The Rig
What this course adds
Chronicler inherits the equipment of the specialties before it — the Cartographer reference and navigation gear, the Demographer census and imaging kit, the Hydrocaster instruments, a CoralWatch chart and slate. What it adds is short, and most of it is one item.
Four reference charts per Team. The ABFO No. 2 photomacrographic scale — the L-shaped plate forensic photographers use, so that a photograph taken at a scene can be measured in a courtroom years later — meets the specification exactly, and is what this course is built around.
Quantities scale by Team rather than by course. A Team is a buddy pair, so four student divers is two Teams and six is three; every Team captures on Dive 1, founds a station on Dive 2 and re-captures on Dive 3, so each needs its own complete set. An instructor planning a class counts Teams first.
Per Team
Five things, and a count that has to come out
Four reference charts
Rigid, matte, non-reflective, of known dimensions, carrying a white and a neutral gray reference. A small backing weight fixed clear of the printed face keeps each one seated on the substrate. All four from one production batch.
A chart pouch
Mesh or perforated, clipped to a diver, for carrying the charts out and bringing them back. The count is the check: four out, four in, confirmed before leaving the station.
Camera and housing
Able to disable automatic white balance and to display a histogram. Raw capture preferred where available. A camera that decides the color balance for you has made an unrecorded adjustment to the measurement.
A graduated line
Marked at 0.5 m, for the taut-line distance from the hub to the photo point — which is how the photo point is found again rather than approximately relocated.
A recording slate
Printed from the Station Report recording forms on waterproof stock, so what goes on the slate is already in the shape the record wants.
And topside
A computer with an image viewer that can measure a distance in pixels — Fiji (ImageJ) is recommended — plus the point-count service used for scoring, or a printed random-point overlay where there is none.
The batch
Why it is written down
Reference charts fade, and printed geometry varies between manufacturers and between production runs. A chart set that quietly changes between visits would appear in the record as change at the reef.
So: buy a set from one batch. Record the batch. Measure each chart's scale dimension against a ruler before first use, and record the value and the date. Replace from the same batch where you can — and where a replacement must come from a different run, record it as a change of instrument, because that is what it is.
This is the reason to buy more charts than you need at the outset. Spares from the original run stay valid for years; a replacement bought later may not.
A small thing worth doing
Write on the charts
The plates have a writable surface. Putting the station identifier, the date and the photo point number on a chart puts that information inside the frame — so the image identifies itself without depending on the archive manifest surviving alongside it.
It is optional, it costs nothing, and it is worth doing. Confirm before the course that the marker you use both writes on the chart surface underwater and wipes clean afterwards.
Every diver also carries a dive computer synchronized to the common time reference before any dive that collects data, and something to write with.