The catch mechanism is a telescopic spearFishingROV

The catch mechanism is a telescopic spear based on a fibreglass telescopic fishing rod.

A drain spring running up the middle pushes it out and pulls it back.

The spring is powered by a brushless RC motor. Auto stop in and out is achieved by monitoring the total amperage drawn by the motor.

The ESC are a lot more responsive now they have been reflashed with the Simonk firmware.

SimonK Firmware:

I am using the Atmel socket tool with a generic USBasp. The standard flight ESC’s can know run like a radio controlled car with a reverse function.

Skywalker 20a ESC copies – needed to be powder while flashing.

UBEC on the ESC was powering the ardueno so it didn’t reset when I unplugged it. This meant that the COM port stayed open.

Still to-do:

Some sort of catch hand/claw/spear tip.
The return mechanism will also need some work. And is likely to be the most challenging part of the development process. I am thinking of floating the catch up the tether to the operator in batches of five. With five floats in a rack possibly returning 25 fish before the ROV needs to be pulled back and the floats reset in the rack. If all the fish were stored in a bag attached to the ROV it might produce too much drag? But If the ROV was powerful enough pulling a bag with all the catch might be possible and would be a lot simpler. The ROV will need a multi catch system if it is to be a useful commercial fishing tool. So the ROV doesn’t need to return to the surface every time a fish is caught.
If the neck of the holding bag was able to rotate it could be positioned in front of the spear and the fish could be pushed into the bag by the spear. A one way flap would keep the fish in the bag as the spear was retracted- as with holding tubes used by lion-fish hunters.