4 strokes outboards IS THIS A MYTH?

MAtt you make me laugh

Seriously though, the reason I started this thread is becuase of this observation:

YAMAHA 225 4-Storkes
RIB MAR.CO 25 CABINATO

4680 LTRS / 2696 Miles = 1.735 LTRS/MILE
according to the chap who saild the boat Giovanni Bracco.

My 200VMax 2-strokes (not the HPDI) with 17" pitch Yamaha Salt Water prop (changed the 21" Yamaha Pro prop I had on it for this one and I may go up to 19") on the same boat gives on the FLOSCAN and between 3500-4000 revs about 1.3-1.6 ltrs/mile in moderate seas, trim -3 and jack plate up 2 notches. I think the speed is between 24-26 knots and the boat is a little heavier (I estimate between 200-300kgs, due to added bulk heads in the cabin, a cooker and a frige, and some added decoration for comfort etc) than when it did that raid when everything was bare for obvious reasons.

The logical thing would have been for the boat to go slower and have higher consumption but it does not.

I thought is very starnge and either the guy who sailed the boat is wrong or I have a great little 2-strokes motor

The 200 V MAX is no fuel miser... so you are getting good fuel use there ..

Generally I dont think you can compare all these numbers as the conditions were different ..

It makes sense that the 150 uses more gas to go as fast or faster as the bigger motors ..

Matt

Yes Mat I agree with what you say.

I think the VMax is doing well as you say it drinks petrol like a bottomless well

However, the numbers showing the cnsumption of the 4-strokes are an indication that it may be a falacy that the 4-strokes have better consumption than the 2-strokes.

By the way the 150 Mariner is a 4-stroke

Here is a chart that I created a while ago ... all motors are Yamaha, 2 stroke, HPDI and 4 stroke compared to a optimax soprtjet ...

Your motor is the purple dotted line ...

You can see that the HPDI and 4 stroke are very simlar and differences probably come mostly from the boat rather the motor.

The 200 VMax is on a very light boat with high pitch prop thus very fast and very hungry (more as it would be otherweise)



Matt