Yamaha F150: Raise motor or different Prop?

[erickrwill]

I have an 04 Yamaha F150 on a Lund Fisherman 1800 and running a 21p Pro Series prop. When I trim it up and the steering feels "even", I'm at 5400rpm (47mph-GPS). I can trim the motor up more to 5600rpm (50mph-GPS) but the steering is very hard to steer. My motor is mounted on the top hole. Just wanted to know if I should raise my motor or should I go to a 19p? Any help would be appreciated. Thanks.

[PJM]

Erickwill

You are in the operating range of the motor but on the low side. If you went to a 19p your hole shot will be better and it should improve your fuel economy. You want to try to get your rpms closer to 6000rpm running wide open. Are you testing your boat with a full load?

[erickrwill]

PJM
This was with my normal load of 2 people, gear and a full tank. I've read that by raising the motor its supposed to increase rpms...but by how much?? I would like to get the optimal speed when the boat is easy to steer...not sure if that would happen by raising the motor. Any suggestions for a 19p Prop? -Thanks

[Johnnielund]

I have a Lund 1700 Explorer tiller, powered by a 75 hp Evinrude E-Tec. I was mounted on the second hole down from the top. When I trimmed out for max RPM at WOT, my boat handling became very squrilly (unstable). I was advised to go up one hole. This required less positive trim angle to achieve max RPM. The line of force from the prop was more parellel to the surface of the water, resulting in less drag and better handling. In short, I wound up with a totally different boat at WOT. Much more stable and better overall feel. I would go up untill you start to cavitate. Then start to play with your prop, to get your WOT RPM up close to 6000. You don't want to lug that motor. Also, would not be a bad idea to install a water preasure gage.

[walfshmn]

. Also, would not be a bad idea to install a water preasure gage.

I have a water pressure gage on my boat and don't know how it would help in getting the right prop or right height. How do you read these?
What should the water pressure be with the F150 on the 1800 Fisherman at 6000rpm?
Is there an optimum water pressure I should be looking for?
I don't want to high jack this thread but thought I would ask these questions as I don't know how to get the most benefit from a water pressure Gage.
Thanks.

[KP]

Each hole equates to 3/4" and approximately 100 to 150 RPM change. So if you are turning 5600 Max RPM now, raising the motor one hole will increase your RPM to approximately 5725. Two holes...5850 and so on. But that is based on the load you had.

Your motor should be turning as close to 6000 RPM as possible when it is just you in the boat and maybe a 1/4 to half tank of gas. Each 150 to 200 pounds of people, gear, and/or fuel added will equal approximately 100 RPM decrease. So if you were turning 5600 with two people, some gear, and half tank of gas, the RPM's would probably be around 5800 with just you in the boat.

I'd suggest raising the motor one hole and see how that does. You could also go up two holes right off the bat but I would not suggest going and higher than that on that rig.

[T Mac]

I have an 04 Yamaha F150 on a Lund Fisherman 1800 and running a 21p Pro Series prop. When I trim it up and the steering feels "even", I'm at 5400rpm (47mph-GPS). I can trim the motor up more to 5600rpm (50mph-GPS) but the steering is very hard to steer. My motor is mounted on the top hole. Just wanted to know if I should raise my motor or should I go to a 19p? Any help would be appreciated. Thanks.

Try Raising first (steer torque will diminish some)
Raised up....into 3rd hole usually works best on that boat/motor.

Also...I'd recommend a Merc 19 Tempest prop on that rig.
(You need more rpms).



I sold and delivered a lot of 1800 Fishermen w/ Yamaha F-150s.

[clarkend not logged]

I have an 1850 Tyee and a F150....I am running a 19P Tempest but can hit my rev limiter....I need to try a 21P. FYI - My max speed with a regular load is around 42mph GPS.

Clarkie

[TomP.]

Johnielund hit the nail on the head and was given great insight.

" I was advised to go up one hole. This required less positive trim angle to achieve max RPM. The line of force from the prop was more parellel to the surface of the water, resulting in less drag and better handling."

By rasing the motor this is where the speed comes from less drag by having to USE LESS TRIM. When raising the motor one needs a prop desighned to run close to the waters surface. Rake of a prop is what enables this or number of blades.

[axual funkshun]

Johnielund hit the nail on the head and was given great insight.

" I was advised to go up one hole. This required less positive trim angle to achieve max RPM. The line of force from the prop was more parellel to the surface of the water, resulting in less drag and better handling."

By rasing the motor this is where the speed comes from less drag by having to USE LESS TRIM. When raising the motor one needs a prop desighned to run close to the waters surface. Rake of a prop is what enables this or number of blades.

Less drag is good.
You raise the motor you get less drag. That is good.
But to get more speed you need to get more boat out of the water. That means more trim, not less. The fastest props on typical V hulls are the ones that allow you to trim higher.
The rake of a prop can help with speed. Higher rake will give best speed, lower rake, more power.
Higher rake teamed up with some cupping on a progressive pitched prop should work best for most walleye boats.
Mercury Tempest Plus props have all of these attributes.

[DaHunt]

I have the same set up 2005 Lund Fisherman 1800 with F-150 Yamaha motor.
I have tested 7 different props so far on this boat and my best prop so far is the Ballistic 19pitch.
This is for speed , the boat as follows:

Full tank of fuel 40 gallons
1 person-200 lbs
3 batterys - 1 rear 2 foward
T-8 Kicker motor
70 #s of gear
less than 1 foot chop
3 seconds to plane out
53.5 MPH by GPS 6000 RPM @ 16.5 Gallons per hour fuel usage
Lowest planing speed 20 MPH@2800 RPM , 3.2 GPH Fuel usage
@35 MPH 4200 RPM 6.8 GPH fuel usage.

I tryed a Yamaha 14 1/4 x20 and its best was 51.6 @ 6000
so I would recomend staying with a 19 pitch, the 20p was slower out of the hole.

Note: I have not tryed the 19p Tempest prop yet that T-Mac recomended but it is on my list!

[erickrwill]

DaHunt,
What hole is your motor mounted on?

[Hot Runr Guy]

I have the same set up 2005 Lund Fisherman 1800 with F-150 Yamaha motor.
I have tested 7 different props so far on this boat and my best prop so far is the Ballistic 19pitch.
This is for speed , the boat as follows:

Full tank of fuel 40 gallons
1 person-200 lbs
3 batterys - 1 rear 2 foward
T-8 Kicker motor
70 #s of gear
less than 1 foot chop
3 seconds to plane out
53.5 MPH by GPS 6000 RPM @ 16.5 Gallons per hour fuel usage
Lowest planing speed 20 MPH@2800 RPM , 3.2 GPH Fuel usage
@35 MPH 4200 RPM 6.8 GPH fuel usage.

I tryed a Yamaha 14 1/4 x20 and its best was 51.6 @ 6000
so I would recomend staying with a 19 pitch, the 20p was slower out of the hole.

Note: I have not tryed the 19p Tempest prop yet that T-Mac recomended but it is on my list!
DaHunt,
As long as you've done the write-up, why not add it to the "what are your numbers" thread?
http://www.walleyecentral.com/forums/showthread.php?t=146839&page=3

HRG

[jcfishing]

I would try the Tempest Plus 19" pitch first. See if you can find a dealer who has one. Some will let you try them before you buy. Your RPMs should be right around 6k with a moderate/medium load. Going to the 19 Tempest will bump up your RPMs and due to the design of the prop, it should also provide a modest speed increase. It will also provide a more suitable RPM range when trimmed for equal steering. Your hole shot and time to plane will improve as well. In order to achieve max performance, it may be a combination of prop selection and raising the motor, but I would get the prop selection figured out first.

[DaHunt]

erickrwill,
Sorry about not posting this quicker, Real busy time of the year.
I looked through all my photos of when I bought my boat and found a picture of it . I will try to post the pic but just in case it is the 2nd hole from the top. I Also tryed two 4 blade props , a yamaha 20pitch max speed 50.7 MPH @ 5600 RPM and a Michigan wheel 18 pitch I didnt even record the stat's on this one, from what I recall it would only do in the high 30's and not much quicker out of the hole. I bought it for the BIG lakes and large loads in the boat but do not like it so far. This prop also cavitated easy in big chop going straight!
My search for a 4 blade is still on so if you find a good one let me know!

[DaHunt]

WOW! didnt think it would turn out so small, when posting it said attachment so I thought it would give you a link to click on to get to a full size photo.
If you want a full size pic. send me your E-mail address and I will send it.
Dave.