First time out w/21' Daytona V drive

[Unchained]

Thanks for all the feedback.
SD, I asked the friend with the 21' Cougar V-drive about the 2 blade and he has one but he said it vibrated so bad it wanted to shake the gauges out of the dash. He's the guy who got me started down this path.
Maybe he didn't have the right style two blade it wanted ? How many variations are there in two blade props?
He doesn't have a trans so his prop requirements are probably different ?
Kurtis, I'm guessing there's some cavitation when turning sharp and that's part of the vibration.
Going straight it cruises pretty quiet and vibration free.
I did put my hand on the gearbox and it feels cool and smooth.
I need some more seat time to figure out what's the norm here.

[Marty Gras]

How deep is the prop center in respect to the sponsons? Often the prop will 'pull in air' just going over a roller, so if it has more "smooth running" than "rough running", you don't have a problem. Unless something is loose! 12" prop seems large, but the prop center may be out of the water at speed (surface piercing). 600HP should be able to turn the 18's at least 5500RPM's with that airplane prop, look at your tune up. I have always put strakes on the outer sponsons of those boats, the center is where the load is riding and the outer angles have no lift, just drag. Does it turn well, above 40MPH without the fins? What is the shaft angle? Where is the motor mounted? The V-drive? At least you got to go boating!

[MAXIMUS]

Have you tried to contact Infomaniac. He seems to have his boat very dialed in. There should be some good similar traits there!

[Unchained]

How deep is the prop center in respect to the sponsons?
**About 7" **
Often the prop will 'pull in air' just going over a roller, so if it has more "smooth running" than "rough running", you don't have a problem. Unless something is loose!
** The prop shaft clearance is real tight in the strut and the whip strut**
12" prop seems large, but the prop center may be out of the water at speed (surface piercing). 600HP should be able to turn the 18's at least 5500RPM's with that airplane prop, look at your tune up. I have always put strakes on the outer sponsons of those boats, the center is where the load is riding and the outer angles have no lift, just drag. Does it turn well, above 40MPH without the fins?
**It turns real well, no problem. There is some cavitation in a sharp turn.**
What is the shaft angle?
** 7 1/2 - 8 degrees from the keel **
Where is the motor mounted?
**25 1/2 " from the inside of the transom to the front of the cylinder head, about as far back as it will go and still have good access to the water pump. **
The V-drive?
**The Casale box is right between the front seats. **
At least you got to go boating!
I swapped the blower pulleys and took it out again today.
Makes about 4# of boost w/9% OD. Better performance but a lot louder.
This is going to take some fine tuning.
It's certainly a different boating experience than the jet boat.
Pros and cons.
Not in the same league as far as performance.
I am going to try some different props.
Thanks for any input.
Mark

[Marty Gras]

Prop centerline is 7" below the outer sponsons? It rides smooth 'cause it is riding on the power. They tried to 'load' the motor with the "airplane prop" instead of going up on the gears. You will find that the boat 'needs' a 3 blade to keep it up out of the water (surface area) because the outer sponsons have no strakes. I would get the motor to run well, then put 29% or 32% gears in the box. Try to borrow a 11 1/2 x 16 three blade, and 'let 'er rip'! Please don't use ANY bronze props EVER, as they will not take the power. You can run your 12" prop, but it will need to be very far forward of the optimal prop placement. Where is the prop in relationship to the #2 & #4 cylinders? Is the prop directly under them? Is the motor forward of the strut?

[Unchained]

Marty Gras,
From the back of the prop to the front of the rudder is 10.5 ". From the back of the prop to the back of the transom is 14". The motor is about right above the strut.
The guy I know with the 21' Cougar runs a smaller prop too but still a three blade. I think he runs 35% to 40% gears with no trans but has about 1000 hp turning it.
The prop centerline is 6 3/8" below the keel at the front edge and the outer sponsons are about 1" above the keel.
I don't know much about props but I feel this one loads the motor down too much.

[Kurtis500]

I'm in the dark as to what prop would be perfect here.
Is that usually a trial and error thing ?
It has a 12 x 16 three blade stainless and 18% OD gears.
It just feels like the motor can't get on top of the prop.
BTW, how heavy is the boat? 18% over gears with a blown motor that cant get it going??....... it does sound like there is a problem somewhere. A lot of heavy daycruisers can pull that and much more.
With just a small adjustment by Dallas at Menkens to my 3 blade cleaver, I picked up 13 mph and .5 in e.t. alone.

[DEL51]

I would look hard into converting it over to a jet boat. J/K. Is this still in carburetor config. It is a different engine, have you checked out the timing, ie ford retard on the cam. Cam timing is crucial on the ford BB.Are you sure this thing is making power? By the way, yu need to come to Shawano with the jet this summer. We want some competion for the fast OB's, And flattie.

[Unchained]

BTW, how heavy is the boat? 18% over gears with a blown motor that cant get it going??....... it does sound like there is a problem somewhere. A lot of heavy daycruisers can pull that and much more.
With just a small adjustment by Dallas at Menkens to my 3 blade cleaver, I picked up 13 mph and .5 in e.t. alone.
The boat doesn't really feel heavy, It gets right up on plane and airs out immediately. I'm convinced the prop dia is too much. I can borrow a 11 1/2" three blade and a two blade to try.
Chris,
The carbs are still on there and I'm working on the tune. I'm questioning the cam too, My experience with Fords is the cam more resembles a piece of bar stock than a bump stick.
I'm a lot more familiar with chevy's where their "born to run".
That meet in Shawano may be do-able for me.
What are those dates ?

[VD CRUISER]

I don't know if the prop requirements are the same for a tunel hull as for a v bottom, but my Howard cruiser always performs better with the smaller dia props. I have used as small as a 11 1/4" X 16 two blade, but of course it takes off better with a 11 1/2 or 11 3/4. I use the small prop with a lot of overdrive,(48%). Three blade will be much smoother, but not as fast. More boost might wake that Ford up.