A word on power packs from Race Chief, Dylan:
"Power pack needs to be kept in 100% sealed, waterproof bag/container, triple sealed if needs be.
The tracker if fully charged will last a full day so no need to charge it while at sea.
Good solar power chargers are improving each year but make sure you get a good one, cheap ones are pretty much useless. Bear in mind that most daylight hours will be spent at sea so make use of every opportunity to change your power pack and your tracker.
I use a 10 000mA power pack that charges the tracker 3 times over if fully charged itself."