Boat Displacement
 

When does a boat go from being light displacement to medium displacement
to heavy? What delineates them? Is it based on the weight, D/L, SA/D,
etc. or some combination of these?

Thanks.

It's like the question of when they go from being a boat to a ship.
There are some commonly agreed on displacement length numbers but they
shift with time and fashion. The scandalously light of fifty years
ago would be a heavy tank today. Where will it ever end?

--

Roger Long



"Dale" wrote in message
.net...
When does a boat go from being light displacement to medium
displacement to heavy? What delineates them? Is it based on the
weight, D/L, SA/D, etc. or some combination of these?

Thanks.

Roger Long wrote:

It's like the question of when they go from being a boat to a ship.
There are some commonly agreed on displacement length numbers but they
shift with time and fashion. The scandalously light of fifty years
ago would be a heavy tank today. Where will it ever end?

Yes, but I see many posts where people refer to HD vs MD with no
discussion on what these are, which tells me that there are some general
ideas about them. So what are the commonly agreed upon numbers for our
current fashion?

Dale wrote:
....snip...
Yes, but I see many posts where people refer to HD vs MD with no
discussion on what these are, which tells me that there are some
general
ideas about them. So what are the commonly agreed upon numbers for
our
current fashion?

I think I disagree about there being generally accepted ideas about
this; but here's my $.02, FWIW.
Heavy = D/L ratio over 275
Medium = 225-275

YMMV,

Frank

Dale wrote:
Roger Long wrote:

It's like the question of when they go from being a boat to a ship.
There are some commonly agreed on displacement length numbers but they
shift with time and fashion. The scandalously light of fifty years
ago would be a heavy tank today. Where will it ever end?

Yes, but I see many posts where people refer to HD vs MD with no
discussion on what these are, which tells me that there are some general
ideas about them. So what are the commonly agreed upon numbers for our
current fashion?


Disp/LWL is probably the most direct measure, though SA/Disp takes into
account the ability to make use of the low displacement.

As for "commonly agreed upon numbers," you won't find specific
agreement. For instance, another poster said "medium" was 225 to 275;
that would make a Nonsuch 30 (at 216) a "Light Displacement" boat.
Also, lots of C&C's, Freedoms, Pearsons, Tartans, etc. are under 225 but
many people wouldn't think of them as "light."

The best thing to do is to use a program like sailcalc to see how boats
that you're familiar with measure up.

http://www.image-ination.com/sailcalc.html

Read the current issue of Sail. There is a good article that explains this.

John

"Jeff Morris" wrote in message
...
Dale wrote:
Roger Long wrote:

It's like the question of when they go from being a boat to a ship.
There are some commonly agreed on displacement length numbers but they
shift with time and fashion. The scandalously light of fifty years ago
would be a heavy tank today. Where will it ever end?

Yes, but I see many posts where people refer to HD vs MD with no
discussion on what these are, which tells me that there are some general
ideas about them. So what are the commonly agreed upon numbers for our
current fashion?


Disp/LWL is probably the most direct measure, though SA/Disp takes into
account the ability to make use of the low displacement.

As for "commonly agreed upon numbers," you won't find specific agreement.
For instance, another poster said "medium" was 225 to 275; that would make
a Nonsuch 30 (at 216) a "Light Displacement" boat. Also, lots of C&C's,
Freedoms, Pearsons, Tartans, etc. are under 225 but many people wouldn't
think of them as "light."

The best thing to do is to use a program like sailcalc to see how boats
that you're familiar with measure up.

http://www.image-ination.com/sailcalc.html