Jessica B wrote:

At first someone claimed that the waterline difference would be tiny.
I found to be what seems a recent photo where that's not the case, and
now you're claiming it's a relic? I don't get that. Either it can be a
factor or it can't be.


If I may again...

Compare a Catalina 27 and My Catalina 26.

My waterline is 3 inches longer.

That's because the 27 has significant overhangs on both ends.
Overhangs are the part of the hull above the waterline forward or aft of the
waterline/hull point.
If there is a lot of hull forward of where the water meets the hull then you
have a long bow overhang. Same for the stern.

Heeled 30 degrees (quite a bit actually) the 27's waterline length just about
matches my 26's.

Any less heel and the 27 is shorter than the 26. Waterline length that is...

So, what does it mean as far as speed goes?

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

Which can be easily hidden by sail trim, rudder position, sea state, etc


Yes, I get that current is only a real help in a few instances. What
about the gulf stream example? I don't think that changes direction
does it?

Current is not tide.
Tides change direction. Currents usually do not.


--

Richard Lamb

In article ,
says...

Jessica B wrote:

At first someone claimed that the waterline difference would be tiny.
I found to be what seems a recent photo where that's not the case, and
now you're claiming it's a relic? I don't get that. Either it can be a
factor or it can't be.


If I may again...

Compare a Catalina 27 and My Catalina 26.

My waterline is 3 inches longer.

That's because the 27 has significant overhangs on both ends.
Overhangs are the part of the hull above the waterline forward or aft of the
waterline/hull point.
If there is a lot of hull forward of where the water meets the hull then you
have a long bow overhang. Same for the stern.

Heeled 30 degrees (quite a bit actually) the 27's waterline length just about
matches my 26's.

Any less heel and the 27 is shorter than the 26. Waterline length that is...

So, what does it mean as far as speed goes?

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

Which can be easily hidden by sail trim, rudder position, sea state, etc


Yes, I get that current is only a real help in a few instances. What
about the gulf stream example? I don't think that changes direction
does it?

Current is not tide.
Tides change direction. Currents usually do not.

That's both right and wrong in so many ways....

Tides go up and down.

Currents caused by tidal differences do change direction---one
or more times per day, depending on whether you have diurnal or
semi-dirunal tides.

Currents in the open ocean--like the Gulf Stream or the Japan Current,
do not change directions---at least during the time span of a normal
cruise.

Mark Borgerson

Mark Borgerson wrote:
In article ,
says...
Jessica B wrote:
At first someone claimed that the waterline difference would be tiny.
I found to be what seems a recent photo where that's not the case, and
now you're claiming it's a relic? I don't get that. Either it can be a
factor or it can't be.

If I may again...

Compare a Catalina 27 and My Catalina 26.

My waterline is 3 inches longer.

That's because the 27 has significant overhangs on both ends.
Overhangs are the part of the hull above the waterline forward or aft of the
waterline/hull point.
If there is a lot of hull forward of where the water meets the hull then you
have a long bow overhang. Same for the stern.

Heeled 30 degrees (quite a bit actually) the 27's waterline length just about
matches my 26's.

Any less heel and the 27 is shorter than the 26. Waterline length that is...

So, what does it mean as far as speed goes?

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

Which can be easily hidden by sail trim, rudder position, sea state, etc


Yes, I get that current is only a real help in a few instances. What
about the gulf stream example? I don't think that changes direction
does it?
Current is not tide.
Tides change direction. Currents usually do not.

That's both right and wrong in so many ways....

Tides go up and down.

Currents caused by tidal differences do change direction---one
or more times per day, depending on whether you have diurnal or
semi-dirunal tides.

Currents in the open ocean--like the Gulf Stream or the Japan Current,
do not change directions---at least during the time span of a normal
cruise.

Mark Borgerson




Much better explination of tidal currents, Mark.
Thanks

--

Richard Lamb
email me:
web site: http://www.home.earthlink.net/~cavelamb

"CaveLamb" wrote in message
...
Mark Borgerson wrote:
In article ,
says...
Jessica B wrote:
At first someone claimed that the waterline difference would be tiny.
I found to be what seems a recent photo where that's not the case, and
now you're claiming it's a relic? I don't get that. Either it can be a
factor or it can't be.

If I may again...

Compare a Catalina 27 and My Catalina 26.

My waterline is 3 inches longer.

That's because the 27 has significant overhangs on both ends.
Overhangs are the part of the hull above the waterline forward or aft of
the waterline/hull point.
If there is a lot of hull forward of where the water meets the hull then
you have a long bow overhang. Same for the stern.

Heeled 30 degrees (quite a bit actually) the 27's waterline length just
about
matches my 26's.

Any less heel and the 27 is shorter than the 26. Waterline length that
is...

So, what does it mean as far as speed goes?

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

Which can be easily hidden by sail trim, rudder position, sea state, etc


Yes, I get that current is only a real help in a few instances. What
about the gulf stream example? I don't think that changes direction
does it?
Current is not tide.
Tides change direction. Currents usually do not.

That's both right and wrong in so many ways....

Tides go up and down.

Currents caused by tidal differences do change direction---one or more
times per day, depending on whether you have diurnal or
semi-dirunal tides.

Currents in the open ocean--like the Gulf Stream or the Japan Current,
do not change directions---at least during the time span of a normal
cruise. Mark Borgerson




Much better explination of tidal currents, Mark.
Thanks



Mark sure is more correct than Bruce. LOL! But, then again, perhaps that's
not saying much.

Wilbur Hubbard

On Mon, 28 Mar 2011 22:16:58 -0500, CaveLamb
wrote:

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

27^.5=5.2 27.25^.5=5.22. Three hundredths of a knot difference.

Casady

On Tue, 29 Mar 2011 05:04:01 -0500, Richard Casady
wrote:

On Mon, 28 Mar 2011 22:16:58 -0500, CaveLamb
wrote:

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

27^.5=5.2 27.25^.5=5.22. Three hundredths of a knot difference.

Casady


Hmmm. HP calculator?

--Vic

Vic Smith wrote:
On Tue, 29 Mar 2011 05:04:01 -0500, Richard Casady
wrote:

On Mon, 28 Mar 2011 22:16:58 -0500, CaveLamb
wrote:

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.
27^.5=5.2 27.25^.5=5.22. Three hundredths of a knot difference.

Casady


Hmmm. HP calculator?

--Vic


Sorry guys
Just late and not paying attention to the numbers.

Half a knot for 3 inches does seem a little funny, doesn't it...

--

Richard Lamb
email me:
web site: http://www.home.earthlink.net/~cavelamb

"CaveLamb" wrote in message
...
Vic Smith wrote:
On Tue, 29 Mar 2011 05:04:01 -0500, Richard Casady
wrote:

On Mon, 28 Mar 2011 22:16:58 -0500, CaveLamb
wrote:

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.
27^.5=5.2 27.25^.5=5.22. Three hundredths of a knot difference.

Casady


Hmmm. HP calculator?

--Vic


Sorry guys
Just late and not paying attention to the numbers.

Half a knot for 3 inches does seem a little funny, doesn't it...



Since the fudge factor is multiplied by the square root of the LWL, the LWL
must be significantly longer than a few inches for the theoretical speed to
go up much. But, every little bit counts. Even a clean bottom makes a huge
difference and many sailors go around with a fouled bottom not realizing how
badly it slows them down. Same goes for those dumb, big, three-bladed fixed
props. What a DRAG!


Wilbur Hubbard

On Tue, 29 Mar 2011 07:52:19 -0500, Vic Smith
wrote:

On Tue, 29 Mar 2011 05:04:01 -0500, Richard Casady
wrote:

On Mon, 28 Mar 2011 22:16:58 -0500, CaveLamb
wrote:

Three inches is 1/4 of a foot.
So..

1.33 * sqrt (.25) = ?
1.33 * .5 = .665 knots difference In theory, at least.

27^.5=5.2 27.25^.5=5.22. Three hundredths of a knot difference.

Casady


Hmmm. HP calculator?

I refer to my HP 48 as " TheCalculatorThatTakesNoPrisoners "

Casady