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1988 13' Super Sport
2000 35hp 3cyl Johnson w/trim tilt & oil injection Mounted 2nd hole....
Rated RPM= 5200-5800
Whale Tail installed

New to me boat W/no history

Took it out today and it only did 26mph GPS @ 6000 RPM (Light load just me and 2gal of gas) 14p 4-Blade Aluminum prop (Engine gear ratio 2.15:1)
I assume that the whale Tail is loosing a few MPH but if the tach is correct it does not make much sense.
It jumps on plane in 2 sec and runs very smooth..
There is tons of info available for the 2cyl engines but nothing on the 3cyl.... It is geared like the E-tec and has tons of power..
Any ideas on a prop to get closer to 32-35mph?
My thinking tells me that a 16 ish pitch would get me close but that just seems crazy for a 13'

Video of it running https://drive.google.com/open?id=0B8w...zB2ZHl2alU
Sorry I can't figure out how to insert it into the post.. It doesn't list what format will work....

Thanks...

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Members have learned that prop size and performance are not universal across brands.

Why the 4 blade? They are good for quick time to plane and heavy loads (like pontoons).

If you are looking for speed, change to a 3 bladed stainless steel prop. If not, go with the same make and model prop you have with 2 more inches of pitch.

If the engine is mounted up 2 holes and you get the right 3 bladed prop I would not expect you to see more than 32 mph with a 35 hp motor.

If you raise the motor to be dialed in, you will gain ~150 rpm's at WOT for each hole up you go so do that first.

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Your numbers work out to 30% slip, which is a crazy value - mostly it's around 10. You've either got a ton of drag or something else is going on we don't know about yet. Try taking the whale tail off, and clarify what height the motor is mounted at - maybe if the whale tail is buried deep the whole time, that's causing your drag.

Is the prop itself in decent shape?

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The motor came with the 4-blade (don't know why) I did some reading and came across someone saying that for the 3cyl motor the recommended prop was a 4-blade. There is not too much info on them!
The installed prop is also new.
The motor is mounted slightly above the bottom...

I am going to remove the tail and give it a try. I don't need it to be crazy fast but 26 with the boat empty and flat calm just didn't seem right. It's crazy that the 2cyl motors tend to turn 13p and the 3cyl seems like it could turn 16p and still be in the RPM range...
Thanks..

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Winter is over and I took it out for a spin!

Removed Whale Tail....
New prop= 15p stainless 3 blade Solas
RPM @ WOT = 5900-6000
Speed= 30mph (trimmed up)
people= 350lbs Me+2 kids
Hole Shot= Instant!
I assume the boat is not waterlogged...I can move the ass end while on the trailer easy...

I am fine with the speed but 30mph (GPS) seems slow compared to many other posts I have read. Is everyone lying or do I have something wrong?

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You are overrevving and if I remember the power curve pictures, two-strokes drop off in power pretty quickly after redline. So I'd be inclined to go up a couple of inches in pitch and see how it goes.


Tim

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When exceeding the WOT range, you are underpropped.

You need more blade pitch. Staying with the same make and model, move up to a 17" pitch.

I would also experiment with raising the motor one hole. You will gain RPM as well. Run the new prop BEFORE raising.

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Do the two cylinders have the same gear ratio as your 35? If the lower unit ratio is different, it's not surprising the motors would need a different pitch.

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The gear ratios are slightly different so I expected to run a slightly higher pitched prop.... 40hp 2cyl OMC outboards seem to run 13-14p aluminum props... This 35hp is spinning a 15p stainless @ 6k! With no problem getting on plane....
It doesn't look like anyone makes a 17p for this motor!

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You are comparing apples to swiss cheese. Propellers are made for gearcases (lower units), not cylinders.

Sizing is not universal across manufacturers or even between models. Some models are offered in even pitch sizes, while others are in odd sizes. A prop of the same size from two different models or companies will not perform the same.

There are 4 elements to a propeller: Diameter of the prop, pitch of the blades, number of blades and prop material (aluminum vs stainless steel).

Given the limited information on the late model Johnson 35 (they changed gear case ratios at some point) I would consult a prop guru.

One respected prop source for Boston Whaler owners is Ken at Propgods. He has provided many owners with spot on advice. Tell them we referred you.

http://www.propgods.com/Content2/Defa...fault.aspx

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Just to update the post for future reference....
I raised the motor to the 3rd hole and added transom wedges (T.H.Marine Reverse Transom Wedge TW-3-DP) to gain more trim angle.
33-34 MPH (GPS) @5900-6000 RPM.... Instant hole shot!