Reply
 
Thread Tools Search this Thread
 
Old 17 February 2012, 13:06   #1
Member
 
HUMBER P4VWL's Avatar
 
Country: UK - Wales
Town: N Wales Chester
Boat name: Mr Smith
Make: Humber
Length: 6m +
Join Date: Feb 2009
Posts: 5,238
Most economical speed?

What is the most economical speed per mile to run at?

Is it the speed to maintain planing ability, whatever your boat/engine?

Or is it slightly quicker to have less boat in the water as long as you're not pushing your engine to its limits?

C'mon techies.
__________________

__________________
HUMBER P4VWL is offline   Reply With Quote
Old 17 February 2012, 13:16   #2
Redbay supporter
 
wiLlfish's Avatar
 
Country: UK - England
Town: onn de moov
Boat name: bote
Make: kevvin
Length: 4m +
Engine: jett dryve
Join Date: Jan 2010
Posts: 455
Quote:
Originally Posted by HUMBER P4VWL View Post
What is the most economical speed per mile to run at?
ow lorng didd yew sitt ther finkin 'wots de darftist kwestiun i cann axe'

ps yorr a still
__________________
fuk mee crismus leeve wiv noe ankul tagg

Wher doo I beegin?😃
wiLlfish is offline   Reply With Quote
Old 17 February 2012, 13:27   #3
Member
 
HUMBER P4VWL's Avatar
 
Country: UK - Wales
Town: N Wales Chester
Boat name: Mr Smith
Make: Humber
Length: 6m +
Join Date: Feb 2009
Posts: 5,238
Quite a while. Sat on a train from Birmingham. Glad to be leaving.

I guess though it's immaterial if I stay attached to a bouy anyway!
__________________
HUMBER P4VWL is offline   Reply With Quote
Old 17 February 2012, 13:30   #4
RIBnet Supporter
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 14,228
RIBase
Quote:
Originally Posted by wiLlfish View Post
ps yorr a still
still aye nobbur yew mean? i fownd diss - doo yew fink itts is?
Attached Thumbnails
Click image for larger version

Name:	antihero-brigade-black-yellow-beanie.jpg
Views:	173
Size:	33.7 KB
ID:	65631  
__________________
willk is offline   Reply With Quote
Old 17 February 2012, 13:32   #5
Member
 
HUMBER P4VWL's Avatar
 
Country: UK - Wales
Town: N Wales Chester
Boat name: Mr Smith
Make: Humber
Length: 6m +
Join Date: Feb 2009
Posts: 5,238
That would be a quality hat for the April Cruise!!
__________________
HUMBER P4VWL is offline   Reply With Quote
Old 17 February 2012, 13:41   #6
Member
 
HughN's Avatar
 
Country: UK - England
Town: Littlehampton, W Sx
Length: no boat
MMSI: 235101591
Join Date: Jan 2012
Posts: 732
I've just made this box (for my non-rib boat!). It is connected to a fuel flow sensor in the fuel line that sends a pulse for every 0.4 ml of fuel that is used. The number of pulses, GPS speed and lat/long get logged to an SD memory card once per second. The SD card also contains a programmable calibration factor to change the 0.4ml to whatever it needs to be to be accurate.


By setting the initial fuel quantity it counts down as fuel is used.

It also generates a little scrolling bar chart of flow rate as it varies with time:


(and shows GPS position, speed, etc.,)

The plan is to use this data to find out exactly how fuel consumption varies with speed (it gets told ho many people are in the boat and the amount of fuel, so total mass is guessable). With enough data, I hope to be able to get a good idea of fuel burn rate vs speed and, if I can log it, r.p.m.

I know wind, tide, etc,., will affect speed over the ground, which is why I will get as much data as I can and weight the data with the number of points at each speed. The aim is to build up a 'map' of " fuel consumption rate" vs "speed" (and also generate KML for each trip that can be viewed in Google Earth).

It might not work in practice, but I'm sure going to give it a try!

The sensor is fuel-proof, air-tight, able to cover a wide range of flow rates and has no metal-to-metal contact. With only 5V going to it, I am confident it won't blow up on me. I just need to get the boat wet now..

Engineers, eh?!
__________________
HughN is offline   Reply With Quote
Old 17 February 2012, 13:48   #7
Member
 
tony t's Avatar
 
Country: UK - Wales
Town: west mids /tywyn
Boat name: HAWK
Make: RIBCRAFT/ Suzuki 250
Length: 7m +
Engine: Tohatsu 3.8/15hpsuzi
MMSI: 235086594
Join Date: Apr 2008
Posts: 4,267
[QUOTE="HUMBER P4VWL"]Quite a while. Sat on a train from Birmingham. Glad to be leaving.



And what's wrong with Birmingham yea Cheshire snob
__________________
When you get to the end of your rope..tie a knot and hang on..!!
Aberdovey Ribs
B.I.O.C.Member
B.S. LEADER
tony t is offline   Reply With Quote
Old 17 February 2012, 13:48   #8
Member
 
MarkM's Avatar
 
Country: Netherlands
Town: Breda
Make: Scorpion
Length: 7m +
Engine: Evinrude 250 DI
Join Date: Oct 2003
Posts: 368
I put it up before, but these are my findings.
The orange line shows the reach with a certain amount of fuel.
At 1000 rpm you get the furthest but it will take ages to get there.
The most economical speed is between 3000 and 4000 rpm though. In my case anyway.

The blue line shows the speed and the pink line the fuel used.
Attached Thumbnails
Click image for larger version

Name:	Verbruik-20110313.png
Views:	236
Size:	68.5 KB
ID:	65633  
__________________
MarkM is offline   Reply With Quote
Old 17 February 2012, 13:50   #9
Redbay supporter
 
wiLlfish's Avatar
 
Country: UK - England
Town: onn de moov
Boat name: bote
Make: kevvin
Length: 4m +
Engine: jett dryve
Join Date: Jan 2010
Posts: 455
Quote:
Originally Posted by willk View Post
doo yew fink itts is?
nar. dis iz iz att

Quote:
Originally Posted by HUMBER P4VWL View Post
That would be a quality hat for the April Cruise!!

wot wiv yew an dat kirny nobbur inn iz ledderhosen wot wil de welch peepuls fink
Attached Thumbnails
Click image for larger version

Name:	porlys att.jpg
Views:	133
Size:	133.6 KB
ID:	65634  
__________________
fuk mee crismus leeve wiv noe ankul tagg

Wher doo I beegin?😃
wiLlfish is offline   Reply With Quote
Old 17 February 2012, 14:02   #10
Member
 
tony t's Avatar
 
Country: UK - Wales
Town: west mids /tywyn
Boat name: HAWK
Make: RIBCRAFT/ Suzuki 250
Length: 7m +
Engine: Tohatsu 3.8/15hpsuzi
MMSI: 235086594
Join Date: Apr 2008
Posts: 4,267
Quote:
Originally Posted by wiLlfish

nar. dis iz iz att

wot wiv yew an dat kirny nobbur inn iz ledderhosen wot wil de welch peepuls fink
You crack me up fishy
__________________
When you get to the end of your rope..tie a knot and hang on..!!
Aberdovey Ribs
B.I.O.C.Member
B.S. LEADER
tony t is offline   Reply With Quote
Old 17 February 2012, 15:31   #11
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: 12,950
RIBase
Quote:
Originally Posted by HUMBER P4VWL View Post
What is the most economical speed per mile to run at?

Is it the speed to maintain planing ability, whatever your boat/engine?

Or is it slightly quicker to have less boat in the water as long as you're not pushing your engine to its limits?

C'mon techies.
It's the one where it does the most MPG
__________________
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 17 February 2012, 16:05   #12
Member
 
ppenman's Avatar
 
Country: UK - England
Town: Wickford, Essex
Boat name: Wanderer
Make: Ribeye, Zodiac FR
Length: 7m +
Engine: Yamaha F300, 25 2S
MMSI: 235095667
Join Date: Aug 2010
Posts: 219
Usually the most efficient compromise (economy versus speed) is around peak engine torque. However this varies according to prop, leg gearing, weight, hull length etc. 4000-4500 is usually near it. Have a look at the testing done by Ribeye and Yamaha a few years ago which may give you a better idea.

RIB Engines
__________________
ppenman is offline   Reply With Quote
Old 17 February 2012, 16:22   #13
Member
 
Country: UK - England
Town: Sussex
Make: RIBTEC 655
Length: 6m +
Engine: Yam 150
Join Date: Oct 2007
Posts: 1,159
A little bit of trim can give you a couple of gallons an hour.
__________________
thomas is offline   Reply With Quote
Old 17 February 2012, 17:13   #14
Member
 
jambo's Avatar
 
Country: UK - Scotland
Town: Girvan & Tayvallich
Boat name: Breawatch
Make: Ribcraft
Length: 5m +
Engine: Mercury 150 F/stroke
MMSI: ex directory!!
Join Date: Sep 2008
Posts: 6,179
RIBase
Quote:
Originally Posted by willk View Post
still aye nobbur yew mean? i fownd diss - doo yew fink itts is?

That would be a 'Cardinal' bunnet. Rules & regs state you must wear one if you are stationary for any length of time
__________________
jambo
'Carpe Diem'
Member of the ebay Blue RIB cover club
Member of SABS ( Scottish West Division)
jambo is offline   Reply With Quote
Old 17 February 2012, 17:38   #15
Member
 
tony t's Avatar
 
Country: UK - Wales
Town: west mids /tywyn
Boat name: HAWK
Make: RIBCRAFT/ Suzuki 250
Length: 7m +
Engine: Tohatsu 3.8/15hpsuzi
MMSI: 235086594
Join Date: Apr 2008
Posts: 4,267
Quote:
Originally Posted by jambo View Post
That would be a 'Cardinal' bunnet. Rules & regs state you must wear one if you are stationary for any length of time
like 6 months
__________________
When you get to the end of your rope..tie a knot and hang on..!!
Aberdovey Ribs
B.I.O.C.Member
B.S. LEADER
tony t is offline   Reply With Quote
Old 17 February 2012, 17:45   #16
Member
 
biffer's Avatar
 
Country: UK - England
Town: swanwick/hamble
Boat name: stormchaser
Make: custom rib
Length: 8m +
Engine: inboard/diesel
Join Date: Aug 2007
Posts: 3,848
I though shall I post or not but thought I thought. What the hell give it a go. My answer turned out to be. Who cares. You can't put a price on fun and happiness
__________________
biffer is offline   Reply With Quote
Old 17 February 2012, 18:50   #17
Member
 
mister p's Avatar
 
Country: UK - England
Town: LONDON
Make: SR4/ZODIAC/3D
Length: 4m +
Engine: 30T/40T
Join Date: Oct 2011
Posts: 1,433
Quote:
Originally Posted by Nos4r2 View Post
It's the one where it does the most MPG
Very true.......but your engine will have it's most efficient point at peak torque.
If you then match the prop to maximise it's thrust at this same speed for the particular vessel then you will be at max mpg.
Now on a rib you will have two max mpg's. One for displacement and one for planing. Your prop will be matched for planing efficiency but you could have it matched for displacement and regear your transmission.
So........engine efficiency is fixed.
It is mated to suit your hull by prop pitch and slip for best economy if you so wish.
Economy is often forgone for maximum speed and so props will not generally be fitted to make the most of a particular engine's torque for the hull it is fitted to. Esp. on RIBs.
A tug however will generally have it's prop suited to best engine torque.
Torque is the rate of change of engine speed. When this rate is high, acceleration at this point is high because the engine is at it's most efficient. In water this point can be maintained because of fluid coupling despite variations in load. Gears or torque converters assist in getting engines to this sweet spot and keeping them there. This is why acceleration drops of as you approach peak revs......because the efficiency is tailing off.
Cool?
__________________
mister p is offline   Reply With Quote
Old 17 February 2012, 18:56   #18
Redbay supporter
 
wiLlfish's Avatar
 
Country: UK - England
Town: onn de moov
Boat name: bote
Make: kevvin
Length: 4m +
Engine: jett dryve
Join Date: Jan 2010
Posts: 455
Quote:
Originally Posted by tony t View Post
like 6 months

admirulty rools

arfter sikks munfs hee becums a azard too navigashun an az succh iz lykely too bee blowen upp bi de royul mareens orr uvver nobburs wiv mor ekslposivs thann comon sence (reed royul enjineers, ira, wna, hizbolla an de menia strait oister cachers.
__________________
fuk mee crismus leeve wiv noe ankul tagg

Wher doo I beegin?😃
wiLlfish is offline   Reply With Quote
Old 17 February 2012, 20:02   #19
Dhf
Member
 
Dhf's Avatar
 
Country: UK - Wales
Length: no boat
Join Date: Jan 2012
Posts: 1,012
Quote:
Originally Posted by biffer View Post
I though shall I post or not but thought I thought. What the hell give it a go. My answer turned out to be. Who cares. You can't put a price on fun and happiness
Just what I thought,
So hear goes,

Well i've got a 120 L tank under deck and inline fuel flow reader fitted just after the water seperater, Which gives me a digital flow rate, display built into the rev counter, So I can easily see how many litre's per hour, at whatever rpm, so this is what I get,
1000 rpm uses 4lt per hour, averaging 7 knots, on full tank = 210 nm, depending on tide flow
3200rpm uses 20lt per h, averaging 24 knots, on full tank = 144nm
5000rpm uses 50lt per h, averaging 43 knots, oft = 106 nm
So yea you'll travel much further useing lower rpm, But probably won't do the engine much good,
__________________
Dhf is offline   Reply With Quote
Old 18 February 2012, 05:59   #20
Member
 
Low Flyer's Avatar
 
Country: UK - England
Town: Portsmouth
Boat name: Cinsirrah III
Make: Oceans
Length: 8m +
Engine: Twin D3 160 Diesels
MMSI: 235089712
Join Date: Sep 2011
Posts: 462
Im with Biffer on this one,if you are worried about cost buy a rowing boat,you can go as far as you like then!!And keep the flow meters for how much ale you drink.....
__________________

__________________
Low Flyer 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 -5. The time now is 13:37.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.