Reply
 
Thread Tools Search this Thread
 
Old 01 August 2016, 12:17   #31
Member
 
dubrus's Avatar
 
Country: UK - Scotland
Town: Glasgow
Make: Ribcraft 6.8
Length: 6m +
Engine: Suzuki df200
Join Date: Jun 2010
Posts: 1,990
i seem to recall that you lose a lot of HP by going to a jet but would need to google to find that info. however what you are saying rings a bell that 80hp jet is actually like a 120hp normal, need to google as i say.

i would do what the folks above are suggesting, sell that engine and buy another one. you will likely make money if you find the right buyer for that engine.
__________________

__________________
dubrus is online now   Reply With Quote
Old 30 March 2017, 17:00   #32
Member
 
Country: Ireland
Town: Dublin
Boat name: Endurance
Make: XS
Length: 7m +
Engine: 2 x 100 Yamaha 4-str
Join Date: Mar 2017
Posts: 4
Fuel consumption

Hi,

I am hoping someone can give me a few pointers regarding the black art of gauging fuel consumption.
I am in a diving club that has an XS700 RIB with twin 100HP Yamaha 4-stroke engines.
We would normally carry 8-10 divers and keep the revs at 4k.
Can anyone give me a rough guestimator at how to gauge fuel consumption.
I will be running a test soon with full tanks and then top up after and do a proper calculation but in the meantime any offers - Just curious!

Rgds.

Mick
__________________

__________________
MickC is offline   Reply With Quote
Old 30 March 2017, 17:15   #33
RIBnet supporter
 
Pikey Dave's Avatar
 
Country: UK - England
Town: South Yorks
Boat name: Black Pig
Make: Ribcraft
Length: 5m +
Engine: DF140a
MMSI: 235111389
Join Date: Feb 2008
Posts: 7,480
RIBase
fuel consumption

Quote:
Originally Posted by MickC View Post
Hi,



I am hoping someone can give me a few pointers regarding the black art of gauging fuel consumption.

I am in a diving club that has an XS700 RIB with twin 100HP Yamaha 4-stroke engines.

We would normally carry 8-10 divers and keep the revs at 4k.

Can anyone give me a rough guestimator at how to gauge fuel consumption.

I will be running a test soon with full tanks and then top up after and do a proper calculation but in the meantime any offers - Just curious!



Rgds.



Mick


Have you got a half decent plotter? If so there will be a trip computer function somewhere that will give you trip distance. Do a brim to brim fuel tank fill & use the trip distance, simples. If no plotter (it's a dive club so I'm assuming you do have one) beg/steal/borrow a Garmin handheld. You can work out the fuel consumption as Nm/l or l/h
__________________
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
Rule#4: See rule#5
Pikey Dave is online now   Reply With Quote
Old 30 March 2017, 17:21   #34
Member
 
Country: Ireland
Town: Dublin
Boat name: Endurance
Make: XS
Length: 7m +
Engine: 2 x 100 Yamaha 4-str
Join Date: Mar 2017
Posts: 4
Tks Dave. I will be doing a proper test once I get the boat in the water - trailer brakes and bearings on the list at the moment. My curiosity was getting the better of me. I saw a rough guestimate on this forim for a single 100HP engine of 1l/KN and was curious or just being plain stupid - Do I just double it??
Mick
__________________
MickC is offline   Reply With Quote
Old 30 March 2017, 17:27   #35
RIBnet supporter
 
Pikey Dave's Avatar
 
Country: UK - England
Town: South Yorks
Boat name: Black Pig
Make: Ribcraft
Length: 5m +
Engine: DF140a
MMSI: 235111389
Join Date: Feb 2008
Posts: 7,480
RIBase
Quote:
Originally Posted by MickC View Post
Tks Dave. I will be doing a proper test once I get the boat in the water - trailer brakes and bearings on the list at the moment. My curiosity was getting the better of me. I saw a rough guestimate on this forim for a single 100HP engine of 1l/KN and was curious or just being plain stupid - Do I just double it??
Mick


I had a 6.4 RC with twin 115 Etecs, I used to get 0.7nm/l, it's not as simple as doubling, as each engine wont be working as hard, but you have twice the drag. I'm going to guess at around 0.6nm/l for your boat assuming it's setup & propped correctly.
__________________
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
Rule#4: See rule#5
Pikey Dave is online now   Reply With Quote
Old 30 March 2017, 17:28   #36
Member
 
Country: Ireland
Town: Dublin
Boat name: Endurance
Make: XS
Length: 7m +
Engine: 2 x 100 Yamaha 4-str
Join Date: Mar 2017
Posts: 4
Tks Dave. it could be an expensive season!!
__________________
MickC is offline   Reply With Quote
Old 30 March 2017, 17:29   #37
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,862
RIBase
Quote:
Originally Posted by MickC View Post
I saw a rough guestimate on this forim for a single 100HP engine of 1l/KN and was curious or just being plain stupid - Do I just double it??
Mick
You will be carrying a load of lardy divers and their insanely heavy kit - so I'd say your figures above may well be very close!

I used to run a twin 90hp 6.5m and kept her pretty heavy. She reliably returned 1.44L/Nm at 22-25kts. They were two strokes and you're a bit bigger, so I'd guess that might even out a bit. Allow 2l/Nm and keep a close track of how it goes. Consumption can change easily based on weather/loads/speed/driving style/boat trim/weight distribution, so always use it as a guide and keep a decent reserve. The old cave diving rule applies to fuel too - 1/3 out, 1/3 in, 1/3 reserve.
__________________
"Who knows what evil lurks in the hearts of men?"
.
willk is online now   Reply With Quote
Old 30 March 2017, 17:39   #38
Member
 
Country: Ireland
Town: Dublin
Boat name: Endurance
Make: XS
Length: 7m +
Engine: 2 x 100 Yamaha 4-str
Join Date: Mar 2017
Posts: 4
Indeed. Couldn't agree more. Cheers
__________________

__________________
MickC 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 15:55.


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