Tropical Revolving Storms which forms in Tropical regions. Northern hemisphere it moves towards north and vice versa in Southern hemisphere.
in addition there are some non-adjustable erroes
graduation error,shade error,optical error, prismatic error,telescopic error
Sextant Errors are of 2 Types:
1) Adjustable error,
2) Non Adjustable errors
1)Adjustable errors:
a)error of perpendicularity,
b)Index error,
c)Side error,
d)Error of collimination
2)Non adjustable Errors:
a)Graduation Error,
b)Shade Error,
c)Optical Error,
d)convex Error..
if the cpa matters , and collision cant be avoided by the give way vsl alone then i will alter other wise , maintain co and speed.
take the series of brg if risk of collision does not exist the maintain co and speed if roc exist the i will give five sort and rapid blast, check nav lights, inform master,inform engine room,put helms men and still she is not taking an action then one short blasta/co to stbd if depth available or reduce speed
velocity of propagation in water, stylus speed error, pythagoras error, multiple echoes, thermal and density layers, zero line adjustment error, cross noise, Aeration.
