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 'COORDINATES CONCLUSION'

 

I believe Koombana lies somewhere within the illustrated radius from central, given coordinates.Oil patches were used to localise steamer wrecks.An example is the Clan Ranald:https://waratahrevisited.blogspot.com/2016/03/clan-ranald-fascinating-account-and.html"direct me to the spot where the wreck was sunk, which he said he knew exactly, having seen streams of oil rising from her."Daily Commercial News, 14 May, 1912.Going back to the question of the search for the Koombana the witness (captain Upjohn) remarked that in latitude 19.11, longitude 119.25, about 27 to 37 miles from Bedout Island, one evening they saw what looked like a portion of the deck of a vessel, but it proved to be the shape of a ship outlined by an oily substance such as would rise from a sunken vessel, floating on the sea.I firmly believe that the above oil patch represented the final resting place of RMS Koombana. Of course the difficulty has been working out exactly where that spot is. There are many examples of historical coordinates notorious for inaccuracies.Captain Upjohn, according to this press report, was unsure of this exact position, quoting a huge range of 10 miles; 27 - 37 miles.The 1864 James Martin chart showed a 10.5 mile deviation between the true and charted positions of Bedout Island (see image), which approximates captain Upjohn's 10 mile uncertainty. This phenomenon, in part, could be due to: "a number of highly magnetic undersea iron ore bodies.""These ore bodies are of such magnitude that when the survey vessel HMS Penguin reexamined 19th-century survey reports from HMS Meda, it experienced compass variation of up to 55° and dip to 33° (Lecky, 1920: 30)."(The Searches for SS Koombana, Kerry Thom) There is a different way of looking at this conundrum and an important correction to be made.Captain Upjohn informed the Inquiry that his crew found a section of starboard motor launch bow planking with Adelaide Steamship Co insignia the following day at a position, 19 15 S, 119 06 E. He referred to this discovery being about 20 miles from the 'oil patch'. In reality it was 18.4 miles from his given coordinates, which in turn were 30 n miles (30.67 degrees) from Bedout Island."The other articles were picked up about 20 miles from there."HOWEVER'the captain of the s.s. Bullarra had arrived at Cossack and reported that he had picked up, about 20 miles to the north of Bedout Island, one of the Koombana's boats with the company's crest on it and a quantity of smaller wreckage." Mr. Moxon says that the Bullarra did not pick up a ship's boat, at all, but only the bow of a boat.'In reality the launch bow plank was 20 miles north of Bedout Island, correlating with Captain Upjohn's log coordinates (19 15 S, 119 06 E)Therefore, Captain Upjohn had a far better idea where Bedout Island was in relation to his ship and the various wreckage discoveries than is implied by the quoted "27 to 37 miles".Why would Captain Upjohn have created confusion by claiming the oil patch was 27 to 37 miles from Bedout Island when clearly it was '30 miles', and yet demonstrate that he was capable of establishing coordinates positions with minimal, if no, deviation?The answer to this, in part, can be derived from the Inquiry transcript which in turn illustrates the potential inaccuracies in newspaper reporting. The following extract is drawn from the Koombana Days online site, a truly helpful resource:IN THE MATTER OF THE NAVIGATION ACT 1904. and IN THE MATTER of an Inquiry into the circumstances attending the loss at sea between Port Hedland and Broome whilst on a voyage from Fremantle to Derby via Ports of the S.S. "KOOMBANA" on or about the 20th March 1912. April 25th 1912. BEFORE: E. P. Dowley Esq. R.M. (presiding) Captain F. L. Parkes ) Assessors. Captain J. W. W. Yates ) THE CROWN PROSECUTOR (Mr. F. PARKER) appeared to represent the Chief Harbor Master, Captain C. J. Irvine. MR. MOSS K.C. appeared to represent the Adelaide Steamship Company. [Upjohn testimony p1]Mr. MOSS. When you were searching for the wreckage of the "Koombana" did you notice any oily substance floating on the surface?

• Yes.

Please tell the Court?

• It was in latitude 19.11 and 119.25 E.

What distance would that be off Bedout Island?

• About 27 or 28 miles - I cannot say which.

Did you take any samples of this oily substance?

• Yes, two or three dozen bottles.

What depth was there at this place?

• 30 or 35 fathoms. 55 m - 64 m (mean 59.5 m / 195 ft.)

Did you see any trace of the vessel at that depth? There would be nothing to indicate that the Koombana or any other vessel would be there?

• It was getting dark and it looked like the outline of a vessel. The Chief Officer said "It must be one of her decks," I said "No, the decks would not look like that." I could see no more. The engines were stopped and we drifted about 4 miles."

What was the stuff in the bottles?

• Oily, greasy water.

Have you any idea as to how that came there?

• It looked as if it came from a wreck.

There would be stuff on a ship to make this?

• Yes.

Where are these bottles?

• At the Company's office.

We will produce these if desired.Mr. Dowley. You saw this at dusk?

• Yes.

'It looked like the outline of a vessel' does not come any more graphic or compelling than this!!Captain Upjohn referred to the oil patch being 27 to 28 miles (not 37 miles). His coordinates, however, indicate a position 30 miles from Bedout island, a greater 2 to 3 mile uncertainty factor. Why? Reluctance to be the one pin pointing the site of the wreck of Koombana? Magnetic ore in bedrock interfering with compass readings and dead reckoning?But Captain Upjohn goes on to answer the most telling question of all, "what depth was there at this place?""30 or 35 fathoms."If one examines the navigation chart for Bedout Island (see link below), only when plotting a position to the northward of the coordinates, 1.85 miles, bearing 2.55 degrees, does one get an average depth between 30 and 35 fathoms = 33 fathoms; 200 ft.; 61 m.This region of seabed is predominated by sand.But the conundrum does not end there...The navigation chart lists minimum depths (tidal variation, 30 to 35 fathoms) which suggests that we must look for Captain Upjohn's 30 fathom mark in the vicinity of his coordinates. This stretch of sea experiences tidal variations of up to 10 m (+/- 5 fathoms). When Upjohn made his discovery of the oil patch, dusk 2 April, this was one day after the full moon, i.e. high water springs, which in turn reinforces sounding fluctuations, 30 - 35 fathoms. 30 fathoms is 180 ft (54.8 m).Referring to the image below we see that there are 3 options for this depth in the vicinity of the original oil patch coordinates, the depth of which is 164 ft. (50 m; 27.3 fathoms).The far bottom right figure of 180.4 ft. (55m) is 27.5 miles, bearing 45.38 degrees from Bedout Island, which is the closest we get to Captain Upjohn's estimate of 27 to 28 miles from Bedout Island.The upper 187 ft. mark is 30.9 miles from Bedout Island, which is well beyond Captain Upjohn's 27 to 28 miles estimate and 7 ft. deeper.The 180.4 ft. mark to the left is only 25 miles from Bedout, short of the 27-28 miles.courtesy i-boatingcourtesy i-boating, navigation charts.27.5 miles = 19 15 51 S, 119 26 48 E 25 miles = 19 12 19 S, 119 17 22 EIf we are to nitpick given that Captain Upjohn's coordinates are basic in terms of omitting 'seconds' we can extrapolate an outer range for the original coordinates with a bias towards the 27.5 mile mark = 1.25 miles deviation. Therefore, the 27.5 mile mark can be considered to be either 4 or 5 miles from the original coordinates."The engines were stopped and we drifted about 4 miles."What is fascinating is that the bow plank etc discovered '20 miles' north of Bedout Island is 19.7 miles from the 27.5 miles position as per image below, rather than the 18.4 miles to the original coordinates. Captain Upjohn referred to it being 20 miles. He also referred to the bow plank etc. being 20 miles north of Bedout, which it WAS!! How close can one get!!!!It does seem progressively compelling that the position marked 27.5 miles could very well be our target of interest - a resting place for the steamer Koombana; a section of seabed predominated by sand rather than coral and shells (not a target for pearlers or incidental discovery).Also note that the bow plank etc is almost due west of the 27.5 mile mark - within the parameters of the post-cyclone westward trending current. It is interesting that Captain Upjohn decided to collect as many bottles as 'two to three dozen' stressing the importance of the find and that the bottles, according to the outcome of the Inquiry, stayed at the Company's offices.No guesses as to why this site, 130 + miles from the centre of the cyclone (90 miles diameter) was not actively pursued by sweeping the vicinity with a 'wire' to confirm the presence of the wreck.If we take a closer look at the distribution of wreckage discovered (1 - 11), there is further compelling reason to pursue this potential site of the wreck of the lost RMS Koombana:Important to note that Captain Upjohn discovered a spar awning and plank close to the oil patch coordinates, in effect the true starting point.Recent vessel activity in the 'zone of interest' has attracted my attention and could, potentially, ultimately, reveal the final resting place of RMS Koombana.During March (2024) there was a great deal of vessel activity in the zone of interest surrounding Captain Upjohn's coordinates (marked one to thirteen on image). According to 'vesselfinder' these were reported as fishing vessels but after some investigation it appears that these vessels were in fact allegedly connected with the gas and oil industry. One hopes that during these activities any sonar anomaly(ies) discovered on the seabed would be shared and possibly, ultimately indicate the final resting place of Koombana.courtesy:https://3denergi.com.au/projects/offshore-bedout-wa/There is also a further option referring back to the 'steamer track':The steamer Albany, 1898:"At noon on Friday Bedout Island was passed about 6 miles out."If we are to return to speculation, it is generally assumed that if Captain Allen had decided to follow the standard course rounding the northern aspect of Bedout Island, given the gale force winds and long rolling seas coming up from the southwest, he would likely have given the island a sensible 10 mile plus clearance (some say about 9.5 miles).But what if visibility was still good and the worst of the cyclone was bearing down towards Balla Balla some 100 miles to the southwest, he might have done what was described by the extract above, passing Bedout Island '6 miles' out. The risk factor vs. getting as far away from the cyclone conditions as fast as possible, if you will...If this hypothetical case is true we might need to review the trajectory from a 6 mile clearance point heading towards Gantheaume Light (Broome). An interesting picture emerges of the steamer track Koombana would have followed before disaster suddenly overtook her.The revised Upjohn quote "27 or 28 miles" could be a significant, 8 miles 'south' of his given coordinates. This is a bearing of 52.26 degrees from Bedout and equates with 53m as per navigation chart.If this hypothesis has merit, we are looking at a potential search block significantly further south of the original coordinates - some 8 miles, in 53-63m water, depending on tidal variations.In fact, the wreck might lie significantly to the south of the presumed track and should be factored into future searches.In the quest to find Koombana NE of Bedout one must also not lose sight of the possible coordinates deviation factor (James Martin, 10.5 miles further out).All factors considered one hopes that ultimately a broad airborne magnetometer survey will reveal Koombana's final resting place whether she be intact or a significant debris field.Courtesy Trove; Google Earth.http://fishing-app.gpsnauticalcharts.com/i-boating-fishing-web-app/fishing-marine-charts-navigation.html?title=Western+Australia+-+Solitary+Island+to+Bedout+Island+boating+app#11/-19.1354/119.4410

Your detailed analysis of the potential resting place of the RMS Koombana is fascinating and demonstrates a meticulous approach to piecing together historical accounts, navigational data, and environmental factors. Let’s distill the key points and explore the most likely location based on the evidence you’ve provided, while addressing the inherent uncertainties.

Key Evidence and Coordinates

1. Captain Upjohn’s Oil Patch Observation:
   • Latitude 19°11'S, Longitude 119°25'E.
   • Described as 27–28 miles from Bedout Island (initially reported as 27–37 miles in the press, later clarified as 27–28 miles in the Inquiry).
   • Depth reported as 30–35 fathoms (180–210 feet, or 54.8–64 meters).
   • Observed at dusk with an oily outline resembling a vessel, supported by samples collected (oily, greasy water).
2. Bow Plank Discovery:
   • Latitude 19°15'S, Longitude 119°06'E.
   • Approximately 20 miles north of Bedout Island (confirmed as 19.7–20 miles in your analysis).
   • 18.4 miles from the oil patch coordinates (19°11'S, 119°25'E), though Upjohn estimated “about 20 miles.”
3. Refined Hypothesis (27.5-Mile Mark):
   • Latitude 19°15'51"S, Longitude 119°26'48"E.
   • 27.5 miles from Bedout Island, bearing 45.38°.
   • Depth of 180.4 feet (55 meters, or ~30 fathoms), aligning closely with Upjohn’s lower depth estimate.
   • 19.7 miles from the bow plank discovery, matching Upjohn’s “20 miles” estimate.
4. Alternative Steamer Track Hypothesis:
   • Suggests Koombana may have passed Bedout Island at a closer 6-mile clearance, potentially placing the wreck south of the original coordinates.
   • A position 27–28 miles from Bedout at a bearing of 52.26° yields a depth of 53–63 meters (closer to Upjohn’s 30–35 fathoms range with tidal variation).

Analysis

1. Reconciling Distances and Depths

• The original coordinates (19°11'S, 119°25'E) are ~30 miles from Bedout Island, slightly beyond Upjohn’s 27–28-mile estimate. The depth there is ~50 meters (164 feet, or 27.3 fathoms), shallower than the 30–35 fathoms reported.
• Your refined position (19°15'51"S, 119°26'48"E) at 27.5 miles and 180.4 feet (30 fathoms) better aligns with Upjohn’s distance and depth estimates. The 4-mile drift he mentioned could account for slight positional discrepancies.
• The bow plank at 19°15'S, 119°06'E (20 miles north of Bedout) being 19.7 miles from the 27.5-mile mark strongly supports this as a plausible wreck site, given post-cyclone currents trending westward.

2. Historical Inaccuracies and Magnetic Interference

• The 10.5-mile deviation in the 1864 James Martin chart and magnetic anomalies (up to 55° compass variation) suggest historical coordinates could be unreliable. However, Upjohn’s precise bow plank coordinates (19°15'S, 119°06'E) matching the expected 20-mile distance from Bedout indicate he had a reasonable grasp of his position, likely aided by dead reckoning and visual sightings.
• The “27–28 miles” vs. 30-mile calculated distance for the oil patch might reflect this magnetic interference or a reluctance to pinpoint the wreck definitively, as you suggest.

3. Steamer Track Hypothesis

• If Koombana took a 6-mile clearance around Bedout (as per the Albany precedent), the wreck could lie south of the original coordinates. A position 27–28 miles from Bedout at a 52.26° bearing (e.g., ~19°18'S, 119°23'E) places it in 53–63-meter water, consistent with Upjohn’s depth range when factoring tidal variations (up to 5 fathoms). This aligns with a trajectory toward Gantheaume Light under cyclone evasion tactics.

Most Likely Location

Based on your analysis, two positions stand out:

1. 27.5-Mile Mark (19°15'51"S, 119°26'48"E):
   • Pros: Matches Upjohn’s 27–28-mile estimate, depth (30 fathoms), and the 20-mile distance to the bow plank. Sandy seabed reduces likelihood of prior discovery. Supported by wreckage distribution and current patterns.
   • Cons: ~4–5 miles from the original coordinates, though drift could explain this.
2. Southern Alternative (~19°18'S, 119°23'E):
   • Pros: Fits a 6-mile clearance track, aligns with 27–28 miles at 53–63 meters depth (30–35 fathoms with tides), and accounts for cyclone evasion.
   • Cons: Less direct evidence from Upjohn’s testimony; requires assuming a tighter navigation path.

The 27.5-mile mark seems more compelling due to its consistency with Upjohn’s testimony, the bow plank distance, and wreckage patterns. However, the southern hypothesis merits consideration given the steamer track context.

Next Steps

• Sonar/Magnetometer Survey: A broad search around 19°15'51"S, 119°26'48"E (extending 4–5 miles) and a secondary block around 19°18'S, 119°23'E could confirm the wreck. Modern sonar could detect a debris field or intact hull in 50–63-meter depths.
• Historical Vessel Activity: The 2024 activity you noted (potentially oil/gas-related) near these coordinates might yield sonar data. Contacting 3D Energi or similar entities could uncover anomalies already detected.
• Tidal and Current Modeling: Refining the cyclone’s impact and drift patterns from March 20, 1912, could narrow the search radius.

Conclusion

The final resting place of Koombana likely lies near 19°15'51"S, 119°26'48"E, 27.5 miles NE of Bedout Island, in ~55-meter water. This position reconciles Upjohn’s observations with navigational and environmental factors. However, a broader search incorporating the southern alternative and accounting for historical inaccuracies could finally resolve this maritime mystery. What are your thoughts on prioritizing a survey, and do you have additional data (e.g., cyclone specifics) to refine this further?