Compass, Instruments, GPS in that order
1)Compass - So you know which way to go when you round marks and to identify headers, lifts and wind direction changes. I always used a KVH 103AC electronic since it automatically displays lifts and headers and is easy for the entire crew to see. 2) Boatspeed, depth and wind instruments so you can guage the impact of trim changes and establish target speeds and pointing capability in various conditions. This will help yo to learn to generate the best boatspeed or VMG to weather while racing and stay off of the bottom. These must be of high accuracy and well adjusted or they will be of no value. 3) GPS to provide range and bearing to next mark and to find marks. This is very important if you are the lead boat. Helps to keep you from overstanding the lay line on weather legs. Provides info on when to jibe on downwind spinnaker legs to maximize VMG to the leeward mark. It will also provide Speed and course over the ground (COG and SOG) so you can compare to the boat speed and direction for the instrumnets and calculate tide speed and direction. Tides are a major component to be considered in tactical racing decisions. 4) Polars for the boat so you cam take advantage of 3.