Reply
 
Thread Tools Search this Thread
 
Old 10 November 2007, 00:37   #1
Member
 
Country: Other
Town: Oakley
Boat name: Zerstörer
Make: Ribcraft
Length: 5m +
Engine: Suzuki DF 140
MMSI: 235050131
Join Date: Jun 2003
Posts: 3,931
Cruising RPM

Whats a good engine REV speed to cruise at. I keep my engine around the 4500 RPM mark for cruising but sometimes it seems a little slow. Is 5000 RPM a fair enough speed for cruising.

I ask because 5000 RPM on a car would be harsh.
__________________
https://www.xfire.com/download/
Biggles is offline   Reply With Quote
Old 10 November 2007, 00:41   #2
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 13,053
RIBase
Quote:
Originally Posted by Biggles View Post
Whats a good engine REV speed to cruise at. I keep my engine around the 4500 RPM mark for cruising but sometimes it seems a little slow. Is 5000 RPM a fair enough speed for cruising.

I ask because 5000 RPM on a car would be harsh.
Depends on your redline really. Mine's recommended 4.5-5.5k max at WOT so cruising at 5k is caning it.

I cruise at around 2/3 to 3/4 max rpm.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 10 November 2007, 00:47   #3
Member
 
Country: Other
Town: Oakley
Boat name: Zerstörer
Make: Ribcraft
Length: 5m +
Engine: Suzuki DF 140
MMSI: 235050131
Join Date: Jun 2003
Posts: 3,931
My engine maxes at 6200 therefore Your saying between 4650 and 4687 RPM. So 4500 isn't too far out. I'll maybe run just a little above that on my analogue gauge.

I ran at 5000 on 10 June when we went to the Dancing Ledge and I surprisingly got a good fuel consumption and didn't seem to be caning it.
__________________
https://www.xfire.com/download/
Biggles is offline   Reply With Quote
Old 10 November 2007, 00:57   #4
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 13,053
RIBase
Quote:
Originally Posted by Biggles View Post
between 4650 and 4687 RPM.

Ah. Didn't realise it was actually such a narrow band-I actually cruise around 3.5-4.2k rpm but it looks like 2/3 to 3/4 rpm when I'm glancing at the revcounter.

Realistically it equates to about 22-28 knots with WOT being 36-39 knots depending on load.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 10 November 2007, 07:48   #5
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,622
Quote:
Originally Posted by Nos4r2 View Post
Didn't realise it was actually such a narrow band
I don't think it is! Biggles is needing to get his calculator serviced.

2/3 x 6200 = 4133 rpm
3/4 x 6200 = 4650 rpm
__________________
Poly is offline   Reply With Quote
Old 10 November 2007, 08:44   #6
Member
 
Andy Moore's Avatar
 
Country: UK - England
Town: Cowes, Isle of Wight
Boat name: TiLT 2
Make: Avon Adventure 620
Length: 6m +
Engine: Optimax 135
MMSI: 235032203
Join Date: Sep 2005
Posts: 1,641
We tend to cruise at around 5000 RPM. By the sound of it the outboard is getting a good workout at those Revs. However, bearing in mind that one is only running like that for 10-15mins at a time, I reckon its okay.

Max Revs is c. 600RPM.
__________________
RIBnet: now available on Facebook!
Andy Moore is offline   Reply With Quote
Old 10 November 2007, 11:29   #7
Member
 
Country: Other
Town: Oakley
Boat name: Zerstörer
Make: Ribcraft
Length: 5m +
Engine: Suzuki DF 140
MMSI: 235050131
Join Date: Jun 2003
Posts: 3,931
Quote:
Originally Posted by Andy Moore View Post
However, bearing in mind that one is only running like that for 10-15mins at a time, I reckon its okay.
I wouldn't call that cruising though. I would say about 30 minutes at least constant running would be cruising ! Maybe even more.
__________________
https://www.xfire.com/download/
Biggles is offline   Reply With Quote
Old 10 November 2007, 11:30   #8
Member
 
Country: Other
Town: Oakley
Boat name: Zerstörer
Make: Ribcraft
Length: 5m +
Engine: Suzuki DF 140
MMSI: 235050131
Join Date: Jun 2003
Posts: 3,931
Quote:
Originally Posted by Polwart View Post
I don't think it is! Biggles is needing to get his calculator serviced.

2/3 x 6200 = 4133 rpm
3/4 x 6200 = 4650 rpm
Maths never was my strong point.
__________________
https://www.xfire.com/download/
Biggles is offline   Reply With Quote
Old 10 November 2007, 13:02   #9
Member
 
Country: UK - Wales
Town: West Wales
Make: Vipermax 5.8, SR4.7
Length: 5m +
Engine: 150 Opti, F50EFi
Join Date: Sep 2005
Posts: 6,299
Quote:
Originally Posted by Biggles View Post
Whats a good engine REV speed to cruise at. I keep my engine around the 4500 RPM mark for cruising but sometimes it seems a little slow. Is 5000 RPM a fair enough speed for cruising.

I ask because 5000 RPM on a car would be harsh.
I was told you Solent boys cruise at 40kts
__________________
Downhilldai is offline   Reply With Quote
Old 10 November 2007, 13:17   #10
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,872
Quote:
Originally Posted by Downhilldai View Post
I was told you Solent boys cruise at 40kts
Yep, I've heard that aswell.
__________________
Mollers is offline   Reply With Quote
Old 10 November 2007, 23:31   #11
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,866
Only down Hill and with the wind behind
__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 11 November 2007, 00:14   #12
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 13,053
RIBase
Quote:
Originally Posted by Biggles View Post
I wouldn't call that cruising though. I would say about 30 minutes at least constant running would be cruising ! Maybe even more.
Nah. It's just a throttle range that's quick enough but not thirsty(in perspective!). You can do that for 5 minutes.

As for cruising at 40 knots, some of them do (coming along the Solent with Bedajim, the Jackeens and Leeway was bloody expensive trying to keep up!)
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 11 November 2007, 00:25   #13
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,866
Quote:
Originally Posted by Nos4r2 View Post
Nah. It's just a throttle range that's quick enough but not thirsty(in perspective!). You can do that for 5 minutes.

As for cruising at 40 knots, some of them do (coming along the Solent with Bedajim, the Jackeens and Leeway was bloody expensive trying to keep up!)
Trouble is, 40 knotts is cruising speed for the Jackeens and Leeway
__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 11 November 2007, 01:19   #14
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 13,053
RIBase
Quote:
Originally Posted by Hightower View Post
Trouble is, 40 knotts is cruising speed for the Jackeens and Leeway
I get the impression that 40 knots is Lee's stall speed....that's when his hull finally drops back into the water
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 11 November 2007, 09:03   #15
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,872
Let's define what 'cruising' speed is, as I tried
to with the member that informed me that he and other Solenteers 'cruised' at 40 knts. Cruising, in my view is passage making over a distance where a reasonable ratio between speed and economy is to be acheived. This is not a flat-out blast for 4 or 5 miles with a bunch of mates or even a dash around the island showing off one's greater HP.
We 'cruise' to the Scillies, from Falmouth this is a 200Nm round trip. Fuel on the islands is £1.45/ltr so we carry enough not to have to buy more over there. Blasting out from Falmouth at 40knts would be crazy, it would get us there a bit sooner and double the fuel bill.Our optimum cruise speed is around 25knts which relates to 4100-4200 rpm on my boat.
__________________
Mollers is offline   Reply With Quote
Old 11 November 2007, 09:45   #16
RIBnet supporter
 
bedajim's Avatar
 
Country: UK - England
Town: Rutland
Length: no boat
Join Date: May 2006
Posts: 2,500
With the added weight aux+fuel on the back I seem to get the best fuel figures at 28 29 knots but don't normally look at the revs more interested in water pressure etc
Go more for comfort in the conditions and staying in a group if out with others, I would think 3500 to 4500 rpm but don't tend to let it sit at constant revs

40kts ruins the wife hair so that's a no no
__________________
bedajim is offline   Reply With Quote
Old 11 November 2007, 09:49   #17
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,872
Quote:
Originally Posted by bedajim View Post
With the added weight aux+fuel on the back I seem to get the best fuel figures at 28 29 knots but don't normally look at the revs more interested in water pressure etc
Go more for comfort in the conditions and staying in a group if out with others, I would think 3500 to 4500 rpm but don't tend to let it sit at constant revs

40kts ruins the wife hair so that's a no no
My figures relate only to flat water.
__________________
Mollers is offline   Reply With Quote
Old 12 November 2007, 12:09   #18
Member
 
Hugh Jardon's Avatar
 
Country: UK - England
Town: Reading, Hants
Boat name: Juicy
Make: Sealine F43
Length: 10m +
Engine: 2 x 370hp
MMSI: TBC
Join Date: Sep 2005
Posts: 2,884
Quote:
Originally Posted by Biggles View Post
I ran at 5000 on 10 June when we went to the Dancing Ledge and I surprisingly got a good fuel consumption and didn't seem to be caning it.
that was a fun trip wasnt it if a bit of a long day for the little kids being over 90 miles.

if we knew you were only at 5k revs we could have picked up the pace a bit......just kidding
__________________
Hugh Jardon is offline   Reply With Quote
Old 12 November 2007, 17:11   #19
Member
 
Country: UK - England
Town: Towcester
Boat name: TBA
Make: Delta
Length: 6m +
Engine: Suzuki 175
Join Date: Nov 2002
Posts: 330
with common sense like that..

Mollers
with common sense like that - I am surprised we have not yet cruised in copmany.
For us (like you) it is making big distances safely without using excessive fuel.

Most RIBs, I guess, are only run for for short periods - but when you are doing 100to 150Nm per day it makes a big difference.

Also comfort wise - why speed and be uncomfortable.
The exception to this (there is always a get out clause) is when you know the weather is deteriating fast and time then is more critical than absolute consumption.
PB
__________________
Paul Beaurain is offline   Reply With Quote
Old 12 November 2007, 19:29   #20
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,872
Quote:
Originally Posted by Hugh Jardon View Post
that was a fun trip wasnt it if a bit of a long day for the little kids being over 90 miles.

if we knew you were only at 5k revs we could have picked up the pace a bit......just kidding
Biggles-Jardon, Jardon-Biggles, Jiggles- Bardon, Jargles-Biggon. Anyone ever seen them both at the same time?
__________________
Mollers 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




All times are GMT. The time now is 17:12.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.