Dan wrote:
Nick wrote:

The horizon depends on the height of your eye - the dipping distance
tables in the almanac give the distance off for height. You will see


objects above sea level 'over the horizon' according to their height

so

as the ship approaches, you will see more of it.


70 foot high ship viewed from 3 metres high. I can't be arsed to do the
maths but I bet it isn't *far* off 22 miles.

What would you estimate?


Not quite that far. Dipping distance(nm) is 2.08 * SQRT(height in
metres). 3 metres gives a horizon at 3.6 nm. The 21 metre ship has a
dipping distance of 9.5 nm. So at 13.1 nm you will see the tops of the
masts and at 3.6 nm you will see the hull down to waterline.