Understanding deadrise?

Deadrise as measured at the transom is a very important factor in how a hull
will handle the water - more deadrise equals less efficient planing but
better rough water handling - but there are other factors, such as fineness
of entry at the bow, how quickly the deadrise changes as it goes astern,
whether there are "pads," "lifting strakes," and "spray rails" built into
the hull or not, and on really high performance hulls, things like "steps."

Also, I would add, I have a 1978 Trojan 26, so much like the Chris Craft you
mention, and it handles rough water like a dream. I don't know the deadrise
number, but it isn't much. Why is it so good? I'm not sure, but I think it's
because it's a semi-planing hull, not full-planing, at least as powered by
its probably original 225 hp Chrylser 318, and so it never ends up planing
on just the aft fraction of the hull. In other words, you don't have to
worry about slamming down onto the water from waves if most of the hull
never leaves the water.

Last year in short 6 footers, I had it slowed down probably to about 12
knots, but not for slamming - it was just too rough to hold on, otherwise.
The boat itself handled it all with great poise - although admittedly not at
very high speed - although observers on land later told me we were throwing
a great deal of spray!

There are lots of design complexities, and the deadrise number, although
important, isn't the entire story.

====

Charles T. Low
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====

"C. J. Klingman" <cklingman DeleteThis @austin.rr.com> wrote in message
news:9SJAc.9405$4g1.7909@fe2.texas.rr.com...
 > Deadrise is measured at the transom.
 >
 > Your numbers are logical to me. Larger boats would be more likely to be
 > offshore boats, needing more 'V' for comfort in the normal choppy seas.
 > Deckboats are heavy damn things for their length and need all the help
they
 > can get to plane, and would almost never be used offshore. Lots of older
 > boats, Crist Craft runabouts, etc. have almost no deadrise, better to
plane
 > with the lower power of the time, comfort be damned.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Understanding deadrise? 

Hello All You Boaters,

I think the deadrise is usually measured at the rear bottom. I think it is
an important thing to look at for any boater.

More deadrise and more weight and more length will allow you to run in
bigger seas.

We fly fish out of our smaller boats (8' to 16') so we are looking for nicer
weather to fly cast anyway. We like wider fairly flat bottom boats with
shallow deadrise of 3 to 10 degrees. These boats are not great for open
water but are very stable for standing and fly casting.

--
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA

Web site: <a style='text-decoration: underline;' href="http://www.kiene.com" target="_blank">www.kiene.com</a>


"Petey the Wonder Dog" <baldycotton2.RemoveThis@mchsi.comedy> wrote in message
news:arj6d0llsd05ongtkmu8gt3vi8jmdi88ri@4ax.com...

 > Reading thru lots of material and lots of brochures, everyone lists
 > deadrise.
 >
 > Seems that the deckboats have a lesser degree of angle, (15 - 17degrees)
 > bowriders of shorter length have middling degrees, 18 -19 and larger
 > boats 23' and up, higher degrees.
 >
 > So the larger the boat, generally, the deeper the vee, and less of an
 > ability to plane. (and also a smoother ride.)
 >
 > What I can't find is where it's measured. Is there a standard, or is it
 > arbitrary based on the hull technology?
 >
 > If that's the case, why bother to advertise it if it doesn't mean much.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Understanding deadrise? 

A lot of good and accurate responses, but the other component is that when the
boat isn't moving, the higher deadrise will tend to rock side-to-side more.

Dan


Petey the Wonder Dog wrote:
 > Reading thru lots of material and lots of brochures, everyone lists
 > deadrise.
 >
 > Seems that the deckboats have a lesser degree of angle, (15 - 17degrees)
 > bowriders of shorter length have middling degrees, 18 -19 and larger
 > boats 23' and up, higher degrees.
 >
 > So the larger the boat, generally, the deeper the vee, and less of an
 > ability to plane. (and also a smoother ride.)
 >
 > What I can't find is where it's measured. Is there a standard, or is it
 > arbitrary based on the hull technology?
 >
 > If that's the case, why bother to advertise it if it doesn't mean much.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Understanding deadrise? 

Dan Krueger wrote:
 > A lot of good and accurate responses, but the other component is that when the
 > boat isn't moving, the higher deadrise will tend to rock side-to-side more.
 >
 > Dan
 >
 >
 > Petey the Wonder Dog wrote:
  >> Reading thru lots of material and lots of brochures, everyone lists
  >> deadrise.
  >>
  >> Seems that the deckboats have a lesser degree of angle, (15 - 17degrees)
  >> bowriders of shorter length have middling degrees, 18 -19 and larger
  >> boats 23' and up, higher degrees.
  >>
  >> So the larger the boat, generally, the deeper the vee, and less of an
  >> ability to plane. (and also a smoother ride.)
  >>
  >> What I can't find is where it's measured. Is there a standard, or is it
  >> arbitrary based on the hull technology?
  >>
  >> If that's the case, why bother to advertise it if it doesn't mean much.
 >


There are alternatives to deep-vee hulls that perform very well in
choppy conditions, and don't have some of the negatives.

Also, uo to a point of length, certain deep vee boats might have more
vee...but the really large offshore sportfishers aren't known for really
deep vee bottoms.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Understanding deadrise?