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Message: [QUOTE="Samuel Halpern, post: 58608, member: 137378"] Capt. Collins. Taking departure off Fastnet 3 miles south of what I used makes almost no difference in getting to the LAN locations I gave in my article. Regarding the evidence, Rowe gave the steering compass course as S85W before the course was altered. You said that corresponds to 242Â° true. What I said in my article was the "intended" course from noon to the corner "rounded to the nearest degree" was 241Â° true. The more precise direction would be 240.6Â° (see footnote 16). Lowe actually said from memory "60Âº 33 1/2' west" which is taken to mean S60Â°33.5'W, or 240.56Â° true. Now we know from Lightoller that N71W (289Â°) on the steering compass corresponded to S86W (266Â°)true. The difference is variation plus deviation error which is 23Â° for that particular heading. Applying the same correction for a steering compass course of S85W (265Â°) gets 242Â° true as you say. But is this the correct correction to apply? The 23 degree correction, which comes from Lightoller was applied after the ship altered course from a compass heading of 265Â° to 289Â°, or after a starboard turn of 24 degrees in the ship's steering compass heading. But what is the correction that should be applied to go from compass heading to true heading before the turn was made? Looking at detailed data from an Olympic 1931 voyage on March 29 westbound, we find the ship was heading from noon to 4:40 pm on a heading of 243Â° true (by gyro compass). The steering compass course was written down as being S89W (269Â°) and the deviation for the steering compass was written down as 1.25Â° E. At 4:40 pm they altered course (at 43Â° 00'N, 50Â° 00'W) to 261Â° true on a steering compass course of N76W (284Â°). The deviation error for this compass course was recorded as 3Â°E. So we see the ship's heading was changed to starboard by 15 degrees by steering compass which resulted in a true heading change of 18 degrees. Part of the 3 degrees of difference between the two was in the deviation error for the two different headings, a deviation difference of 1.75Â° for only a 15Â° course change. The remaining 1.25Â° difference in this example would be the change in variation from noon to 4:40 pm. So be careful in what you assume when converting from compass course to true course, especially when applying a correction that may not be valid to the old course heading. A compass heading of S85W as Rowe said could very well have corresponded to Lowe's 240.6Â° true. As we have seen, a deviation error change 1.5 degrees for a course change of only about 25 degrees is not only possible, but has been recorded in the Courses on Board book of Titanic's sister ship on her 200th voyage from Southampton to NY. Welcome to the world of real practical navigation. Cheers, [/QUOTE]

Verification: In which year did the Titanic sail?