rooster tails and speed?

[pcrussell50]

almost all video clips i see of boats hauling azz have some amount of rooster tail. this makes me think this is more than just showboating, [pun intended], and that there is a good physical reason for this. will anyone explain to me the reason behind the rooster tail?

is it the prop, ever-so-slightly breaking the surface of the water because the drivers are trimming the motor as far up as possible, [and still maintaining water pressure]?

-peter

[Charger200]

At high speeds it has less to do with the trim of the engine and more to due with the height at which the engine is running in the water.

The high performance outboards run high engine heights some even with pad, some above, some slightly below. This means that usualy only half the prop is in the water. Some of the fast tunnels run with a negative angle of trim to keep the bow down but due to the height of the motor and the thrust of the propeller cutting through the water there is still a tail of sorts but it is more elongated and low rather then high

[pcrussell50]

so it IS prop coming out of the water. sweet. thanks for that. do most motors that run like that have a low water pickup, or can a fishmota run like that?

-peter

[Charger200]

All motors that KEEP running like that have a low water pickup. The ones that dont(fishing motors) dont last very long.

[pcrussell50]

that is a very wise tip for a newbie like me. thanks for that. happy new year.

-peter

[Charger200]

Happy New Year:cheers:

Jay

[HStream1]

Just one thing to add to the already good advice. All props are not meant to be run on the surface.

[pcrussell50]

Just one thing to add to the already good advice. All props are not meant to be run on the surface.

carp! nothing's ever as easy as you think it's gonna be. are the [highly regarded] omc rakers ok for breaking the surface? or is that for choppers and cleavers?

-peter

[Forkin' Crazy]

A raker isn't really designed for that. So choppers, semi cleavers and cleavers are it.

Mine is a fishing motor but the lower had been modified by adding a nose cone with a low water pick up.

My rule of thumb, if your tail is taller than the engine's cowling, it has too much up trim. Perhaps this is to lift the bow, if so, more weight needs to be shifted aft of the center of gravity either by moving rigging aft or more set back.

[Mr. Demeanor]

Nothing to add except my favorite rooster tail video. It is intersteing to watch how it changes during this 202mph pass. Volume up!!!
http://www.youtube.com/watch?v=uBmJ2cuFTcE

[Vegas XT]

That is without a doubt one of the best aquatic vids ever!!!never get tired of watching that one,talk about the right set up,3000hp doesnt hurt either.

[Charger200]

Yeah I guess i didnt touch on the Prop's but its been taken care of. I wouldnt get too carried away with surfacing a raker. You might find a small ear chopper work well with your rig and power, give you the bow lift you need aswell as allowing you to surface the prop

[pyro]

Roost is also higher when SLIP % is higher.

Watch the prop spray off a Mirage or STV at 30 mph-- Watch it disappear above 80.

[HStream1]

Roost is also higher when SLIP % is higher.

Watch the prop spray off a Mirage or STV at 30 mph-- Watch is disappear above 80.

Bingo :thumbsup:.

[Forkin' Crazy]

Here is my XB2002 running mid 90s. Not much tail here.

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[pyro]

again here, some roost accompanying the slip and midrange acceleration, then it goes away as the slip numbers drop. ..

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Look at the sig photo below. Motor leg is straight up-and-down-- The motor's angle doesn't change with respect to positive trim-- The BOW's attack angle does-- Until you're over-trimmed, then the motor just aims the thrust toward the sky.

[JrCRXHF]

My boat is on the bigger side of things. But my 24p raker does not like anything to do with the surface. When i come out of the hole and the bow comes down it just burns. Then when going at full tilt i can run 800 more rpm then i can with a 24p trophy plus at close to the same speed.


I am running LWP with a OMC V8. The hall does have a pad. and 28 inch setback.

[Deweydaddy]

500+ HP. and a good pump helps.:D

[Mark75H]

500+ HP. and a good pump helps.:D

That's all about the show

[BeefKid]

Flatter is faster!!

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http://i83.photobucket.com/albums/j286/koolkid620/airedout2.jpg

:cheers::thumbsup:
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[Deweydaddy]

That's all about the show Yea, its a nice roostertail for show. Boat seats 6-8 people, runs mid 70's so its got a little go.:) This is my go boat. :D Lay-off forces sale of one of them, anyone looking for a jet or a v-drive give me a shout.

[Forkin' Crazy]

Yea, its a nice roostertail for show. Boat seats 6-8 people, runs mid 70's so its got a little go.:) This is my go boat. :D Lay-off forces sale of one of them, anyone looking for a jet or a v-drive give me a shout.

That's nice! Looks well done also! :cool: What hull is that?

[Forkin' Crazy]

Flatter is faster!!

Nice vid Beefy. Motor sounds good too. :cool: Looks a bit bow high to me though! :eek:

[Deweydaddy]

That's nice! Looks well done also! :cool: What hull is that? Thanks!! Its a 93 Taylor 500 ci BBF. Better than new. You gotta like attention, my son and I blast by the sandbar come back and anchor and have all kinds of people swimming over to check it out. Happy New Year.

[John Hice]

Said it before and I'll say it again. That is one sweet Taylor! :thumbsup:

[Kimmerly.performance]

My boat is on the bigger side of things. But my 24p raker does not like anything to do with the surface. When i come out of the hole and the bow comes down it just burns. Then when going at full tilt i can run 800 more rpm then i can with a 24p trophy plus at close to the same speed.


I am running LWP with a OMC V8. The hall does have a pad. and 28 inch setback.

I tried a raker for a poker run once in my earlier days (Just learning) I was surfacing it a little, propshaft about 4 to 5 inches below pad and I cracked all three blades. My brother noticed it before anything happened, but it don't really think it is a good idea.

[Jay Smith]

I find that if a rig is "set up" correctly the rooster tail at WOT should not be higher than the cowling top and should be thick and be apparent far back from the engine/prop. If rooster is higher than cowling the motor is too high or angle of trim is trimmed out to far or has wrong prop applied for the type of hull. For ultimate PUSH that a motor and prop can give a rig is for the CG of the boat to be set up so that at WOT the motor optimal trim angle is about 1 degree tucked under NOT trimmed out. If the motor must be trimmed out to achieve ultimate speed the CG of the hull is WRONG..If a motor must be trimmed positive the motor is now having to correct a bad set up by expelling its energy or power trying to lift the hull because the weight or set back in the rig is WRONG.. Setting a boat up for ultimate speed is basic math princible applied to weight and a simple fulcrum ...

from what I have found,
Jay

[mirage243]

Watch how quick my rooster tail lay's down on this pass. This is with no trim being touched during the run.

http://www.youtube.com/watch?v=GttikliUW34</EMBED>

[Deweydaddy]

Said it before and I'll say it again. That is one sweet Taylor! :thumbsup: Thanks. Your Taylor is badazz too! I've read everything about it on the roost. Wish I had your motor!!!!

[John Hice]

I guess you could call mine a "Surface Drive" :thumbsup:

http://i514.photobucket.com/albums/t341/gcmsinc/Pump%20Upgrade/New%20Exhaust/DRAGNFEVER34.jpg

[Deweydaddy]

Watch how quick my rooster tail lay's down on this pass. This is with no trim being touched during the run.

http://www.youtube.com/watch?v=GttikliUW34</EMBED> Nice vid. Looks fast. What kind of speed?:cheers:

[mirage243]

Nice vid. Looks fast. What kind of speed?:cheers:

10 second 1/4 miles in the 110 - 114 mph range.

[Forkin' Crazy]

10 second 1/4 miles in the 110 - 114 mph range.

Is that with or with out the eagle one nose cone job? :o :eek:

[Deweydaddy]

10 second 1/4 miles in the 110 - 114 mph range. Nice. Wow. Nothing that fast in my garage.:thumbsup:

[Deweydaddy]

I guess you could call mine a "Surface Drive" :thumbsup:

http://i514.photobucket.com/albums/t341/gcmsinc/Pump%20Upgrade/New%20Exhaust/DRAGNFEVER34.jpg Love that pic. Thats gotta be a 1/8 mile long roostertail!!!!!!!

[HStream1]

10 second 1/4 miles in the 110 - 114 mph range.

Not fudging a little bit there are ya? LOL

[mirage243]

Not fudging a little bit there are ya? LOL

Nope, not one bit. I have around 150 passes at sanctioned events this year, with time slips to prove it. Most of your 10 second (Modified Eliminator) boats run between 100 and 115 in the quarter. This is not like the heads up racing where somebody waves there underwear in the air. We race on highly accurate clocks that measure to the .001 and give you speeds to the third digit. ie(110.257)

[mirage243]

Is that with or with out the eagle one nose cone job? :o :eek:

I wouldn't go 55 MPH with one of those pieces of sh*t.:D

[Deweydaddy]

I wouldn't go 55 MPH with one of those pieces of sh*t.:D looks like your messin with a couple V-drives in your pics.

[mirage243]

looks like your messin with a couple V-drives in your pics.

We race mostly v-drives, there is no limit as to what you run. It is an indexed class. If you run a 10 second dial in, you can't run 9.99 or quicker. It is an automatic loss, unless the other guy runs even quicker. You must be deadly at the lights and have your boat tuned very well. My boat will actually run quite a bit faster but we have to detune a bit to run 10's. The next index is 9's and my boat can't be safely ran there.

[Deweydaddy]

We race mostly v-drives, there is no limit as to what you run. It is an indexed class. If you run a 10 second dial in, you can't run 9.99 or quicker. It is an automatic loss, unless the other guy runs even quicker. You must be deadly at the lights and have your boat tuned very well. My boat will actually run quite a bit faster but we have to detune a bit to run 10's. The next index is 9's and my boat can't be safely ran there. Looks like you do well against them. You probably noticed I have a v-drive too. Laid-off in Dec. so I have to sell a boat. Would like to sell the jet and keep the V, but cant be too picky right now. Looks like a long lay-off.

[HStream1]

Nope, not one bit. I have around 150 passes at sanctioned events this year, with time slips to prove it. Most of your 10 second (Modified Eliminator) boats run between 100 and 115 in the quarter. This is not like the heads up racing where somebody waves there underwear in the air. We race on highly accurate clocks that measure to the .001 and give you speeds to the third digit. ie(110.257)

Just pulling your chain. I knew you can run faster than what you posted :thumbsup:.

[mirage243]

Just pulling your chain. I knew you can run faster than what you posted :thumbsup:.

Can't tell everything you know.:D:thumbsup:

[HStream1]

Can't tell everything you know.:D:thumbsup:

You have PM

[BeefKid]

Nice vid Beefy. Motor sounds good too. :cool: Looks a bit bow high to me though! :eek:

thanks man... i aint fly it that high my brother on the other hand is really comfortable in that boat:nonod::rolleyes:

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[Terry Jackson]

Just make sure you are looking at the roostertail, and not surfacing prop overspray. They are different.

[Mark75H]

Just make sure you are looking at the roostertail, and not surfacing prop overspray. They are different.

What is the difference?