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Old 13-01-2015, 07:05 PM   #1
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Yam vmax reliability

HI,

I have been offered a yam VMAX 300 not sure of the year yet seeing it next week. Has anybody had experience with these units and are they any good? Or would you stick with a Optimax 250?

Putting somthing on myP21 in a few months?

Or is it worth looking at converting a Optimax 250 XL to a 20" leg. If so how can this be done?

Paul
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Old 13-01-2015, 09:14 PM   #2
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Country: FRANCE
Interests: speed on water/technics
Boat make: INVADER
Engines: MERC 250XS/SM 1.62
Cruising area: south Britany

Join Date: May 2007
Posts: 518
300 vmax

We have 2 engines like this with friends,one on a Solent Rib 750 the other on a batboat 26, both with hydrotech stage 1 kit, they have only 140 hours they are quiter than 250 opti, good torque, run smooth, yami's parts are not cheap, gearcase with regular shaft size instead of fat shaft on mercury XS or later optimax version, but the VMAX is pleasant to use, Both engines are very well maintened and look almost new after years.
Have heard they don't like hi rev, and hard offshore use . Finding Used parts for these engines are far more difficult to find than for opti, be carefull. The power head is pretty heavy too, and in hard use the saddles suffer a lot as they are not strong like racing XS series.
But puttting a VMAX 300 on a P21 is not reasonable in term of weight distribution, the COG of powerhead is going to be very high, and the transom will suffer a lot, you are going to have stability problems . If you plan to use the boat on mirror falt water all the time why not, but for me this good engine is not a ggod choice for a P21. JMHO...

The conversion af a 25'' opti to 20" is not a simple work to do, especially if the vertical shaft of your gearcase is in one part on the 25'', at this point you need to open the gear case and check gears backlashs, shimming, you need special merc tools, or some mecanical skills, the middle section, casing is very expensif too, bettter to find a broken powerhead on a 20'' an swap the powerhead to the 20'', making one engine with 2 in fact.
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Old 13-01-2015, 10:00 PM   #3
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300 v max

Thank you FRENCHBRUNO much appreciated.

Another option i have is to fit a 250 merc with 25" leg, I have not set the transom hight as we are rebuilding the boat. Is there any reason why a 20"leg is better than a 25" i know gravity and the centre point might be affected. Will it make that much difference? Were not racing, maybe the odd poker run.

Paul
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Old 13-01-2015, 10:26 PM   #4
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Country: FRANCE
Interests: speed on water/technics
Boat make: INVADER
Engines: MERC 250XS/SM 1.62
Cruising area: south Britany

Join Date: May 2007
Posts: 518
P21/250 opti or 300 hp VAM

Hi Paul,
the main difference using the 20" or the 25" leg on you P21 is that you've to install the ventilation plate higher than a standard leisure boat, so if you're using a 25"" leg, to make the gearcase efficient in the water the COG will go in the sky, and on a narrow and short boat like the P21, from my experience on 21 feet like RING,Cyclone, is to find a 20'' leg for your P21, on Cobra P21 in France a guy installed a 200XS gen 2 on the boat the top speed was not so good, after this the boat was sold to a friend and the engine sold to Sweden and perfpormed very well on a light hydrolift T17 at 76knots, so the engine power was not the problem. Now this P21 cobra is fitted with a 250 XS Gen 1 leg 20'' top speed is 121km/h without jackplate, stability ok, but this P21 kevlar built is not a super lightweight too, not the same they use in Scandinavia.
You've a guy here on boatmad using a P21 with a 250 xs, named ''temprarily insane'' with a nice P21/250 XS. he will be able to tell more how this setup works. http://www.boatmad.com/forum/member.php?u=810 send him a PM.... May be a 200/225 HO evinrude is the solution too, in 20" leg for this boat. hope that helps.
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Old 13-01-2015, 10:46 PM   #5
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Is this v max in Essex?
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