Jet Boats

 Morning everyone,

Looking at getting an old Crayboat to fit out and use for trips offshore and extended trips etc.

Came across a jet boat around 10m but I dont know much about maitenance and fuel consumption for these particular styles. Are they any good ? Or are they just good because of being around alot of rope?

 

If anyone on here can give some insight into them it would be appreciated.

 

 

Thanks 


Stumpytail's picture

Posts: 2

Date Joined: 24/10/17

 ring dave at westjet

Tue, 2017-10-31 09:41

 ring dave at westjet propulsio hes your man 

9430 7082

Walfootrot's picture

Posts: 1213

Date Joined: 23/07/12

Unless you plan on doing a

Tue, 2017-10-31 11:37

Unless you plan on doing a bit of reef hoping, leave them alone. more $ on maintenance, not to good on the fuel.

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More drum lines, kill the bloody sharks!

ranmar850's picture

Posts: 1382

Date Joined: 12/08/12

Ali hull? What exact size?

Tue, 2017-10-31 12:17

 Most of the jets in the industry were ali 23-32 ft. A lot were built by Millmans in Geraldton, as they really were Abrolhos specialised. Jet is a pretty inefficient way of converting horsepower to forward thrust, and they were always thirstier than the equivilant size hull/motor configuration in a shaft drive.  Used mostly for access  across shallow water--don't be driving across slack rope because they WILL suck it up and then you've got problems.  Tend to be flat bottomed so also rode pretty hard for their size. Ever driven one? Not for the faint hearted, bags of fun if you know how. Heaps of revs needed to provide thrust and steerage, try to idle around and you'll be blown sideways. And you'll always be the bloke who can take the shortcut home

Rob H's picture

Posts: 4457

Date Joined: 18/01/12

 Yep, crap with a following

Tue, 2017-10-31 13:46

 Yep, crap with a following sea as when you back off theres no steering at all.

I have been looking very closely for a while contemplating building a jet boat for islands but just cant get past the open water handling

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 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

Browndog's picture

Posts: 472

Date Joined: 10/04/12

Jets

Tue, 2017-10-31 20:30

Jets can actually be one of the most efficient propulsion systems available, all depends on the application and engineering that goes into them. Many of the large ferries that Austal build have jet propulsion, for one reason - high speed fuel savings. Also popular for tugs due to ability to vector the thrust.

That said, agree with most of the comments above, fantastic for shallow water capability, different to drive (no throttle = no steering) but also highly nimble.

Cheers,

BD

Rob H's picture

Posts: 4457

Date Joined: 18/01/12

 Interesting, I have never

Tue, 2017-10-31 20:59

 Interesting, I have never seen a proper tug with a jet?
Usually tugs for vectoring have Z pellors/Schottel azimuth drives.

Can you chuck up a link to one, curious to see the setup?

Generally jets are quite inefficient unless planing as the "action reaction" principal requires the nozzle to be above the water

____________________________________________________________________________

 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

Browndog's picture

Posts: 472

Date Joined: 10/04/12

Sorry - Workboats

Wed, 2017-11-01 07:35

Hi Rob, sorry I may have given the wrong impression when I said "tug:, I'm not talking about the very large units that bring in iron ore carriers, I'm thinking more your smaller workboat type of arrangement like this: http://www.boatersresources.com/bfs_detail.php?adid=400328

Agree that they need to be planing to be most efficient, that's why a lot of the larger military/ferries have a combination of diesel driven props for low speed work, and a turbine driven water jet for sustained high speed planing - best of both worlds, but not really practical for a fishing boat lol.

Some good reading here: http://articles.maritimepropulsion.com/article/Combat-applications-for-waterjet-powered-ships20428.aspx for those that are interested.

 

Cheers, BD.

Rob H's picture

Posts: 4457

Date Joined: 18/01/12

.

Wed, 2017-11-01 12:50

 yeah no worries, I work on tugs and never heard or seen of any

____________________________________________________________________________

 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

pemboss's picture

Posts: 12

Date Joined: 29/10/16

buy it

Sun, 2017-11-05 16:36

ive got an 8m custom with a steyr 305hp turbo diesel running throgh a hamilton jet unit. will get anywhere and do anything. good on juice and if you know how to drive a boat they steer just fine... like the first comment said give dave a call...