Friday 3 April 2015

HMCS IROQUOIS: Steering the ship (updated)

Having covered, in previous blog posts, the propulsion and power generation of the ship, I thought I would now cover the very basics of steering the ship. Starting with the primary helm station on the bridge:
Bridge helm station.
The bridge helm station is located towards the aft of the bridge (not including the flag officer area). It includes not only the wheel (which looks like it belongs to an aircraft, and not a ship), but also an array of buttons and switches (some of which appear to control the ship's gyro navigation). As noted below, there are two steering motors, and the switches and indicator lights appear to control and show the health of separate port and starboard units. There is only one rudder. The helm station provides input to the electronic steering system, and there are several ways of operating this system. The wheel can be used, as can some of the switches on the black panel to the left of the wheel, to control the rudder.

The original steering gear setup is described in the original movie "Sisters of the Space Age" on YouTube (0:47 of Part 2). 

Helm and throttle positions on the bridge.
As well, the separate position to the right provides direct throttle control for the engines. This is one of four locations onboard the ship that can directly control the two main and two cruise gas turbines, and presumably the display screen has access to the appropriate parts of the machinery control system (MCS). The helm station shown in the YouTube video indicates that the original helm station was also set up in this location (though the station itself has been updated and replaced, and relocated aft from a position near the forward bridge windows).

This is a different setup than the previous generation of RCN destroyers, which did not have direct helm and throttle control on the bridge, but rather relied on a telegraph to the engine room for throttle settings and the helm station was several decks below the bridge, with the helmsman relying on instructions from the bridge.

The ship's wheel controls the steering hydraulics, located in the tiller flats (ahem....Steering Gear Compartment). 

Steering hydraulics in the Steering Gear Compartment.
The rudder is turned via a double-headed hydraulic steering ram that is connected to two separate steering motors which in turn are controlled by the ship's helm. Linear motion from the hydraulic ram is turned into rotary motion via a rapsom slide mechanism.  In the background of this image, looking aft and starboard, is one of two auxiliary helm stations (the other being in the MCR). 

Auxiliary helm station in the Steering Gear Compartment.
At the top of the photo is a compass repeater, so that the auxiliary helmsman can steer a course based on instructions from elsewhere in the ship. The ship only has one rudder, but there are two steering motors, and there is one steering station for each motor. There is a second auxiliary helm position, similar to the one on the bridge "...but with way less buttons...", in the Machinery Control Room (MCR). Unfortunately, I did not get a photo of this station.

Rudder post in the Steering Gear Compartment.
The rudder post protrudes up into the Steering Gear Compartment, as seen above.

The grease covered rudder post in the Steering Gear Compartment. The indicators showing port and starboard steering angles is visible towards the bottom of the image.

The destroyers, as with the frigates that followed them roughly 20 years later, are steered by a single large rudder:

IROQUOIS' rudder. Not the greatest photo, sorry.
The ship's rudder is located right aft on the hull, and just behind (and between) the ship's twin propellers. In the event that the single rudder is disabled, the ship might still retain limited maneuverability via the twin propellers, but this would presumably only be useful at sea with lots of room to spare, and would be of limited use if the rudder were jammed hard over. I'm told that steering by the main engines via the twin shafts is very effective when the ship is stopped.

Note: Input from crew members has been incorporated to update my original post. For instance, a previous version of this post indicated that I was unsure if there was still an auxiliary helm position in the MCR, as I did not take photos of it - it was confirmed to me that this exists in the MCR. Other errors have also been corrected since this was first posted. 

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