HMCS IROQUOIS: Electrical Power Generation (Corrected)

Warships have large electrical power requirements, in order to run everything from heating and the lights, to galley equipment, electric fire pumps, sensors, and weapons systems. On IROQUOIS class destroyers, the Auxiliary Machinery Room (AMR) houses two 750 kW Solar Saturn gas turbine generators and one 1000 kW diesel generator to provide this power. A third 750 kW Solar Saturn is located forward of the bridge at deck level, in the port side of the deckhouse that formerly housed the Sea Sparrow launcher pre-TRUMP. If truth be told, I managed to get myself completely turned around in the AMR, and didn't take enough video and wide shots to help properly orient myself in the photos that follow, so some of my typical directional commentary will be lacking in this post. I didn't get a clear picture in my head of where each piece of machinery is located.

Looking down into the lower level of the AMR. Port propeller shaft at left of ladder. The AMR is a very crowded space that houses a variety of equipment, not just the generators.

In the 1960s when the IROQUOIS class was designed, gas turbines provided the best "bang for the buck" in terms of high power from a compact package, so the Solar Saturns are the primary power source. As with the propulsion engines, all the generators are housed within skin-tight enclosures that serve to insulate the surrounding space from noise and, in extreme events, fire. They are also generally shock mounted, but I have no specific details regarding this.

The Solar Saturn gas turbine generator in the main engine room with the cover rolled back.

The two Solars in the AMR are located port and starboard on the upper level of this space. During the time of my tour, two of the three Solar Saturns onboard had been dismantled and transferred from IROQUOIS to ATHABASKAN for spare parts on the latter ship. ATHABASKAN is the last remaining IROQUOIS class destroyer remaining in active service, and was on deployment at the time of this tour.

No.2 Solar Saturn gas turbine generator, looking forward in the AMR.

Possibly to hedge their bets, a diesel generator was also included (originally a 500 kW Fairbanks Morse opposed piston engine, replaced during TRUMP by a 1000 kW Detroit Diesel). It is installed at the forward end of the AMR's lower level, between the two propeller shafts. The local control switchboard for this generator was retrofitted during the TRUMP refit, to accommodate the larger 1000 kW generator.

The diesel generator sits inside this enclosure, the interior of which doesn't appear quite as easy to access as the rolling enclosures for the Solars.

1000 kW diesel generator inside its enclosure through an open port.

Local control switchboard for the diesel generator. Built in 1987, this would have been a retrofit during the TRUMP refit.

All the electrical power on the ship is routed through the main switchgear, which is located elsewhere in the ship.

Main switchgear compartment.

As with the propulsion gas turbines, all the generating equipment is controlled remotely in the Machinery Control Room (MCR) which I will cover in a subsequent post on this blog.

Correction: Previous versions of this post were mistaken in the location of all three Solar Saturn generators. In fact, only two are located in the AMR (upper level), and the third is located at deck level in the deckhouse forward of the bridge. Many thanks to members of various Facebook groups for setting me straight.

HMCS IROQUOIS: propeller shaft & running gear

Following on from my earlier post with a tour of IROQUOIS' engine room, this post will trace the path of the propeller shaft after it leaves the gearbox. After departing the gearboxes, each propeller shaft passes through a thrust block (which transfers the thrust of the propeller to the hull) and several plummer blocks (which support the shaft along its length).

Looking down into the AMR. A yellow and black propeller shaft runs down the left side of the photo.

  Immediately aft of the main engine room, where the propulsion machinery is located, is the Auxiliary Machinery Room (AMR). The AMR houses three Solar Saturn 750 kW gas turbine generators plus one 1000 kW diesel generator, as well as numerous other pieces of smaller equipment. The port and starboard propeller shafts also pass through the AMR.

A propeller shaft (painted yellow & black) runs through the AMR heading aft (e.g. to the right).

Plummer blocks support the propeller shaft at the aft end of the AMR.

Due to the shape of the hull and there being two of them, the shafts must pass through not only the AMR, but also a DFO service tank, and finally the Gland Compartment before passing through the hull.

Starboard propeller shaft running through the Gland Compartment. I believe the blue hose is a hydraulic hose from the hydraulic pump for the CP props.

CP prop hydraulic pump unit.

Modern warships, including the IROQUOIS and HALIFAX classes, often use variable-pitch or controllable-pitch (CP) propellers, where the blades of the propeller can be rotated to different pitches. This is necessary because gas turbines can not be run backwards, and otherwise it might be necessary to include an extra "reverse" turbine on each shaft as was done with steam powerplants in the previous generation of warships. The CP prop allows the gas turbines to run in the same direction at all times, and the transition between forward and astern power is handled by the pitch of the propeller blades. The hydraulic pump that controls the pitch of the propeller blades is located in the Gland Compartment, two compartments aft of the AMR.

The starboard shaft passes through seals and exits the hull in the Gland Compartment.

The other side - the port shaft exits the hull.

Port propeller shaft intermediate support strut.

Port variable (or controllable) pitch propeller. A V-shaped strut supports the shaft just ahead of the propeller.

Starboard "running gear": the propeller shaft showing both intermediate and V-shaped support struts.

The original variable pitch propellers fitted to IROQUOIS and her sisters were only four bladed and were shaped differently (as I recall), and new propellers (presumably quieter and more efficient) were retrofitted at some point, possibly during her TRUMP refit in the early 1990s.

Update: The port variable pitch propeller, removed from HURON before she was sunk, is on display at the Naval Museum of Alberta in Calgary.

HMCS IROQUOIS engine room (Updated & Expanded)

As my first blog post ever, this will probably be slightly unpolished, as I see how this all works.

The heart of HMCS IROQUOIS: her engine room is home to four propulsion gas turbines, producing between 12,788 shaft horsepower (cruise) and 51,000 shaft horsepower (main), along with various other equipment.

The port main (boost) turbine enclosure (left) and the local controls for all propulsion gas turbines (right, see below for better photo). I never did figure out what the Tabasco sauce was for.

The starboard Allison cruise turbine within its enclosure. The compressor stages are to the left, while the turbine is to the right.

The propulsion gas turbines are mounted backwards (compared to an airplane), with the compressor intakes pointed aft (left in the photo) and the turbine and exhaust pointed toward the bow (to the right). The shaft to the gearbox comes off the compressor end of the engine.

Starboard cruise turbine enclosure with insulation on the exhaust seen at the forward end.

Looking aft at the exhaust ducting from the starboard cruise turbine.

The starboard MAAG gearbox. Each of the green inspection ports covers a transparent window displaying part of the gearbox interior.

Each gearbox accepts two shafts on the forward end - one from each of the cruise and boost turbines. 

The aft end of the starboard gearbox (to the right of the photo) connects to the starboard propeller shaft, which I will cover in a subsequent post. 

Port gearbox. Note that the inspection ports are painted red (port) and green (starboard) to help identify which gearbox is which.

Looking forward from behind the starboard gearbox. Protective wire mesh at the bottom of the photo is probably covering where the propeller shaft exits the gearbox.

Although all the various bits of machinery onboard IROQUOIS and her sisters are controlled from the MCR (Machinery Control Room), there are also local controls mounted in the engine room, seen here (and seen to the right of the image at the top of this post).

The local control panel for the four propulsion gas turbines is located between the two main (boost) gas turbines. This panel is generally manned whenever the engines are started, and can provide local control if contact with the MCR is lost.

 This panel provides direct control to all four propulsion turbines, and the diagrams and layout on this panel show the basic machinery arrangement - the cruise turbines are located outboard toward the hull on the port and starboard sides, and the boost turbines are located inboard on either side of the ship's centreline. This panel allows local control of not only the gas turbines, but also the two gearboxes (the long rectangles on the lower half) as well as the equipment that controls the pitch of IROQUOIS' controllable pitch propellers.

Cruise turbines are intended to propel the ship economically, typically at speeds of up to 20 knots or so (I'm guessing, I don't have the exact figure in front of me), while the main (boost) turbines are used to propel the ship up to its published maximum speed of 29 knots and possibly beyond. The basic arrangement of the gas turbines and gearbox is very similar to the Y100 steam turbine powerplant arrangement as designed for the ST. LAURENT class of destroyer escort in the 1950s, which I have written about elsewhere.

The ship's power generating equipment is located in the Auxiliary Machinery Room (AMR), immediately aft of the Engine Room. 

IROQUOIS will pay off this spring, just shy of 43 years after she was commissioned into the Royal Canadian Navy.