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The one Dave is referring to is a Titus, the one I got from you is a Dwald

Thought so. So it looks like most of the better OMC race props are:
12 x 23 texas cut
12 x 22 thru hub full blade
12 1/2 x 21 either full or Texas cut
BETTER ADD ERIK'S 11 1/2 x 22 and 23 based on his weekend report.
That should help the new people.
Remember you can always re-pitch up or down 2 inches and you can always reduce the diameter. So you can make a 12 3/4 x 24 into a 12 x 23 etc.

Lesson #4 Motor Height …THE SWEET SPOT
One rule is the ability to alter the size and shape of the water pick-ups. You cannot relocate them, but you can change their size and shape. You can also run a nose cone. The nose cone rule is there so you can buy new lower units from Sea Way. These lower units are SST 60 and have a nose cone. Another rule is the prop shaft must be below the bottom of the boat. This is a safety rule which will be explained later.

You do not run the motor as high as you think. Most run with the prop shaft 3 to 4 inches below the bottom of the boat. The amount of setback, the boat and the driving style are all part of the equation.

Basic facts
[1] too high, you starve the motor for water.
[2] the higher the less trim to have.
[3] the higher the more you reduce the boats ability to turn.
This is the reason for the prop shaft being below the bottom RULE. The boat will not turn.
[5] the higher the more chance of blowing out.
[6] the higher the more chance of blowing over.
[7] the higher the faster on calm water and the slower in rough water.
[8] too low and the boat does not turn well. Watch a APBA VP75 race with the prop shaft 5 inches below.. NOT PRETTY!

THE SWEET SPOT is the perfect location where the boat works best for YOU!
A transom jack is an asset in finding the correct location.
A seasoned T boat racer can give you an educated guess.

Lesson #5 The relationship between RPM and Horsepower

The power head does not always have the same of maximum horsepower all the time.
The manufacturer’s show the horsepower normally where the motor reaches its highest level.
Example 70 hp at 5000 to 5500 rpm.
The range of 500 rpm is common. The maximum horsepower depending on the model will have a different rpm for the maximum. Example a 70CES Yamaha is 70 hp at 6400 rpm. A 50 Tohatsu is around 6000 rpm and an SST 60 will be about 7200 rpm.
The fishing motor at 4000 or 6500 rpm is not producing 70 hp. It is much less. Maybe 60-50-45 hp.
The T boat SST 60 motor would be 75hp at 6500 and much less at 4000.
Here is an important fact to remember. The higher rpm it takes to reach maximum hp. the less horsepower the motor makes at lower usable rpm ranges.
Let’s compare a T boat SST 60 powerhead to a T boat fishing motor 56 powerhead.
The SST 60 at 4000 rpm is producing 52 hp.
The finishing motor at 4000 rpm is producing 60 hp.
Remember the video in Lesson #1?
That boats corner exit speed was about 38 to 40 mph and approximately 4000 rpm.
If that was a T boat, what happens?
The fishing motor pulls the SST 60 motor off the corner and likely up to 60 mph.
It is producing more hp at the 4000 rpm corner exit .
The SST 60 will catch it depending on the length of time it takes to drive the straight.
It makes for GREAT racing in T because of the different characteristics of the motors.

So why does the boat go faster at rpms well above the motor is making the maximum horsepower?
Reason Drag or resistance. There is less drag at the higher speed, so the motor doesn’t require the same amount of horsepower to push the boat.

We have a lot of followers to this thread. I hope your finding it interesting.

First exam Question:
Both Larry and John, find their T boats are 25 pounds light. Larry puts lead shot behind the seat. John puts 25 pounds of feathers in the boat. Who had the better plan and why?
Larry or John?

And where exactly does John puts his 25 pounds of feathers in the boat and are they LOOSE ?
P.S. You guys rock, great info.
Mike

Can't tell if this is a joke or not haha, but fo r the fun of it here we go.
But john could distribute the 25 pounds of feathers throughout the boat to wherever the weight is needed, and larry's 25lbs is stuck behind him, possibly making it harder for him to air out?
(multiple choice is my favorite)

it doesn't matter what you use as long as cog stays the same!and is adjusted for a 25lb. heavier boat!

Larry, has the better idea. If the weight doesn't work in that position it is easy to move a small volume item to a different location in the boat. Also the weight is lead shot so he can could put a small amount of weight in a number of places. John has alot of problems. First think the the amount of space 25 lbs of feathers would take up. The feathers could fill the boat and there maybe no space in the boat for John. Even if you compressed them they would take up alot of space and limit your options. So the big advantage is MORE OPTIONS!
There are several racers building or restoring T boats this winter. If you can build the boat strong and keep it a bit light then you have more options when rigging the boat on where you can distribute the weight.
It is very difficult to take weight out of a boat after it is completed and rigged. People in general put on body weight with age. It is far easier to diet off 20 lbs that it is to take 20 pounds out of the boat without structure weakness. Remember the lesson about weight position in the T boat? Weight in the front half affects the boat 3 times greater than weight in the stern. Unlike other stock outboard class where the driver shifts his weight, the T driver sits in a seat in the front part of the boat. You could spend thousands of dollars on the powerhead to gain 2 miles an hour. You lose 20 lbs and get the same result. Plus better boat handling and you look and feel better.

PROPS REVISITED
I got some e-mails from people who are very surprised at the small diameter 11 1/2 to 12 props the racers are running and the 66 to 68 mph speeds at 6600 to 6800 rpm.
Remember what was said in the lesson on props. Pitch on the inner part of the blade and smaller props working better in calm water.
So before you go out and cut your prop down to 11 1/2, remember the rest of the lesson.
Also remember that for a fishing motor 6800 is a very good rpm. The porting characteristic is just about at the max and the horsepower drops quickly.
Erik is testing not racing. The water conditions after lap 2 are very rough. An 11 1/2 diameter prop is not going to work great in the rough. The motor is going to rev, but not get proper thrust from the prop. It just cannot hold the water on the blades. A 12 inch prop would work much better in the pack. Especially pulling out of the corner where you need bow lift to accelerate quickly. Talk to a Yamaha racer. They have this problem because there are limited options with the Yamaha. They can run a 22 x 11 to get the 65 mph speed they need. However, the 11 inch diameter hurts them coming out of the corner. Their only option is to go 11 1/2 or 12 diameter to get punch out of the corner. Soon as they go larger diameter. they must reduce the pitch down to 20-19-18 to get the torque. The smaller pitch takes away the top end. You need a very extreme set-up to run a Yamaha 65 to 66 mph with an 18 x 12 pitch prop. But you will accelerate out of the corner with the best of them.
IMPORTANT NOTE!
A 12 to 12 1/2 prop can still provide the same performance in calm water and work well in rough. It is all about the design of the prop.