Yamaha 55AE Prop Size Please

[John]

Hi all,

Can anyone help me with finding out the size of prop or what the correct size should be.

Bacically i need to find out the right size prop for my 2 stroke 84/85 55hp yamaha engine with through prop exhaust.

I brought a boat which came with the engine and from the start we had problems with it. First we were told that it would cost £2000+ to replace the gear box. I didnt like the sound of that so i personally stripped the gearbox freed up the prop (coz thats all that wrong) brought 3 new fiber washers for £1.80 and run fine. Just had a service and was told that the prop is the wrong size.

He told me to ask a yamaha dealer but all the ones i ring nd contact either dont answer the phone or dont reply to emails so was wondering if someone here could help me.

I need to find out the prop size of my Yamaha 84/84 55hp 2 stroke. model numbers are as follows:-

> Yamaha 55AE
> 663 L 30043

I know these are european models but i'm sure that the prop size would be the same as most other 55hp size engines.

I have just brought a prop from ebay which is a 11 3/4 x 12. Dont know if its right but i though id try it.

If anyone could help i would be very very grateful.

Many thanks in advance.

John Ewing

My email address is budbecks@aol.com if anyone can help me.

[Ken]

John,
The prop size (pitch) will depend on the load the motor is trying to push. You want the rpm to fall within the max recommended range at WOT and the motor trimmed out for max speed. I believe the max rpm range for your motor is 4500-5500 rpm.
An ideal prop would put you at approx 5000.
If the hole shot is more important to you than max speed, then you want to go down in pitch to give you max rpm of 5500. Conversely, if max top end mph is more important, then you would go up in pitch.
Good luck [img]smile.gif[/img] ,
Ken K

[John]

Hey ken,

Thanks for the reply.

I took a visit to boat-props.com and found out a lot of info about props and what the difference is and like you say it all depends on what its pushing.

I have a 17 1/2FT pilot dory/wilson flyer. we normally take 4 onboard wihch is pretty heavy really but then the engine is no different with 1 2 3 or 4 people.

I dont have a rev counter yet and am looking to buy one right now.

I just wondered. is there a standard size for engines, or are these purchased seperatly when buying a new engine. This is all new to me and any info would be good.

Thanks again.

John

[Ken]

John,
When you buy a boat and motor from a dealer, they usually have an idea of what prop to use.
But the best test, though, is the one I've already discussed.
I can refer you to a prop expert - you can find him on another forum - go to www.maverickboats.com and link over to the forum and look up Marcus, aka "funky monkey" - he is the Power Tech prop rep in Louisiana and he really knows his stuff. You can e-mail him and tell him what boat you have and model outboard and "normal" load, and he can come up with a prop that will get you pretty close to max performance.
Good luck [img]smile.gif[/img] ,
Ken K

[John]

Hey Ken,

Thanks a lot for your help and i guess its just trial and error until you really know which prop is the right prop. I have 3 different props now which are all different sizes for me to test.

I'm gunna head over to the other forum and find 'funky monkey' who could hopefully save me a lot of time and effort.

Thanks again for your input.
John

[hkps1]

I'm going through the same thing with a 50 HP. I have tried several pitch changes. I also have tried several blade types. Each change, pitch and blade type, have made choosing the right one very interesting.
I have just purchased a 10 3/8 X 12 round ear blade made by Power Tech. Their same prop in a 14 pitch was only spinning up to 4900/5000 but was very good. I also tried a Balistic in a 10 1/8 X 13. This prop over reved by about 750 RPMs. It is a simi cleaver blade design.
Oh.. These are being used on a 2000 16'Express alum. bass boat. I'm guessing loaded, full fuel and two batteries, weight is around 1150-1200 pounds.

[John]

Hey thanks for the info.

It looks like i am not going to be able to try my props till next year as the weather is too bad.

But at least this give me plenty of time to get a collection of blades together.

Thanks again
John