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Old 19-01-2008, 05:20 PM   #1
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How Fast

With all the knowledge on here i would be interested to know what speed my Hunton Rib (sorry its not a hard boat ) will achieve when its finished.

Length 33 foot
Width 8 foot
Weight 2.3 Ton approx dry
Engins twin 496 Ho mercruisers XR Bravo drives
Power 850 HP


The hull is the same as the Hunton Maverick non stepped.

Boat should be in the water by March
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Old 19-01-2008, 05:28 PM   #2
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According to your website - 90mph+
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Old 19-01-2008, 05:45 PM   #3
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[QUOTE]
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According to your website - 90mph+
[/QUOTE
]

We live in hope.
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Old 19-01-2008, 06:32 PM   #4
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Not wanting to throw a spanner in the works but my guess would be 76-79mph when first set up then with further adjustments with props tabs etc may be even drive's it may creep up to 82-85mph although this is all based on a weight of around 2500kg if you use the P1 formula I recon you would be lucky to see 80mph all a bit harsh I know, I had looked forward to the Brass Monkey to see how it all worked out...anyhow good luck
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Old 19-01-2008, 06:41 PM   #5
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Hunton69
Remember for RBR its not gonna be all about the top speed but keeping up that average speed per leg
Especially when it chops up.
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Old 19-01-2008, 06:46 PM   #6
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Not wanting to throw a spanner in the works but my guess would be 76-79mph when first set up then with further adjustments with props tabs etc may be even drive's it may creep up to 82-85mph although this is all based on a weight of around 2500kg if you use the P1 formula I recon you would be lucky to see 80mph all a bit harsh I know, I had looked forward to the Brass Monkey to see how it all worked out...anyhow good luck
Not at all. After all thats why i asked the question it will be interesting to see what people think and then what it will achieve

Out of interest i thought the Scorpion ribs with 630Hp diesel engines weighing 3500kg were pulling 70 mph.
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Old 19-01-2008, 06:48 PM   #7
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In order to be successful in the RB08 I think you will require one thing above all else.....................RELIABILITY
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Old 19-01-2008, 06:54 PM   #8
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In order to be successful in the RB08 I think you will require one thing above all else.....................RELIABILITY

Couldn't agree more. Thats why everything is new
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Old 19-01-2008, 10:23 PM   #9
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80mph
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Old 19-01-2008, 11:08 PM   #10
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80mph
72mph
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Old 19-01-2008, 11:18 PM   #11
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72mph
I will be if thats all it does
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Old 20-01-2008, 12:49 AM   #12
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I will be if thats all it does
have you weighed it
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Old 20-01-2008, 12:56 AM   #13
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I think the Hunton Maverick that John Evans refurbed, with 496 HOs ran about 80. I can't imagine why the rib would be any heavier, indeed, I would think it would be lighter, so at least 'as quick' with the same power.
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Old 20-01-2008, 01:54 AM   #14
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Out of interest i thought the Scorpion ribs with 630Hp diesel engines weighing 3500kg were pulling 70 mph.
The stock, non stepped ones are I think capable of more like 62-63mph.

Mike Deacons light, stepped RB record boat (which almost certainly makes more than 630hp) is quicker, I believe as you say, around the 70 mark.

Also, 630hp is the total crankshaft hp of a pair of Yanmars (not propshaft hp), comparing like for like, you have 910hp, not 850.
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Old 20-01-2008, 07:25 AM   #15
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[
Quote:
QUOTE=skull666;124338]have you weighed it
[/QUOTE]

Not yet as the the boat isn't finished. What we do know is the bare hull weighs about 750 kg the engines abd drives 1100kg. The fuel tanks, seating and consol is unknown. Thats why i estimated 2300kg

That gives us a Power to weight ratio of 2.7Kg per HP

The Hunton XRS weighs around 5000kg with these engines pulls about 70mph

P1 supersport have P to W of 4.5kg per HP and they pull 80. That is why we estimated about 90mph.

Is there ways of working out top speed, very interested in to know if there is.
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Old 20-01-2008, 08:56 AM   #16
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hunton speed

i think john evans boat ran about 74-76 thats what niel said when i enquired about buying it surley it must b a lot heavier than the rib i reacon 78
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Old 20-01-2008, 10:43 AM   #17
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Quote:
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Is there ways of working out top speed, very interested in to know if there is.
If you know exactly how fast John Evans boat went (not bar room talk) and exactly what it weighs (accurately, not a guess), you can establish a 'C' number for the design type which will closely resemble yours (not exactly the same, as C of G will differ, and you have different drive locations)

If you can then decide on a fairly sure total weight of yours, the Levi formula will give you a pretty accurate estimate on top speed.
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Old 20-01-2008, 11:00 AM   #18
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1 1/2 tons of fuel!
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Old 20-01-2008, 12:00 PM   #19
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What weight is Mr Noisy as this is a 30' boat with 2x450hp petrol engines, although from all the various threads about it I understand the outdrive's and propellers continue to pose a setting up problem but it does crack 80 mph on a good day from what has been posted, is this not true

Hunton 69 your surmising ran similar to mine on guestimating performance and I also came up with less than the 80mph mark for a P1 P/W ratio but I still do not see anywhere near 90 even set up for a pier to pier run at 2300-2500kg although I can see you breaking into the 80's
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Old 20-01-2008, 07:15 PM   #20
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I will be if thats all it does
72mph set up for rb08 all the kit and fuel i would be happy with that, its a good hull and they are well built
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