Donzi Roostertails

[slapshot11]

I've seen several videos which show a Blackhawk shooting up a substantial roostertail. I love roostertails. Is it the duo prop type set-up or, is it the fact that the prop is closer to the surface of the water that makes the roostertail? I'd like to have a roostertail like that on my 22' classic someday. Do I eventually need a blackhawk drive, IMCO Shortie or what? :bonk:

[mattyboy]

you want roostertails, you can't handle roostertails ;)
forget the blackhawk just get some "hard candy"

[gero1]

jetovator's don't count

[RickSE]

That's not a jetovator it's a Geoo-vator.

[Chili 18]

you want roostertails, you can't handle roostertails ;)
forget the blackhawk just get some "hard candy"

That would be a cool photo for the calendar contest if the file size is big enough...

[MOP]

No thats not Geoges 18, it is an very nice 18 jet from up on the St Lawrence. It has a big block Ford stuffed in it and does put on a great show.

Rooster tails are due to the closeness of the prop to the surface amd speed, I enjoy running offshore on calm days. The ocean rolls 2-3 feet high spaced maybe 50 feet apart, running at a high clip you get an ever changing rooster tail when the boat gets light coming over the crests.

Phil

[txtaz]

Why Phil...I must declare sir, you are showing your youthfullness.
Da Taz <<--We don't need no stinkin rollers. A nice big trawler works just fine.

[Greg Maier]

I found this on a Hydroplane website:
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.

[slapshot11]

Great info everyone, thanks. Looks like an IMCO Shortie won't do it. Is GEOO the only one to ever do a surface drive? His was on an 18", anyone ever do one on a 22'? I guess that big bucks right?

[MOP]

Great info everyone, thanks. Looks like an IMCO Shortie won't do it. Is GEOO the only one to ever do a surface drive? His was on an 18", anyone ever do one on a 22'? I guess that big bucks right?

I tried a Blackhawk on my 22 it worked great to a point, the handling was super quite a bit better then the Bravo I have on it now. It ran fine up to about 4000 then it went flat and could not raise the bow. A pretty good chance Rocker Plates would have cured it but my shallow pockets did not allow for any more experimenting. I still have the drive and will hang on to it for a little longer, it is a good spare and nothing will carve tight turns as good. Maybe some $$'s will fall off a tree! To go to a surface drive you need to induce bow lift, they give little to none. A really good guy to speak with is Geo he ran the gambit getting his right but ended up with the fastest 18 in the world.

Phil

[roadtrip se]

Great info everyone, thanks. Looks like an IMCO Shortie won't do it. Is GEOO the only one to ever do a surface drive?

Nope, an IMCO shortie sure won't throw a rooster...

[MOP]

Fess up Todd you have one of those little Pee Pee tubes like the Jet SKies have Ya Ya!

[roadtrip se]

Fess up Todd you have one of those little Pee Pee tubes like the Jet SKies have Ya Ya!

but I know for a fact that Dr. Dan has one of those little pisser thingys on the King Cobra, I saw it!

[MOP]

but I know for a fact that Dr. Dan has one of those little pisser thingys on the King Cobra, I saw it!

:shocking:

[boldts]

Put a Hydromotive nose cone on your Bravo I, add a GPS Speedo since you just covered your speedo intake on the Bravo I and last, put a Turbo 1 prop on the drive. You can now trim that Bravo I out enough to not only run 4 mph faster, but make a nice rooster tail to impress those watching your Donzi from the shore. :biggrin.:

[slapshot11]

Scott,
This sounds like an interesting possibility. I have a Bravo 1 with a Turbo 1 prop already in place. Why does adding a nose cone have the effect of allowing the lower unit to be trimmed out further?

[boldts]

Slap,

I'm no expert on nose cones and many have said they are useless below 75 or 80 mph. All I know is when I put a Hydromotive cone on my 22 with a Bravo 1, I could run more trim and still keep the prop hooked up. I believe this to be because of the prop now getting a better, less disturbed water flow to the prop. I've also been told that you run more trim because the cone tends to pull the transom down. I personally think you run into that more with the pointed type cone. Hydromotive is a wedge type. Not the very defined point of the other type. My biggest speed increase came from the prop. 65 to 68 GPS. I had hoped to get the boat to 70 by adding the cone, but fell short at 69.8 GPS. My Bravo 1 had a 1.65:1 drive ratio due to the boat having a supercharged engine at one point. That was also the reason the stock 454 MAG could only turn a 22" pitch prop.