A tally tag is what turns a roll call from a clipboard into a tap. Each person is given a tag at the registration desk, taps out as they launch and taps back in as they land, and the safety lead has a live list of who is still on the water. This is a buying guide for clubs.
You need 13.56 MHz NFC tags. Most wristbands sold as "RFID" are 125 kHz, which no phone can read, and they look identical. If a listing says 125 kHz, EM4100, T5577 or just "proximity", it will not work. If it says NFC, NTAG213, NTAG215, NTAG216 or "works with phones", it will. Finding this out on the morning of an event is a ruined day.
For sailing, silicone wristbands are the right answer almost every time. NTAG213 is the cheapest chip that does everything needed; the extra memory in an NTAG215 or 216 is memory nothing uses. WeMuster supplies silicone NFC wristbands printed with a club's branding at no extra cost — get in touch with rough numbers and a date.
Count the largest likely turnout, add about ten per cent, and round up. Tags are reusable season after season, so spares are not wasted, and running out at the desk on a Saturday morning is the one failure mode with no workaround. Clubs running junior events should buy a separate batch of small bands.
Android phones read tags by tapping, using Chrome, and this is what almost every club uses. iPhones cannot: Apple does not let a web page read NFC tags, so a browser on an iPhone cannot tally by tap however new the phone is. Borrow one Android handset for the desk, or use a USB or Bluetooth reader on a laptop — any reader sold as a "keyboard wedge" works, and it is quicker than a phone at a busy desk. Test one band on every device a few days beforehand rather than on the morning.
Bands belong to an event, so the same box comes out week after week with nothing to reset or clear. Whoever picks up band 47 this Saturday is simply the person wearing band 47 this Saturday.