Tuesday, 20 June 2017

DRAUGHT AND POWER COMPARISONS.

The following comparative steamers all had significant top hampers, but crucially, significantly lower maximum draughts compared with Waratah. Waratah should in reality have had a draught in the region of 27 ft.. But due to inherent top heaviness, this was not possible, resulting in functional overloading (including ballast). Furthermore Waratah was significantly under powered which, taking into consideration her functional overloading and reduced freeboard, was never going to be a recipe for a successful steamer:

SS Otranto:

Type:Passenger liner 
Tonnage:
Length:535 ft 4 in (163.2 m)
Beam:64 ft (19.5 m)
Depth:38 ft 8 in (11.8 m)
Installed power:14,000 ihp (10,000 kW)
Propulsion:
Speed:18 knots (33 km/h; 21 mph)
Capacity:
  • Passengers:
  • 235 1st class
  • 186 2nd class
  • 696 3rd class

mean draught 25.75 ft. 

Note that although Otranto had a similar depth to Waratah (38 ft. 8 in. vs 38 ft. 6 in), she was registered for a max mean draught of 25.75 ft., not 30.375 ft.



SS Otranto



SS Falaba

details
tonnage4806  grt
dimensions116 x 14.45 x 7 m
materialsteel
engine1 x 3 cyl. triple expansion engine, single shaft, 1 screw, 4 boilers
power424  n.h.p.
speed14  knots
yard no.414
IMO/Off. no.124000

mean draught 22.9 ft.




SS Falaba



SS Dongala

SS DONGALA                                      SS WARATAH

Built:           1905                                                    1908
Builders:      Barclay, Curle, & Co                          same
Gross tons:   8038                                                   9339.07
Net tons:       4723                                                  6003.96
Length:         470 ft.                                                465 ft.
Beam:           56.25 ft.                                             59.45 ft.
Draught:       27.75 ft.                                             30.375 ft.
Engines:       twin quadruple                                   same
Power:          8000 ihp                                             5400 ihp

mean draught 27.75 ft.

Note 8000 ihp vs 5400 ihp.



SS Dongala



RMS Morea

  • Gross tonnage: 10,890 grt                                                   9339.07 grt   
  • Net tonnage: 5,960 nrt                                                        6003.96 nrt   
  • Deadweight: N/K
  • Length: 164.53m (540.0ft)                                                   465 ft.     
  • Breadth: 18.65m (61.2ft)                                                     59.45 ft.   
  • Depth: N/K
  • Draught:  7.53m (24.7ft) - corrected.                                  30.375 ft.  
  • Engines: Quadruple-expansion steam engines                     similar 
  • Engine builders: Barclay, Curle & Co Ltd                             same
  • Works: Glasgow
  • Country: UK
  • Power: 13,000 ihp                                                                 5400 ihp 

mean draught 24.7 ft.

Note 13 000 ihp vs 5400 ihp.


RMS Morea



SS Anchises

SS Anchises:                                                      SS Waratah:

10046 gross tons                                           9339.07 gross tons
6380 net tons                                                 6003.96 net tons
493 ft. length                                                  465 ft. length
60 ft. beam                                                     59.45 ft. beam
37 ft. depth                                                     38.5 ft. depth
29 ft. draught                                                  30.375 ft.
2 x triple expansion engines, twin screw      2 x quadruple expansion, twin screw
14 knots                                                          13.5 knots

mean draught 29 ft. 

This is the only comparative steamer with a draught approaching that of Waratah's, without reported problems.


SS Anchises



SS Assaye, built 1899, 7396 gross tons, 4484 net tons, length 450 ft. beam 54.25 ft., draught 26 ft. 2 in.

mean draught 26 ft. 2 in.


SS Assaye


SS Erinpura, 5128 gross tons, length 411 ft., beam 52.5 ft., draught 23 ft. 5 in

mean draught 23 ft. 5 in.


SS Erinpura




SS Devanha, built 1905, gross tons 8092, length 470 ft., beam 56 ft. 3 in., draught 27 ft. 8 in.

mean draught 27 ft. 8 in.





SS Sicilia, Barclay Curle & Co, built 1901, gross tonnage 6696, net tonnage 4174, length 450 ft., beam 52 ft. 4 in., draught 26 ft. 8 in.

mean draught 26 ft. 8 in.


SS Sicilia



HMHS Varela, gross tonnage 4645, net tonnage 1932, dead weight 5160 tons, length 390 ft., beam 53.3 ft., draught 22.9 ft.

mean draught 22.9 ft.




Let's revisit SS Indarra, a steamer which suffered similar problems to Waratah and had to be materially altered to reduce draught.

           SS INDARRA                                           SS WARATAH:

Engines:     twin quadruple                                     same

Launched:  1912                                                     1908

Gross tons: 9735                                                     9339.07

Length:       450 ft.                                                  465 ft.

Beam:         60 ft.                                                    59.45 ft.

Draught:      32 ft.                                                   30.375 ft.


mean draught 32 ft. takes the cake and prize. Her upper deck was removed during a major refit.


Waratah's twin quadruple expansion engines were under powered for her size. I have put together a few examples (from many) of twin engine (screw) steamers of the era:

SS Waratah, built 1908

gross tonnage      9339
length                  465 ft.
beam                   59.45 ft.
power                  5 400 ihp
speed                   13 to 13.5 knots


SS Omrah, built 1899

gross tonnage     8130 
length                 490.5 ft. 
beam                   57 ft.
power                  9 000 ihp
speed                   17 knots


SS Wiltshire, built 1912 

gross tonnage      10 390
length                   526.5 ft.
beam                    61.4 ft.
power                   13 000 ihp
speed                    14 knots


SS Hororata, built 1914

gross tonnage       9461
length                   511 ft.
beam                    64.3 ft.
power                   8 493 ihp
speed                    14 knots


RMS Morea, built 1908

gross tonnage       10890
length                    540 ft.
beam                     61.2 ft.
power                    13 000 ihp
speed                     16 knots


SS Indarra, built 1912

gross tonnage        9735
length                    450 ft.
beam                     60 ft.
power                    8 132 ihp
speed                     16 knots


SS Assaye, built 1899

gross tonnage        7396
length                    450 ft.
beam                     54.25 ft.
power                    6 500 ihp
speed                     16 knots


SS Devanha, built 1905

gross tonnage         8092
length                     470 ft.
beam                       56 ft.
power                     8 000 ihp
speed                      15.5 knots


To put this important issue into perspective, let's take a closer look at the famous RMS Baltic:


Tonnage:23,876 GT
Length:729 ft (222.7 m)
Beam:75.6 ft (23.1 m)
Propulsion:Two four-cylinder quadruple expansion engines powering two propellers.
Speed:16 knots (30 km/h; 18 mph)
Capacity:2,875 people

At the time of launch Baltic was the largest steamer afloat (until 1905). On her maiden voyage, she completed the distance between Liverpool and New York (2871 n miles) in 7 days and 13 hours, which matched her registered speed of 16 knots. Despite the excellent crossing time, Baltic was proven to be under powered, her twin quadruple expansion engines being the same capacity as her smaller siblings, Celtic, Cedric and Adriatic. Power output was 14 000 ihp, but for her size, should have been 16 000 ihp. Modifications were made at a later stage to improve the output. It is important to note that being under powered did not affect speed under normal conditions. However, in heavy seas, an under powered steamer would have had difficulty maintaining speed / heading = unsafe. Manoeuvrability would also have been compromised, catastrophic if the vessel was caught broad side in a fierce gale. 

If one uses the Baltic as a frame of reference the Waratah should at the very least have had a power output of 6 226 ihp, not 5 400 ihp.

This casts an intriguing light on circumstances off the Wild Coast, 27 July. The falling barometer and physical signs presaging the approach of a cold front storm of 'exceptional violence' would have alerted Captain Ilbery to potential problems. Waratah was heavily laden and under powered. A decision might have been taken to come about irrespective of whether there was a fire on board or not. Captain Bruce remarked that Waratah was smoking fiercely, which might very well have been due to a fire, but also a sign (excessive, dark smoke from funnel) that the engines of the Waratah were being 'pressed' to outrun the approaching storm. It was mentioned at the Inquiry that 15 additional tons of coal were consumed daily on the final voyage, partly due to 'pressing' under powered engines. 

There might not have been a fire at all !

Mr Grigg summed up Waratah's limitations to perfection:

The Waratah, he said; lurched very badly, 
and in an unusual way, and would breast 
the waves in a wriggling, zigzag manner, 
giving the passengers some misgivings
concerning her.




SS Indarra









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