Offshoreonly.com - Conventional V-bottom hydronamics question..........

Offshoreonly.com (https://www.offshoreonly.com/forums/)

- General Boating Discussion (https://www.offshoreonly.com/forums/general-boating-discussion-51/)

- - Conventional V-bottom hydronamics question.......... (https://www.offshoreonly.com/forums/general-boating-discussion/175826-conventional-v-bottom-hydronamics-question.html)

You guys focused on the picture too much! Too many pretty colors!

Items 1-4 on my post were in order of importance.

Quote:

Originally Posted by Sydwayz (Post 2378876)

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 :)

Quote:

Originally Posted by BAJA WILL (Post 2379083)

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:ernaehrung004:

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

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

Quote:

Originally Posted by mikes280 (Post 2379128)

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

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!!!!!!!!!!

Quote:

Originally Posted by Semper Fi (Post 2379145)

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.

Quote:

Originally Posted by PARADOX (Post 2379032)

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.

Michael

Man, hull designs sound like rocket science. Minimal friction=minimal drag=minimal boat in the water. What happens to the stability of the boat if most of it is out of the water?

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.
Attachment 315752