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Old 11 September 2005, 13:40   #1
nik
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jet drives

Hello all,
I was wondering if any of you had experience of jet drives and what you thought of them.
I realise that there are pro`s and con`s. So to kick you off, here is a list of what I have been told about them.

Pro`s
safe (no mincer at the back), can be used in shallow water (no prop to damage), highly manoueverable, very quick stopping, no reverse gear to engage.

Con`s
more expensive to run, or less efficient, if they leave the water, they land "dead in the water" because the drive needs to refill with water. However it has also been put to me that these drives are usually found in larger boats therefore less likely to leave the water. I also know of an ocean dynamics rib in the scillies that ingested some seaweed and had to be towed back to port, I dont know how common that is.

And I have absolutely no idea about maintenance, but I am aware of some of the shortcomings of drive legs.

Thanks, Nick.
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Old 11 September 2005, 13:52   #2
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Hi, I looked after a Copy of a Hinckley Picnic boat for a guy last summer. It had a 300hp Yanmar driving a Hamilton jet unit. Didn't go much on it at all.It weighed around 2.5 tonnes and struggled to do 24 knts. This may have been due to a poor impellor set up, but was rubbish for the amount of HP.Don't be fooled by that shallow water guff. They hate shingle etc. and we also stuffed it full of weed. It took all afternoon to get it all out. The dump bucket would jam, which was scarey when going along side, as you then had no astern (brakes). The big plus is, as you say safety. Otherwise. not for me., I'll take a prop antime.
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Old 11 September 2005, 16:25   #3
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Quote:
Originally Posted by nik
Hello all,
I was wondering if any of you had experience of jet drives and what you thought of them.
I realise that there are pro`s and con`s. So to kick you off, here is a list of what I have been told about them.

Pro`s
safe (no mincer at the back), can be used in shallow water (no prop to damage), highly manoueverable, very quick stopping, no reverse gear to engage.

Con`s
more expensive to run, or less efficient, if they leave the water, they land "dead in the water" because the drive needs to refill with water. However it has also been put to me that these drives are usually found in larger boats therefore less likely to leave the water. I also know of an ocean dynamics rib in the scillies that ingested some seaweed and had to be towed back to port, I dont know how common that is.

And I have absolutely no idea about maintenance, but I am aware of some of the shortcomings of drive legs.

Thanks, Nick.
I have used jets for years and now run the 9 mtre Seawolf with twins of which we built.

You will not get quite get the same top end speed but the jet has no losses like a prop.

You have had a response from some one else running them down, obviously has had little experience of them.

Most jets will drive direct from the engine, but you can fit a gearbox giving you the option to back flush.

You have ultimate manoueverability with jets, you do not get that with props.

I am a proffesional boatman with some 30 years experience, and have used all sorts of combinations in boats.

If you would like to try out jets, PM me.
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Old 11 September 2005, 16:38   #4
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Quote:
Originally Posted by pressman
I have used jets for years and now run the 9 mtre Seawolf with twins of which we built.

You will not get quite get the same top end speed but the jet has no losses like a prop.

You have had a response from some one else running them down, obviously has had little experience of them.

Most jets will drive direct from the engine, but you can fit a gearbox giving you the option to back flush.

You have ultimate manoueverability with jets, you do not get that with props.

I am a proffesional boatman with some 30 years experience, and have used all sorts of combinations in boats.

If you would like to try out jets, PM me.
Dear oh dear, that old "I've been a boatman for 30 years" shit and so was my father and his, going back 300 years. It was my opinion. And,yes you obviously are far more jet experienced than I and more biased as you sell them. The boat I ran did have a reverse gear flush facility. I could have flushed it until christmas and it wouldn't have gotton the weed out. We had to remove the inspection plate and grab handfulls of it at arms length until we got enough out of the pick-up grid to allow flow.
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Old 11 September 2005, 16:44   #5
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Originally Posted by Mollulnan
Dear oh dear, that old "I've been a boatman for 30 years" shit and so was my father and his, going back 300 years. It was my opinion. And,yes you obviously are far more jet experienced than I and more biased as you sell them. The boat I ran did have a reverse gear flush facility. I could have flushed it until christmas and it wouldn't have gotton the weed out. We had to remove the inspection plate and grab handfulls of it at arms length until we got enough out of the pick-up grid to allow flow.
ok, each to their opinion,we're all entitled to that!! Dolphin boats do sell jet boats, also outboards and outdrive legs. whatever the customer requires.
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Old 11 September 2005, 17:00   #6
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and grab handfulls of it at arms length
dats cuz yew cawnish nobburs av gott verry shawt arrms.

eyve bin onn de pis wiv sum ov yorr lott an ther ands downt seam too reech ther fkin pokkits.

gArf
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Old 11 September 2005, 17:04   #7
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That's coz weez rite on at gettin' you English to stick your 'ands in your own pockets! Tiz Cornish enterprise.
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Old 12 September 2005, 04:32   #8
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Have used them a lot. OK they do block occasionally (mainly idling about in harbours) and you can loose power if the intake comes out. BUT... if you have one set up properly to the boat you will never want to drive anything else. It is in the harbour where they are great and shallow work - you really can turn on a sixpence and with a little practice go sideways. Real fun when you have mastered it. Unblocking is normally easier if you simply open the inspection cover.
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Old 12 September 2005, 04:40   #9
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You're right Rodin, with experience, great fun. We never had a lot of luck or fun with the "Hinckley". I did the "jet" thing in Westport, South Island, NZ in a 15ft Aluminium thing with a tuned 7.4ltr lump driving a 2 stage Hamilton jet. It genuinely scared me shitless! Apparently Shotover river in Queenstown is a bit "over done" now. The boats are so big it's like a jet bus ride.
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Old 12 September 2005, 08:00   #10
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Quote:
Originally Posted by Mollulnan
Dear oh dear, that old "I've been a boatman for 30 years" .
As it happens experience does usually bring knowledge, small experience usually brings the relevant amount of knowledge.

I drive Jet boats and Prop boats for a living and have a couple of thousand of hours on props and nearly a thousand on Jets type so heres my view.

It depends on what you want your boat to do?

The versatilty and moanouverability that a jet brings will never be able to be achieved with a Propped boat. The jet drive is safer and more reliable. but less fuel efficient. Therefore is mostly suited to the commercial and rescue world.

Outboards and stern drives are great cos they go faster and require less power to get you going
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