The higher the sun is a LAN, the more accurate you may get, using your
method. However, the lower the sun at LAN, the less accurate.
It has less to do with rough seas and poor horizons.
Biggest problem with your method is getting an accurate time for LAN.

otn

Simple Simon wrote:
That's a good way to do it when the seas are rough and
the horizon hard to judge. We call that extrapolation.

S.Simon