is the 150 yammi he's suggesting a four stoke - if so you will notice its got less out of the hole compared to the 2 stroke - go the 200 and run at less revs and have more in reserve.

 New 200 Yamaha 4 cylinder seems made for your situation.

Just put a 225 on my 6.8 metre seaquest as 200's weren't available until late february 2014  - utterly brilliant, incredible economy.  In my view the 200 would be perfect for a 6.1 assuming they are becoming available short term   

 Hey sunshine what sort of economy are you talking about do you have any numbers at all cheers mate

Last trip was a measured total travel of 37 nm and we used 39.5 litres - I honestly could not believe it! The yammie fuel use gauge read 49 litres but try as we might the overflow bled fuel at 39 and a half when trying to top it off at the servo, even looked twice to see if the boat was on  a slope but we always fill up there and also removed and then replaced the fill nozzle in case it was blow back or an air lock but no change, it overflowed. 

We never got over 26 knots heading down the sound early morning, only hit 19 in yucky seas heading out to the 40's and then ran back with the swell along the back of GI before crossing the sound to Woodies at 26 again.  It is the brand new lightweight 225 fitted by Chivers   

 Have a look at their website and the test results for each motor on a hull that is a similar wieght/size to yours. You'll find that most of the Yammy 4 strokes get around an average of 2kms/ltr cruising.

I was tossing up between the 150 and the 115 for a 6m Quintrex ,basicly the same fuel usage but at different speeds. I went with the 115 because the sea conditions don't allow me to run fast very often. The end result is 2 - 2.4 kms/lt depending on conditions at 22knots.

 What is your boat rated for. 4 strokes weigh more than 2 strokes. Going from a 150 2 stroke to a 200 4 stroke would put an extra 120 kilos off the back of the boat. 

 Heavier than my old old 200 Jonno two stroke and bluntly the extra weight makes the ride softer but mine is the new lighter version

Weight on the transom can make a HUGe difference to how a boat rides......add exttra weight to a boat that is bum light will make it feel brilliant, reducing  broaching and making it feel way more stable.

Add extra weight to a boat that is already a little bit bum heavy and it will result in a boat that bangs really hard no matter how you trim it. In an ali boat, this can be a disaster. The new 4 strokes are much lighter than previous, but still more than the 2 strokes I think.

Its all about balance, but try and get max hp you can afford (both $ and weight)

 150 plenty. Got 6.4 plate and 200 and just not needed to be honest.

go the 200, mate had a 6m ali and had an old 150 2 stroke, was fast and reliable, now he switched to 200 yami fourstroke, much quiter, better km/l and can push up to 50 knots.