Enclosed spaces are one of the most dangerous parts of a vessel. This is one of the first things we learn during our STCW, and the instructors caution us to take them seriously. For some, however, that training may have been years ago. So, let's go over what it means in the bigger picture of legality and safety on board.
An "enclosed space" on a vessel is "not designed for continuous worker occupancy and has either or both of the following characteristics: limited openings for entry and exit and inadequate ventilation." That definition can cover many areas on a vessel, whether yacht or commercial freighter. For deck crew, it will commonly be chain lockers, or void and storage spaces, while for engineers, enclosed spaces will likely be the ballast, water, fuel, and any other type of tank.
Remember, these are just a handful of examples — your captain and chief officer should be familiar with all enclosed spaces on board.
So we know they're important, and we know they're dangerous as they can hold deadly gases because they're not ventilated like the rest of the vessel. What else?
For legal context, "enclosed spaces" fall under Safety of Life at Sea (SOLAS). SOLAS is just one of the many conventions formulated by the international maritime organization (IMO). Others include the international convention on standards oftraining, certification, and watchkeeping for seafarers (STCW) and the international convention for the prevention of pollution from ships (MARPOL). These are an officer's bread and butter.
These conventions are ratified and enforced by the participating countries of the IMO, which is currently just about every seafaring country. This means that many tasks we do, from garbage logbooks to performing entry into an enclosed space, have specific procedures required by international law.
Much the same as road rules for driving, there are fines for disobeying them and you or your superiors responsible for your safety may get fined for not following maritime rules. Only in the maritime world, the stakes are much higher — potential loss oflife, property, and destruction of marine environments — and the consequences aren't just fines. Your maritime license could be revoked, and you could even face jail time along with massive fines, depending on the severity.
As much as we may sometimes chafe against them, without the rules, the world's shipping lanes, superyacht hotspots, and fishing industries (to name a few) would be unsafe, much the same as navigating inner-city London or Sydney with zero road rules. They keep us safe, and they keep the global maritime machine running smoothly.
Now that we've got an understanding of the standardization of procedures on board and how they fit into the IMO's SOLAS Convention. We know this applies to nearly everyone on board, so let's now break down the procedure for entering an enclosed space. You should follow a checklist throughout this process.
First, your permit(s) to work should be completed by whoever is your responsible officer on board, and they must then be signed by the master, who is ultimately responsible. We know the risks involved with an enclosed space - harmful gases and physical hazards - and we must also understand what risks are involved with the work we're performing in that enclosed space. Welding or drilling may require additional permits to work.
Next comes ventilation, which involves opening all hatches and entrances to the space (provided the vessel is in an operational position to do so), tagging out necessary equipment in the space, and, if possible, using mechanical blowers to assist in ventilation. If using unassisted ventilation, the recommendation is to do it at least 24 hours before making entry.
Next, we'll use our gas detector (recently made mandatory under SOLAS for vessels of more than 500GT) to measure for safe, breathable air. These detectors will typically measure four gases: oxygen, the lower explosive limit (LEL) of carbon monoxide, hydrogen sulfide, and methane. We want a reading from 19.5 percent to 23.5 percent for oxygen. You might want to read up on why we test for LEL and for specific oxygen ranges before the space is deemed safe. More importantly, read the detector kit's manual; these kits are sensitive units and so will require regular calibration to function correctly.
Use the detector and any attachable wands to measure not just in the enclosed space, but also on the floor and in corners as some gases may sink and become disturbed when entry is made, despite a "safe" gas reading. Note the readings on your checklist.
Now it's time to make entry. We have the master's signature for the permit to work and a "linkman" or "standby" to maintain constant communication with whoever is in the space. A breathing apparatus (BA) set should be on standby in case a rescue is required. Note that we would have specified a work duration in our permit to work and, if we exceed that duration, we must exit the space regardless and update the permit before re-entering.
In summary, determine the nature of the work, complete permits to work, and follow a checklist. We've now performed ventilation, measured gases in the space, and now, with the proper PPE, BA, and personnel, we've performed entry and done what was needed. Time for tea.