight on these is further away from the transom than on a regular outboard, making it "heavier" but maybe not so much. All the forces acting on the transom will be magnified (except thrust), I would really like to check/redesign the bracing of the transom before adding one.
    Mike
    Mike
    www.alaskaatvclub.org
    There is a faster way off the mountain, might hurt a little though.

  6. #6
    Member Rod in Wasilla's Avatar
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    Sure, the center of gravity for the pod would be farther back than for twin outboards. But the website says that there is up to 500 pounds of bouyancy inherent in the pods, so it would effectively weigh half as much as a pair of Honda 135's while it was in the water. And while it was out of the water there would be effectively no weight hanging off the transom if the trailer was modified to support the pod.

    Still don't see a problem here...

    Besides, I'm sure the manufacturer has already thought of the issue of the "extra" weight and has designed their mounting systems accordingly. They certainly won't be around long if their product tends to rip the transoms off boats.
    Quote Originally Posted by northwestalska
    ... you canít tell stories about the adventures you wished you had done!

  7. #7

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    True enough! Has anyone heard of or seen a diesel powered Jet unit? I'm not that experienced with diesels but aren't they RPM range limited? And wouldn't that be a factor for the jet?
    Mike
    Mike
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    There is a faster way off the mountain, might hurt a little though.

  8. #8
    Moderator AKmud's Avatar
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    Default Diesel

    I wonder if they make up for the low rpm with the much higher torque? Maybe the impeller for a diesel is much more agressive.
    AKmud
    http://i78.photobucket.com/albums/j96/AKmud/213700RMK1-1.jpg


    The porcupine is a peacful animal yet God still thought it necessary to give him quills....

  9. #9
    Member Rod in Wasilla's Avatar
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    Hey Mike-
    Did you read this? It's from their website and explains their reasoning behind their use of a diesel and large diameter jet impeller. I might be a little sceptical unless I could find other data to verify their conclusions, but at first blush it sounds good. By the way, I don't have any intention of putting one of these on my boat, but it gives me something to think about it if I were to upgrade. Especially if I was looking at the possibility of buying a good hull with a blown outboard.
    Quote Originally Posted by northwestalska
    ... you canít tell stories about the adventures you wished you had done!

  10. #10

    Default OK, read it now!

    I did miss that piece on the first run thru.
    Agreed that this unit will pull the C of G back over a standard jet but whether this is good or bad depends on the hull design and weight of all the rest of the pieces on the boat. If you trim out the boat with tabs, the more trim you put in - the more drag the tabs create. Anyway, that is all dependent on to many variables for me to proclaim right or wrong on it.
    Like you say, I would have to look at it as a repower option. I wonder if it mounts more spread out across the width and height of the transom or more localized like a regular outboard. Could it breathe a new life into a boat with a weak transom by spreading the forces out more? I guess the more pressing question would be will my new motor unit float after I rip the transom out of my boat by overpowering it?? :-)
    Mike
    Mike
    www.alaskaatvclub.org
    There is a faster way off the mountain, might hurt a little though.

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