Prop rotation again
10-15-2003, 02:43 PM
#12
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Gary, I agree. However, I was not asking the board for help on prop rotation, I am asking mmwalters if he is sure of his prop rotation. I have witnessed much confusion from others on what is "in" vs "out". Just like some of the advise on this thread is causing confusion. In fact it is way off.
Last edited by Brad Zastrow; 10-15-2003 at 03:01 PM.
10-15-2003, 03:11 PM
#13
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Brad I agree IN is right prop on left side Left prop on right side. OUT would be right prop on right side left prop on left side. My lowers are mounted with propshafts1 7/8'' above the bottom. The centers are 62'' maybe a little wide Seems to work ok though.
10-15-2003, 11:13 PM
#15
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Boat setup specifics are ALWAYS going to be confusing. That;s cause each setup is different and will behave differently.
MMwalters has tested back to back and runs faster turning out. Zastrow runs better turning in.
Just cause Zastrow's setup runs noticeably better turning in doesn't mean that all cats run better turning in, in fact it doesn't mean that all MOTION cats run better turning in.
The Chris Cat point about drives mounted close to the tunnel ALSO shows that even more variables come into play.
We've got a guyin this thread, too, who is running around 150 mph - this opens up even more questions (does extreme speed change the rules again).
In/Out, Cleaver/Chopper/Bravo/Hydromotive, Diffuser ring/no diffuser ring, X-height, skeg length, toe-in/toe-out - we got lots of things to mess with here...
MMwalters has tested back to back and runs faster turning out. Zastrow runs better turning in.
Just cause Zastrow's setup runs noticeably better turning in doesn't mean that all cats run better turning in, in fact it doesn't mean that all MOTION cats run better turning in.
The Chris Cat point about drives mounted close to the tunnel ALSO shows that even more variables come into play.
We've got a guyin this thread, too, who is running around 150 mph - this opens up even more questions (does extreme speed change the rules again).
In/Out, Cleaver/Chopper/Bravo/Hydromotive, Diffuser ring/no diffuser ring, X-height, skeg length, toe-in/toe-out - we got lots of things to mess with here...
10-16-2003, 11:18 AM
#16
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I am assuming by your avatar you have a V bottom Formula. No offense, but cats and V hulls are different animals. My cat runs 140+ the other three ran 105, 114 and 116. Most every high performance cat will run faster with more stern lift turning in (loose). Go to a kilo run and look at setups. Offshore racing guys will sometimes turn out for better cornering abilty. I am not the expert, but I did listen to the ones who are on setup. Merlin 540, leave your setup alone.
10-16-2003, 12:29 PM
#18
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No offense taken, Brad. In fact, if someone tries to offend me they usually gotta shove my nose in it cause I always look for the positives.
Sure, I run a vee hull as my primary playboat. I've had and/or helped tweak single vee bottom outboards, single outboard tunnel vees, single outboard Champ hulls, twin outboard circle track vees, twin outboard tunnels, triple outboard vees, twin sterndrive vees, triple sterndrive vees, and ONE (which may be less than you have messed with) 43' twin sterndrive cat.
Theory is always helpful for baselines. Nothing beats trying measured combinations and, I repeat this only from my experience, just cause it works on yours doesn't mean it works on everybody's.
Your personal and observational experience here is valuable and hopefully helpful to mmwalters, who started the thread. He appears to be experiencing a different result than you, though, and that doesn't make him wrong (or you wrong). It just shows that every combination adds a different twist to the equation.
I expect that his motor centers may be one of the factors that causes his results to differ from yours.
Maybe he should go to a kilo run, though, and copy whatever he sees there...
Sure, I run a vee hull as my primary playboat. I've had and/or helped tweak single vee bottom outboards, single outboard tunnel vees, single outboard Champ hulls, twin outboard circle track vees, twin outboard tunnels, triple outboard vees, twin sterndrive vees, triple sterndrive vees, and ONE (which may be less than you have messed with) 43' twin sterndrive cat.
Theory is always helpful for baselines. Nothing beats trying measured combinations and, I repeat this only from my experience, just cause it works on yours doesn't mean it works on everybody's.
Your personal and observational experience here is valuable and hopefully helpful to mmwalters, who started the thread. He appears to be experiencing a different result than you, though, and that doesn't make him wrong (or you wrong). It just shows that every combination adds a different twist to the equation.
I expect that his motor centers may be one of the factors that causes his results to differ from yours.
Maybe he should go to a kilo run, though, and copy whatever he sees there...
10-16-2003, 02:51 PM
#19
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You want the lower units behind the sponsons just out of the tunnel. I do not remember the exact measurement but the prop shaft was about 3" out and 1.5" up. On mine the props were swinging into the tunnel. I have talked to guys who moved the centerlines out a little with mixed results. You are at the max speed of that boat at 109 with twins. Be happy. If out is best leave it alone.
10-16-2003, 11:19 PM
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I think my lowers are out about 6'' per Motion's recommendations. But I don't think there is much more speed left maybe 1-2mph in the props. I think my boat is running very good now I am just amazed how those skaters run so damn fast.
