Garmin GPS 72H

Originally posted by Buzz

I'm not sure that it's the keystroke sequences you need.  Mark laying with a GPS doesn't need any very sophisticated use of the GPS.  You can get by with just Pinging a position, setting GO TO and display of bearing and distance to a waypoint.  Using Project Location is a bonus.
You can't expect the Garmin manuals to tell you how to use a GPS to lay marks, that's what your RYA RO or mark layers course will do.

The ISAF Race Management Manual (RMM) contains all you really need to know.

Marks can be laid by GPS using the following methods
specific coordinates (RMM L4 ( a ))
Bearing and Distance from Reference Point (RP)
-  Sequential Waypoints (RMM L4 ( b ))
-  Bearing and Distance from common RP (Appendix F9)

I prefer the common Reference Point method because it's simplest (very simple for 60 degree triangles and 70 degree trapezoids).

For what it's worth, here's what I do (a real RO or IML may come along and put me right).
Set the GPS to the standard settings (RMM H5)
Edit waypoints and add and delete dummy waypoints as necessary so that the first waypoint you will create on the water, which will be the RP, will have a nice memorable number (on the even tens) and the waypoints you create for each mark, will end with the number of that mark as shown on the course diagram.  For example, suppose you already have 65 waypoints in your GPS, and you are going to use the RC Vessel as the RP.  Create and delete Waypoints 066, 067, 068, and 069, so that the next waypoint that you create will be 070.  You will thus be using the '70s' for your mark waypoints for the day.
Go to the racing area, confirm with the RO that the RC Vessel is anchored in its correct position and Ping the RC vessel (Garmin Manual p 6 To Mark your Current Location).  This will create WP 070.
Set the GPS to GO TO the RP (WP 070), with display showing Bearing and Distance to the waypoint.
Get the approximate wind direction and expected windward leg length from the RO.
Bog off upwind until your GPS shows Distance to RP = leg length or a little more.
Drift, observe wind strength and direction and radio report to RO.  Repeat every 5 minutes or when wind changes are noticeable.
Work out the reciprocal of the wind direction bearing and if necessary, manoeuvre your mark boat so your GPS shows this bearing to the RP and distance = the leg length.
When you think the wind is settled, agree the Axis bearing and leg length with the RO, work out the reciprocal of the Axis, and manoeuvre your mark boat so that your GPS shows this bearing to the RP and distance = leg length.
Set the mark, let it settle, check its correct location, then come along side it and Ping it.  It will now be WP 071.
Using the RMM Appendix F9 tables or mental arithmetic, work out the reciprocal bearing and distance from the RP to the next mark to be laid (usually the wing mark).
Go there, manoeuvre to get the reciprocal bearing and distance to the RP right, lay the mark, check and ping it (WP 072).
Repeat for subsequent marks.

Edited by Brass - 16 Jul 14 at 6:14am