4 blade prop??

[Destroyer]

Once you get your engine height dialed in here are some things to consider:

4 blade props will give you a better hole shot and the least vibration, but at the cost of top end. (The more blades in the water, the more drag/friction on your engine.) A 2 blade prop gives the best high end, but at the cost of more vibration and poorer low end, which is why most people run 3 blade props. They're a good compromise between the 2 blade and the 4 blade props.

Right now you're running a 19P stainless prop. The equivlant prop in Alum would be a 21 pitch. As a general rule of thumb you drop 2 inches of pitch when you switch from Alum to SS...so if you're going from SS to Alum you add 2" to your thinking. So if you're thinking about dropping to a 4 blade 17P, the same prop in Alum would be a 19P. To my way of thinking, that's too much prop for a 150 engine. I think that the first prop I'd try would be a 17P Alum for a baseline, and then work from there once i saw what my RPMs were.