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Conventional V-bottom hydronamics question..........

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Old 12-20-2007, 08:32 PM
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You guys focused on the picture too much! Too many pretty colors!

Items 1-4 on my post were in order of importance.
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Old 12-20-2007, 08:37 PM
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Originally Posted by Sydwayz View Post
WHOAH Gerrard!! You opened up a can here!

There are a LOT of things that matter.

1. Weight is a bigger factor than anything.
2. The step itself is not what makes a boat faster. Its the natural pitch or trim that it places the thrust, as well as depth in the water in relation to the weight being pushed or displaced.
3. There are so many bottom designs out there, that you CAN'T generally title one as better (fast/ride/efficiency) than the other based on categorical design. You have to take into account strakes, hook, rocker, tabs, etc. etc.
4. Multiple steps are actually slower a single step; and a straight bottom should be faster. (Given ALL things equal, but how could you accomplish that?) Think of it in plumbing terms. If point A and point B are exactly 8' apart, and you have three equal diameter tubes to pour 2 gallons of water through; which one do you think is going to empty First? Second? Third?

Thanks for the analogy. I wasn't hoping to open up a can of worms.....just thought that it's an interesting subject! Hey, it's wintertime
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Old 12-20-2007, 08:50 PM
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Quote:
Originally Posted by BAJA WILL View Post
Velocity, are much lighter than similar boats with the same power and size, they are usually 15-20% lighter. Thus faster.

On a personal note WOT stepps don't even matter, how much of a boat is in the water at WOT, about 20" in the rear, way past the step, however a pad can make a huge diff.

Just my 2 cents

WILL
Baja-- I think you may have a point. I was just looking at a few different boats as comparisons.....

38 Fountain - 9,800lbs
38 Cigarette - 9,900lbs
39 Nor-Tech - 9,200 lbs
38 Hustler - 8,500 lbs
39 Velocity - 8,000 lbs

In the smaller boats (under 30') the weight difference is alot smaller, if any
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Old 12-20-2007, 09:07 PM
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i would be will to bet that none of those weight's are close to right on those boats. not saying you are wrong and i know you got them from the manf. but i bet they are not close
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Old 12-20-2007, 09:15 PM
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Originally Posted by mikes280 View Post
i would be will to bet that none of those weight's are close to right on those boats. not saying you are wrong and i know you got them from the manf. but i bet they are not close
Mike,

I couldn't say for sure, as I was getting the weights off each own manufacturers websites
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Old 12-20-2007, 09:21 PM
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I enjoyed the thread and the various explanations on hull design and performance. I have a pad velocity and wondered how the pad would perform against multi step hulls at WOT. Thanks for the explanations guys. Merry Christmas!!!!!!!!!!
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Old 12-20-2007, 09:27 PM
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Quote:
Originally Posted by Semper Fi View Post
Mike,

I couldn't say for sure, as I was getting the weights off each own manufacturers websites
i know you did but what i have found is they all tend to lie a little about weight. some thank that heavy is stronger so they say theres is heavy and some say that light is faster so they do the same.
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Old 12-20-2007, 10:52 PM
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Originally Posted by PARADOX View Post
Velosity's rakes and ribs are not true parallel to the sides or the bottom / keel, they divert some of the water to the outside so the boat stay more on top. (I don't know what the deadrise is) Less friction = speed.
I don't follow how diverting water to the outside is going to lift the boat. If anything, it would think it would cause it to drop in the hole left by the diverted water, and plow even more water.

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Old 12-20-2007, 11:32 PM
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Hard to draw with a mouse, sorry, but I think you got the idea.
"A" standar design, "B" hyperbolic and faster. more lift, more air, less friction.
Conventional V-bottom hydronamics question..........-v-bot.bmp
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Old 12-20-2007, 11:33 PM
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Have you ever seen a really fast V-hull boat? The thing is running on the back 2 or so feet of the boat (LESS on smaller boats like a hydrostream). My old hydrostream actually rode on the bullet of the lower unit more so then the bottom of the boat. At that spead and angle of attack the steps would do nothing in the way of reduced drag. I would think that they would hurt by adding wind turbulence.
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