jimi
Well-known member
Are they any good, is it worth converting my Yanmar 3GMF into one?
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Jet Drives
- Thread starter jimi
- Start date
powerskipper
Well-known member
then you could say you are just jetting off somewhere
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Julie
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Julie
Gludy
Active member
I refuse to be drawn into this one ... 
<hr width=100% size=1>Paul
<hr width=100% size=1>Paul
BrendanS
Well-known member
Oh go on, but do it as a fun exercise?
I'll start if you like
<hr width=100% size=1>Me transmitte sursum, caledoni
I'll start if you like
<hr width=100% size=1>Me transmitte sursum, caledoni
Gludy
Active member
Hey .. we are four posts into this thread and no discussion of the subject .... I must have been converted in my sleep!
I am not starting it .. althoughg I reserve the right to change my mind and join it ....
<hr width=100% size=1>Paul
I am not starting it .. althoughg I reserve the right to change my mind and join it ....
<hr width=100% size=1>Paul
powerskipper
Well-known member
OK starter
Lack of turning except when power is applied.
So low speed manoeuvring is interesting to say the least.
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Julie
Lack of turning except when power is applied.
So low speed manoeuvring is interesting to say the least.
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Julie
Gludy
Active member
OK - units like Hamilton jets are so manoeuvrable at low speed that they dispense with the need for any thrusters and can manoeuvre the boat, in any wind, in any direction you like .... super manoeuvrability is offered by a pair of jets.
On the other hand slow speed manoeuvrability on a single jet, like a jet rib, is limited but these units cannot be compared with the full size jet units that can work in any direction and have easy joystick control units.
Jets are most efficient at their cruising speed and in the correctly designed hull.
They can dry out and are not prone to prop damage or snagging because they have no prop.
Unless the hull I designed for jets though, it would probably be the wrong way to go in changing to jets.
<hr width=100% size=1>Paul
On the other hand slow speed manoeuvrability on a single jet, like a jet rib, is limited but these units cannot be compared with the full size jet units that can work in any direction and have easy joystick control units.
Jets are most efficient at their cruising speed and in the correctly designed hull.
They can dry out and are not prone to prop damage or snagging because they have no prop.
Unless the hull I designed for jets though, it would probably be the wrong way to go in changing to jets.
<hr width=100% size=1>Paul
Gludy
Active member
Just to add a point:-
Modern jets are having power applied all the time, even when standing still. They are designed so that you cam move the boat in any direction at any heading.
They have the power to do this, in even very high winds.
They can stand still in a windy situation with high current .... there is nothing like them for control within the marina or harbour. ... in a league of their own.
<hr width=100% size=1>Paul
Modern jets are having power applied all the time, even when standing still. They are designed so that you cam move the boat in any direction at any heading.
They have the power to do this, in even very high winds.
They can stand still in a windy situation with high current .... there is nothing like them for control within the marina or harbour. ... in a league of their own.
<hr width=100% size=1>Paul
Divemaster1
Well-known member
Just to get into this one .... and if you know:
Assuming twin's ... What kind of hull is then considered "best design" for jet drives?
Is it the Deep V ?? or do we have mor hydrodynamics in here, which involves the whole spectrum of waterline length vs beam, angle of V, displacement, RPM of engine/impeller etc?
Just curious as this and surface props facinate me, and if I were to re-power, I'd consider both as well as traditional...
<hr width=100% size=1>Regards,
Alf
Assuming twin's ... What kind of hull is then considered "best design" for jet drives?
Is it the Deep V ?? or do we have mor hydrodynamics in here, which involves the whole spectrum of waterline length vs beam, angle of V, displacement, RPM of engine/impeller etc?
Just curious as this and surface props facinate me, and if I were to re-power, I'd consider both as well as traditional...
<hr width=100% size=1>Regards,
Alf
Wiggo
New member
Excellent idea, Jimi, though I think more power in order. Say a pair of TAMD75's? You'd need to make sopme other mods, while you're at it - I think the keel needs to go, and you'll lose most of your accomodation to the engines, so I'd consider getting rid of the mast and adding a sort of upstairs room thing over the engines. If you build it with a flat roof, you could even add another driving position on top of it, and it'd give the girls somewhere to sunbathe.
<hr width=100% size=1>Si hoc legere scis, nimium eruditionis habes.
<hr width=100% size=1>Si hoc legere scis, nimium eruditionis habes.
jimi
Well-known member
Actually I thought og knocking off the bulb at the bottom & replacing it with a jet drive. Would appear to be an asset in getting in and out of tight spots.
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jimi
Well-known member
This morning whilst cycling up a hill I found my own personal jet drive quite useful, just stood up in the pedals and let rip .. whee off I shot .. only problem was the skid marks. Hope that helps.
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tome
New member
<slow speed manoeuvrability on a single jet, like a jet rib, is limited>
Try telling that to Maritime Rescue in Stonehaven! If you do one of their fast rescue craft courses in a jet rib, you have to be inch perfect with your boat handling at very slow speeds. It's just a matter of technique.
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Try telling that to Maritime Rescue in Stonehaven! If you do one of their fast rescue craft courses in a jet rib, you have to be inch perfect with your boat handling at very slow speeds. It's just a matter of technique.
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Gludy
Active member
Then your related experience supports that .... a small single jet engine on a rib is much more difficult to handle, Twin jets on a cruiser with the proper controls is in a league of its owm.
<hr width=100% size=1>Paul
<hr width=100% size=1>Paul
tome
New member
Well, if that's what you want to believe then so be it. It isn't actually what I'm saying though/forums/images/icons/smile.gif
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Gludy
Active member
I agree that a single jet rib, whilst more difficult than the twin jet systems, with technique can be berthed inch perfect etc.
I am not saying anything different but it is not in the same class as a twin jet Hamilton system.
<hr width=100% size=1>Paul
I am not saying anything different but it is not in the same class as a twin jet Hamilton system.
<hr width=100% size=1>Paul
tome
New member
You're not really listening, are you Paul?
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Gludy
Active member
I actually think its the other way around.
Please spell out what the issue is.
I am frankly a bit fed up with your attitude on what is a fairly light topic.
I claim was made that jets are not good for control at slow speeds etc.
I replied to say that single jets like a jet rib are not good but twin hamilton jets are great.
You respond to point out that in trainiing folks have to position some jet ribs to the inch.
I agree and point out that yes, the technique can do that but the twin hamilton jet system is eaven easier and better..
No please spell out what you are on about
<hr width=100% size=1>Paul
Please spell out what the issue is.
I am frankly a bit fed up with your attitude on what is a fairly light topic.
I claim was made that jets are not good for control at slow speeds etc.
I replied to say that single jets like a jet rib are not good but twin hamilton jets are great.
You respond to point out that in trainiing folks have to position some jet ribs to the inch.
I agree and point out that yes, the technique can do that but the twin hamilton jet system is eaven easier and better..
No please spell out what you are on about
<hr width=100% size=1>Paul
Soong
N/A
Wow, the early post suggested this was going to be a lively one!
I converted from a petrol sterndriven cruiser to a jet driven rib, oh yes! I would not go back for all the tea. Except maybe for when its cold, like last weekend; I digress.
Certainly at slow speeds, jets are the devil to handle - but its practice practice practice.
For high speed/ high efficiency cruising they really do the trick. Lovely.
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I converted from a petrol sterndriven cruiser to a jet driven rib, oh yes! I would not go back for all the tea. Except maybe for when its cold, like last weekend; I digress.
Certainly at slow speeds, jets are the devil to handle - but its practice practice practice.
For high speed/ high efficiency cruising they really do the trick. Lovely.
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