Shake and Break Part 13 - August 6 2015
 

On 9/14/2015 5:48 PM, Wayne.B wrote:
On Mon, 14 Sep 2015 05:37:09 -0600, Paul Cassel
wrote:


===

It's basically simple vector algebra. Assume a speed through the
water of 5 kts on a course of due east. Also assume a north flowing
current of 5 kts. The resultant course made good would be north east
at 7 kts.



I see where we disagree. My logic was course to the destination and
that's not enhanced by a current which is 90 degrees to the desired course.

I guess until Skip checks in, we'll not know exactly what he was about.

-paul

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Shake and Break Part 13 - August 6 2015
 

On Mon, 14 Sep 2015 19:48:36 -0400, Wayne.B wrote:
On Mon, 14 Sep 2015 05:37:09 -0600, Paul Cassel
wrote:
On 9/13/2015 9:47 AM, Wayne.B wrote:
On Sat, 12 Sep 2015 14:24:12 -0600, Paul Cassel

I'm guessing that he might have been quoting SOG from a GPS and
getting some boost from the Gulf Stream. My old Cal-34 used to exceed
hull speed under sail fairly frequently however. It's not an absolute
limit, just a point where you need a lot more power to start climbing
the bow wave.

I doubt it. If he were headed north, then yes, but the Stream runs
roughly 90 degrees to the intended course here. I can't see how that can
add to speed made good. Maybe Skip will drop in and clarify.

It's basically simple vector algebra. Assume a speed through the
water of 5 kts on a course of due east. Also assume a north flowing
current of 5 kts. The resultant course made good would be north east
at 7 kts.

You don't actually think Skippy is sitting there the whole time
steering east do you? Nope, Skippy has so much crap aboard that
surely he uses an autopilot. He leaves Florida and sets his AP
to steer to a Great Sal waypoint. His AP corrects for any current
encountered so Skippy doesn't have the first clue as to correcting
for set manually.

--
Sir Gregory

Shake and Break Part 13 - August 6 2015
 

On Tue, 15 Sep 2015 08:35:03 +0700, wrote:
...

I see. Skipper, who goes sailing, is divorced from the reality of
cruising, while a bloke who is permanently moored (with stainless
steel chains) is the realist.

A rather perverse logic, to say the least.


Please, no comments from the Peanut Gallery!

Shake and Break Part 13 - August 6 2015
 

On Mon, 14 Sep 2015 05:37:09 -0600, Paul Cassel wrote:

On 9/13/2015 9:47 AM, Wayne.B wrote:
On Sat, 12 Sep 2015 14:24:12 -0600, Paul Cassel

===

I'm guessing that he might have been quoting SOG from a GPS and
getting some boost from the Gulf Stream. My old Cal-34 used to exceed
hull speed under sail fairly frequently however. It's not an absolute
limit, just a point where you need a lot more power to start climbing
the bow wave.


I doubt it. If he were headed north, then yes, but the Stream runs
roughly 90 degrees to the intended course here. I can't see how that can
add to speed made good. Maybe Skip will drop in and clarify.

It simply cannot add to speed (through the water) made good.
Hull speed is hull speed is hull speed on a displacement hull.
No amount of current from any direction can change that.

Set (current) can only add to or subtract from speed and distance
(over ground) made good.

--
Sir Gregory

Shake and Break Part 13 - August 6 2015
 

On Tue, 15 Sep 2015 08:04:56 -0600, Paul Cassel
wrote:

On 9/14/2015 5:48 PM, Wayne.B wrote:
On Mon, 14 Sep 2015 05:37:09 -0600, Paul Cassel
wrote:


===

It's basically simple vector algebra. Assume a speed through the
water of 5 kts on a course of due east. Also assume a north flowing
current of 5 kts. The resultant course made good would be north east
at 7 kts.



I see where we disagree. My logic was course to the destination and
that's not enhanced by a current which is 90 degrees to the desired course.

I guess until Skip checks in, we'll not know exactly what he was about.


===

You're talking about VMG (Vleocity Made Good) as opposed to SOG (Speed
Over Ground). Some GPS units can report VMG if you have a waypoint
set but most people just look at SOG.

Shake and Break Part 13 - August 6 2015
 

On 9/15/2015 5:40 PM, Wayne.B wrote:
On Tue, 15 Sep 2015 08:04:56 -0600, Paul Cassel
wrote:


===

You're talking about VMG (Vleocity Made Good) as opposed to SOG (Speed
Over Ground). Some GPS units can report VMG if you have a waypoint
set but most people just look at SOG.


My term for it is course made good or your progress rate toward your
goal. I agree that we were not in disagreement as much as discussing
different things.

For me, I don't care if I'm doing 20 kts over the mud if I'm also only
moving 1 kt toward where I want to go.

Why I'd hoped Skip would check in is to see what he used to determine
whatever showed him doing those 12 kts.

-paul

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Shake and Break Part 13 - August 6 2015
 

Howdy, peanut gallery :)

Our STW is available from three sources. All require calibration. All
were, at one time, using a 5 knot SOG in both directions. Up from there
usually had some distortion on the plus side. Down from there usually had
some distortion on the negative side. So, I expect that my STWs are a
best-guess in most cases.

That said, SOG frequently exceeds 8 knots in non-current infected water; we
push a lot of water at that speed and our platform, 2' above the water, is
usually awash on the heeled side. In this case, we were so squatted that a
good half of it was awash.

Block-to-block is a more useful measure; we averaged, for example, 8 knots
from anchor up to anchor down, on the 480 miles from Raccoon (in the
Raggeds) to Ft. Pierce (across from the CG station) on our return in 2011;
it was 60 hours exactly.

On the second trip over this year, we didn't have the same advantage of a
beam reach for the entirety, including the southing we made initially, but
it was still a fast trip, including the 40knot squall, briefly.

I crewed on Sleeper, an OI41, during one of the Morgan Invasion races; we
were doing well over hull speed at the finish, throwing a very impressive
bow wake.

Hull speed is only useful in determining how fast you can go before you're
no longer at a displacement speed.

The time we went from Lucaya to St. Simons Island involved a half-gale,
running wing-and-wing. SOG was 14.3 before we struck the pole and
preventer, due to building seas which might have had us roll to the degree
that one of the boom or pole would catch. At the very best, the GS might
have contributed 4 knots, more likely 3.5, to that.

It's not a speed I'm comfortable with, but it was exciting at the time!

L8R

Skip, calling to make arrangements for the non-covered Medicare (long story,
it kicked in July 1, weeks after her hospitalization) patient's making
monthly payments...

Morgan 461 #2
SV Flying Pig KI4MPC
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