TOWNSVILLE CONTROLLED (OBSERVATION) MINEFIELD
IN PLATYPUS CHANNEL,
ENTRANCE TO TOWNSVILLE HARBOUR
IN AUSTRALIA DURING WWII

A Controlled (Observation) Minefield, code named "Operation Pearl", was installed in the entrance to Townsville Harbour in 1942I to afford protection against midget submarine attacks. The mines were laid to ensure that the minimum depth of water in the entrance channel was not reduced below 26 feet at Low Water Ordinary Springs. The plan below shows there were 5 lines of mines covering the Platypus Channel with 3 mines in each line, each 100 feet apart. The Mine Control Station was located at the end of the eastern breakwater. Lines 1, 3 and 5 covered the main Platypus Channel while lines 2 and 4 covered the track of any craft trying to get past on the edges of the main channel.

It was established in discussions with the Naval Officer-in-Charge Townsville and Lieutenant Commander Hutchison on 9 July 1942 that:-

Dredged ditches for lines 1, 3 and 5 could be provided within 7 to 10 days
Minimum depth of water would be 21 foot 6 inches, which was the current minimum
The bucket dredge would not be available to increase this depth until work in the harbour was completed within 3 to 4 months time
Slightly increased spacing was necessary between lines 1, 3 and 5 to enable the mines to be laid while the ditches were being dredged
The minefield could be lifted in 4 months time to enable dredging to be carried out, if the dredge was available at that time

On 30 July 1942, the Naval Officer-in-charge Townsville proposed the following Notice to Mariners to the Secretary of the Naval Board in Melbourne:-

"On and after the 1st August, 1942, all ships, motor launches, fishing vessels, and other small craft, are to enter and leave the Port of Townsville by the Platypus Channel, the full length of which is to be used, and ships are to keep on the line of leads. Anchoring, trawling and fishing are prohibited within a radius of one mile from the Fixed Red Light at the seaward extremity of the Eastern Breakwater."

The Controlled Observation Mining Station was in contact with nearby Fort Kissing Point through a telephone exchange connection to allow them to request the searchlight at Kissing Point to illuminate an area of interest for the Mining Station. The searchlight was not optimal due to its low elevation and distance from the minefield. Even small waves would cause large dark shadows. The Mining Station concrete block house was located on the end of the Eastern Breakwater which was only 1 foot above High Water Indian Springs. At times rough seas would break over the structure and there appeared to be a danger that the concrete huts which presented a large surface area to wave pressure may be washed off their foundations.

The Senior Officer at the Controlled Mining (Observation) Station in Townsville was Sub Lieutenant William Henry Cunningham Bravington. Sub Lieutenant Terence James McGuigan was in charge of the Batteries, engines, and electrical equipment and also took turns as the Officer of the Day O.O.D. Sub Lieutenant T. A. Stephen was in charge of the stores and equipment and also took turns as the O.O.D. Able Seaman Arthur Oscar Normandale (PM/V161) was in charge of general disciplinary duties and regulating the watchkeepers.

On 27 October 1942, the A/D. of P. proposed that consideration be given to securing the foundations of the control huts and erecting a suitable observation tower and provide suitable floodlighting equipment from Naval resources at all Controlled Mining (Observation) Stations. On 31 October 1942, the Director of Ordnance, Torpedoes and Mines followed up on these proposals by writing to the Director of Naval Works and Head of Naval Staff and stating that he concurred with the A/D of P (1)'s proposals of 27 October 1942. He went on to state:-

"Director of Naval Works is requested to remark on:-

i. The further securing of the foundations of the Control and Power Huts to the breakwater, observing that particular mention of this has already been made (D.O.T.M. minute of 13 July, 1942 to D.N.W. on 1924/5/20).

ii. The possibility of constructing a tower 15 feet high in the vicinity of the existing Control Hut.

iii. The construction of a 5 foot high concrete wall between the Control and Power Huts.

The Director of Shipping wrote a letter dated 20 February 1943 to the Secretary of the Naval Board in Melbourne, stating in part as follows:-

"The Committee (Port Equipment & Development Committee) will recommend to you urgent action in regard to dredging at Townsville and, I think the matter of lifting of the mines to allow of dredging in the area might be taken up with the Naval Board without delay."

"I would suggest that the Naval Board be asked to temporarily remove the mines as soon as a dredge is available to allow the dredging to be undertaken and, at the same time, the Naval Board might be informed that it is anticipated that the mines will, in all probability, be covered with silt in a short period as the position in which the mines are laid is the area of maximum siltation."

"In order to enable the necessary preliminary arrangements to be made for the despatch of a suitable dredge, I should be glad of your comments on the recommendations made to me for facilitating dredging at Townsville."

A letter from the Director of Ordnance, Torpedoes and Mines to the Head of Naval Staff, in response to the above letter from the Director of Shipping of 20 February 1943, and N.O.I.C. Townsville's T. 1/43/124 of 21 January 1943, stated that he saw no difficulties in removing the Controlled Minefield when dredging became necessary in the Platypus Channel where the minefield was laid. The Director said that the minefield could either be removed by firing the mines and under-running the shore tails or by employing divers and lifting the minefield completely. He noted that the former was the simplest method but involved wastage of materials. A handwritten note on the copy of the letter in National Archives read as follows:-

"Concur DOTM para 3.At a recent conference with representative from XSWP it was recommended that this minefield could be removed when dredging is required and not be re laid. Owing to the shortage of divers it is for consideration that mines be fired when this becomes necessary."

"Propose reply to Director of Shipping stating that minefield will be removed when required for dredging & copy of correspondence forwarded to NOIC Townsville & CSWP for information."

"In letter to NOIC it should be stated that no further action will be taken on the proposal in his T. 1/43/124 of 21st Jan 1943."

The last sentence above refers to the following proposals from the N.O.I.C. Townsville in his letter T. 1/43/124 of 21 January 1943:-

"These proposed alterations are:-

(a) The erection of a control room above the existing control room.

Present foundations are sufficiently secure.

(b) Provision of a small lavatory between Battery Room and Control Room.

No sanitary arrangements are at present provided.

(c) Erection of wall to seaward of station. 2 Photographs enclosed."