The improper use of ROVs (Remotely Operated Vehicles) can be highly detrimental, especially during critical phases of projects, as it can lead to down time: a scenario that is to be avoided due to the high day rate of offshore projects. For this reason, working on an ROV, or integrating external equipment on to it, is reserved for well trained and seasoned personnel. However, there are times when an ROV will be on stand-by while a 3rd party service company awaits for spare parts to be shipped offshore to repair their equipment, for example. And in this backdrop, it is not uncommon for an ROV to do test dives while the faulty equipment is brought back online. It is in this backdrop, as well as in non-critical path scenarios—an ROV is able to slightly "loosen up" it’s a business tie. And how does this an ROV do this? The following examples illustrate the manner by which and ROV "loosens up" its tie.
Often times when shopping for a wrist watch, you will find a water resistant mark stamped on the non-dial side, calling out the depth it can operate at in a submerged setting. Divers, for one, take great pride in using these watches to time their dives. Conversely, ROV personnel equally take such pride in pressure testing their watches, especially ex-divers who have transitioned in to the ROV line of work, to not only validate their rating, but to equally exceed their rating and to see at what point sea water begins to ingress, during an ROV’s dive. I must note that I have witnessed ROV personnel submerge high end watches to test their robustness, only to have them no longer working once recovered. This gives way to the following question: why subject your watch to conditions that can potentially render it inoperable?
Though there is no universal answer, the fact is that ROV crews are assigned to projects that require validating the pressure rating and the overall validity of new subsea equipment/tools, and as shown by the wrist watch test, this too is applied to their personal items. This may perhaps seem peculiar, but if looked at objectively makes perfect sense as to why wrist watches are tested at sea by ROV personnel.
Figure 1: ROV technician inspecting watch, after successfully submerging it to 321'—watch rated for 328'
Figure 2: Styrofoam cups tied to the ROV's cage via laundry bag
The primary driver for the emergence of modern day ROV technology—as a staple of offshore operations— is due to the fact that they can perform at deepwater depths that would otherwise crush saturation divers. Which brings us to the following question: what if you could capture the effects of hydrostatic pressure on a physical object—in a deepwater setting?
Executing the aforementioned is not difficult to accomplish, you simply need a cotton laundry bag, and Styrofoam cups. It is imperative to securely tie the laundry bag to an ROV’s cage to avoid sea pollution. Tying it there is key, as the cage simply transports the ROV to depth: the ROV then launches from the cage to its point of interest, to perform work tasks. For this reason, it is important that it remain tied to the cage. Furthermore, once an ROV and its cage are brought back to surface, you can now retrieve your compressed styrofoam cop, whichhyou can bring back on land to give as a gift; or to keep at your desk/workshop to remind you of the pressure that ROVs and subsea equipment must contend with.
Ad Hoc ROV Tooling
I was previously involved in a project where a client required developing a tool—on site—for clearing unexpected marine growth, which made it difficult to access key interface points on a subsea asset. This particular project required working in tandem with an adjacent vessel which was waiting on spares to bring its dewatering spread back online. This, in turn, gave us—the subsea intervention team and ROV crew—two days of creative freedom in testing different ROV mountable pumps and valve configurations, while the spread was fixed. Of high benefit was the fact that there was a variety of pumps to choose from. In addition, a wand would also have to be configured, as it would be making actual contact with the marine growth by way of the pump.
We ultimately configured an optimal solution with the resources on board, and tripped the ROV to its required depth: once there—this ad hoc setup—delivered ideal results and successfully removed the marine growth, while allowing us to access the previously unaccesible interface points.
Figure 3: Tooling technician making final adjustments on wand
As very advance vehicles, work class ROVs are to be treated accordingly, as this ensures they operate in an optimal state during critical path/operations. However, when operations permit on offshore projects, an ROV can also be utilized as a medium to experience and interact with the subsea world in a creative fashion, as illustrated in the above examples.