NavList:

   

Reply

Mr. Huxtable, I'll try to answer your questions to the best of my ability.I
like it when you degress.I enjoy reading all your posts.I've learned quite a
deal from you and all so far.
I don't make the rules of the exams.I was told these are the conditions that
the U.S.C.G. set.It's a government organization,so they have their rules.I
do know that in the states the timed mile markers that are along shore for
checking speed are in statute miles and that is what the examiner was
looking for.I calculated 351.7 mi.(nautical mi.)and got it wrong.That's all
I can tall you on that.
No,taffrail logs are not used.It's not common to drag anything off the stern
unless it's a tow.There are more suffisticated pieces of equipement used
today.The revs. are feed into the Inertial Nav. System along with other data
for positioning.
I know what you're saying about true(observed)slip.That is where the mile
markers come into play.You get your observed speed by useing them.Slip is a
factor to be concidered.It is used mainly for calculations of advances and
fuel consumption(mainly fuel consuption as crude was around $37.00 a barrel
and if you burn 3 barrels every 15 minutes you can see the cost.).At best it
is an approximation as I stated.Yes when speed changes slip will also.What I
should have said is at the start of the leg the speed and distance of the
vessel is calculated with slip factored to give a "better" future pos.This
is only a tool used as a check against other calculations or equipement.Out
there you are useing every tool you have to keep on top of ever changeing
conditions.Heavy weather is a factor.When it can't be avoided you slow down
and everything has to be recalculated.In a 6 hr. watch period I can go
through 15-50 sets of calculations because of changeing conditions.Mr.
Huxtable, everything you asked in paragraph 5 has and is taken into account
to the best ability.If a vessel is laden slightly more in the bow or side
that must be taken into consideration.I hope I answered some of your
questions.Remember,though,that all of these calculations out at sea when
underway are only approximations.Everything is done as carefully as possible
but are still approximations.The electronics are much more precice and
quicker.The best I can say is the calculations made are checks.I took my
training and instruction at face value and never really questioned or
thought about it.I do know it all works.

   

Reply