Whilst on the surface at sea only one hatch is open, that is the access to the conning tower or fin and the casing. There are two hatches one at the top and bottom of the trunk this enables it to be used for escape purposes in an emergency. The lower hatch is accessed from the control room. The main purpose of the fin is to house in a streamlined shape all the masts that are used when on or just below the surface. There are seven in all from front to back the attack periscope, search periscope, radar mast, electronic countermeasures [ECM] mast, air intake snort mast, radio transmit / receive mast [ W/T ] and snort exhaust mast these are operated from the control room.

The fin also provides a position from which the boat can be controlled when on the surface. Like the deck casing it is constructed of fibreglass, steel and aluminium and is free flooding. It also provides storage space, place for navigation lights and houses some sensors for the sonar system.

At the top of the access tower is the dive klaxon when sounded twice this is a signal for the crew to go to [or those at ] their stations to dive the boat. This happens only on the second signal just in case the first was accidental. Access to the fin is not possible during a tour of HMAS Ovens.

Follow the Guide

Take your own tour

Developed and produced by John Eade for the WA Maritime Museum 2002