change prop, mounting hole, or both

[Eazy Mony]

Situation: Bought a used 2003 Hewescraft 200 Searunner Soft Top with a 2009 Yamaha F150. Have approx 150 hours on engine and came with a 3 year warranty. It also came with a Yamaha painted Stainless Steel Prop, stamped 15M and measured 15 1/4 x 15. A second spare prop, Yamaha Aluminum, stamped 17M and had 14 1/2 x 17 stamped on the inside hub. The new 2009 engine has been mounted in the #1 hole. (first hole from the top of the mounting bracket on engine)

Weather: Cloudy, water calm.
Load: 85gal tank with approx 60gal onboard, 2 adults, normal fishing gear.

1st run Performance: With the setup using the 15M prop: WOT, 5900 RPM, 36MPH, trimmed motor for max RPM.

2nd run Performance: With the setup using the 17M prop: WOT, 5200 RPM, 39MPH, trimmed motor for max RPM.

According to the Manufacture Permormance sheet I should be able to setup for WOT, 5900 RPM, 47 MPH. As the two runs indicate, I am well below expected performance and would like to be able to improve these results. I have been through prop swapping on a different boat, but I really dont know which way to go with this one. Any help with ideas, suggestions, where to even start would be greatly appreciated.

And of course, the fishing report from Whittier, AK....little too early for Salmon, Halibut spotty, Shrimping is great!!!

Thanks, Howard

[99yam40]

what prop did they show being used in the performance bulletin?
and was that with a F150?

Best thing to do would be to have motor tested with the Yamaha test prop to make sure the motor can produce the HP and can hit the proper RPMs.
Then it is just up to getting it set up properly if motor is doing what it should

[BaileysBoat]

5900 is where you want to be. I run a stock Yamaha aluminum 17 pitch on the Stanley. The 19M aluminum was just too tall and would only get me 5400 no matter what I did.
When I took delivery of the Stanley the dealer had installed the engine on the #1 hole. It now runs very happily at #3. 5900 rpm, 44 mph.

I would put the engine up to #3 and water test with both props. I don't see any way in the real world you will be able to run a prop bigger than 17p. The F150 will "make oil" if you can't get close to 6000 rpm WOT.

Once you establish the correct height you can play with props. I would try to borrow a 17P Reliance.

Easy way to lift the motor by yourself is to have it on the trailer with a block of wood under the skeg. Loosen the 2 slotted mounting bolts and remove the 2 bolts from the #1 holes. Than all you do is jack up the front of the trailer until the the desired holes line up.

Good luck

[Eazy Mony]

Thanks for the quick reply....I just made a visit to the local dealer and was able to speak with the head technican. He is telling me to go by the RPM's and not by the MPH, the sheet they put out is not a realistic or typical performance of this setup. I had the motor inspected, tested, and serviced last fall, so motor is up to specs. Mounting hole did not seem to be an issue. Have to say, not really satisfied with the answers relating to the performance. I have been to the Yamaha Performance Bulletin page and looked at other Hewescraft with the F150. All of them are posting much better results than I am getting. I am not looking for a speed boat, just can't help but think a F150 should be able to push this 20 foot Searunner a little better. One thing dealer did say, was not to use the 17M alum, at 5200 RPM would put excess loading on the head and possible failure. Am still open to suggestions.
Howard

[99yam40]

Sounds like someone is blowing smoke up your *** unless it is tested on a dyno or run with the test prop how do you now it is producing the rated HP and running properly

[Eazy Mony]

yep, and i have no place else to go...they are the only local dealer within 100 miles. you mention a test prop and dyno, is this a certain pitch/diameter prop for a particular hp model and do they test it in a shop? can i obtain a test prop myself? I dont have much hope this dealer is interested in this situation, as soon as he heard it hit 5900, everything is good. Sorry for so many beginner questions, but i want to understand the process for obtaining the correct or best performance. I am definately down to fewer and fewer choices here. Could there be that much difference in performance in the second prop i was using, the 17M alum? Assuming the engine is ok, would another try at a different prop seem logical or should i just be satisified with running the 15M black stainless and call it good, since it is operating within the WOT specs?
thanks again, howard

[99yam40]

You never answered my question of what prop was run on the boat in the performance bulletin and if it is the same as the one you are running. That will tell you if you need to get you hands on a test prop to see if your motor has a problem. The test prop is a cut down one that can be run while boat is on the trailer at WOT in water. Ask Yamaha dealer what the part number is and if they have one for your motor

[SkinnyRaven]

Thanks for the quick reply....I just made a visit to the local dealer and was able to speak with the head technican. He is telling me to go by the RPM's and not by the MPH, the sheet they put out is not a realistic or typical performance of this setup. I had the motor inspected, tested, and serviced last fall, so motor is up to specs. Mounting hole did not seem to be an issue. Have to say, not really satisfied with the answers relating to the performance. I have been to the Yamaha Performance Bulletin page and looked at other Hewescraft with the F150. All of them are posting much better results than I am getting. I am not looking for a speed boat, just can't help but think a F150 should be able to push this 20 foot Searunner a little better. One thing dealer did say, was not to use the 17M alum, at 5200 RPM would put excess loading on the head and possible failure. Am still open to suggestions.
Howard

I can guess the name of the dealer you speak of, heard the same dealing with a 115. From the research I have done first correct the engine mounting position, the cavitation plate should at or slightly above the water line when on plane, then work on the prop selection. Mine was originally mounted in hole #1 (all the way down) we went from a 15 to 14 pitch prop which increased rpm's but my prop slip was in the 30% range with the cavitation plate running 2" below water level. Had the dealer raise engine one hole, still some what low on the cavitation plate but picked up 200 rpm's and 3 mph, prop slip is at 22%. Have raised the engine to the third hole but have not had a chance to test it yet. I'll let you know how it goes.

[Eazy Mony]

You never answered my question of what prop was run on the boat in the performance bulletin and if it is the same as the one you are running. That will tell you if you need to get you hands on a test prop to see if your motor has a problem. The test prop is a cut down one that can be run while boat is on the trailer at WOT in water. Ask Yamaha dealer what the part number is and if they have one for your motor

You are correct, never got a straight answer from the tech either. I will find out, they have printed this info on their brochures, so it must be documented somewhere. I should have mentioned I have a 9.9hp yamaha kicker also mounted on the back. One of the reasons I bought this boat with the 150 was the extra hp and performance. I was really discouraged with the lack of interest from the dealer, even the question of the mounting hole was not a real concern. I will be back will the prop info, and check into the test prop. Feel like I am heading in the right direction. Thank you for taking the time to help me narrow this down, dont care if I gain 2MPH in the end, just want to make sure it is set up correctly.

[Eazy Mony]

5900 is where you want to be. I run a stock Yamaha aluminum 17 pitch on the Stanley. The 19M aluminum was just too tall and would only get me 5400 no matter what I did.
When I took delivery of the Stanley the dealer had installed the engine on the #1 hole. It now runs very happily at #3. 5900 rpm, 44 mph.

I would put the engine up to #3 and water test with both props. I don't see any way in the real world you will be able to run a prop bigger than 17p. The F150 will "make oil" if you can't get close to 6000 rpm WOT.

Once you establish the correct height you can play with props. I would try to borrow a 17P Reliance.

Easy way to lift the motor by yourself is to have it on the trailer with a block of wood under the skeg. Loosen the 2 slotted mounting bolts and remove the 2 bolts from the #1 holes. Than all you do is jack up the front of the trailer until the the desired holes line up.

Good luck

thanks for the reply, looks like I am on the right track to narrowing this down, you mention the 17p prop, I am also finding a big choice of diameters with the pitch. do you know what your diameter is on the 17p you finally selected?

[Eazy Mony]

I can guess the name of the dealer you speak of, heard the same dealing with a 115. From the research I have done first correct the engine mounting position, the cavitation plate should at or slightly above the water line when on plane, then work on the prop selection. Mine was originally mounted in hole #1 (all the way down) we went from a 15 to 14 pitch prop which increased rpm's but my prop slip was in the 30% range with the cavitation plate running 2" below water level. Had the dealer raise engine one hole, still some what low on the cavitation plate but picked up 200 rpm's and 3 mph, prop slip is at 22%. Have raised the engine to the third hole but have not had a chance to test it yet. I'll let you know how it goes.

Well, can't say anything too bad...so far they haven't charged me anything. You are the second one to mention the mounting hole. I have read it is also very critical and the first thing to get straight before messing with prop swapping. Can you measure anything with the boat out of the water and on a trailer, as far as the outdrive all the way down and distance from the cavity plate to the bottom of the transom? I am going to show my experience here but, how do you measure your prop slip? did you move the engine yourself for the 3rd hole, or having a shop do it? And please do let me know after the next run. I dont want to miss a weekend with out another shrimp catch.

[upnorth73]

BaileysBoat was spot on with how easy it is to change the mounting hole. My local dealer set my boat/engine up from new and it was really buried, which I gather most dealers do as it lessens the cavitation in corners for inexpierienced drivers.
I lifted my outboard using the method described by BaileysBoat and picked up almost 400rpm, switched to a better pitch prop and is now a much better performing boat (speed, cruise and fuel economy). Have a look at the Mercury prop web-site, they really hammer home setting the height right...

Cheers

[SkinnyRaven]

I am going to show my experience here but, how do you measure your prop slip? did you move the engine yourself for the 3rd hole, or having a shop do it? And please do let me know after the next run. I dont want to miss a weekend with out another shrimp catch.

First you need to calculate your theoretical speed

(Prop Pitch X RPM) / (Gear Ratio X 1056) = Theoretical Speed

Theoretical Speed - Actual Speed divided by Theoretical Speed = Slip

Prop slip should be in the 15% range for best performance and economy.

So far the dealer is working with me on the engine mounting.

[Rowdy's runabout]

installing impellor

i am trying 2 install a new water pump impellor. It is suck water instead of spitting it out? Does someone have a instruction manual about the installation they can email me?

[BaileysBoat]

Easy, I would agree that as your rig is set up now you can't swing a 17 pitch, but if you optomize the engine height it could be possible.

BTW you are getting decent performance with the 15 pitch Yamaha prop.

As far as getting a test wheel to see if the F150 is performing ok I see it as a waste of time. You are able to get 5900 rpm and only have 150 hours, so don't worry about it.

Like Skinny & I already said the dealer likes to bury the engine. The Yamaha test bulletin shows they run at #2 so why not start there? I went from 1 to 3. Every boat is different.
You well might gain enough RPM to try a 17P

As to your diameter question I run the stock Yamaha 17P and the diameter is 14.5. But don't worry about diameter, your only concern is pitch. One caution, the 15P Reliance is not recommended for the F150.