FDD good to get some stats, I was surprised at how much your speed dropped off after 4000 rpm, it should start to flatten the gradient not reduce the top end speed which to me would be a question you should be asking as it could relate to prop size/pitch and or motor height. Maybe once this is resolved your range would be increased although I have no idea what the efficiency stats are for your motors.Originally Posted by Fairdinkumdan
What a difference a set of 4 stks can make.
660 NC with twin 140 yammy's swinging 19 inch props with 4 blokes and loaded for a 3 day trip getting 1.9 to 2 ltr per km.
Same trip with 115 merc 4 stks swinging 13.5 x 15 solas props with a cruise speed of 24knts at 4800rpm using 1.15 ltr per km and no 2 stoke oil burn.
A set of 140 or 150's would be better but every one i talk to thinks all i will save is .15ltr per km but more hp would be better.
1.3ltrs to the K in a Yalta 555HC with a 150 4strk.
OUch! Are you sure on that? Even swapped around to 1.3km/L that sounds very high for a 5.5m mono running a 150 4stk.
If those figures are true then you have some setup issues.
I do get 1.3Ls to the K. Which is 200Ks to a 150L tank.
I think your maths may be a little out Julian. 1.3l to the K will only see you getting around 115km for your 150 litres.Camhawk is right I think mate. 1.3km to the Litre will see you getting 195km from your 150 litres. Still I would have thought you would get better than that too. At least 1.5km/l??
My bad, never was good at maths. Normal things affect fuel eco. like outboard height, prop? Anything else?
Trim Julian. When it is flat trim it out. I get 1.2km/l in good conditions with a 115 2 stroke on the same hull. Goes down when things get choppy to about .8km/l.
You should be getting around 1.8km/l with your motor.
Remember to always log on before heading offshore.
Yep trim and revs. If you are at WOT everywhere you go, your efficiency will suffer. Once you creep above 5000rmp you start to drink a lot more.
What motor is it? As the others have described, economy has a lot of room to improve. Will be worth checking some of the sea trials, Yammie has a lot on their web site, as well as sea media. You will get a better idea of where the most economical rev range is - for the Yammies as an example it is 3500-3800.
Scott.
Yammie 2007 150HP, injectors cleaned 1 year ago. Has a 17P prop. I drive from 4000-4400. Never drive at WOT other then having a play. I get 5800 - 5900 at WOT but more around the 5800 mark. When on the plane you can kind of see the Hydro foil, but it is not that obvious.
I'm still learning the art of trimming. I basically trim till the steer gets easier and the ride feels good.
THat all sounds good. How are you measuring your fuel usage? Wouldn't be 1.3l per NM by any chance?
Just by fuel used according to my fuel guage(not refueling till I get to 1770). I did 99odd nms and my fuel guage is near on empty. I have an LMF200 that I have to finish calibrating which should assist also in getting a better figure.
On a good trip leaving from Scarborough heading out to Hutchies and troll only until heading back to port I'll get .8nm/Ltr. A touch under 1.5Km/Ltr.
135 Optimax swinging 17p Vengeance prop. I can improve this figure more yet just need to motivate myself. I'll cruise at 24Kn at 3990-4000 RPM. Jim
Haines Signature "FinaLeigh" 580F 135 Optimax
CH 81 & 72 VHF
that is one very thirsty boat
try to fill up to the top, clear trip meter on your GPS, drive around 50km in one way then drive 50 km back to ramp,
go to servo and top the tank up,
that should give you very close figures
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