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Re: Silicon Sea: Leg 83 Answers
From: Peter Fogg
Date: 2002 Sep 27, 09:05 +1000
From: Peter Fogg
Date: 2002 Sep 27, 09:05 +1000
Dan Hogan wrote: > > Here are my calculations "COURSE TO STEER" ARE IN PC-8 font from NavPO93. > 5. CC to clear Cape Kumukahi by 4 Nmi > 19d 30.0'N 154d 45.6'W > - 4.0' > 154d 41.6'W > > ����������������������͵ [2] COURSE TO STEER ���������������������������ͻ > � > Variation 10.0� E Deviation 1.0� E � > � > Lat 1 19� 25.1' N Speed 10.0 Lat 2 19� 30.0' N � > Lon 1 154� 31.9' W Drift 0.7 Lon 2 154� 41.6' W � > Set 95.0� � > Desired ===Needed===>> CompCrse 285.5� � > TrueCrse 298.0� SpMdGd 9.4 � > Distance 10.4 Time 1h 06.9m � > � > �������������������������������������������������������������������������* > > 6. Dist Cape to Hilo > > ����������������������͵ [2] COURSE TO STEER ���������������������������ͻ > � > Variation 10.0� E Deviation 1.0� E � > � > Lat 1 19� 30.0' N Speed 10.0 Lat 2 19� 44.0' N � > Lon 1 154� 41.6' W Drift 0.4 Lon 2 155� 04.0' W � > Set 270.0� � > Desired ===Needed===>> CompCrse 293.7� � > TrueCrse 303.4� SpMdGd 10.3 � > Distance 25.4 Time 2h 27.7m � > � > �������������������������������������������������������������������������* > > 7. ETA Hilo Point > > RFIX 01:44:36 UT @ 16/07/2001 > 14:00:00 Hrs. = 140 Nmi / 10 Kts to DR > 01:06:54 Hrs. to Cape > 02:27:42 25.4 Hrs to Hilo > -------- > 19:19:12 UT @ 16/07/2001 > -(+10) ZT > ----- > 09:19:12 ZT 16/07/2001 For the first segment we are given, apart from the speed of 10 k, a Current Set 095d, Drift 0.7 Kts. Yet the time above for the 140 nm run, 14:00:00 Hrs, indicates the speed used was the 10 k rather than a lesser speed influenced by the contrary current, a SMG of about 9.3 k.It makes for about an hour's difference. I don't understand this apparent inconsistancy. The rest is minor - Distance 10.4 / SpMdGd 9.4 = 1h 06m 23m, rather than 01:06:54 Hrs, just as Distance 25.4 / SpMdGd 10.3 = 2h 27m 58s, rather than 02:27:42 Hrs. Can imagine these small differences come about from the calculator using internal data that is more precise than that displayed, which is rounded to specification. Despite these whinges and moans, enjoy these Silicon Sea exercises greatly. Long may they sail.
