Redneck boat guy #15 Race Boat Props 101 the basics

Race Boat Prop Basics by Rusty Sitton

[normal]

I really enjoy this information about props. Thank you for sharing 👍🙏

[benashby]

Thank you for sharing your knowledge. Great video.

[johndomingue]

Thanks Great Information miss the racing days

[James.Richter]

Very interesting content. Thank you for sharing. I'm having trouble gathering good Intel on small speed boats. I am currently working on building a small 7' boat for my children to play with at the cabin and I'm also gathering ideas for a small speed boat for my self. Thank you very much.

[carmelpule]

Sir, it is interesting how you look at the pitch of your propellers. Many people define pitch as the distance moved forward by the propeller as it covers one revolution. This may apply to the nut moving along a threaded rod, but a propeller in water is not so simple. You mentioned that the pitch needs to change as one moves across the blade and also as one moves out along the radius of the blade. I would agree with you about the change of pitch as water moves across the blade, but ideally, there is no change in pitch as one moves out along the radius of the blade unless, as you mentioned, the entry speed into the propeller front face varies as you mentioned when the water goes around the outboard leg, it speeds up a little and so the pitch has to be accounted for.
With some propellers, where the pitch across the blade is constant, then the velocity across the blade is constant and the low pressure and high pressure exist before and behind the propeller. With cambered blades or those where the pitch varies across the blade, then that type of blade will have a good entry of water at the leading edge and the water is accelerated while it travels across the blade. I presume the propellers you show are acting as surface propellers and so the curve or the change of pitch while the water moves across the blade are imperative to accelerate the water. That change of pitch across the blade would decide the slip of the propeller.
Congratulations on your great experience in making propellers, I designed a few, but I have not the facilities to cast them or make them in a professional manner, I made the model to be cast at the foundry, and on some propellers, I decreased the pitch at the hub as I felt that that zone acted as a paddlewheel during standing starts and the hub zone would cavitate due to thigh angle of attack. All propellers have wonders and secrets of their own. Well done on such a presentation based on practical values.
Note that At 4:34 With a gear ratio of 16:21, the shaft from the engine has 16 teeth while the propeller shaft has 22 for a reduction gearbox.
Your video took me back more than 65 years when I was 20 years old and did some racing but not on very fast hydroplanes, only just small offshore boats in the Mediterranean off Malta which were not as fast as you went. Thank you for presenting this video.

[andrekemp]

Im really Interested.
Please make more videos

[leshudson]

Great info. I have a 10ft 3 point hydroplane with a new Tohatsu 20hp motor. Can you please advise a prop size and pitch? Where I can get one?

[morongspearfishingtv]

New friend sir from philippines i have a boat 20hp what is the best size of propeller you recommend for me .i like the style of your propeller

[RichardSacher]

Thanks for the information great video

[mrendu]

Hello whare can i buy this propeller you are holding in your hand, or maby 3 blade version?

[richardgreene]

I have a 1987 johnson gt3.6 300hp 14½D 19P prop came on it what can I use to achieve high top speed?

[fidelbaco]

i have 13hp loncin sir
5/8x2x8.5 prop it is fit to run fast

[reminoel]

Who still make small props like those? I have this 12hp Chrysler project i want to make fly but small cleaver props seem impossible to find

[doesntmatter]

What you said about tip speed at the beginning of this video is very wrong.
Airplane propellers are designed *never* to exceed super sonic speeds.
They lose efficiency very fast at and above, not to mention, it very dangerous.
What your hearing is the air passing thru the blades as the pilots checks the motion of his constant speed prop.
Meaning the blades can change pitch while in flight.
Has for gears, "gear teeth" have nothing to do with any ratio. It the diameter of the gear is what stipulates it ratio.
The actual "gears teeth" are only there to create movement.