More Prop Talk ......Ramblings of an Amateur!

[MarkS]

Subject boat = 1971 GT150 - 1978 Evinrude 115 V4 w/PT&T - Mission is to get WOT at 55-5600, with max SAFE speed. (Looking for 55!)

Starting point/baseline - 1st Prop - OMC brand 12 3/4 X 21P ALUM  - WOT 5400 @ 54MPH - Note: gets a little hairy over 53mph, nature of the hull design as I am told.

2nd Prop - OMC SST 12 3/4 X 21P Stainless (teflon coated) - *WOT 5200 @ 52MPH - Note: more left on the table in the speed, *chine walk gets too severe to continue.  Porpoising at lower speeds if trimmed above 1/4.  Probably going to be the fastest/best all around, if the set-up can be refined to control the boat at top speed.

3rd Prop - OMC Raker 13 3/4 X 22P Stainless - WOT 5100 @ 50MPH - Note: Too much pitch & bow lift, didn't like much if any trim, porpoise and chine walk prevalent, much better suited to CVX style hulls with pad.

4th Prop -  OMC SST II 13 3/4 X 19P - *WOT 5800 (pulled back, was still winding up!) at 48MPH - Note: not enough pitch, might be a good prop for heavy loads or pulling barges.

5th Prop - Power Tech PT03(?) 13 1/5 X 19 w/custom cupping and pitch added - WOT 5200 @ 48MPH - Note: Stern lift created by this prop gives a whole new "feel" to the boat, thought we had it here.  RPM and MPH just not where they need to be.

Back to props 1 and 2, with a Solas Amita 3 13 X 19P as a back-up/spare/emergency.  Will probably try raising the motor up another hole as suggested, and maybe add a Bob's True Tracker to help with stability.  All numbers posted from recollection, so please forgive me if they're not exactly as stated earlier.

Special thanks to David P., & Tim at Performance Props Inc - Soddy Daisy, TN.

[Rosscoe]

Great comparisons Mark. You just need some fine tweaking and you'll be "there".

[David CVX-16]

Mark, your efforts will pay off.

Sorry to hear that the Power Tech did not work out.

On Prop Number II, the 12 3/4  x  21 SST, was it the SST or SST II? It may be your best prop with more weight in the front of your boat.  

Might also try a OMC 2-blade bronze 12 3/4"  x  21" pitch, part number 38-4140 still sold new for around $130.

I have a OMC SST II 13 7/8"  x  21" pitch for sale for $140 but it probably has too much bow lift for you. Went around 52 1/2 MPH on the CVX-16 and I am selling it because the Rakers are faster. Let me know if you want to try it out.

Sharpen the blades of prop number one, the 12 3/4  x  21 alum. It probably is the same as the stainless steel version at a lower cost. It would be willing to sharpen the blades for you.

Wait for my Quicksilver 2-blade bronze 21" pitch matched to a Johnson hub to fail for me.

[MarkS]

Thanks Ross, just sharing in hopes it may help somebody else down the line...... I still have a few "rigging issues" to address, waiting for the fun money supply to recover some.

No worries David, I'm having fun trying them all out, and getting valuable seat time in a new-to-me boat too!

On Prop Number II, the 12 3/4  x  21 SST, was it the SST or SST II? It may be your best prop with more weight in the front of your boat.

Not sure David, it's a #0389512.  It's back in the box in my garage, I returned the PT prop and got it back.  I'm also thinking this will end up being the  one, after the rigging issues are addressed.

Might also try a OMC 2-blade bronze 12 3/4"  x  21" pitch, part number 38-4140 still sold new for around $130.

I've still got my eye on that one, we'll see how Santa treats me!  LOL

I have a OMC SST II 13 7/8"  x  21" pitch for sale for $140 but it probably has too much bow lift for you. Went around 52 1/2 MPH on the CVX-16 and I am selling it because the Rakers are faster. Let me know if you want to try it out.

My setup seems to prefer the 12 3/4" props, but I appreciate the offer.  Remember my motor is rated on the old "crank HP" system.  By today's standards, probably 90-100HP at the prop if I'm lucky.  I have trouble spinning the bigger props fast enough, and the torque steer is noticeably greater as well.  (Almost impossible to steer at high speed with any trim input at all!)

[David CVX-16]

Mark, your 12 3/4  x  21 is a SST II, double cupped. Do not know enough about Johnson props to give advice on the SST model.

Did PowerTech give you your money back?  It is really hard to find a better prop than the maker of the motor. Mercury has their lineup of Laser II, Trophy, Tempest, Fury, Chopper, etc. OMC has Raker, Renegade, SST, STX, etc. These props have been tested and tested in real life by the manufacturers of the motors and are matched to the power and torque characteristics.

Other prop manufactorers do not have the resources to test and fine tune a whole lineup of props. Power Tech must have at least 100 different props. I have tested two on the Glastron V-153 and was disappointed. But have seen good results from their props in prop tests, so it is a hit and miss situation.

[Hyperacme]

This just came up on CL ...

Evinrude Cleaver Prop - $200 (Twin Cities
http://minneapolis.craigslist.org/ram/boa/3481074910.html

[bellj]

Careful...that Craigslist Cleaver would be a stern lifter, which might be just the ticket for the typically bow light GT-150...but the one pictured looks like a solid hub racing type. Might work great (depending on your motor height) - but keep in mind that as a solid hub, if you hit something solid, you might take out your lower unit. Might over ventilate since it's over the hub exhaust as well - but depends on your specific setup.

Might be worth a try - if it could be gotten cheap enough or trialed first - but the solid hub is the scariest part in my mind. Racers rebuild lower units all the time, so usually not as big an issue for them.   

Did they have Cleavers with rubber hubs and/or thru-hub exhaust for your make & size engine? I know they did for Mercury (I have some - not your specific size though), but not sure about for Evinrudes (although I've heard of drilling some of the Mercury props to fit OMC shafts - I think one of my eBay "prizes" is like that).

Good luck.   

[Retro Performance]

If it does not sell it can be tested in the spring......I am selling off some stuff, this Cleaver was on my Carlson Challenger (sold) with the OMC........I have some other stuff for V4 omc as well.

Retro

[Retro Performance]

OMC did make a rubber hub/Thru hub Cleaver for the V6's it is known as SSTR, I have one on Craigslist Today. Otherwise as far as I know they were all solid hub.

[MarkS]

The 4th and 5th props came from Performance Props in TN, David.  Tim was kind enough to work with me on the search for excellence, they have a "prop swap" program.  When we were unable to improve the numbers from where I started, my original prop (the SST II) was returned to me and I was only charged one "swap fee" for the whole ordeal.  I remembered your statement from earlier about staying with the props the engine mfg. offers, and at this point would have to agree!

Thanks for the scouting Gregg, but Jim has a valid point about the solid hub (I believe) !  My home lake is notorious for semi-submerged junk floating around, my budget couldn't stand to take a hit on the lower unit.

I should have a better idea about this time next week where my "fun money" stands Don (Retro), I'd love to talk to you about whatever you have available for the Cross Flows.

[Hyperacme]

Was just reading your thread over on CGOA ...
I think our hull's are pretty close performance/handling wise.
The 2 blade prop was very smooth with out the torque steer of all the other props and came within a mph of the best.



My prop test thread ...

http://forum.cgoamn.com/index.php?topic=3265.0

[MarkS]

Thanks for the info Gregg, and you're right - very similar numbers there!  I'm kinda leaning toward getting it (the two blade 21P) to give it a try, we'll have to see how it ($) shakes out after Christmas.  There's a little voice in my head screaming "buy it before somebody else does!", but I'm trying to be a responsible husband.   

[dorelse]

...but I'm trying to be a responsible husband.   

The reason I don't have an interior in Goldie yet...LOL!