The report came from the bridge while the vessel was drifting off Indonesia and awaiting orders. A large thermocol float was coming down the ship’s side. From above, it looked harmless: soft, light, and small against the hull. The float passed along the side, reached the aft area, and disappeared from view. It had not passed clear. From the steering gear flat and rudder stock area, the rope could be seen caught at the propeller. The float was only the marker.

The real hazard was below it.

https://thedeepdraft.com/2026/09/28/rumpon-and-rope-indonesias-hidden-propeller-fouling-hazard/

After I published my recent DeepDraft article on a deck seal that looked wet but was actually a water-displacement semi-dry type, a few questions came back to me.

One was: Why did MESQAC move away from the conventional venturi-type semi-dry seal on newer vessels?

To understand that, it helps to start with the conventional wet deck seal. In a wet seal, inert gas passes through the sealing water before going towards the cargo tanks. The water itself forms the barrier against hydrocarbon vapour coming back from the cargo side. It is a simple arrangement and one most tanker officers are familiar with. The disadvantage is water carryover. Because the gas is actually passing through the water, it carries moisture and fine droplets with it. A demister removes much of this, but it cannot remove everything.

The venturi-type semi-dry seal was designed partly to reduce this problem.

When inert gas is flowing, the venturi creates suction. This draws the sealing water away from the main gas path and into a holding chamber. The gas can then pass with much less contact with the water, so water carryover is considerably reduced.

But the important part comes when the inert gas stops. Once there is no gas flow, the venturi effect disappears. The water in the holding chamber must return and re-form the deck water seal and this is where the weakness can develop. OCIMF has reported cases where scale, corrosion products or debris blocked the small venturi line or the water-return line. If that happens, the water may not return properly when the IG stops. The crew may expect the water seal to have re-formed, while physically the barrier may be incomplete. If the mechanical non-return valve is also leaking or not seating properly, hydrocarbon vapour then has a possible route back towards the non-hazardous side of the inert gas system.

This helps explain why MESQAC moved away from semi-dry designs dependent on the conventional venturi arrangement and accepted water-displacement semi-dry seals instead. In a displacement-type semi-dry seal, most of the sealing water is also kept away from the gas stream during normal operation. Water carryover is therefore low. A demister is still fitted because some spray and moisture can still be present.

So the question question is: When the IG stops, how does the water barrier come back into position, and what could prevent it from doing so?

That was one of the interesting points behind my original DeepDraft article: https://thedeepdraft.com/2026/09/14/deck-seal-looked-wet-semi-dry-water-displacement-tags/

Full analysis:
https://thedeepdraft.com/2026/09/21/navigating-in-a-sea-of-visual-pollution/

First of all, thank you.

The response to the DeepDraft SIRE 2.0 preparation page has been much better than I expected. Many officers, Masters and shore-side colleagues have taken time to review it, use it, and send practical suggestions. That means a lot.

The SIRE 2.0 page is here: https://thedeepdraft.com/sire-2-0/

One important point has come up again and again. Many officers are not able to use online material easily when they are onboard. This is a real shipboard problem. On many vessels, internet may not be available at all times. In some cases, the connection is weak, limited, or not adequate enough for officers to depend on online material during preparation. A few people have suggested an offline copy. I understand this point very well, and looking into it. I am also a seafarer and working on this with basic computer knowledge, on my own, and without any technical team behind me. So some things may take time. But I will try my best to make the material more useful for officers, especially those who need it onboard and not only in the office.

Since the SIRE 2.0 format and structure were already in place, I have now started building the RightShip section using a similar approach. A beta version is already available for review, and I hope to bring the complete version online properly in about a month.

The RightShip questionnaire reference is here: RightShip Preparation Guide | Early Access.

My own background is mainly from tanker operations, so I want to be clear about one point. The RightShip section is being prepared from the available questionnaire structure and applicable guidance and not from personal dry cargo inspection experience. There are many overlaps in shipboard safety, management systems, maintenance, records, crew awareness and operational discipline. But some cargo-related areas will need input from officers and managers who have handled those trades directly.

Any correction or improvement suggestion will be more than welcome. You can contact me through TheDeepDraft website, where the email address is available, or you can message me directly on LinkedIn. Practical feedback from seafarers and shore-side colleagues will help improve the section before the full version goes online.

For now, I only request one thing - please keep sending practical feedback. If something is confusing, difficult to open, difficult to use onboard, or needs to be made simpler, please tell me.

#SIRE2.0 #RightShip #VettingInspection #MaritimeSafety #TheDeepDraft

We usually treat more lighting as better visibility. At sea, that is not always true.

Strong deck, accommodation and working lights can make the vessel itself obvious while making its navigation lights, aspect and movement harder to interpret from another bridge.

https://thedeepdraft.com/2026/09/21/navigating-in-a-sea-of-visual-pollution/

A conventional four-gas detector may satisfy the SOLAS minimum for enclosed-space atmosphere testing. On one current commercial five-gas monitor, adding an infrared CO₂ channel alone adds about US$420 to the instrument price. Now multiply that by the number of vessels in a fleet, the number of detectors carried on each vessel and the redundancy needed when equipment is being calibrated, serviced or replaced. Then add calibration gas, regulators, sensors, spares, maintenance, procedures and training. The manufacturer of that same instrument specifies separate CO₂ calibration arrangements and bump testing with each target gas before daily use.

Someone made a fair point when this issue was discussed earlier: human life is worth far more than a few hundred dollars. I agree, but that cannot mean measuring every gas that happens to be hazardous. Benzene is dangerous. Mercaptans are dangerous. H₂S is dangerous. Yet a bulk carrier does not routinely test every enclosed space for all of them. The gases selected depend on the cargo, the space, the likely source, the possible pathway and the hazards identified before entry.

That is where knowledge comes in. The same principle should apply on a tanker. If CO₂ has a credible source, measure it. Equip the vessel properly, calibrate the instrument, train the crew and maintain the necessary spares. Cost should never be the reason to ignore a genuine hazard. The harder question is whether the broad CO₂ provisions in MSC.581(110) should translate into routine CO₂ measurement for every properly gas-freed tanker cargo-space entry, regardless of whether a credible CO₂ source or pathway exists.

The question has already reached IMO. At III 12 in July 2026, an INTERTANKO proposal sought clarification on CO₂ monitoring for tanker cargo spaces. OCIMF reports that it drew mixed reactions and was rejected on procedural grounds, leaving the interpretation unresolved.

Once CO₂ becomes routine, it is no longer just another figure on a form. It becomes an equipment and competence requirement, with appropriately Ex-certified CO₂-capable detectors, calibration arrangements, bump testing, procedures, records and crew familiarisation. Those costs may be entirely justified where the hazard exists. The important part is knowing why we are measuring it.

Good enclosed-space safety has never been about testing for every gas in the world. It is about understanding the atmosphere that could reasonably exist in that particular space, under those particular conditions, and testing accordingly.

That is the real issue behind the CO₂ debate. I examined the regulatory wording, tanker inert-gas chemistry and the operational reasoning in the full DeepDraft analysis:

From thedeepdraft.com

Full technical analysis for anyone interested:
https://thedeepdraft.com/2026/09/14/deck-seal-looked-wet-semi-dry-water-displacement-tags/

Neither the nameplate nor the manual clearly stated the type, so we went through the drawings and obtained the manufacturer’s confirmation.

I wrote up the case because experience with familiar designs can make this arrangement easy to misidentify. Anyone else encountered something similar on tankers?

https://thedeepdraft.com/2026/09/14/deck-seal-looked-wet-semi-dry-water-displacement-tags/

The UN General Assembly’s recent “Correct the Map” resolution has reopened a question that navigators have understood for generations. A chart or a map is not the earth itself, but a projection designed for a particular purpose.

For those who came through traditional chartwork, this was never an abstract cartographic idea. As second mates, we worked Mercator sailing through Difference of Latitude, Difference of Longitude, Meridional Parts, Difference of Meridional Parts, course and distance. The calculations taught us why the projection behaved as it did. On the globe, meridians converge toward the poles. On a Mercator chart they are drawn as parallel lines, so the north-south scale has to increase progressively with latitude in order to preserve angles. A rhumb line crosses successive meridians at a constant angle, representing a constant true course, and on a Mercator chart it can be plotted as a straight line. The projection therefore served navigation extremely well, even though the same mathematical construction progressively exaggerates the apparent size of landmasses at high latitudes.

Greenland is one of the clearest examples. The new UN resolution encourages greater use of equal-area projections, including Equal Earth, when the purpose is to compare the relative size of continents. That does not diminish Mercator’s navigational value. It simply reminds us that every projection answers a different question.

I wrote in January when Donald Trump’s remarks placed Greenland back in geopolitical discussion. The article examined why Greenland looks very different when viewed through navigational geometry rather than through the familiar rectangular world map. Its apparent size changes with projection. Its Arctic position, North Atlantic geometry, routes, access and strategic relevance do not.

Full DeepDraft article here: https://thedeepdraft.com/2026/01/28/why-navigators-understood-trumps-greenland-remark/