I am not a sailor or navigator by any means, so please forgive me if I've misunderstood you in any way. I'm just an interested amateur and was checking the math out of idle curiosity.

Your post from this morning calculates noon April 14 as 2:58pm GMT (14d14h58m) if I'm reading correctly. Meaning that at this point, the voyage has lasted 3 days, 2 hours and 26 minutes, correct? At that point Titanic has covered approx. 1,549 miles for an average speed of 20.81 knots. That's within the realm of reasonableness, I think.

By my math, the average speeds work out as follows :

April 11 : 21.38 knots (484 miles / 22.633 hours)

April 12 : 20.98 knots (519 miles / 24.733 hours)

April 13 : 22.08 knots (546 miles / 24.733 hours)

April 14 : Either 22.29, 21.55 or 20.97 knots, depending on how much clock setback you think happened between noon and the collision (260 miles / 11.667, 12.067, or 12.4 hours)

At noon, Titanic had about 1,345 miles to go before reaching Ambrose Light. If she continued to average about 22 knots, she had 2 days, 13 hours and 11 minutes to go. If my math is right, that works out to an arrival time of 4:09am GMT on April 17, or 11:09pm EST April 17 in EST. Again, assuming I haven't made a big goof here somewhere, that works out to a crossing time of 5 days, 15 hours and 37 minutes, and an average speed of 21.35 knots (2,895 miles / 135.617 hours) That matches well with what we know about Olympic's performance on her maiden voyage, so I think your calculations pass the "reasonableness check". Do your figures agree with mine?