HMCS PRESERVER: Tour of electical power generation and the bow thruster

Where the power generating equipment is located across multiple spaces, some of which I have already covered, I decided to break out my summary of power generation onboard PRESERVER into a separate blog posting. As a result, a few photos and descriptions from previous postings may get repeated here. This should be read in coordination with those earlier postings covering the engine room, boiler room, and machinery control room. 

I will also cover the bow thruster, as it is powered by a rather large diesel engine that isn't in the engine room. As always, I will note that I am by no means an expert on these systems, and am relying on information gleaned from my guides during my tour as well as my own assumptions. Mistakes are my own!

Electrical power generation onboard a warship is a particularly critical capability, required to start propulsions engines, run hotel loads and combat systems, and is therefore designed for redundancy. In PRESERVER, this means that three types of generators (2 steam turbines, 2 diesels, and 1 gas turbine) are distributed across three different spaces (engine room, boiler room, and forward of the bridge respectively).  

Port turbo-alternator (steam turbine generator).

While at sea, the two 1000 kW turbo-alternators (installed port and starboard in the engine room) would normally provide the majority, if not all, of the ship's power requirements. Being steam driven, these generators require steam from the boilers, so these generators would not be used while the ship is alongside with cold boilers. Therefore, in order to provide power to start up the boilers, power is required from other sources.

Poor quality video capture of the two diesel generators, looking forward and to starboard.

The two 500 kW diesel generators are located port and starboard in the boiler room, between the two boilers - this should put them on the ship's centreline. The diesel generators are more or less self contained, and can begin generating power fairly soon after a cold start. The diesels would provide power to the boilers to get steam up, after which power generation would be transferred to the turbo-alternators, and the diesels would be shut down to save fuel. Not only are the diesel generators separated from the turbo-alternators by being located in separate spaces within the ship, they also rely on a separate fuel source, providing additional redundancy. 

Gas turbine generator.

Located forward on No.1 deck on the starboard side of the deckhouse forward of the bridge is the emergency generator compartment, home to a single gas turbine generator. I believe this is the same model as used in the IROQUOIS class destroyers, albeit in a different type of enclosure. If so, this is a Solar Saturn unit rated for 750 kW. Gas turbine generators have the advantage of being able to run up to full power from a cold start almost instantaneously, and therefore they have great value as emergency generators that can come online very quickly when other sources of electricity unexpectedly fail. In addition to being able to be started using local controls, this generator could be fired up remotely from the Machinery Control Room (MCR).

In the photo above, we are looking at the generator enclosure, with the generator itself being installed inside. As I recall, the exhaust pipe for this generator exits the ship not quite six feet above deck level on the starboard side, and is therefore a bit of a head knocker for those not paying attention.

Another angle on the Solar Saturn gas turbine generator.

It is my assumption that the gas turbine generator would not typically be used either alongside or at sea, apart from occasionally being exercised, and that it would be reserved for emergency use. I could be wrong.

Gas turbine local switchboard.

There is a local switchboard installed in the same compartment as the gas turbine generator.

For lack of a better spot, I will also cover the bow thruster here. 

Bow thruster diesel engine.

Being rather large, and driven by a single shaft, these ships are not the most maneuverable. During a refit at some point, during the 1990s I believe, both PRESERVER and PROTECTEUR received bow thrusters to reduce their reliance on tugboat assistance when leaving port or coming back alongside. The bow thruster is effective at speeds of up to 5 knots, and is driven by its own direct drive diesel engine. This diesel does not generate electrical power, but rather is connected mechanically to the bow thruster by a vertical shaft.

Bow thruster diesel engine

I  believe the vertical cylinder on the end of the diesel engine in the photo above is the top of the direct drive shaft leading down to the bow thruster. I am assuming that either the diesel would have to reverse direction in order to allow the bow thruster to direct thrust from port to starboard, or the impeller would need to have adjustable pitch blades. I didn't think to ask at the time, so I don't know how this is done. 

Bow thruster impeller tunnel.

The bow thruster impeller itself is necessarily installed very low in the ship's hull, and we descended several ladders to reach this compartment. I believe this photo is taken looking to port. The impeller for the bow thruster is installed in a water-tight tunnel, as seen here, which allows it to throw water out either side of the ship. The tunnel is roughly as tall as a man, and the direct drive shaft enters the tunnel at top-centre in this photo.

In the compartment above the bow thruster are the guts of the blackwater (sewage) treatment system onboard PRESERVER. The blackwater tanks are in close proximity, and no space on a warship goes unused.

HMCS PRESERVER: Engine Room Tour (Updated with corrections)

At the time of writing this, only two steam-driven ships remain in the Royal Canadian Navy: HMC Ships PROTECTEUR and PRESERVER. Indeed, these Auxiliary Oiler Replenishment (AOR) vessels were the last two RCN ships designed and built with steam power, and shortly after they were commissioned the RCN introduced new surface warships with all gas turbine propulsion (IROQUOIS class), and later a combination of diesel and gas turbine propulsion (HALIFAX class). Similar ships to PROTECTEUR and PRESERVER built today are most likely diesel powered.

Being the last steam-powered vessel remaining in RCN service in Halifax, and soon to pay off and be discarded, I was keen on photographing PRESERVER's engine and boiler rooms for posterity. While I have done something similar for the Y100 steam plant in the ST. LAURENT and subsequent destroyers, the ships I toured had been out of service for several years, and my camera gear was somewhat deficient. This time around, the commentary won't be as good, but at least the photos will be better. 

Entering PRESERVER's engine room from the Machinery Control Room (MCR) (which itself will be covered in a later post), I was greeted by one of the largest open spaces onboard ship (second only, I think, to the helicopter hangar):

Engine room looking forward and to starboard from #2 Deck level.

The two grey items in the centre of the photo above are the low pressure (LP) and high pressure (HP) turbines, respectively. The astern turbine is mounted within the LP turbine casing, and on the same shaft. The grey shape to the bottom right (both forward and aft of the catwalk) is the double reduction gearbox. Immediately port of the LP turbine on #3 Deck (main level) are the two evaporators that make fresh water for the boilers (of which I have video, but no still photography for some reason). Aft of the gearbox are the two 1000 kW turbo alternators (steam driven generators). 

Another view from Deck #2, from further to starboard. The HP turbine is top left.

Another view from Deck #2, from further to starboard. The LP turbine to the right. The evaporators are behind the piping in the centre of the image.

A view looking directly down on top of the gearbox, giving a better idea of its size.

In the photo above, you can see the two shafts coming out of the two turbines, and connecting to the gearbox. A single shaft exits the gearbox along the ship's centreline, below the platform at the bottom of this photo, which connected directly to the propeller shaft. The reduction gearbox is required to transfer power from the high speed turbines to the propeller. Steam turbines are at their most efficient at relatively high revolutions per minute (RPM), while a ship's propeller is most efficient a much lower RPM. In this case, the gearbox also combines the power from the two turbines, and transmits it to a single propeller shaft.

After taking these photos, I descended the ladder to the left of the image to Deck #3, which is the main level of the engine room.

The Joy pump  compressor supplies control air. I don't remember what it does, apart from make noise.  

Port turbo alternator, looking aft and starboard.

Under normal conditions, electrical power is provided via the two 1000 kW turbo alternators, which are located port and starboard at the aft end of the engine room. These turbo alternators are self contained (they have their own condensers), although they receive steam from the main boilers. 

Port turbo alternator, looking aft and to port.

It was one of these turbo alternators in PROTECTEUR that caught fire while she was sailing off Hawaii in 2014, leading to her (slightly) early retirement. A lube oil line burst, sending a mist of 150 psi oil up into 500+ degree steam piping causing it to ignite. The fireball went forward in the engine room, hampering fire fighting efforts and attempts to shut off the oil supply. It was a very unfortunate event, and the crew did well to save the ship with no loss of life.

At times when steam is not available, auxiliary power is provided by a diesel generator, and a Solar gas turbine generator up forward on main deck level. This auxiliary power is necessary to start the boilers, and bring up enough steam to start the turbo alternators and main engine when bringing the steam plant online, after which the diesel and gas turbine generators can be shut down (and kept in reserve for emergencies). 

Errr....a dooflicky. Don't remember what this is Located immediately starboard of the HP turbine are the main engine air ejectors, which "...remove air and non-condensable gases from the main condenser to create and maintain main engine vacuum". The tank to the right, with the John Deere logo, is a deaerator. Get it? Deere? Oh, dear.

Looking forward over the tops of the two steam turbines.

You can get an idea, from the photo above, of the rat's nest of steam pipes connecting the boilers to the propulsion turbines and the turbo alternators, the turbines to the condensers, and back to the boilers. As in any aging powerplant, the piping can get old and brittle, and sometimes leaks or breaks. The difference with a steam plant is that not only do you have to worry about fuel and lube oil lines breaking, but you also have to worry about the steam lines. It was explained to me that a corn broom could be used to identify steam leaks - it is waved in the air around a steam line, and if there is a steam leak, the escaping high pressure steam (at up to 865 degrees at 600 psi) will cut the corn off the broom like a knife. It doesn't bear thinking about what that would do to human flesh.

The HP turbine looking forward and to port. The springs on top of the HP turbine are part of the auxiliary throttles.

The steam turbines are normally controlled from the MCR, however, local controls are provided for the turbines in case control from the MCR is lost. The auxiliary throttle station is located at the forward end of the HP turbine.

Auxiliary throttle station looking to starboard. The telegraph repeater is the circle to the left of the clock, below what appears to be a SHINCOM panel.

The auxiliary throttle station provided manual control to both steam turbines, as well as the astern turbine. The local telegraph reports throttle settings ordered from the bridge, independent of the telegraph in the MCR - presumably throttle settings could also be transmitted by other shipboard communications, including SHINCOM, in the event the telegraph was inoperative. There are two red pipe handles, one of which can be seen to the left of the image, which are used to control the auxiliary throttles. 

Auxiliary throttle, with one of the pipe handles installed. The grey rod attached to the base of the throttle handle, below the red rod, is normally hanging down, but is flipped up to attach to the throttle itself in this photo.

The operator at this station would operate the red handle to provide the required revolutions ordered from the bridge.

Looking down on the gearbox at the aft end of the HP turbine, to starboard and aft.

The double reduction gearbox, looking forward and to port.

The gearbox, looking forward and to starboard. The platform bridges the propeller shaft.

Immediately behind the catwalk over the shaft is the thrust block, which transmits the propeller's thrust to the hull and presumably prevents that thrust from affecting the shock mountings of the gearbox and turbines. 

It was at this point during the tour that a classic (in my mind, anyway) miscommunication occurred. Knowing that the old steam DDEs had a way of stopping the shaft from turning when the ship was being towed at low speeds, to prevent the turbines from being turned backwards (or when the auxiliary inflatable stern seal is in place, see below), I asked if they had a "brake". Misunderstanding me, my ever helpful guide replied that "Yeah, at 10:00, we have soup if you want." Apparently, it is actually known as a "lock", and is placed on the shaft when needed.

(As an aside, I did get soup in the wardroom during a "break" in my tour. It was french onion, and it was delicious.)

Looking forward along the propeller shaft, with the gearbox in the background. The plummer block is the grey object around the shaft.

Looking aft along the propeller shaft.

Having a deep displacement hull, and only a single shaft, the propeller shaft leaves the gearbox and travels maybe 30 feet to the stern seal, which can be seen in the background of the photo above, where the shaft passes through the bulkhead. In that 30 feet, the shaft leaves the gearbox, passes through the thrust block, a plummer block (which supports the weight of the shaft), and then the stern seal or stuffing box. In the case of the stern seal leaking, there is an inflatable auxiliary seal that can be installed, but only if the shaft is stopped and not turning.

With PROTECTEUR laid up after her fire, and PRESERVER similarly laid up due to hull corrosion issues, the RCN will likely never have another steam plant in operation - these were the last two. And this is largely a good thing, as modern gas turbines and diesel engines are more compact, lighter, have higher power to weight ratios, require less manpower to operate, and are generally less hazardous to the crew. That said, there will be former and serving Navy sailors (and my guides were good examples of the latter) who will miss these powerplants now that their page in the RCN history books has been turned.

(Updated on 21 May with corrections to some equipment descriptions, based on comments to my Facebook post.)

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.