Wayne.B wrote:
On Fri, 10 Mar 2006 19:23:54 -0500, Jeff wrote:


What kind of boats do you guys have??? You sound like a powerboater
claiming you don't have to think about currents because you're doing
30 knots all the time.

Where I sail there are frequently currents of 2 knots or more, plenty
to cause "spiral" for a slower sailboat.


You're doing something wrong. Before you start, first solve the
current vector problem using an estimated speed for your boat and the
average current speed/direction from your tide tables. Use that as
your initial offset to the rhumb line course direction. Once enroute
check the bearing to your destination using the weapon of your choice
- bearing compass, RDF, whatever. Your bearing should stay constant
if your offset is correct, otherwise make a correction plus or minus
and continue to recheck. There is really no excuse for being
accidently swept down current, even in Vineyard Sound.


In other words, if you don't do this, you'll spiral in, just like I
said. Even with a GPS, you'll have to understand setting waypoints,
x-track, etc.

If you take the position that humans are completely competent and
never make mistakes, and that equipment never fails, then your
conclusion follows quite naturally.