Reply
 
Thread Tools Search this Thread
 
Old 08 April 2004, 10:31   #21
Member
 
Country: UK - England
Town: Portsmouth
Boat name: Not sure
Make: ABC/Priddy
Length: 10m +
Engine: 2 x 500 FPT
Join Date: Jul 2001
Posts: 926
Scary Des, I take your point but on you do not get big waves in a force 6-7 and the pacific's along with most rib's are ok in conditions that the winds will generate, in the right hands of course.In open sea in big seas Jet boats are bloody dangerous! Once the wave gets under the sponson the boat lifts and the jet cannot suck enough water to give sufficiant propulsion, the wave turns the boat sideways and you have a whole lot of poo on your hands. The next time it is blowing 50 knots of southerly wind on an out going tide, try and get around the needles in a jet boat and report on your experiances.

Alan P
__________________

__________________
Alan Priddy is offline   Reply With Quote
Old 08 April 2004, 11:40   #22
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Quote:
Originally Posted by Alan Priddy
The next time it is blowing 50 knots of southerly wind on an out going tide, try and get around the needles in a jet boat and report on your experiances.

Alan P
Happy to do this if you can provide the boat

The naval expression ‘to stay on station’ means that the boat will be launched and used in a way that takes little account of the weather conditions (other than the usual). Pacific 22’s will still be launched in any sea state because it is the main (and sometimes only) rescue boat on a war ship.

With a jet you have to approach boat control in a different way to a propeller, throttling back as you would with an outdrive to prevent broaching results in a loss of directional control so with a jet you keep the thrust on and use the forward reverse control to hold position. In other word with a propeller you match revs to hold position with a jet you half drop the bucket to match thrust.

As I said I am not trying to start an argument I just want to under stand why you hold your views.

Incidentally did you know that the RNLI have order several jet boats?
__________________

__________________
Scary Des is offline   Reply With Quote
Old 08 April 2004, 18:12   #23
Member
 
Country: UK - Wales
Town: St Davids
Boat name: 6 vessels -various
Make: Quinquari/Humber
Length: 10m +
Engine: Twin ETEC200s
Join Date: Nov 2003
Posts: 130
Quote:
Originally Posted by Pete7
Alan / John this is quite interesting, are you therefore saying that modern injection outboards are a cost effective alternative when compared to the complexity and cost of bulding inboards and jets, assuming a commerical operator can get the tax back on petrol ?
-------------
In terms of power to weight ratio, performance and space the OBs now do win. The cost per mile works out about the same provided duty and VATrebate is in place. Other factors such as ease of replacement, leg or jet wear etc also come into play.

Critically the resale value of OBs after say 12 months use is very high compared to an IB.

The major drawback is obtaining fuel supply and it is for this reason that a number of our customers have set on IBs.

One f the difficulties with IBs is the limited number of suitable units on the market suitable for a production RIB. Yanmar and Volvo hold the lead at present but with units of 315hp a single installation is barely adequate to power a 10m (noting that if they were OBs twin 150hp would be adequate). Thus twin installations are required which on say a 3m overall beam gives very little space to play with. Worse is the cost of a twin IB of say £40k as oposed to £16k for twin OBs !.

I am no great fan of OBs and they have their share of downsides (we need to lug 250 galls on a busy day !!) but after many years of playing the cards they have won in our view.

The reference to the RNLI and jets I believe is for shallow water/estuary work and is one of the applications including close quarters handling when the jet will win every time.

Cheers

John.
__________________
quinquarimarine is offline   Reply With Quote
Old 08 April 2004, 19:24   #24
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
John, thanks, quite enlightening.

Pete
__________________
Pete7 is offline   Reply With Quote
Old 09 April 2004, 10:49   #25
Member
 
Country: UK - England
Town: Sheerness
Boat name: TBA
Make: Parker
Length: 8m +
Engine: Mercruiser
Join Date: Mar 2004
Posts: 114
Tiger Class RNLI steyr inboard / jets

Have had experience on this class which is 10 mt . all i can say on the thames in anything less than a ripple its superb , stop on a sixpence , walk sideways , turn like you would not believe........................put it in a sea and forget it stick with outdrives you will not regret it.

David
__________________
David B is offline   Reply With Quote
Old 13 April 2004, 05:38   #26
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Quote:
put it in a sea and forget it stick with outdrives you will not regret it.

David

That's not what the guys in poole are saying. It's also on 14mtr RNLI boat.
__________________
Scary Des is offline   Reply With Quote
Old 13 April 2004, 07:58   #27
Member
 
Country: UK - England
Town: Sheerness
Boat name: TBA
Make: Parker
Length: 8m +
Engine: Mercruiser
Join Date: Mar 2004
Posts: 114
Guys in poole

Hey the guys in Poole you refer to perhaps do not use one every day !
feedback is the in word right now ..............

Whilst being in the RNLI I can tell you what the crews suggest and what actually happens is not the case ! we suggest a seating layout , an office suit decides to do it his way over a gin and tonic. Now thats not being bitchy its become a fact that there are to many suits in the RNLI and constructive comments from crew and feedback on equipment is not always listened too.

When you use one every day..........experience tells you whats good and whats not. I agree in certain classes of craft and I note somebody mentioned the new craft on trila in maine with the US coast guard jets have been very successful but they do have their down sides too

Simply e.mail tower lifeboat or gravesend crew and ask for their opinions on jets in a sea state

Who are "the guys in Poole " ?

I have
__________________
David B is offline   Reply With Quote
Old 14 April 2004, 08:13   #28
Member
 
Country: UK - England
Town: South West
Make: Halmatic/Ribtec
Length: 6.5m/7m
Engine: 200/225hp Optimax
Join Date: Apr 2004
Posts: 12
Dyfed & Powys Police took delivery of a 11.5 m rib in 1999. Anyone have any knowledge of that one or any contact email addresses for any one/organisation using jets?
__________________
Simon A is offline   Reply With Quote
Old 14 April 2004, 09:06   #29
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
it's a Delta with twin 230 Yanmar and twin hamilton jet.
__________________

__________________
Scary Des is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 16:53.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.