This weekend I was able to test my prototype SeaPerch. The SciTech club is rapidly building their ROVs, so I needed to get on and test my UK version of the US Navy’s SeaPerch project.
The SeaPerch is now complete. The control box is assembled with double-throw, double pole switches enabling the three thrusters to be easily controlled by the operator.
In the picture here, the SeaPerch is not yet ballasted. It required about 250grams of ballast. I could have reduced the size of the floats, but we want to add different sensor packages to the SeaPerchs to enable different survey experiments. Each sensor package will alter the SeaPerch buoyancy status, so having more buoyancy than necessary is a bit of forward planning.
I found suitable ballast from the local hardware store – using sections of M42 stud and different sized washers to meet the required ballast requirements.
UK SeaPerch first pool trial
The pool had been readied for the winter, so this was a very much a quick test of the system and waterproofing of the thrusters.
The ROV performed well. Speed through the water is far greater than expected, however, as more tether is let out the ROV will need that speed to pull it forward. The tether is CAT-5 network cable. This cable is quite stiff, so the tether affects the ROVs ability to turn left or right. It is fair to say the ROV bears to the left and right rather than turning on the spot. As the project is further developed I expect to try different tether materials and techniques which will hopefully improve the manoeuvrability.
The ROV’s ability to dive and surface is pretty good, taking only a few seconds to travel the 1 metre depth of the pool. the ballasting is pretty good at this point, with the ROV sitting close to its driven depth without the motors running. Again, a long tether will affect the ROV’s performance.
All in all I am pleased with the performance of the ROV. The motors are only sealed into the 35mm film canisters with the sculpture’s wax which prevents the canister from filling with water, but water can still get into the motor housing. I have since tried several dives with the ROV and discovered that some corrosion of the vertical thruster beaing appears to have taken place. This motor requires a little assistance in spinning now, and then some ‘warming up’ before it reaches top speed and the ROV can be used in water again. This is a minor issue, and takes only a minute to sort out before each mission.