Actively variable deadrise
 

wrote in message
...
On Mar 19, 5:24 pm, "Don White" wrote:
"Vic Smith" wrote in message

...



Not bad when you consider it took Edward G. Robinson 606 tries before
he arrived at the "magic bullet" cure for syphilis.
Killed a lot of people doing it too.
Just like WD-40 is still killing bearings.

--Vic

So it's not a good idea for JohnnyPrepH to lubricate/winterize his
outboards
cylinders with WD-40?

Cylinders don't have bearings, idiot.

************************************************

I didn't say they did jackass.

Actively variable deadrise
 

HK wrote in
:

Jim Willemin wrote:
Frogwatch wrote in
news:571e39b1-f812-459a-b9e6-
:

It seems that deadrise has a radical effect on the ability of a boat
to get on plane quickly and thus use less fuel. More deadrise makes
a boat punch through waves better but increases draft and reduces
fuel economy in smaller seas. I assume that variable deadrise has
been tried. Of course there are boats that try to use hull shape to
accomodate varying conditions but not too successfully.
My Tolman has about 10 degree deadrise and is very light so is very
fuel efficient but pounds a lot in chop so I have to slow down to
about 12 kts. Why not some mechanism that would consist of another
outer variable hull layer that would be hinged at the chines
allowing the keel portion to move downward to increase deadrise. It
would have a flexible stiff plastic piece at the front to keep water
out of the area between the two hulls. Is this simply too complex
for too little benefit?


Having pondered this for a couple of days, I am struck by the problem
of changing the area of the floor between the keel and the chine.
This might be tractable near the transom (overlapping leaves,
perhaps, kinda like a 'sliding lapstrake' construction), but as you
get near the stem you gotta worry about major changes in geometry as
well as area. I imagine a really clever designer could do it. I
suppose the question is where in the hull would variable deadrise be
most effective in the transition to planing? That might make an
interesting thesis for someone...



Bring a lifejacket.


I was thinking more of models in a wavetank. But seriously: where in
the hull is deadrise most important to achieving planing status? Is it
in the forward third, the midships third, or the aft third? Since
planing is essentially the result of climbing one's own bow wake, or the
wave whose wavelength is equal to your waterline length, my hunch is
that the geometry near the stem is probably most significant in
acheiving planing. But there has to be some kind of optimum - it seems
to me that a flatiron skiff, say, would take more energy to achieve
planing mode than a runabout of identical length. So if the critical
region is in the forward third of the hull, where major changes in both
hull geometry and hull area occur as you mess with deadrise, it seems to
me probably not worth the effort.

Actively variable deadrise
 

Jim Willemin wrote:
HK wrote in
:

Jim Willemin wrote:
Frogwatch wrote in
news:571e39b1-f812-459a-b9e6-
:

It seems that deadrise has a radical effect on the ability of a boat
to get on plane quickly and thus use less fuel. More deadrise makes
a boat punch through waves better but increases draft and reduces
fuel economy in smaller seas. I assume that variable deadrise has
been tried. Of course there are boats that try to use hull shape to
accomodate varying conditions but not too successfully.
My Tolman has about 10 degree deadrise and is very light so is very
fuel efficient but pounds a lot in chop so I have to slow down to
about 12 kts. Why not some mechanism that would consist of another
outer variable hull layer that would be hinged at the chines
allowing the keel portion to move downward to increase deadrise. It
would have a flexible stiff plastic piece at the front to keep water
out of the area between the two hulls. Is this simply too complex
for too little benefit?

Having pondered this for a couple of days, I am struck by the problem
of changing the area of the floor between the keel and the chine.
This might be tractable near the transom (overlapping leaves,
perhaps, kinda like a 'sliding lapstrake' construction), but as you
get near the stem you gotta worry about major changes in geometry as
well as area. I imagine a really clever designer could do it. I
suppose the question is where in the hull would variable deadrise be
most effective in the transition to planing? That might make an
interesting thesis for someone...


Bring a lifejacket.


I was thinking more of models in a wavetank. But seriously: where in
the hull is deadrise most important to achieving planing status? Is it
in the forward third, the midships third, or the aft third? Since
planing is essentially the result of climbing one's own bow wake, or the
wave whose wavelength is equal to your waterline length, my hunch is
that the geometry near the stem is probably most significant in
acheiving planing. But there has to be some kind of optimum - it seems
to me that a flatiron skiff, say, would take more energy to achieve
planing mode than a runabout of identical length. So if the critical
region is in the forward third of the hull, where major changes in both
hull geometry and hull area occur as you mess with deadrise, it seems to
me probably not worth the effort.

Deadrise isn't important in achieving planing status: a flat-bottomed
boat will plane just fine. The more deadrise, the more power it takes to
get a boat up on plane.

Actively variable deadrise
 

On Fri, 20 Mar 2009 12:25:30 -0400, HK wrote:

Jim Willemin wrote:
HK wrote in
:

Jim Willemin wrote:
Frogwatch wrote in
news:571e39b1-f812-459a-b9e6-
:

It seems that deadrise has a radical effect on the ability of a boat
to get on plane quickly and thus use less fuel. More deadrise makes
a boat punch through waves better but increases draft and reduces
fuel economy in smaller seas. I assume that variable deadrise has
been tried. Of course there are boats that try to use hull shape to
accomodate varying conditions but not too successfully.
My Tolman has about 10 degree deadrise and is very light so is very
fuel efficient but pounds a lot in chop so I have to slow down to
about 12 kts. Why not some mechanism that would consist of another
outer variable hull layer that would be hinged at the chines
allowing the keel portion to move downward to increase deadrise. It
would have a flexible stiff plastic piece at the front to keep water
out of the area between the two hulls. Is this simply too complex
for too little benefit?

Having pondered this for a couple of days, I am struck by the problem
of changing the area of the floor between the keel and the chine.
This might be tractable near the transom (overlapping leaves,
perhaps, kinda like a 'sliding lapstrake' construction), but as you
get near the stem you gotta worry about major changes in geometry as
well as area. I imagine a really clever designer could do it. I
suppose the question is where in the hull would variable deadrise be
most effective in the transition to planing? That might make an
interesting thesis for someone...


Bring a lifejacket.


I was thinking more of models in a wavetank. But seriously: where in
the hull is deadrise most important to achieving planing status? Is it
in the forward third, the midships third, or the aft third? Since
planing is essentially the result of climbing one's own bow wake, or the
wave whose wavelength is equal to your waterline length, my hunch is
that the geometry near the stem is probably most significant in
acheiving planing. But there has to be some kind of optimum - it seems
to me that a flatiron skiff, say, would take more energy to achieve
planing mode than a runabout of identical length. So if the critical
region is in the forward third of the hull, where major changes in both
hull geometry and hull area occur as you mess with deadrise, it seems to
me probably not worth the effort.

Deadrise isn't important in achieving planing status: a flat-bottomed
boat will plane just fine. The more deadrise, the more power it takes to
get a boat up on plane.

....therefore, deadrise *is* important in achieving planing status. The
more deadrise, the more difficult to achieve plane.

Actively variable deadrise
 

On Mar 20, 1:29 pm, John H wrote:
On Fri, 20 Mar 2009 12:25:30 -0400, HK wrote:
Jim Willemin wrote:
HK wrote in
:

Jim Willemin wrote:
Frogwatch wrote in
news:571e39b1-f812-459a-b9e6-
:

It seems that deadrise has a radical effect on the ability of a boat
to get on plane quickly and thus use less fuel. More deadrise makes
a boat punch through waves better but increases draft and reduces
fuel economy in smaller seas. I assume that variable deadrise has
been tried. Of course there are boats that try to use hull shape to
accomodate varying conditions but not too successfully.
My Tolman has about 10 degree deadrise and is very light so is very
fuel efficient but pounds a lot in chop so I have to slow down to
about 12 kts. Why not some mechanism that would consist of another
outer variable hull layer that would be hinged at the chines
allowing the keel portion to move downward to increase deadrise. It
would have a flexible stiff plastic piece at the front to keep water
out of the area between the two hulls. Is this simply too complex
for too little benefit?

Having pondered this for a couple of days, I am struck by the problem
of changing the area of the floor between the keel and the chine.
This might be tractable near the transom (overlapping leaves,
perhaps, kinda like a 'sliding lapstrake' construction), but as you
get near the stem you gotta worry about major changes in geometry as
well as area. I imagine a really clever designer could do it. I
suppose the question is where in the hull would variable deadrise be
most effective in the transition to planing? That might make an
interesting thesis for someone...

Bring a lifejacket.

I was thinking more of models in a wavetank. But seriously: where in
the hull is deadrise most important to achieving planing status? Is it
in the forward third, the midships third, or the aft third? Since
planing is essentially the result of climbing one's own bow wake, or the
wave whose wavelength is equal to your waterline length, my hunch is
that the geometry near the stem is probably most significant in
acheiving planing. But there has to be some kind of optimum - it seems
to me that a flatiron skiff, say, would take more energy to achieve
planing mode than a runabout of identical length. So if the critical
region is in the forward third of the hull, where major changes in both
hull geometry and hull area occur as you mess with deadrise, it seems to
me probably not worth the effort.

Deadrise isn't important in achieving planing status: a flat-bottomed
boat will plane just fine. The more deadrise, the more power it takes to
get a boat up on plane.

...therefore, deadrise *is* important in achieving planing status. The
more deadrise, the more difficult to achieve plane.

I've been reading about "variable deadrise" hulls where the deadrise
changes as one goes from center of the keel area toward the chines.
The pictures all show a series of areas with reduced deadrise toward
the chines. Why not make this a continuous change? I am not sure
what the advantage would be however one can imagine a large deadrise
range at the bow area going to significantly less at transom.
Why does a hard chine boat ride diff from one with rounded chines?

Actively variable deadrise
 

Frogwatch wrote:

Why does a hard chine boat ride diff from one with rounded chines?


Is that a serious question? You can't visualize it?

Actively variable deadrise
 

On Mar 20, 3:26 pm, HK wrote:
Frogwatch wrote:
Why does a hard chine boat ride diff from one with rounded chines?

Is that a serious question? You can't visualize it?

Of course its serious

Actively variable deadrise
 

Frogwatch wrote:
On Mar 20, 3:26 pm, HK wrote:
Frogwatch wrote:
Why does a hard chine boat ride diff from one with rounded chines?
Is that a serious question? You can't visualize it?

Of course its serious


Try to visualize the surface and edge a hard chine boat presents to the
water.

Then visualize the surface and lack of edge a round chine boat presents
to the water.

The hard chine boat tends to bang onto the waves; the round chine boat
tends to slide into the water.

Water doesn't compress too well.

Actively variable deadrise
 

Einstein did not say faster than light travel was impossible. Speed was
limited by energy contraints. Maybe there is another factor in the energy
equation that we do not realize is there in our universe. Just happens to
be 1 or unity on Earth.

Actively variable deadrise
 

"Richard Casady" wrote in message
...
On Thu, 19 Mar 2009 15:14:35 -0500, wrote:

All good ideas are proceeded by lots of bad ones.
WD-40 followed 39 failed attempts.

My great uncle, before he worked on the atomic bombs, invented a
perfume, Chanel #4, a soft drink, Six-Up, and the five pack of beer.
Finally got something to work: the Little Boy.

Casady

And the name 7-up? Was to define that the bottle was bigger than the 6 oz
bottles that coke came in.