ABC 1515 for 20 Stock Tunnel

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Jerry Dunlap

Well-Known Member
Supporting Member
Joined
Apr 1, 2002
Messages
4,068
I had an opportunity to test a Mark Sholund ABC 1515 on my stock O.S. 21/ VS1 today. I had previously been running an ABC 38 mm dia. prop that worked very well. Using my "Eye Ball" radar, the 1515 appeared to be a little faster. Most noticeable was the solid ride attitude of the boat. The water conditions were flat, 60 F, 60% fuel, same needle valve as last run, and no changes to prop height/thrust. The 1515 allowed the stock O.S. to unload. Very pleased with this prop.

The picture shows the prop I was running and info on the ABC 1515.

JD
 
Jerry,

I have the older 1515-17 degree rake and 45% blade area for you to test

next week. It will be interesting to see the difference of 7% more blade area on

your O.S.-21 outboard set up?

Wish we had the numbers on the ABC 40 X 53

to compare the two different rakes and blade areas?

Thanks For Sharing With Us All Jerry,

Mark Sholund
 
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Carl,

You just cut out some of the trailing edge cup so it will

Rev Easier. A lot of the performance depends on the load

you place on the engine. I have found some very good results

with less cup on some of the newer ABC propellers. The newer

19 degree rake and 38% blade area propellers have less cup in

the trailing edge now. These will work well on higher rpm engine

set ups.

Mark Sholund
 
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I have try the 1515-17 45 deg prop on a stock 21 OS and it is to much blade.I have ground out some of the trailing edge pitch and still to much prop.

Dave
 
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I have try the 1515-17 45 deg prop on a stock 21 OS and it is to much blade.I have ground out some of the trailing edge pitch and still to much prop.

Dave
I have try the 1515-17 45 deg prop on a stock 21 OS and it is to much blade.I have ground out some of the trailing edge pitch and still to much prop.

Dave
It will be interesting to see what results I have. The stock O.S. 21 likes props that let it "buzz."

JD
 
Jerry,

I have a few other ideas also.

Just waiting for them to arrive?

Thanks,

Mark Sholund
 
Jerry- I am not sure if you are running the water cooled or air cooled engine. It is our observation that Air-Cooled O/S with the muffler extension spacer will pull more prop through and off the turns than the original water cooled version (as an out of the box engines go) but I am not sure that they rev quite as high on the end of the straights as the short muffler does. The drawback to the air-cooled engine is that its life span of the piston / liner is a bit shorter but well worth the added performance gain if you cant change anything and are stuck with one version or the other. Here in the South where summer days can reach 100+ degrees, the out of the box air-cooled version can cause over heating issues if you are not free wheeling your prop. I am not sure if you guys are allowed to restrict the water flow in your "NAMBA stock" engines but if not but if I Lived in your area I think I would run the air cooled engine in the winter and the water cooled version in the summer.

For running IMPBA in the south, the water cooled head with the muffler spacer with a simple orifice controlled water cooling is probably the best combination year round.

Mark- Another thing to consider when comparing how much prop the O/S engine will pull is how high the hull you are using will allow you to run your prop and still stay on the water and also turn properly. With the small engines, this is a huge advantage because (as you mentioned) they develop their performance through RPM.

For the guys who always run the same setup and the same prop, If you want to take advantage of these new ABC props, you will have to do the unthinkable and change your setup! These props will not work without changing something. Plan to spend the day at the pond doing nothing but working with your setup and give these new props a try. They are fast props!

-Carl
 
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Carl,

It is hard to convince someone to change their set up?
default_ohmy.png


These propellers with more rake will lift the transom less than other propellers.

So to keep the ride angle of attack correct you will most likely have to set the

propeller a little deeper into the water to get the same ride angle of attack that

you had with the other propeller. These propellers just have different : blade areas,

pitches, and diameters that we never have had in the past. We need to thank

Jim Schaefer at ABC Propeller who is responsible for giving us these better options.

Testing is the best way to learn about these newer design changes and how they

respond to your particular set up?

Thanks For Reading,

Mark Sholund
 
Our pond is only 130 feet above sea level and our water is better than most places we go. That probably has a lot to do with what we can pull verses what someone up north can pull.

-Carl
 
The rain and wind finally let up allowing a day of testing. Frank Ward, of Wardcraft Deep Vees for you veteran model boaters, brought his VS 1 and JD WOF 29 to the test session. We ran both boats with the props that had been working on the boats and then tried each boat with the 1515 19Rake, 38% Blade. Each boat was noticeably faster with the 1515. The O.S. on the WOF was water cooled with the larger muffler, like Carl mentioned in the previous post. I've watched that WOF 29 run for 4 years and never seen it go as fast with a stock motor.

I did try the 1515 R17 45% blade area on my VS 1. Without making any adjustments to the motor height/prop thrust angle, the motor wouldn't unload and the ride was not as smooth as the 1515 19R, 38% BA. I didn't attempt to make adjustments to the motor because I had a Sport 20 I'm setting up for a new model boater that needed much more attention than the VS 1. Time permitting after our race next Sunday, I'll try the 1515 R17, 45% BA and make motor adjustment.

JD
 
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