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31-08-2004, 09:53 PM
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#1
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The Doc
Join Date: Mar 2004
Posts: 8,291
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How Fast
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 boats....like 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
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31-08-2004, 11:44 PM
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#2
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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depending on engine height, probably somewhere around 60 to 65mph
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01-09-2004, 12:09 AM
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#3
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The Doc
Join Date: Mar 2004
Posts: 8,291
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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!
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01-09-2004, 12:13 AM
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#4
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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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.
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01-09-2004, 10:24 AM
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#5
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Registered User
Country: US
Location: Virginia
Interests: Quiet desperation
Boat name: A Little Noisy
Boat make: Excalibur 24
Engines: Express Racing 525
Cruising area: Mobjack Bay (where?)
Join Date: Mar 2004
Location: Virginia
Posts: 1,974
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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
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01-09-2004, 11:54 AM
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#6
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The Doc
Join Date: Mar 2004
Posts: 8,291
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It has done on previous occasisions
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01-09-2004, 01:59 PM
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#7
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Registered Mental
Country: UK
Location: UK
Cruising area: I like towing it round the M25
Join Date: Jun 2004
Location: UK
Posts: 115
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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!
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The Exxon Valdez of Boatmad
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01-09-2004, 02:34 PM
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#8
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The Doc
Join Date: Mar 2004
Posts: 8,291
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why thankyou Andy, I think you'll find its "OUR" special sock
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01-09-2004, 06:58 PM
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#9
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Registered User
Country: Ireland
Location: Dublin
Occupation: Boatbuilder
Boat make: Hydrostream V-king, 650SS OCR ,Ring 21, Ring 18, Phantom 18.
Engines: 300Hp Mercury 2.4, 130 Yamaha, Bridgeport EFI, XR6, Merc 200.
Cruising area: Malahide, Dublin
Join Date: May 2004
Location: Dublin
Posts: 1,803
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Quote:
Originally posted by Matt
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.
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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!
Alan
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02-09-2004, 01:10 PM
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#10
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Registered Mental
Country: UK
Location: UK
Cruising area: I like towing it round the M25
Join Date: Jun 2004
Location: UK
Posts: 115
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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.
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The Exxon Valdez of Boatmad
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02-09-2004, 03:55 PM
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#11
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Registered User
Country: England
Location: South West
Occupation: Development engineer
Interests: Fast boats
Boat name: Xtreme
Boat make: Bernico 21
Engines: Mercury F1, 300 Drag, XR2 "Fingerported"
Cruising area: South West
Join Date: Mar 2004
Location: South West
Posts: 1,043
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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
Cyco
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02-09-2004, 04:18 PM
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#12
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The Doc
Join Date: Mar 2004
Posts: 8,291
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so that would work a treat on a phantom 21 then?
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02-09-2004, 06:44 PM
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#13
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The Doc
Join Date: Mar 2004
Posts: 8,291
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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!!
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02-09-2004, 09:40 PM
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#14
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The Doc
Join Date: Mar 2004
Posts: 8,291
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Could you imagine the damage to that poor bus!
Stop encouraging me! I'm too easily led!!!
And NO PM's TO JF INSTRUCTING HIM TO INSTRUCT ME TO BY ONE......YOU KNOW WHAT HAPPEND LAST TIME!!
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03-09-2004, 06:19 PM
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#15
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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captain,
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)
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03-09-2004, 06:37 PM
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#16
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Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
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my mate has a P21 with a 220hp merc xri and we only saw 61mph
this 1
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05-09-2004, 12:51 AM
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#17
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hello
Join Date: Mar 2004
Posts: 2,739
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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
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05-09-2004, 01:02 AM
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#18
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The Doc
Join Date: Mar 2004
Posts: 8,291
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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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05-09-2004, 01:21 AM
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#19
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hello
Join Date: Mar 2004
Posts: 2,739
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Dont you mean what motors
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