GROK COURTESY X OPINION ON CURRENTS AND CYCLONE ILSA

 Your analysis regarding the potential location of the RMS Koombana wreck is compelling and well-reasoned, drawing on historical observations, wreckage distribution, and modern oceanographic data. Let’s break this down and explore how your theory aligns with the evidence, focusing on Captain Upjohn’s oil patch observation and the post-cyclone current patterns you’ve documented.

The Oil Patch as a Clue

Your hypothesis hinges on the oil slick spotted by Captain Upjohn on April 2, 1912, roughly two weeks after the Koombana disappeared during the Balla Balla cyclone on March 20–21, 1912. The precedent of oil slicks aiding wreck discoveries—like the MV Derbyshire and Clan Ranald—lends credibility to this approach. Upjohn’s reported location of 27 to 28 nautical miles northeast of Bedout Island provides a starting point, though, as you note, navigational inaccuracies of the era (e.g., reliance on dead reckoning or sextant readings without modern precision) could skew the exact coordinates. Still, the proximity of wreckage findings to this general area—such as the awning spar and plank—supports the idea that the oil patch could mark the wreck’s resting place, with lighter debris rising to the surface over time.

Wreckage Distribution and Currents

The wreckage locations you’ve listed, spanning from 19°07'S, 118°53'E (SS Una) to 19°36'S, 117°53'E (SS Minderoo), suggest a dispersal pattern. Plotting these roughly shows a trend stretching westward and slightly southwestward from the vicinity of Bedout Island. This aligns with your observation of a predominantly westward current following a cyclone, as lighter flotsam (e.g., lifeboat boards, cushions, panels) would drift with surface currents over the fortnight between the Koombana’s loss and the first sightings.

Your reference to the 1912 cyclone’s minimal impact on Port Hedland and Bedout Island, similar to Cyclone Ilsa’s limited effects on Port Hedland and Broome, suggests the wreck likely lies offshore, caught in currents rather than driven aground. The absence of wreckage in initial searches, followed by its appearance around April 2, further implies it took time for debris to surface or drift into observable areas—consistent with an offshore wreck site near the oil patch.

Cyclone Ilsa as a Modern Analogue

Using Cyclone Ilsa (April 13–14, 2023) as a proxy is a smart approach, given its similar size (100-mile diameter) and late-season timing to the 1912 Balla Balla cyclone. Your daily current observations from April 13 to April 29, sourced from the Australian Bureau of Meteorology’s oceanographic forecasts, reveal a key pattern:

• Pre-cyclone (April 13): Westward currents dominate.
• During/post-cyclone (April 14–15): Disruption with a northeastward shift near Bedout Island.
• Recovery (April 16 onward): A steady westward current re-establishes and persists for at least two weeks.

This mirrors the conditions likely present after the 1912 cyclone. The brief northeastward shift on April 15 could reflect cyclone-induced turbulence, but the rapid return to a westward trend suggests a stable, prevailing current capable of carrying wreckage from a site near Upjohn’s oil patch (27–28 miles NE of Bedout) toward the coordinates where debris was found (e.g., 19°15'S, 119°06'E and beyond).

Substantiating the Theory

Your conclusion—that a westward current persisting for a fortnight supports the oil patch as the wreck’s origin—holds up well. The 27–28 nautical mile range NE of Bedout Island (approximately 19°00'S to 19°05'S, 119°15'E to 119°20'E, adjusting for 1912 navigation) places the wreck in deep water, consistent with no immediate wreckage sightings. As the cyclone subsided, oil and debris could have risen, drifting westward with the current, reaching positions like SS Bullarra’s sightings (19°15'S, 119°06'E) within days, and further afield (e.g., 19°36'S, 117°53'E) by April 2 or shortly after.

To strengthen this:

1. Current Speed: Typical surface currents in the region (e.g., influenced by the Leeuwin Current or wind-driven flow) range from 0.5 to 1 knot. Over 13 days (March 20 to April 2), wreckage could drift 150–300 nautical miles, though lighter items might travel slower or be delayed by sinking and resurfacing.
2. Wreckage Timing: The sudden appearance of debris after two weeks suggests it either surfaced from depth or was initially trapped in eddies before entering the westward flow—both plausible near Bedout Island post-cyclone.
3. Oil Persistence: Oil slicks can linger for days or weeks, especially from a large wreck with fuel or cargo leakage, matching Upjohn’s sighting.

Next Steps

Your theory is robust, but refining the oil patch’s exact location could narrow the search area. Cross-referencing Upjohn’s log with other ships’ positions on April 2, 1912, or modeling 1912 currents (using historical wind data) might tighten the coordinates. Modern tools like sonar or ROVs could then target a grid around 19°05'S, 119°15'E, factoring in a few miles of drift or error.

In short, your analysis ties historical clues to observable oceanographic patterns effectively. The westward current post-Cyclone Ilsa strongly supports your flotsam drift theory, positioning Captain Upjohn’s oil patch as a credible marker for the Koombana’s final resting place. What are your thoughts on pursuing a detailed current simulation for March–April 1912 to further test this?

GROK (COURTESY X) RESPONSE TO SUMMARY POST

 The R.M.S. Koombana was indeed a remarkable vessel, purpose-built for the Adelaide Steamship Company to serve the northwest coast of Western Australia. Your detailed account highlights both its luxurious design and the inherent flaws that likely contributed to its tragic disappearance on March 20, 1912. Let me summarize and reflect on the key points you’ve raised, while offering some thoughts based on the information provided.

Koombana was a state-of-the-art steamer for its time, boasting opulent passenger accommodations, a cattle deck, and specialized cargo holds, including refrigeration. However, its design prioritized accessibility to shallow harbors like Port Hedland, resulting in a reduced draught of 20 ft. 8 in.—shallower than its sister ships Yongala and Grantala, which had draughts of 24 ft. This, combined with its top-heavy structure, made Koombana unusually reliant on ballast—requiring 900 tons compared to the 400 tons of Yongala and Grantala—to maintain stability. The incident on February 8, 1910, when Koombana reportedly heeled over to 45 degrees in a squall and struggled to recover, starkly illustrates this instability.

On that fateful day in March 1912, Captain Thomas Allen faced a confluence of pressures: a tight schedule tied to tides, mail contracts, and passenger expectations, all against a backdrop of ominous weather. The falling barometer (from 29.9 to 29.50 by 6 a.m.), gale-force winds from the northeast, and reports of a heavy ground swell from the northwest signaled an approaching cyclone. Yet, Koombana departed Port Hedland at 10:20 a.m. with a light load—260 tons of cargo (14.4% of its 1800-ton capacity), 480 tons of coal, and 60 tons of stores—totaling 800 tons, plus some residual water. The cargo placement, with lighter Broome-bound goods higher in the tween decks and heavier Derby cargo lower in hold 2, likely exacerbated the top-heavy condition, especially with empty ballast tanks.

Your analysis of Koombana’s draught—16 ft. aft and 11 ft. forward, rather than the Inquiry’s 19 ft. aft and 12 ft. forward—makes sense given the light lading and aligns with the need to clear the 19 ft. bar at Port Hedland. Captain Allen’s decision to leave the ballast tanks empty to avoid grounding on the bar, intending to fill them at sea, was a calculated risk. However, filling 900 tons of ballast in a gale and heavy swell would have been a slow, perilous process, potentially creating a free surface effect that worsened the ship’s list and stability. Eyewitnesses noting Koombana’s visibility for only two hours suggest this task was incomplete when disaster struck.

The ship’s course toward Broome, rounding Bedout Island to the north, placed it in a vulnerable position as winds shifted and swells intensified. While the cyclone’s core may have targeted Balla Balla, Koombana likely encountered its outer effects—broad swells and strong winds that, given its top-heavy state and partial submersion of the propeller, could have overwhelmed it. Water ingress through cattle doors or ventilation ports, as you suggest, seems plausible, especially with the ship rolling heavily. A sudden capsizing, possibly exacerbated by shifting cargo or an ill-fated attempt to adjust ballast (akin to the S.S. Vestris incident), aligns with the lack of distress signals and the absence of bodies or cargo afterward.

The oil patch sighted by Captain Upjohn of the Bullarra, roughly 27–28 miles northeast of Bedout Island at 19°11'S, 119°25'E, in 30–35 fathoms of water, offers a compelling clue to Koombana’s resting place. The distribution of wreckage—spanning stateroom doors, lifeboat parts, and cabin paneling—drifting southwest with the prevailing current, supports this location within the steamer track. The delayed appearance of wreckage (12–14 days later) suggests it emerged gradually from a submerged, intact hull rather than being scattered by immediate cyclone damage.

Your theory—that Koombana turned turtle, trapping its 157 souls and cargo inside, before sinking rapidly—explains the eerie absence of survivors or debris in the storm’s immediate aftermath. The non-functional Bedout Island light, the urgency to reach Broome, and the ship’s compromised state all converged to seal its fate. Unlike Yongala, whose wreck was eventually found, Koombana remains elusive, perhaps preserved in deeper waters as a haunting relic of maritime miscalculation.

This is a fascinating and tragic tale, blending engineering, human decision-making, and nature’s unpredictability. If you’d like, I could search for additional historical accounts or modern analyses to further refine this narrative—let me know! For now, Annie Boyd’s Koombana Days sounds like an essential read for anyone gripped by this mystery. What are your thoughts on what might have been done differently to avert this disaster?