STV with a 250ho ETEC

[stv250]

Hi all

Was wondering if anyone could offer some advice please? I am pretty new to high speed boats I live in Australia and own a STV with a 250ho etec on it. I am having problems trying to find a prop to get it to do decent speeds.
The engine has the M2 gear case with 1.85:1 ratio. I run a Detwiller hydraulic jacking plate so can adjust engine height on the move. I have tried all sorts of props different diameters and pitches ranging from 28px141/2 diameter to 34px151/4 diameter at different engine heights and trims. The best prop I own for it so far is a 34px141/2 Hoss style chopper it runs 89mph on the gps and hits the rev limiter. The best speed I have seen on the gps was when I borrowed a 32px141/2 4 blade Et cleaver it ran 92mph and hits the rev limiter. I have just installed a nose cone to my gear case and hope that it might help. I appreciate any advice.


Cheers Chris

[FrenchPhil]

Hi Chris welcome aboard. You'll get lots of help here. How many STV's in Australia ? Any pics ?

[stv250]

Hi thanks

I know of 8 stv's that are here in Australia but would say there would be more out there. Will try to post some pics soon.

[patchesII]

You need more gear than a 1.85. Does OMC offer something in the 1.60's?

[Jimboat]

Hi all

Was wondering if anyone could offer some advice please? I am pretty new to high speed boats I live in Australia and own a STV with a 250ho etec on it. I am having problems trying to find a prop to get it to do decent speeds.
The engine has the M2 gear case with 1.85:1 ratio. I run a Detwiller hydraulic jacking plate so can adjust engine height on the move. I have tried all sorts of props different diameters and pitches ranging from 28px141/2 diameter to 34px151/4 diameter at different engine heights and trims. The best prop I own for it so far is a 34px141/2 Hoss style chopper it runs 89mph on the gps and hits the rev limiter. The best speed I have seen on the gps was when I borrowed a 32px141/2 4 blade Et cleaver it ran 92mph and hits the rev limiter. I have just installed a nose cone to my gear case and hope that it might help. I appreciate any advice.Cheers Chris

Hi Chris - what does your rig weigh?

[Chummy]

A cleaver would be your best bet

[baja200merk]

I have been 103 on a stock m2 case with a 15x34 et on rev limiter. You need to get your slip down. Do you have a torque tab?

we have converted a few to 1.62 sport masters and it's about the only way you can bolt on 15-20mph gain.

[SANTAFE]

Hi Chris. If you want to go considerably faster get a Mercury.

[Hot Shot Merc]

a nose cone with low water pickup will help you increase you're speed because you can get the prop shaft higher out of the water than you were previously. Please post your numbers after you try it with the nose cone and the prop shaft an inch above the pad

[speedinstream]

a nose cone with low water pickup will help you increase you're speed because you can get the prop shaft higher out of the water than you were previously. Please post your numbers after you try it with the nose cone and the prop shaft an inch above the pad

Yup what he said

[Hot Shot Merc]

I also agree that more gear is needed as well to try and keep off the limiter. What rpm is the limiter on that motor?

[baja200merk]

6250 limiter

the cone will help you but you will be able to put a 36 on limiter so your 34 will get there even easier.

[action1923]

Chris, my STV with a 250 E-TEC runs best with a 14.5 x 34 Mercury cleaver. You may want to look into running an L2 Lightning gearcase with a low water pick-up nose cone and a 1.71:1 gear ratio. They are getting hard to find as they are no longer in production. A Mercury Sportmaster with a 1.62 ratio also makes a good choice. Transom height is also crucial to getting the most out of that big Evinrude. Keep us posted on your progress and include some pics.

[montyman]

SANTAFE Really!!

[Michael J Giesler]

He could go an easy 125 + with a bump up rev limiter to 7300 rpm but that ship has now long sailed away post a picture of the boat it's nice to see go fast boats all over the world