I have a 2002 208 Adventure with a 200 Yamaha 4S. The boat is turning 4800 rpm @ full throttle and 38 mph. The engine should be 5000-6000 rpm. I am turning a 19 pitch SS prop. Was thinking about dropping to a 17 SS prop. The engine seems to be running fine but I am wondering if there might be another issue I am overlooking. 2" drop in pitch with give me about 400 rpm which puts me in the lower end of the recommended power range. Anyone out there have a similar setup? Any recommendations?
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Need help with prop selection.
- Thread starter Harleyfxdl
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ocnslr
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The performance specs for the 208 on the GW web site show that engine hitting 6000 RPM at 45MPH with a 15.25"x17" Yamaha SWS prop.
You didn't indicate it you were running a 19" Yahama, but I would expect that to have you in the middle of the designated range.
Are you getting that 4800RPM with the engine trimmed up, or tucked all the way down?
I would suggest you change to a Yamaha 17" SWS prop, then see what you get with the engine trimmed up. Trim it up, watch the RPM and speed increase, then when you hear the engine start to ventilate, just trim down a bit. You should be able to get very close to 6000RPM with a light load, so you are still in the top of the range when heavily loaded.
I assume that you have a clean bottom..
Brian
You didn't indicate it you were running a 19" Yahama, but I would expect that to have you in the middle of the designated range.
Are you getting that 4800RPM with the engine trimmed up, or tucked all the way down?
I would suggest you change to a Yamaha 17" SWS prop, then see what you get with the engine trimmed up. Trim it up, watch the RPM and speed increase, then when you hear the engine start to ventilate, just trim down a bit. You should be able to get very close to 6000RPM with a light load, so you are still in the top of the range when heavily loaded.
I assume that you have a clean bottom..
Brian
Hi Brian, the motor trimmed up , clean bottom and running the 19" Yamaha SS prop and the best is 4800 rpm 38 mph.
ocnslr
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Something isn't right.
Borrow a 17" SWS prop from someone, and see what you get. Logic says only 300-400RPM increase.
If that is the case, then a couple of thngs come to mind:
1) have the engine checked to make sure the throttle is indeed fully opened.
2) was this a factory engine install? many installers mount engines too low - reduces blowout, but also overloads the engine and keeps the revs down.
How long have you had the boat? Has it always been this way, or only recently? If you just purchased it, then what about sea trials - was this apparent at that time?
Brian
Borrow a 17" SWS prop from someone, and see what you get. Logic says only 300-400RPM increase.
If that is the case, then a couple of thngs come to mind:
1) have the engine checked to make sure the throttle is indeed fully opened.
2) was this a factory engine install? many installers mount engines too low - reduces blowout, but also overloads the engine and keeps the revs down.
How long have you had the boat? Has it always been this way, or only recently? If you just purchased it, then what about sea trials - was this apparent at that time?
Brian
Hi Brian, I just bought the boat and did not have the opportunity to seatrial. The setup looks to be a factory install. The cavitation plate is level with the keel. I had planned on checking to see if the throttle is fully open. The boat has 140 hrs on it. The other thing that comes to mind is timing. I just purchased a used 15 1/4x17 SS Yamaha prop. I will try this and get an idea of where I stand. This is the same prop Grady used for their test. I think the 19" pitch prop I have now is a little big. I'll post results.
ocnslr
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If you trim the engine so the cavitation plate is parallel to the bottom, then lay a straight-edge along the bottom, the cavitation plate should be above the bottom. I think about 1" is normal.
Have a good Yamaha mechanic check that throttle. And I think he should be able to read the ECM as well...
Have a good Yamaha mechanic check that throttle. And I think he should be able to read the ECM as well...
Yeah, I was hoping to eliminate all other variables before I brought it into the shop. The yamaha dealer near me does not leave me feeling confident so I found another in CT. Not sure if this place is any better. Their website states the mechanic is a master tech, we'll see :roll: .