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#11
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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 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#12
posted to rec.boats.cruising
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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 |
#13
posted to rec.boats.cruising
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Shake and Break Part 13 - August 6 2015
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#14
posted to rec.boats.cruising
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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 |
#15
posted to rec.boats.cruising
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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. |
#16
posted to rec.boats.cruising
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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 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#17
posted to rec.boats.cruising
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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 See our galleries at www.justpickone.org/skip/gallery ! Follow us at http://groups.yahoo.com/group/TheFlyingPigLog and/or http://groups.google.com/group/flyingpiglog When a man comes to like a sea life, he is not fit to live on land. - Dr. Samuel Johnson |
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