226 Seafarer Prop

[Dublin]

Greeting Fellow GW 226 Owners
I have a 2000 GW 226 with a 200 HP Yam HPDI Z200 that is equipped with the original 17 M aluminum prop. Has anyone done the prop evaluation/investigation on this setup to improve cruising performance? Due to my age I am not really interested in going more than 30 mph so top end performance is not important to me. Currently with the 17 M I need 4200 rpm to do 30 mph over a flat surface with moderate weight on board. 3800 rpm delivers 26 mph. In both examples the boat/motor seems to perform best with the trim at 2-2.5 on the trim meter.
My goal is to cruise at 30 mph with the lowest possible fuel consumption.
Thank you in advance for you experience and input.

 

[Doc Stressor]

That's pretty much the same performance I used to get with my Yamaha F250 running a 17" stainless steel prop. I have also run 19" and 16" pitch props, but got the best fuel consumption numbers with the 17". The engine would turn 5700 rpm with the 17", 5900 with the 16", and only 5400 with the 19". The 19" would run 30 mph at 4000 rpm, but burned about 10% more fuel than the 17" which would run 30 mph at 4200 rpm. These numbers are with a light load. The 19" prop would really burn a lot of fuel with the boat loaded up. The 16" performed the best when I had 4 people and scuba tanks on board.

Unless you are close to WOT where the hp differences come into play, a 200 hp and a 250hp engine will give similar speeds turning the same prop. I doubt if you will be able to improve your mpg much by changing props. Your cruise speeds seem about right for the 226.

 

[Dublin]

That's pretty much the same performance I used to get with my Yamaha F250 running a 17" stainless steel prop. I have also run 19" and 16" pitch props, but got the best fuel consumption numbers with the 17". The engine would turn 5700 rpm with the 17", 5900 with the 16", and only 5400 with the 19". The 19" would run 30 mph at 4000 rpm, but burned about 10% more fuel than the 17" which would run 30 mph at 4200 rpm. These numbers are with a light load. The 19" prop would really burn a lot of fuel with the boat loaded up. The 16" performed the best when I had 4 people and scuba tanks on board.

Unless you are close to WOT where the hp differences come into play, a 200 hp and a 250hp engine will give similar speeds turning the same prop. I doubt if you will be able to improve your mpg much by changing props. Your cruise speeds seem about right for the 226.

 

[Dublin]

Thank you Doc
I should have also asked whether a SS prop would do much to improve the performance?

 

[Doc Stressor]

My old '75 Grady came with a 15" aluminum prop that I switched over to the same pitch SS prop after a few years. I picked up 2 mph at top speed, but didn't really notice an increase in fuel economy at cruise. The thinner blades and better cupping found on SS props usually bite the water better than aluminum props giving less slip. But the greatest effect is typically seen at higher speeds. SS props don't flex as aluminum props do. So mid-range performance differences are not that great.

Finding the best prop for a given engine/boat combination is largely a matter of trial and error. You can often find a 10-15% difference in performance (speed and/or economy) between the best and worse props with the same pitch. It's really hard to get more than general information from boats that are different from your own.

 

[seasick]

On my prop the actual diameter and pitch is stamped on the inside of the hub. I never did understand what exactly the M in the 17M stamped on the outside was supposed to mean. Perhaps someone can educate me.
Assuming you have operated the boat for a while, my first reaction to your query was to ask if your performance figures have always been the same. If performance parameters have changed over time, you probably need to find out why.
It could also be that the prop needs a tune up or the hull has more drag. Are you sure your current prop is aluminum? I ask that because many of the oem props on those motors were painted stainless. So they don't look like stainless due to the paint but are ( By the way, even though they may be stainless, if not painted they tend to oxidize a bit and get rust spots.

 

[Doc Stressor]

The "M" just indicates the prop shaft type. M is for the V6 engines. The smaller Yamaha engine props I've seen either have a "K" or no stamp after the pitch.

 

[Heyspike]

Here's the numbers on my prop. 2006 228. Yamaha 225
It's a Yamaha Salt Water Series. Not sure of all the performance numbers yet.