Correct prop for new boat?

[GLXMAN]

What is the best procedure getting the best prop for a boat and motor size,
Mine is an Allison 4.95 with 60hp Merc 4s
Regards,
Gary

[Fed]

First get a tacho Gary.
http://www.tinytach.com/tinytach/index.php

[GLXMAN]

First get a tacho Gary.
http://www.tinytach.com/tinytach/index.php

Hi Fed,
I have a Merc tacho that came with the installation,
Now the motor has been run in, I get 5500 easy,
Hole shot is slow, takes forever to get on the plane, then wants to go too fast

I've heard that a wrong prop will also "overload" the motor so not sure which way to go,

Dealer said just try a few of my mates props out? They haven't needed or bothered any way

Might have to give Solas a ring I guess
Regards,
Gary

[bassfan]

Hi GLX, I have an Allison 4.95 too and am very happy with it but also feel that the dealer fitted prop is wrong for the boat/engine. Your 60 hp 4 stroke is IMHO, a bit on the small side for your boat, and generally 4 strokes should rev out to about 6,000rpm. If your isn't then you may need a smaller prob or pitch. My vessel has a 90hp e-tech outboard, and wont rev more than 4,500rpm (2 strokes should do 5,000 rpm) which indicates to me that it is also overproped. I have heard the Solas props are very good, but they don't come cheap. Good luck.

[GLXMAN]

Tks for the info Bassfan,

I can actually get to 6000 but bit afraid to rev it out too hard,
I usually sit on around 4200-4500
The 60hp 4s Merc runs extremely economical at the above revs
Its just getting up on the plane is vey slow
Regards,
Gary

[Moonlighter]

Hi Gary

The recommended rev range for a 60 Merc is 5500-6000 rpm, so it won't hurt it pulling 6000.

There are so many props around these days and 4 strokes are notoriously hard to prop.

The correct procedure is as follows:

1. Make sure your engine height is right. The plate above the prop should be just skimming the surface or water just splashing over it when you are at a decent cruising speed with normal load and trim position. There is no point at all playing with different props until the engine is set at the right height. So get this right first!!! Whilst it sounds like your engine is hitting the right rev range, if it is set too low the extra drag on the leg can really stifle acceleration and speed, and many engines are in fact set too low on the transom. You would be reall amazed at the difference lifting the engine up one or two holes can make.

2. When engine height is right, do a test to see what max rpm you are getting. Find a smooth straight bit of water somewhere. If you are near the max rev range for your engine, you are probably not too far off the right prop. From a standing start, record your speed every 500 rpm until you are flat out with engine trimmed as far out as it can be before the prop loses grip. The rev limiter will protect from over revving.

If the speed onto plane is still ordinary then send the data youve recorded to Steev at Solas and he will advise you on props.

Did I mention step 1 - get your engine height set right first before messing with props? Do nothing until you've sorted that!!!!

Cheers

ML

[bf90]

Garry, moonlighter is right on the money all the way!!!! Solas is the way to go!!! . Steve at solas is a true gent, as I had a 2 year old stainless from solas, I fitted my motor to a bigger boat so the current prop was to tall, took it to steve at solas and all I had to give him was $100 and my old prop and I got a spanky new one which is spot on for my boat. I pull 6200 rpm full noise and I am running a honda. cheers. Brad

[GLXMAN]

Much appreciated ML,
I always wondered about the height as I used to do a lot of ABT comps and always heard the guys "banging on" about motor height but never got a satisfactory answer

I'm pretty sure your on the money! The motor cavitation plate is a bit low,
Will check how low next time out,
Tks again,
Regards,
Gary

[GLXMAN]

That is great news Brad,
Will have a chat before I move the motor
Tks for the heads-up on Solas
Regards,
Gary