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View Full Version : What creates a rooster tail?



Kikwear
01-27-2004, 12:12 AM
Type of drive, prop, raw HP or combo of above?

Lenny
01-27-2004, 12:19 AM
One of these if you have the money for starters...I don't

Lenny
01-27-2004, 12:53 AM
... a high X-dimension, shortie lower, a surface piercing prop, or insane trim arrangement...I don't think power comes into the equation that much, it is more or less a " better prop/hull efficiency" if slip is still kept in low numbers.

Forget "squirt boats" in this scenario.

Cuda
01-27-2004, 03:54 AM
Or two of these.

Cuda
01-27-2004, 03:55 AM
:)

Greg K
01-27-2004, 06:59 AM
Easier with a surface prop, but it can be done with most drives. High speed and trimmed out pretty far with a King Cobra.
http://www.donzi.net/photos/redtail1.jpg

Craig
01-27-2004, 07:06 AM
An egg... (get it, an egg?)

...Or a nice Berkley Jet Drive.

Where's that picture of a blue Donzi 18 with a big rooster tail?

ToonaFish
01-27-2004, 07:09 AM
You mean my screensaver? :D

Craig
01-27-2004, 07:54 AM
That's the one!

BillG
01-27-2004, 08:26 AM
Originally it was a name given to the tail behind a hydro because they run with only half of the prop in the water.

Bill G

Greg Maier
01-27-2004, 08:32 AM
Here is the roostertail from a Blackhawk. This is about 60 MPH.

Greg Maier
01-27-2004, 08:40 AM
To add to BillG's comments:

It is the propeller that creates the symbol of the hydroplane ... a roostertail. As I mentioned before, the propeller is only halfway in the water when it is up to speed; this concept is known as "prop-riding". Because of this particular situation the blades of the prop, or "flukes", are repeatedly going in and out of the water. Each time the blade comes out it kicks spray high into the air and by the time it falls and hits the water again the boat has traveled a good many yards beyond that point. The combination of the spray rising and falling causes the formation of an arch of water known as a "roostertail".

The roostertail is not only beautiful, it can be a fearsome weapon in the hands of an expert driver fighting for an advantage over another driver and is a very good indicator of the boat's performance. The longer the 'tail', the faster the boat's going. A smooth looking 'tail' denotes a smooth ride and conversely a jagged one tells that it is pretty rough and the boat is bouncing. A thin, wispy 'tail' says the hydro is riding too light because not enough prop is in the water, a heavy short roostertail means it is riding too heavy and that the shaft is probably dragging.

The principle of prop-riding also causes a problem known as "propeller torque". Because the prop rotates in a clockwise direction, every time the blade strikes the water it pushes the transom to the right which causes a constant left turn. To counteract this effect the rudder is placed on the left side of the transom. The rudder is also made of forged steel and is coated with Cadmium in many instances ...they also cost more than a thousand dollars. In competition the hydro will only turn towards the left, which is another reason for the rudder's placement. An evasive move to the right is possible but cumbersome and unresponsive in handling, as one must fight both the prop torque and the left sided rudder to do so.

Cuda
01-27-2004, 09:17 AM
The drives on my boat are Kaama drives. They have surface piercing props, much like the better known Arneson drives. You can actually see each "bite" of the prop in the roostertail.

MOP
01-27-2004, 06:32 PM
Even a prop that is set pretty low can generate a rooster tail, On one of my other boats I went from no cup to a heavy cup my rooster tail was a fair bit lower. To me it is caused by the water flying off the prop's tips, the closer to the surface the more dramatic and yes Beautiful! I love the pics in the above posts.

GEOO
01-27-2004, 07:19 PM
HUM?? ;)

MOP
01-27-2004, 07:37 PM
Mighty Mouse the ultimate rooster tail maker:D

Cuda
01-28-2004, 06:47 AM
Originally posted by MadPoodle
Speaking of seeing the prop bites...

Wow, cool photo. That must have been a pretty good camera to catch that.