This is a complicated, confusing subject and it helps a little to review Captain Upjohn's fuller inquiry transcript at:
https://koombanarevisited.blogspot.com/2019/09/revelations-and-contradictions.html
The Inquiry transcript extracts below reinforce Captain Upjohn's decision not to defend Captain Allen's decision to depart Port Hedland with 'empty tanks'. Captain Upjohn disingenuously suggested that Koombana, with her tanks pressed up, would have had a draught aft of 17 ft. which should have cleared the outer bar, 19 ft. deep, 20 March, 1912. In other words he suggested that Captain Allen could have departed Port Hedland that morning without ANY tanks empty.
The following document illustrates the subdivisions of tanks being used as required for trimming; e.g. fresh water port side subdivision and sea water starboard subdivision. What combinations and how Captain Allen ultimately achieved his goal remains in the realm of speculation.
https://koombanarevisited.blogspot.com/2019/09/revelations-and-contradictions.html
The Inquiry transcript extracts below reinforce Captain Upjohn's decision not to defend Captain Allen's decision to depart Port Hedland with 'empty tanks'. Captain Upjohn disingenuously suggested that Koombana, with her tanks pressed up, would have had a draught aft of 17 ft. which should have cleared the outer bar, 19 ft. deep, 20 March, 1912. In other words he suggested that Captain Allen could have departed Port Hedland that morning without ANY tanks empty.
But this was NOT the full picture by any stretch of the imagination.
Captain Upjohn contradicted himself and in the course of his session on the witness stand gave draught figures for when Koombana's aft tanks were empty; 16 ft. 6 in. and 13 -14 ft. forward, representing these forward tanks filled.
The above post link fleshes this out in more detail:
17 ft. (referenced above) equated with just the after peak empty and 16'6 ft. (16.5 ft.) with both after peak and number 6 tank, empty.
Compare these figures with alleged claims made by the Port Hedland harbour master that Koombana departed that fateful morning with draught figures: 16 ft. aft (further reduced from 16.5 ft.) and 11 ft. forward (normally 13.5 ft.). These figures confirm that most, if not all, of Koombana's tanks were empty; further enhanced by minimal cargo (14%) stowed forward.
It appears that before Captain Allen's tenure the practice was to empty either the after peak or the after peak and number 6 tank for clearing the bar at Port Hedland, leaving the remaining forward tanks full.
In fact Captain Allen copied this trend exactly on Christmas Day, 1911.
Captain Allen was a cautious master who understood Koombana's inherent top heaviness and when he took command, initially preferred to keep all tanks full accessing Port Hedland. However, on numerous occasions Koombana suffered damaging bar strikes in the process.
It stood to reason that by 20 March, Captain Allen had learned lessons too well, deciding to opt for empty tanks, i.e. 16 ft. aft, 11 ft. forward to ensure uncomplicated clearance of the outer bar (19 ft.) during a significant groundswell and gale from the NE, when his tender vessel would be pitching and rolling, requiring at least 3 ft. clearance. But this decision forced him to fill all tanks at sea.
In previous posts I have drawn attention to the fresh water component which was not replenished at ports and potentially created a free surface effect (loose water) in demarcated fresh water tanks. Captain Upjohn explained that in order to reduce the free surface effect (increasing heeling instability) in selected fresh water tanks midships 4 and 5, longitudinally sub-divided (voyage from Geraldton to Port Hedland) this water could be replaced / topped up by water from the after peak tank (see image - most rear tank) which consequently would be 'empty' on arrival at the outer bar reducing aft draught to 17 ft., facilitating clearance of the bar and solving two problems simultaneously. Subsequent to this the afterpeak could be filled with salt water for the remainder of the voyage north.
Captain Upjohn contradicted himself and in the course of his session on the witness stand gave draught figures for when Koombana's aft tanks were empty; 16 ft. 6 in. and 13 -14 ft. forward, representing these forward tanks filled.
The above post link fleshes this out in more detail:
17 ft. (referenced above) equated with just the after peak empty and 16'6 ft. (16.5 ft.) with both after peak and number 6 tank, empty.
Compare these figures with alleged claims made by the Port Hedland harbour master that Koombana departed that fateful morning with draught figures: 16 ft. aft (further reduced from 16.5 ft.) and 11 ft. forward (normally 13.5 ft.). These figures confirm that most, if not all, of Koombana's tanks were empty; further enhanced by minimal cargo (14%) stowed forward.
It appears that before Captain Allen's tenure the practice was to empty either the after peak or the after peak and number 6 tank for clearing the bar at Port Hedland, leaving the remaining forward tanks full.
In fact Captain Allen copied this trend exactly on Christmas Day, 1911.
Captain Allen was a cautious master who understood Koombana's inherent top heaviness and when he took command, initially preferred to keep all tanks full accessing Port Hedland. However, on numerous occasions Koombana suffered damaging bar strikes in the process.
It stood to reason that by 20 March, Captain Allen had learned lessons too well, deciding to opt for empty tanks, i.e. 16 ft. aft, 11 ft. forward to ensure uncomplicated clearance of the outer bar (19 ft.) during a significant groundswell and gale from the NE, when his tender vessel would be pitching and rolling, requiring at least 3 ft. clearance. But this decision forced him to fill all tanks at sea.
In previous posts I have drawn attention to the fresh water component which was not replenished at ports and potentially created a free surface effect (loose water) in demarcated fresh water tanks. Captain Upjohn explained that in order to reduce the free surface effect (increasing heeling instability) in selected fresh water tanks midships 4 and 5, longitudinally sub-divided (voyage from Geraldton to Port Hedland) this water could be replaced / topped up by water from the after peak tank (see image - most rear tank) which consequently would be 'empty' on arrival at the outer bar reducing aft draught to 17 ft., facilitating clearance of the bar and solving two problems simultaneously. Subsequent to this the afterpeak could be filled with salt water for the remainder of the voyage north.
Captain Upjohn alluded to the 'routine' filling of tanks at sea in the following extract and thus confirmed my assumption that Koombana's aft tanks were routinely empty for departure from Port Hedland.
"As a rule the Engineer would run them (tanks) hard up outside (at sea after departure). When plenty of water inside he may have run the fresh water tanks hard up" presumably consolidating from other partially filled sub-divisions and reducing the free surface effect.
Therefore, it does appear that filling Koombana's tanks at sea was not as uncommon as Captain Upjohn initially tried to implicate.
The tanks were numbered 1 through 6 from front to back (see image below).
Number 1 did not have a central water tight division and thus had to be either completely full or completely empty, in this instance allegedly completely filled with fresh water.
Number 2 tank had a central water tight division (effectively dividing these tanks into port and starboard separate tanks) and on this occasion was filled with salt water.
Number 3; 4 and 5 had central divisions.
Number 3 contained salt water.
Numbers 4 and 5 contained fresh water.
Number 6 tank did not have a central division and like number 1 either had to be completely full or completely empty. This tank, it is assumed was filled with salt water.
The allegation was therefore true that Koombana's draught was indeed in the region of 16 ft. aft 20 March, all remaining cargo forward in the ship and all tanks empty. With the upper limit of the propeller more accurately approximating 16.5 ft., it makes sense that with an aft draught of 16 ft. it would have been partially exposed i.e. 'flogging the air'. Under normal circumstances with just the after peak empty, drawing 17 ft. (forward tanks full), the propeller would have been submerged.
Captain Upjohn confirmed that it would take at least 3 hours (usually 3 1/2 hours) to fill the after peak and number 6 tank at sea. But if all tanks required filling and it took 3 hours plus just to fill the after peak and number 6, I do strongly wonder if there were empty or partially empty tanks when Koombana made her run for the north of Bedout Island. Furthermore, we know that Koombana was seen by two sets of witnesses only filling tanks for about 2 hours.
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| courtesy Annie Boyd. |
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| courtesy State Records Office, Western Australia, series 2357, cons 066 |
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| courtesy State Records Office, Western Australia, series 2357, cons 066 |
The following document illustrates the subdivisions of tanks being used as required for trimming; e.g. fresh water port side subdivision and sea water starboard subdivision. What combinations and how Captain Allen ultimately achieved his goal remains in the realm of speculation.
 |
| courtesy State Records Office, Western Australia; series 2357, cons 006 |
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