How Fast

Captain Chaos

The Doc
Mar 12, 2004
Heres one gang........

Whilst bombarding the man-genious that is JF with questions on sat evening, we momementarilly diverted our focus away from twin-screw 30ft monsters to more civil my fletcher.

Matt informed that my 16fty fletchr + 200hp was actually IHHO one of the most mental boats of any forum member.............then, i think Robbie-Slug spilt some more salsa all over Matts fine uphoustery...and our attention turned elsewhere!!

So the question is.............what speed do you all estimate she does???? The mercs got a 21p Laser II........& the speedo dont work!!!

Just a passin thought;)
The way this summers weather has gone + the fact i hope to have an up & running phantom by atleast easter........I'll probably never Know!
you tend to get calmer tides in the winter so borrow a handheld gps, get your wooleys on and maybe a dry suit and give it a go.:D
Theoretical top speed.

max revs (times) prop pitch (divided by) gear ratio (times) .00094976. Subtract approx 15% for prop slippage.

i.e 6000 x 21 / 1.87 x .00094976 = 63.99 x 85% = 54.39 mph
Captain C, getting your boat ready is another one of your fantasies, just like you getting married to Venus Williams and the time that you said you found a fiver on the floor. The nearest it has got to gallons of salty water was on the first day you got it when your special "sock" leaked onto it. I reckon you'll even sell your jeep before you get it running!
Matt said:
Ned's sum is fair based on the current prop.
But with a different prop and a bit of setting up, I reckon that baby would fly. Probably quite literally. :D

Raise the engine to the bottom set of mounting holes, block the top 2 water intakes on each side with epoxy and try a 24 or 26" chopper, you should be mid to high 60's! It will probably get very unstable past 70mph!

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Can you at least wash it properly beofre you give it back. Last time you had used so much starch it was completely solid.
Get the compression up by using 150 heads, oh and rejett the carbs.
Worked a treat on Burtys remember he saw 76mph on the GPS
26 chopper @6600rpm
And your is a smaller boat.

Have fun

feck off nobstick!

when comes to being lightweight....think you best shut uppa ya mouth!!! Mr fifty-ton-formula!

I've been on those US sights eyeing-up promax's again!!! SILLY BOY!!
Could you imagine the damage to that poor bus!

Stop encouraging me! I'm too easily led!!!

i think you will be lucky to see 60mph with that engine set up on your P21
hope you can prove me wrong ( but no seeray speedo's allowed):D
my mate has a P21 with a 220hp merc xri and we only saw 61mph
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Its not 220hp its 200 they just call it a 220xri, the 200xri came out first then they changed the name to 220xri but its the same motor, probably to distinguish (did I spell that right) it from the carb motor!!! Just like the 245 and the 260efi, both make 260hp but they called the carb motor a 245 so as to make it seem less powerfull than the more expensive efi motor.

Also the motor on Pure Adrenalin is mounted very low and he runs a 26 chopper which is probably to tall.

I reckon if ya set it up right you should see the best part of 65mph :cool:
So in an ideal world, what motor, mounted exaxctly where would all you lot recommend i put on my 21 in order to have a "FAST" pleasure boat??

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