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Before swimming

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Buoyancy

You also need to tune the bouyancy of the robot to be close to neutral (in most normal use cases). Note that the runing is different for sal water or fresh water, but pretty much the same for fresh or chlorinated (pool) water. See Buoyancy_calibration and,if this is unfamiliar, check the nice Wikipedia article [1].

Considerations before putting the robot in the water

There are five main areas that can provide a water-path into the vehicle: the battery doors, the top and bottom lids, the shell ends, ports, and the leg shafts. Before deploying the vehicle in an aquatic environment is it essential that these seals are operational.

  • All seals need to be present and in good condition. Seals, especially those around the battery doors, must be inspected for contamination (grit). Any such contamination must be removed. Seals must be properly treated with the appropriate silicone grease in order to maintain the seals in good repair.
  • As a result of the battery doors' design, it is normal for some water to remain just outside of the door seal. Open the battery doors slowly while paying attention to the presence of water. Under certain conditions it is possible that the robot interior under vacuum when the first battery door is opened. The vacuum can draw water into the robot, giving a false indication of a leak. If water is found just inside of the door sealing area, carefully inspect the rest of the interior of the robot for water, and the door seal and sealing surface for dirt and/or damage. If nothing of consequence is found, then close and retest the robot for leaks prior to redeployment.
  • All the components need to be present and properly positioned
  • The main body seal needs to be properly seated in its groove. Although it is not normally necessary to remove the top or bottom plate of the vehicle, whenever this is done it is essential that the seals be properly reseated in their groove. The main body seal must be properly lubricated using the specified lubricant. Using the wrong type of lubricant can damage the seal, in particular it can cause the seal to elongate, in which case the seal will need to be replaced; see Figure 16 in the User Guide.
  • It is also important to make sure that the O ring is present in the fiber-optic (FC) connector on the robot, otherwise there is a good chance that a serious leak could occur. If the O ring is missing, it must be replaced with an O ring of size 4mm OD x 1mm CS.
  • A single person should be made responsible for the sealing of the robot in order to avoid confusion. They should know the recommended procedure for tightening the screws
  • If you are using the fiber-optic cable underwater, make sure you have the wet end (waterproof is cross-hatched, not striped) plugged into the robot itself. If your cable has a non-waterproof end (dry end) it is got vertical stripes on it.

fiber optic dry and wet connectors

Note that SC/FC refers to the ending on the cable. FC stands for "Ferrule Connector" and SC can stand for "square connector" (or equivalently "subscriber connector"). Note that these connectors are delicate and also very sensitive to dirt. Typical connectors are rated for 500–1,000 mating cycles.

See also

The pre dive checklist provides a short summary suitable for bringing to the waterfront. You can also get the pretty printable File:Pre-dive-checklist.pdf.

Don't forget to read the section on what to do After swimming