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Invasive starfish injector

(John Griffiths) #1

Hi all

I have attached some pics of a new ROV I am about to test this week. All BR components in a single 4’ acrylic tube. This ROV is designed for two roles. Primary one is to inject invasive Crown of Thorns starfish (which are destroying much of the Great Barrier Reef) with either vinegar or bile salts which kills them. The orange bag has the poison in it. The other device bolted on is a sedative dispersant which allows for collecting rare small reef fish. The motor reverses to suck them into the container once sedated.
As you can see, I have run the motor wires inside the acrylic tube necessitating drilling holes into the tube

. I have no idea if and by how much this has compromised the structural integrity of the tube. If anybody out there has any clues or experience that will save me from learning the hard way, please feel free to let me know. That applies to anybody that can see any other obvious design flaws as well.


I have a question:

Your ROV seems a little unstable when it comes to pitch, my guess is that it will hang with the nose down 90 degrees.

When you activate the thruster for injecting the poison, don’t you get a thrust upwards, tilting the ROV and thereby mooving away from the Starfish?

Would it be possible to use this pump for the poison in stead? https://www.amazon.co.uk/Whale-Unisex-Premium-Inline-White/dp/B004E1VQWC

(John Griffiths) #3

thanks for your input. I am adding buoyancy along the carbon fibre tube to the injector to compensate for the weight and also the orange poison bag will have a little bit of air inside it to hold the bag and also the ROV somewhat stable. I will have to apply a little downward thrust at the same time I inject to offset the thrust of the injector motor. I chose that type of injector because of of the capacity to very accurately preset the dosage.
I tried various in-line pumps but found that the seals gave in at depth. Obviously lots of trial and error to get the unit to function inn the way that I hope it can.