I would like to build a rowing performance device similar to a SpeedCoach produced by Nielsen-Kellerman.

The feature set for these devices includes the following:

• Heart rate monitor integration
• Speed and splits measured by GPS
• Stroke rate measured by an accelerometer
• Display with backlight
• Battery with simple charging interface
• Waterproof and floats
• Transmit live data to a another device to be monitored by a coach

Accelerometer

• Sparkfun accelerometer tutorial
• Sparkfun MMA8452Q accelerometer breakout hookup guide
• Arduino-MMA7361-library

GPS

Sparkfun recently released a $16 GPS receiver, but unfortunately it is currently sold out. Alternatively, in Sparkfun’s GPS Tracking Comparisons tutorial the receiver with the best results was Trimble’s Corpernicus II, which can be purchased on a breakout board for $75.

• Sparkfun GPS Buying Guide

Display

Selecting a display setup may be the most complicated component to select. Touch provides no benefit since the device will have to run within a waterproof enclosure. Also, an interesting alternative may be to use a small number of alphanumeric LED displays that each display one character.

• Adafruit HDMI to 40-pin TTL breakout