Ok all you Deadrise guys,i have a few questions

[ctoolman]

Everyone says more is better,how come Fountain boats have 21 degree deadrise ?they are still fast and ride good(so i hear)i am way to poor to ever think of getting one..


also i went for a sea trial today in a key west 268 21 degree deadrise same as my 23 whaler...the 2 rides could not be more different...i guess a few extra feet and weight really mean more than the actual deadrise number...

what say you?

[YankeeBoater]

Well, I agree with you that it's not only transom deadrise, but also weight and length at the waterline that are important factors in ride.

There is also the fact that most hulls do not have constant deadrise - they are variable deadrise or 'warped' hulls, in which case, you have an entire schedule of varying deadrise to describe, from bow to stern. Even two boats with the same transom deadrise might have quite different schedules for varying the deadrise forward of the transom.

One boat might have more of a stub 'keel' than another, which will generally enhance tracking and minimize effects of windage.

I'd guess both of those boats have straight sides, square stern and hard chines, so probably no difference there.

If running in waves at a good speed, you can notice stuff like concave topsides - bow flare (that would keep you dry), convex topsides, that would add greater reserve buoyancy, or just plain straight, the default.

[240 Coastal]

ctoolman,

21 is good but 24 is better FOR MY APPLICATION. Everything is a tradeoff but I'll take the softest ride possible every time. Pounding $ucks!

Yes, the 24 degree boat will "rock more" than a lesser degree would, but I always say, "I'm going boating, you want stability?... stay home."

Tom

[TraderVic]

240 Coastal - 11/4/2006 6:09 PM

ctoolman,

21 is good but 24 is better FOR MY APPLICATION. Everything is a tradeoff but I'll take the softest ride possible every time. Pounding $ucks!

Yes, the 24 degree boat will "rock more" than a lesser degree would, but I always say, "I'm going boating, you want stability?... stay home."

Tom

One could argue that the softest possible ride would also be found at home.

[toleary]

In general, more deadrise means less stability at rest, deeper draft and more power (and gas) needed to attain a given speed. I would go with the minimum needed for how and where you operate your boat, keeping in mind that deadrise is only one of the factors that affects the ride.

[B-Faithful]

240 Coastal - 11/4/2006 6:09 PM

Yes, the 24 degree boat will "rock more" than a lesser degree would, but I always say, "I'm going boating, you want stability?... stay home."

Tom

I guess you spend too much time running and not enough time fishing

[240 Coastal]

B-Faithful,

90% of my time is trolling for stripers, but they aren't within sight of the ramp. I have to look for them, they aren't lookin' for me.

Tom.

[ndb8fxe]

Like the above poster said there's more variables than dedrise alone bow entry being one of the bigger factors along with weight. My boat has relatively low dedrise at 19 deg, but the sharp entry keeps is somewhat smoothe.

[Brad1]

There was an article in Trailer Boats magazine a few years ago about what factors affect how a boat rides in rough conditions. Deadrise was only one of numerous factors. Beam was another. Narrower beams are better for rough water. Take a look at an offshore racing boat if you want to see the combined factors that affect ride. Deep V, narrow beam (for given length).

[kerno]

Another big factor in how a boat rides is its aspect ratio. The aspect ratio is the ratio of length to width at the waterline. A 23 foot boat with an 8 foot beam will have an aspect ratio of well under 3, since the length at the waterline may be about 20 feet and the beam at the water can still be close to 8 feet. 20 divided by 8 is 2.5, which is a low aspect ratio. A boat which is 32 feet at the water line and 8 feet wide will have an aspect ratio of 4. Generally, anything under three is going to be pretty stiff riding. Once you get to an aspect ratio of 4 or higher, the ride is going to be decent even with less deadrise. Many offshore race boats will have aspect ratios of 5 or more.

The amount of deadrise under the console or steering station is usually a good indicator of how the hull will ride. There seems to be a controversy over the terms "constant" and "variable" deadrise. On many boats, the deadrise is relatively constant from the stern to where the bow taper and entry begins. That means the deadrise at the stern and the deadrise a few feet forward will be the same. On other hulls, the deadrise will change constantly as it goes from the bow back to the stern. To me, that is what I'd call variable deadrise and also means the hull will have more deadrise under the steering station.

So, in looking at a boat and wondering how it will ride, first look at the entry. How sharp is the bow and how quickly does it transition to the bottom? Then look at the deadrise under the console. Is it steep or fairly flat? A highly pointed bow will cut through rough water very well, but it also is easier to bury than a broad bow or one with a lot of flare. No design meets every purpose. There are a lot of compromises driven by the desire to have lots of room in the boat and a lot of stability - The differences in the hull design of a 24 footer long with a full cabin, microwave and refrigerator will be a lot different from a 31 foot center console.

[YankeeBoater]

Brad1 - 11/4/2006 10:46 PM
Narrower beams are better for rough water.

That's true, and I have half a dozen nice books on design - and all of them say the same thing regarding lwl/bwl ratios and ride, efficiency, and ultimate seaworthiness. But, the average consumer doesn't know that, and so everyone is asking for 24 foot boats with a 12 foot beam, and the builders are just following suit - their job is not to build what's best, but to build what customers want to buy.

[Mr. Demeanor]

My boat is 23' with the bracket (really 21.5) with a 7.5 beam and a 22 degree deadrise. Rides very nice for its size. The downside is its tippy and small. The upside is its a soft ride and fast. I dont think any one thing can shed light on the issue of tradeoffs better than boats.

[RiptideCharters]

A few other things come into play as well. If you have two identical hulls if you set the console farther back so you stand closer to the stern the ride will "feel" softer than if you were standing farther foreward. Also the attitude of the boat plays a role. The Albin I posted photos of rides very flat so the first contact with the water is 2/3s the way foreward. The transom deadrise plays less of a factor than on a boat that runs with a more bow up attitude. The deadrise at the mid point or even a bit foreward of the midpoint would be more important since thats where firs contact with the water would be made.

[prockvoan]

Lets face it,seas,speed and weight play a big factor in how a boat rides.Oh,lets not forget,how the boat is set up and the person behine the wheel knows what he/she is doing.

[Captain Stanman]

Degree of entry is one of the keys, then the manner in which this ties in with the degrees of deadrise.

My 23 Regulator has an entry of 48o. Most makers dont advertise this measurement, but its one of the most important aspects in the comfort level of the ride you can expect from a given hull.

[YankeeBoater]

Mr. Demeanor - 11/5/2006 1:43 AM
I dont think any one thing can shed light on the issue of tradeoffs better than boats.

A classical empiricist! Experiment is the ultimate 'truth' and is always needed to help refine and to validate theory, but I would say that theoretical understanding is a more economical way of knowing.

[Mr. Demeanor]

Here at THT, there are no "truths"....experiment only brings more questions

[Bugbuster]

Captain Stanman - 11/5/2006 7:21 AM

Degree of entry is one of the keys, then the manner in which this ties in with the degrees of deadrise.

My 23 Regulator has an entry of 48o. Most makers dont advertise this measurement, but its one of the most important aspects in the comfort level of the ride you can expect from a given hull.

60 degree entry, 24 deadrise below.

[B-Faithful]

Anything above 12 degrees is wasted

[prockvoan]

B-Faithful - 11/5/2006 12:32 PM

Anything above 12 degrees is wasted

For marsh fishing For offshore,I'm to old to take a beating anymore.