Sub-surface prop for a .45 mono

[Kez]

By sub-surface, I mean the center line of the shaft being 1/2" below the vee. What would be a good Octura prop to start?
I have a X548 on it right now. I am surprised the old P-45 is asking for more! The prop at 1/2" below the vee should be putting more load on the engine. Since the P-45 is really screaming, I want to load it up a little. Would a X-450 be too much prop? How about a Prather 235?

Thanks,
k

 

[FloridaScaleBoater]

X450/3 should do ya right

 

[Wasted wages]

try bending a little cup into the tips of the X548 yet ??

 

[Kez]

Hi Rick, I have a X450 and I am planning to try that next week.

Hi Frank, i do not have the tool nor the skills to cup a prop. I can sharpen and balance my own props quite well. I will leave cupping to the pros. The x548 appears to have smaller blade area than a 450. But the former has more pitch. Not sure if it will load the P-45 properly. I am really surprised at 1/2" below the vee, that the P-45 can swing that much prop and on 25% nitro.

k

 

[FloridaScaleBoater]

I think your X548 is actually a Y548 which is a X448 with 10% more pitch
Back in the day, on a subsurface drive mono, the X450/3 was the "go to" prop
If you don't have a 3 blade, you may also want to try an X452/2 blade

 

[shoboat]

Ken,

That Picco should have no problem pulling an X-450/3.
They are still really good engines if you take care of them.
The old Picco‘s always had plenty of torque. You will get
a nice smooth ride with the three blade as well.

Have Fun Testing,

Mark Sholund

 

[Kez]

Hi Mark, at 1/2” below the vee, wouldn’t the prop put more load on the engine? I use X450 and X648 on a sport 40. And I automatically reach for a smaller prop in a sub-surface setup. But I will try a 450 next weekend

The X548 has more pitch than a 450. So I can expect slower top speed. Correct? Is it possible for a lower pitched prop to go faster because of increased efficiency and reduced slippage?
Thanks,
K

 

[Wasted wages]

Hi Rick, I have a X450 and I am planning to try that next week.

Hi Frank, i do not have the tool nor the skills to cup a prop. I can sharpen and balance my own props quite well. I will leave cupping to the pros. The x548 appears to have smaller blade area than a 450. But the former has more pitch. Not sure if it will load the P-45 properly. I am really surprised at 1/2" below the vee, that the P-45 can swing that much prop and on 25% nitro.

k

Doesn't take much...if you don't have a pair of cupping pliers, maybe someone else at the pond has a pair you can borrow...

Or even a pair of small channel locks will work.
I was even shown by Louie Bauman how to cup a prop using a common trailer hitch ball and a small brass tapping hammer. I still do this at the lake if I don't have my ball anvil with me.

It doesn't take much cup to load a prop if it is working well on the boat and just needs a little bit more...

 

[Wasted wages]

and yes, it is possible for a sub surface prop to be more efficient the deeper it goes, as long as lift doesn't start to blow the back of the boat loose... if the prop starts to ride up on the tips of the blades, it can push the nose of the boat down and make it start to plow or bow steer...

I found that I can go a lot faster and pull much bigger props by going to surface drive...drive tube inside the hull and as flat on the bottom of the boat as possible,,, even making a groove in the V inside the boat to get the tube as flat as possible exiting the transom.

I pull 275/280 Prather SS props with old CMB .90's in my 45" H-craft boats no problem...
surface driven...

 

[Jeff Barnes]

I us a 450 /3 blade on my surface drive seaducer I don't think it would turn it if it was subsurface drive I have a 45rs evo in it

 

[Kez]

I us a 450 /3 blade on my surface drive seaducer I don't think it would turn it if it was subsurface drive I have a 45rs evo in it

I, too, think a X450/3 is too much prop for the P-45 at 1/2" below the vee. But based on the recommendation of everyone who posted, I will try it on my next trip to the pond. I am really surprised that it can turn the X458 and really scream.

k

 

[brad nichols]

Elevation and air density can have a lot to do with it.