[MERCURY OUTBOARD MAN]

The z 21 with 225 proxs will run 4 mph over rpm

Originally Posted by all star rod

if you are looking at getting a yamaha go on their web site and look at the test data they have done on boats. Maybe yours was not tested but i am sure you can find one that is pretty close to the weight and hull design of the one you are looking at(haynie). Hard to believe that boat has a weight of 1,350# and rated for a 250hp. The test results/data that yamaha did with the 4 stroke 150/xpress x22bay are pretty dang accurate compared to the way mine runs....fuel ecomony, top speed, speed @ rpms, and plane time. If anything the test data is conservative based on the load weight during the test. I usually have more weight in my boat since i fish three 90% of the time. Also, a 4 stoke can run at higher rpms than a 2 stroke di motor. I bet the optimax has the same range as the hpdi...5,500 rpms compared to a 4 stoke at 6,000 rpms. I bet that boat would fly with a 225 optimax!
I think the 150 yamaha 4 stoke is more than enough motor for that boat...get a jack plate.