Reply With QuoteThat seems to be cookin' pretty good especially for OMC's http://free.***boat.net/ubb/wink.gif What kind of RPM's are you turning those 32 inch cleavers?
I have talon 25 equipped with 225 HO Johnsons
14 1/2 32 cleavers and fiber reeds
my boat is going 93 mph is ok for this boat?
please tell me
That seems to be cookin' pretty good especially for OMC's http://free.***boat.net/ubb/wink.gif What kind of RPM's are you turning those 32 inch cleavers?
6700 rpms
Alright, something is not adding up here! I ran your numbers through the mathematical calculation and came up with about 15% slip which is too much! What gear ratio in the lower units? I used 6,700 RPM and 1.86:1 gear ratio. At 10% slip which is the general rule of thumb, you should be running 98.24 mph. How did you measure speed? Speedometer or GPS? Are you sure your tachometer(s) are accurate?
Here is the mathematical formula for all those who are interested:
(Motor RPM/Gear Ratio) x Prop Pitch
Divide that No. by 5280 and then again by 12
In your case the number is 1.819......
Take that number and multiply by 60! This is your theoretical speed without slip. Subtract slip of 10% or whatever.
You can also figure out slip factor if you know how fast you are actually going. Divide actual mph by theoretcial mph (no slippage). Subtract the resulting number from 1 (in your case 1-.851991045=14.8%)
Good Luck!
I would say that is a pretty good number. My 2000 Mach 26 with twin (280 hp) merc 2.5's ran a best of 106 at 7500 rpm's. Your slip numbers are higher than mine, but we are talking about merc racing motors with sportmaster gearcases versus OMC. I ran the best speed with my 15x30 3 blade labbed cleavers. I had some round ear Lightning et's for holeshots, but I think the cleavers ran better overall.
BTW: I think the talon is a very nice boat. My engine builder has a 25, and the boat is very solid and the glass work is very good.
[This message has been edited by MrHavasuCat (edited March 22, 2002).]
Hey Badtrip25 how does your boat turn? I hear the Talon has one of the best turning bottoms for a cat on the water. Is this your experience?
Anyone else wish to chime in?
I have a boat based off a talon, its a howard cat. It turns very well and doesnt tend to slid or leanto the outside. handles rough water very good as well.
i had a american offshore which is from a tallon and it would throw you on the floor it turned so hard.
Originally posted by HavasuDreamin':
Alright, something is not adding up here! I ran your numbers through the mathematical calculation and came up with about 15% slip which is too much! What gear ratio in the lower units? I used 6,700 RPM and 1.86:1 gear ratio. At 10% slip which is the general rule of thumb, you should be running 98.24 mph. How did you measure speed? Speedometer or GPS? Are you sure your tachometer(s) are accurate?
Here is the mathematical formula for all those who are interested:
(Motor RPM/Gear Ratio) x Prop Pitch
Divide that No. by 5280 and then again by 12
In your case the number is 1.819......
Take that number and multiply by 60! This is your theoretical speed without slip. Subtract slip of 10% or whatever.
You can also figure out slip factor if you know how fast you are actually going. Divide actual mph by theoretcial mph (no slippage). Subtract the resulting number from 1 (in your case 1-.851991045=14.8%)
Good Luck!
hi thanks for your reply
I have 1:86 gear ratio and gafrig speedo
tachs are ok but one engine rpm lower 200-300 rpm lower what can be the problem?
how can i reduce my slip?
gear cases are nose coned and its mounted 2.5 inches above the lowest point.
thanks
The 225HO's make 247hp at the prop shaft. You need to work on the slippage. Maybe try somebody else's props. Also get with a OMC guy and take the rev limiters off those motors and let em eat. You should see 96 or 97 if the boat is not to heavy.
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