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Discussion Starter · #1 ·
I have a 1986 Eagle by Seebold I/O 350/260 horse I have searched the net and cannot find anyone that has a boat like this. Is this a rare boat? It has the stock engine and will go 76 MPH with a 21 pitch prop I'm looking to bust into the 80 MPH range any clues as to what i can do to reach these speeds any information will help
I just got the tips for my through hull exhaust, i know this wont do much if anything but my boat needs an agressive bark to match its bite.

Any info will help thank you!
 

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76 MPH with a 21P prop?!?!?!?!? Whats the secret??

Without punching in the numbers, you must be spinning that motor about 8,000 rpms.. Or maybe running a 1:1 outdrive?? Or more likely, the stock speedo is WAY off.. 21P prop shouldnt get any boat over 60 in the stock RPM range standard merc motors spin..
 

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Discussion Starter · #4 ·
I use gps for speed and my engine rpm is only around 5000 i have had several props on to finally find my top speed with a 21. I have had 23 and 24 pitch props and the motor revs but the boat doesnt go faster. This boat is 21 feet long and really low profile. I beat boats with bigger engines all the time with ease. actually my best competition are nice bass boats or a small outboard boat. I will get the specs on my prop when i get home but its a straight cut prop never had one like this before.
 

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If you're RPMs are at 5000, and you're seeing 76 on gps with a 21 pitch prop, I'd guess it would have to be OD gearing :confused:

With the "usual/comon" 1.5 OD gear ratio, RPM's would need to be about 6400 to hit 76 with a 21 inch prop. That's with about 10% slip.

When you find out the details, please, fill us in on what's hapening :)


edit .......... Like Julie from Throttle Up said, give her all the details ya can. She IS the prop guru :D
 

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I ouned a 236 Seebold did 75 with a 330 and a 23 P prop. The bottom on there boats calculated speeds closer to that of a tunnel. Wish I still had the boat. At max speed they will do a 180 like a jet ski. They handle great at speed very forgiving. Bumped the power up about 100+ but never got a chance to reprop it. Agtthat poit it just poped out of the water. Did a number on a lot of 16 / 18' big dollar jet boats. Seebolld advertize there boats hit at least 70 with stock power. Their tunnel hull is awsome. With all there wins in racing over the last 30 or more yeaar they must know something about bottom design.
 

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Seebold Eagle!

back in the day 89' my buddies father had a 21' closed bow seeBold eagle with a Mercruiser 350 Mag 260hp and they had some mild cam and head work done and he could run a 22p 4 blade about 5400 rpm around 72mph but only when it was calm, Not a rough water boat at all....
 

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I currently own a 91 seebold eagle 27 with twin built vortec 5.7's great little boat but very little info she will run a tick over 80 it's great on simi smooth water but not on big ruff, like to find more people that own some of these boats
 

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76 MPH with a 21P prop?!?!?!?!? Whats the secret??

Without punching in the numbers, you must be spinning that motor about 8,000 rpms.. Or maybe running a 1:1 outdrive?? Or more likely, the stock speedo is WAY off.. 21P prop shouldnt get any boat over 60 in the stock RPM range standard merc motors spin..
If still you still have your boat I have one with supercharger and ss mercrusier lower unit runs pump gas that get you there I'm trey
 
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