Astoria, OR, USA More User infoCaptain Level IV Status: Really Big Time Sailor Qualified days: 151
Sixty D Street
Posted 2016, Apr 28 23:31
When teaching the basic navigation skills for U.S. Sail & Power Squadron the memory reminder for calculating Speed, Time or Distance is "Sixty D Street". That is 60*Distance = Speed * Time. Perhaps this will help NauticEd Students as well.
Just be careful here of the units. If you use that formula you must use minutes for time.
In engineering school, they drummed in that the Units always must match.
For nautical miles as D (distance) and knots for S (nautical miles per hour) and hours for t (time) then the formula works fine when you analyse the units.
Nautical miles = nautical miles per hour x hours
nm = nm/hr x hr - i.e the units all cancel out and match.
If using 60D=S x t you have to add in that the 60 comes from 60 minutes per hour.
the units work out like this:
minutes per hour x Nautical miles = nautical miles per hour x minutes
m/hr x nm = nm/hr x m - i.e. consistent
Thus, if you use 60D = S x t, the time units must be in minutes.
Personally - I hate remembering formulas - I use the fundamental concept that units must always match. But this is my own personal engineering training. Everyone remembers things differently so a mnemonic like 60 D Street is a good one - thanks Darroch.
I'm such a geek sometimes. LOL