Conventional V-bottom hydronamics question..........
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12-20-2007, 07:37 PM
#22
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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?
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
12-20-2007, 07:50 PM
#23
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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
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
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
12-20-2007, 08:07 PM
#24
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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
12-20-2007, 08:15 PM
#25
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I couldn't say for sure, as I was getting the weights off each own manufacturers websites
12-20-2007, 08:21 PM
#26
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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!!!!!!!!!!
12-20-2007, 08:27 PM
#27
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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.
12-20-2007, 09:52 PM
#28
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Michael
12-20-2007, 10:33 PM
#30
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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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