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Old 06-07-2010, 12:12 AM   #1
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Forward planing 4 P21

The R20 has gone and now looking at defecting to the 'P' side (nothing personal Mr Ring)

In a few months hopefully i will be in the market to treat myself to a P21 ideally with over 200hp. Twins would be nice, look the part but double the price for fuel/rebuild etc for how much gain, Would they be viable for a pleasure user.

If i where to go for the twin set up what would be the max engine size you could sensibly put on the P21...2x150...2x200? Or a single 300hp be a better set up?

Also what engines are more reliable and have longer running hrs between rebuilds, im guessing the cost of a rebuild being in the region of 1500-2k now days (obviously double that for twins) I'm also guessing a rebuild would be between 50-100hrs running. But as i only get a chance to use a boat half a dozen times a year the running hrs would be quite low, so in theory it would take me about 3 yrs to do 50 hrs engine running, but should the engines be rebuilt every year regardless?

Thanks guys

P.s if anyone is thinking of selling such a boat later in the year i may well be interested.
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Old 06-07-2010, 12:19 AM   #2
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For a twin set up the top speed gain for pleasure may not be as high as you think, not with all that extra weight.
250ho would be a nice motor on that, good fuel economy too.
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Old 06-07-2010, 08:46 AM   #3
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Quote:
Originally Posted by Renegade View Post
For a twin set up the top speed gain for pleasure may not be as high as you think, not with all that extra weight.
250ho would be a nice motor on that, good fuel economy too.
Thats what i was thinking for the the little gain i will get is it worth the extra expence of running a twin, except for asphetic reasons? But aint that what its all about? Plus I like asphetic reasons lol. And ok if you have more money than sense i guess.
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Old 06-07-2010, 09:40 AM   #4
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[QUOTE=Carl_B;184194]The R20 has gone and now looking at defecting to the 'P' side (nothing personal Mr Ring)

I have no problem with that Carl !!

As long as you stick to quality boats


I hear the Phantom brand is quite good . ( I have this first hand from a furry little Ginger Gremlin )


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Old 06-07-2010, 10:47 AM   #5
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you missed the word "gay" out of that description Mike
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Old 06-07-2010, 06:22 PM   #6
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a well set up P21 with a 200hp merc (old school, ie. not a new heavy engine)should see 70mph if you twin it with same motors i'm guessing 80mph single 2.5 260 / 280 and you should see 80mph anyway or 90mph plus with twin 2.5's however if you want to run twins then you would need a P21 built for it or you will be ripping transoms out!!!
I personally wouldn't run a 250 HO or 300xs on this hull as they are too narrow to spin that size of prop.
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Old 07-07-2010, 10:53 AM   #7
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Well that sounds like sound advice. As thought a twin set up not going to make hell of a difference apart from looking the part, but double the expence for another 10-20mph. Advice taken on board. I would be happy hitting the 70 mark, 80 would be better, and if i can achieve that with a single engine 260/280hp 2.5 that will suit me fine. Thanks
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Old 07-07-2010, 11:15 AM   #8
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What would be the result of running a 250HO or 300xs? Im guessing torque twist? What result would you get with a 225 opti or promax, would that compare to a 2.5 260 or 280hp? These engine choices confuse me some what.

Thanks Carl
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Old 07-07-2010, 01:37 PM   #9
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A friend in Salcombe (virtually insane) has a P21 with a 250XS - he likes it! - A 2.5 EFI with 280hp on a 15" leg would lower the C of G and give you some more HP at higher RPM - you can use gear ratios to alter prop speed ...........
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Old 07-07-2010, 05:38 PM   #10
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Wacky Racer had a 300xs on a P21 for a season, i'm sure he can explain better than me but because you effectively lose 2000rpm (8000 2.5 to 6000 300xs) you have to spin a much bigger prop and as you say the torque twists the boat over! The 250 HO's are even worse because they have even more torque!
A twin setup will always be more stable than a single installation as you will effectivly have no torque steer
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