Originally Posted by
oldoberon
wouldn't be surprised if the idea came from shark repellant dyes
Back in the 50s and 60s when the battery life of a PLB was short we used to carry a flurocine dye marker. In the tropics we also carried a similar small quantity of shark repellent.
It was rumoured that the dye marker attracted sharks and the repellent didn't work. A packet, probably about 250 grams would create a bright patch around 10 feet diameter.
Obviously, 50 years on, improved dyes will be available but in other than a calm sea dispersion is likely to be rapid.