Correct prop for 228 Seafarer with F225 Yamaha?

[c1steve]

My 1996 boat has the 15.5x17 Saltwater Series II prop, and it seems to be too much. Hole shot is good, midrange is okay, but above 22 knots it struggles somewhat. Max speed is 26 knots and 5,100 rpm.

The original prop on a 258 with the same engine is 13.75x19. What do people recommend?

 

[Mustang65fbk]

Yikes... yeah a max speed of 26 knots and only 5,100 rpm is much too slow. I'm not positive as to what I have on mine, just know that it's a 3 blade stainless steel prop. Here's a copy of the performance bulletin from Grady White on a 228 Seafarer with a Yamaha F225 on it. Looks like a 13 3/4" by 17M prop, I imagine it's likely a 3 blade. Good luck!

 

[c1steve]

Thanks for the quick reply. That is a much smaller prop than the 15.5" diameter currently on the engine. Engine is definitely overloaded.

 

[DennisG01]

Steve, something sounds amiss - like maybe something else is going on. Also, I believe you're thinking of prop pitch backwards. Overloaded means the prop is too big - as in too much pitch. If you go up in pitch, you will lose RPM, not gain.

Are you trimming up as high as feasible when going full WOT?

Is the prop in perfect condition?

Is hull bottom perfectly clean?

Responding only based on what you wrote, it sounds like you're not trimming properly

 

[Fishtales]

Two ideas. See if there is a local prop shop where you can test a few different ones out, then buy the one that performs best. 2nd is to check the GW website and see if there are any performance bulletins on the model. If so, they will highlight what was likely shipped from the factory.

 

[c1steve]

Steve, something sounds amiss - like maybe something else is going on. Also, I believe you're thinking of prop pitch backwards. Overloaded means the prop is too big - as in too much pitch. If you go up in pitch, you will lose RPM, not gain.

Are you trimming up as high as feasible when going full WOT?

Is the prop in perfect condition?

Is hull bottom perfectly clean?

Responding only based on what you wrote, it sounds like you're not trimming properly

I am new to running a GW, so do not know the best settings for trim. Yesterday had the Bennett trim tabs down 3-4 LED lights on the display, and set the motor trim to where the boat seemed to run relatively level. Where I am, NorCal, there is always a swell running so it is best to keep the bow down somewhat to reduce pounding.

What do you recommend for trimming the tabs and the engine?

Prop is in excellent condition, hull bottom is clean.

 

[SkunkBoat]

Steve, something sounds amiss - like maybe something else is going on. Also, I believe you're thinking of prop pitch backwards. Overloaded means the prop is too big - as in too much pitch. If you go up in pitch, you will lose RPM, not gain.

Are you trimming up as high as feasible when going full WOT?

Is the prop in perfect condition?

Is hull bottom perfectly clean?

Responding only based on what you wrote, it sounds like you're not trimming properly

the smaller diameter 13.75 vs 15.5 comes into play also Dennis. You can go down in diameter and up in pitch... or vice versa.... or just do one....

 

[DennisG01]

the smaller diameter 13.75 vs 15.5 comes into play also Dennis. You can go down in diameter and up in pitch... or vice versa.... or just do one....

I agree - yes. But he would lose push with the smaller diameter - so I don't think that would be a way to go? Am I thinking correctly there?

 

[DennisG01]

I am new to running a GW, so do not know the best settings for trim. Yesterday had the Bennett trim tabs down 3-4 LED lights on the display, and set the motor trim to where the boat seemed to run relatively level. Where I am, NorCal, there is always a swell running so it is best to keep the bow down somewhat to reduce pounding.

What do you recommend for trimming the tabs and the engine?

Prop is in excellent condition, hull bottom is clean.

When you want to find max speed and RPM (a different thing than normal running) it's just a hull - so really no different than other V-hulls for this purpose. Tabs refracted, WOT and keep trimming up and up. Forget the gauges - do it by feel and sound.

 

[Mustang65fbk]

I am new to running a GW, so do not know the best settings for trim. Yesterday had the Bennett trim tabs down 3-4 LED lights on the display, and set the motor trim to where the boat seemed to run relatively level. Where I am, NorCal, there is always a swell running so it is best to keep the bow down somewhat to reduce pounding.

What do you recommend for trimming the tabs and the engine?

Prop is in excellent condition, hull bottom is clean.

I live in the Seattle area and fish/boat almost solely in the Puget Sound where it's protected and we don't get a ton of bad weather or anything. I usually leave the trim tabs on my boat set to where the bow is up and rarely ever adjust them. The same with the trim/tilt on the motor, I usually row out to my boat that I have on a mooring buoy in front of our beach cabin, start her up, unhook from the buoy and then start trolling for salmon from there. Typically I'll have the motor at around the "2-3" mark on the indicator gauge and again, I rarely adjust it. About the only time I ever do adjust the trim tabs or the trim/tilt on the outboard is when cruising, if we get into some chop, if I'm trying to see how fast I can go, etc. I'd start with the correct prop, of which I imagine the one I sent you will likely be the best bet and what Grady White will recommend, as it's from their website. A quick call to Ken at PropGods will also likely verify the same thing as well. After that, it's just going to take some time/practice getting used to a different boat, the trim tabs, trim/tilt on the outboard and all of the other "quirks" of it being a "new" boat. Practice a bit, go out after you get the correct prop in perfect or almost perfect conditions, and get a baseline for how you feel, how the boat reacts to the different inputs you give it and then go from there. Good luck.

 

[SkunkBoat]

I agree - yes. But he would lose push with the smaller diameter - so I don't think that would be a way to go? Am I thinking correctly there?

I think he wants to lessen the load on the motor. That can be done either way, lower dia or lower pitch. or in some cases lowering one and raising the other. I'm not an expert on these things
There are reasons and trade offs for everything. I know the "Offshore" props tend to lower diameter and raise pitch (or go to 4 blades). I think to keep prop tips in solid water in rough seas.

You can calculate things to some extent but trial and error always finds the right one for the particular situation.

 

[c1steve]

Thanks to all for the advice. I will try another prop, then do another sea trial in smooth water, and learn what trim and tab settings work for speed.

 

[DennisG01]

Thanks to all for the advice. I will try another prop, then do another sea trial in smooth water, and learn what trim and tab settings work for speed.

Wait on the prop, Steve - from everything you've written so far the "issue" appears to be a free fix... just trim it up more for max speed/RPM.

Besides, before playing with props, you still need WOT max RPM data.

 

[c1steve]

Wait on the prop, Steve - from everything you've written so far the "issue" appears to be a free fix... just trim it up more for max speed/RPM.

Besides, before playing with props, you still need WOT max RPM data.

Online I see that the engine max rpm is 5,000-6,000.

Yamaha WOT RPM Chart

Wide open throttle RPM range chart for Yamaha powered boats.

www.rubexprops.com

 

[DennisG01]

Online I see that the engine max rpm is 5,000-6,000.

Yamaha WOT RPM Chart

Wide open throttle RPM range chart for Yamaha powered boats.

www.rubexprops.com

Yes, that is the "spec" for the engine - and you want your WOT to fall in that range - ideally towards the top end. However, that's different than what we're talking about. You need to find YOUR boat's WOT (ideally with a normal load). Since you haven't yet really been able to do a real WOT test, we don't yet know what the RPM & speed are - and making any changes now could very well be a waste of time and money.

 

[Mustang65fbk]

Yes, that is the "spec" for the engine - and you want your WOT to fall in that range - ideally towards the top end. However, that's different than what we're talking about. You need to find YOUR boat's WOT (ideally with a normal load). Since you haven't yet really been able to do a real WOT test, we don't yet know what the RPM & speed are - and making any changes now could very well be a waste of time and money.

I'm not sure if you're confusing this with another thread or what's going on... but go back and reread his first post as he literally already said that his max speed/WOT is only 26 knots @ only 5,100 rpm and did a "real test" on it. Unless there's something drastically wrong with the outboard itself, there's no reason why he should only be hitting 26 knots @ only 5,100 rpm. He's already said that the bottom is clean and the current prop is in perfect condition. With the considerable difference between the OP's prop and the prop that Grady White recommends, I imagine that's the reason why he has such a low max speed/WOT as well as rpm. The OP's prop being a 15.5" x 17, whereas the recommendation per Grady White should be a 13 3/4 x 17 M. Comparatively, and yes I know it's not entirely an apples to apples comparison here as the OP has a slightly older boat than I do, but my max speed is right around 43 mph and @ just under 6k rpm. I don't know the size/pitch prop that I've got on my boat, but I imagine with it being quite similar in numbers to the performance bulletin from Grady White that I posted in my first reply, that it's likely much closer if not the same as the one they recommend. I'm not sure why we're overthinking this or making more work for ourselves or the OP.

To C1Steve, several boat owners will install the wrong props amongst other things, on their boats over the years and I'm guessing this is likely the case for your boat. Get yourself the correct prop for your boat. If you want to get a case of the warm fuzzy feelings and triple check that you're making the right decision, then a quick call to Grady White and/or Ken at Prop Gods will confirm our/your thoughts on the matter. Good luck.

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