"Degrees of deadrise at the transom"

[MagicMtnDan]

OK, so it's time to admit that I don't understand the term "deadrise at the transom."
I was told that a flat hull results in cavitation and too much "V" slows a boat down and can compromise handling. I understand that deeper vees make for smoother ride in rough/big water. What constitutes a deeper vee (is it a bigger number of "deadrise at the transom" - if so then 24 degrees would be a deeper V than 22 degrees, right?).
I've seen V-bottoms with 20-24 degrees of deadrise at the transom. How is that measured? (I assume it's the angle from the water to the underside of the hull on one side - is that correct? I used to assume the term related to the V of the boat but I quickly realized that wouldn't make sense
I assume that the degrees of deadrise at the transom is more important than towards the bow since the stern is the wetted portion of the hull but what about the vee at the bow - does it matter?
A boat hull is a complex thing and I'm trying to understand the basics. Thanks.

[01RENEGADE]

Good question... I would like some answers also the 25 tremor has 24 in at transom the lavey and essex have flat pads? :confused:

[eliminatedsprinter]

The v at the bow matters a lot when you enter a wave. The v at the bow is the angle of entry or bow entry. A sharp angle of entry is a big factor in obtaining a smooth stable ride in the rough stuff.
[ August 08, 2003, 10:48 AM: Message edited by: eliminatedsprinter ]

[eliminatedsprinter]

It is my understaning that a small pad on the bottom of the transom (ie my boats delta pad) will not have much negitive effect on rough water performance, if it is properly designed and incorpetated into a hull with a nice sharp angle of entry. The theory is that when the boat rides on the pad at speed it is faster and more efficient. It seems to work well for my boat as it has a much smoother ride than I expected from a low profile 19 footer. Cole Boats got fantastic efficiency and rough water ride from their pad bottom Vs.
[ August 08, 2003, 11:06 AM: Message edited by: eliminatedsprinter ]

[BENZEEN]

This is how it was explained to me. Imagine that the boat is sitting on the ground, not leaning more to one side than the other. The ground represents a flat horizontal plane. If you were to measure the angle formed from that horizontal plane to the highest point of the bottom of the hull at the transom on either side, you have your degree of dead rise. You have to view this picture from the rear of the boat. Kind of tough to explain without a picture. This would form an open ended triangle on either side of the keel.
-Vik

[MagicMtnDan]

BENZEEN:
This is how it was explained to me. Imagine that the boat is sitting on the ground, not leaning more to one side than the other. The ground represents a flat horizontal plane. If you were to measure the angle formed from that horizontal plane to the highest point of the bottom of the hull at the transom on either side, you have your degree of dead rise. You have to view this picture from the rear of the boat. Kind of tough to explain without a picture. This would form an open ended triangle on either side of the keel.
-Vik Thanks! That's what I thought.
So, next questions - I'm looking at buying a V-bottom (25+ footer) for big lakes and once/twice a year in the ocean:
1. How much difference does it make if the degrees of deadrise at the transom is say 20, 22 or 24 degrees? What kind of numbers matter - what should I look for in deadrise?
2. What about the rest of the hull's specs? Bow entry? What else matters?
Please let me know your thoughts on hulls and what's important and what isn't. (I already have an idea which boats I like more than others but I'm trying to better understand the differences in hulls). Thanks again...

[spectras only]

MMD, Look at the boat my friend builds at www.Kazulinboats.com (http://www.Kazulinboats.com) . It has 20 degree deadrise at the transom , one step and an extremely sharp bow entry.We have this boat running silky smooth in the roughest conditions and without trimtabs wink .The boat is 24' .
[ August 08, 2003, 12:11 PM: Message edited by: spectras only ]

[rivercrazy]

The steeper the angle the better the ride. Especially if the keel comes to a sharp point. Rounded keel bottoms do not ride as well as.
A V all the way to the transom lets a boat re-enter the water easily and land softly. You dont need to completely air the bottom to get this effect. (Any re-entry along the length of the boat). Pad or delta keel bottoms on re-entry have a flat area to land on and will ride rougher as a general rule. However, pad/delta bottoms are little more stable than a strait V if you know how to drive them. It gives the boat something to ride on to stabilize the hull. This of course assume the bottom is a good design.
I can tell you one thing, A 24 degree bottom will ride much better than a 20-21 degree bottom.
One thing to remember is weight and length also play very important roles in how a boat will take the rough stuff.

[TPI]

Dan,
I have a friend that has a boat that has a steep deadrise(>24 degrees) I love to ride in his boat! But the guy constantly complains about the speed. The fact is it would take so much power to make it go fast (an honest 70 mph in the summer) it would not be worth it. Its a give an take. Delta pads are cool, until you crest 80 mph or go through some really big water. Either one, >80 or big water is scary for most delta pad boats. Drive them all!!!!!!!!!! You will see........

[HOSS]

Naw Gt I have to disagree. What kinda water we talkin` here? I meen come on. Bro 6 ft swells? Pads do great for everyone except the serious. And the serious don`t cruise with people. If they do then the people hate the ride. A cool ride does have a steep rise. But at the dock it sucks cause every boat that passes rocks the **** outa your shit. And if your smoked, then gettin` your shit rocked sucks. Water hittin` a wall does tend to make movement. Especially if the wall ain`t planted. Rakes and designs like Regal came out with were radical. I`m suprised i`m typing this good. I`m alittle lit. WEw arnold is my boy. I use to idolize and still do thios guy.
I think the original question was pertaining to transom angle from bottom or keel. This really is a guessing game. Let me startva new paragraph.
Transom angle depends on a wbhole lot of shit and its all theory. But one thing is for surte. Deffinate. If you could have the hul bootttom to transom RAZOR sharp?, thats a good thing. Angle and set back is a funny game. Here is a great thing to think about. If the hull is advertised at 20, 30, 40, 50, or ****in` 15 then why add a pad? Right? Well its like this you bought what you bought and your foolin` the boat (actually foolin` the water) into thinkin` your boat is longer. Make since. Thought it didn`t. Why not buy a bigger boat? OK,,,,where do yuou stop? Jackplates, trim tabs, ride plates, setbacks, angles, trim, degrees, ****, what do I do? You buyb a hull and improve. Not everything works for every hull. Or every hp even given the sam ehull and hp. Fibergass and carbon fiber are not protected to weight and deminsion fluctuations. You got wat you got. And here is the kicker,,,,you are dealing with an ever changing surface. Cool he? Don`t go back to cars. I `havent. Because I`m gettin` older lazier, wife makes cash, I quit work, and I`m a ****in asshole. If ya wunna knoe the truyth.

[TPI]

Huh??????????????????????Man, at this point, one of two things needs to happen: 1. I need to go back to school and sharpen up my knowledge on boat design/handling/stability/hydrodynamics or #2. Find Hoss and go have a few beers and stir up some shit somewhere :D Im Mojave bound: see you all in a week.