Refitting the Last Corvette, HMCS SACKVILLE

Although SACKVILLE last received a refit and maintenance during a docking period in 2018, that refit identified a number of critical areas that still required attention, and money and time were limited. After receiving new funding, the ship has once again been docked via the Navy's Syncrolift and Submarine Maintenance Facility, and is undergoing more work. I'll provide a more detailed report as time goes on, but for now will share some photos of the docking itself on September 24th. 

Once on the lift, the ballast tanks were pumped out, and the ship was lifted the rest of the way.

Although divers have removed the majority of the growth on the ship's bottom, some growth remained and was cleaned off in the coming weeks using high pressure water. The sacrificial anodes were in very good shape.

Once the lift was secured, the ship was pulled forward into the maintenance building. The previous customer, HMCS WINDSOR, recently completed a refit in the same shed.

The tug pulls the ship along this chain.

SACKVILLE viewed from one of the platforms along the side of the shed.

The refit is expected to last into the spring, and will involve the cladding of critical areas of the ship's existing plating under the waterline. This refit is intended to buy the ship another 10 years before more significant work needs to be done.

HMCS SACKVILLE relaunched

SACKVILLE returned to the water after a 9 month docking and refit period that started in January 2018 - her initial haulout was covered here at that time. She was relaunched on Tuesday, October 9th.

The refit included an extensive condition assessment of the hull and internal support structure that provided the basis for the repairs that were carried out - I'm unclear on the finer details, but I know that there was a considerable amount of new plating applied to the exterior of the hull. The hull was completely repainted both above and below the waterline, and a new suite of anodes was installed.

Rolled out of the shed and onto the Syncrolift platform, SACKVILLE sits ready for relaunch.

Lowering the platform, with the wood deck still visible under the water's surface.

The overcast sky at least made for more balanced lighting for photography purposes.

SACKVILLE was lowered to the 8' depth marking on her bow so that the riding crew could check for leaks inside the ship. Two previous launch attempts ended at this point after the ship took on some water. The patchwork of riveted and welded steel plate means that watertight integrity isn't certain until tested.

Afloat and off her blocks, SACKVILLE was pushed to the side of the Syncrolift to make room for the tugs.

With the usual configuration of a Glen tug astern and a Ville tug forward, SACKVILLE is backed out of the camber.

SACKVILLE still requires some re-ballasting before she rides correctly in the water.

Although relaunched, SACKVILLE's refit is not quite over. The mast needs to be reinstalled, and extensive cleanup above and below decks remains to be done before she can take her position on the Halifax waterfront in Spring 2019.

My photo album of the haulout, refit, and relaunch can be found here.

Flower-class Corvette chart house

As a child growing up in Liverpool, Nova Scotia, there were a number of similar garden sheds around the town - boxes with windows sitting in various backyards. I probably played in more than one of them over the years.

But these were no ordinary garden sheds - they used to be sea going structures. Not only that, but they used to be installed on the bridges of warships - well, corvettes anyway - small commercially -built ships based on whale catchers that were gerrymandered into submarine hunters and convoy escorts. 

Not a Tardis - this humble shed used to be a charthouse mounted on the bridge of a Flower-class corvette. This example has been restored and sits in front of the Queen's County Museum in Liverpool. 

The first batches of Flower-class corvettes came from the builder's yard with a short foc'st'le and a small chart house (also known as a compass shelter or "Asdic hut") on the open bridge platform above the wheelhouse. On the early RCN corvettes, this hut housed the ship's only compass - in contrast with the RN corvettes with their gyro compasses and multiple repeaters, it was a magnetic compass with no repeaters. Macpherson & Milner's "Corvettes of the Royal Canadian Navy 1939-1945" recounts that this made it impossible for the corvette's captain to direct a submarine battle from the open bridge while having direct sight on the ship's compass. Some ships had a monkey's island on top of the chart house, and judging from the many photos of early corvettes in the above mentioned book, the construction of the chart houses themselves might vary from ship to ship in terms of size and the number of windows.

The following photos show early Flower-class corvettes with their charthouses fitted - in fact, as these photos were copied from the memorial wall of the Royal Canadian Legion's White Ensign branch, I believe all of these ships were sunk with the charthouses still mounted.

HMCS WINDFLOWER - one of the original batch of Flower-class corvettes built for the Royal Navy in Canadian yards but taken up by the Royal Canadian Navy. The chart house is seen on top of the wheelhouse, and just behind the mast. Photo courtesy Royal Canadian Legion, White Ensign branch.

HMCS SPIKENARD in the original configuration, though with an early SW1C radar at the masthead. Photo courtesy Royal Canadian Legion, White Ensign branch.

HMCS WEYBURN. Photo courtesy Royal Canadian Legion, White Ensign branch.

HMCS LOUISBOURG. Photo courtesy Royal Canadian Legion, White Ensign branch.

The original batches of corvettes had a number of issues which were rectified in refits later in the war (assuming the ships survived that long), and later batches of corvettes were built from scratch with the modifications incorporated. These modifications included (but were not limited to) a longer foc'st'le (to improve seakeeping abilities among other reasons), moving the mainmast behind the bridge (to improve visibility from the bridge), and the removal of the charthouse - it was replaced with an open pilotage, as can be seen today onboard the only remaining Flower-class corvette, HMCS SACKVILLE.

Liverpool was home to Steel and Engine Products Limited - STENPRO for short (I've been corrected that it may have been called "Thompson Brothers" during the war). Later bought by Irving (and since shuttered and sold), this little ship repair yard (a short hop from the house in which I grew up) with its single marine railway, was active during the Second World War refitting corvettes - and not being ones to throw things away, the chart houses ended up in people's back yards, and some were still there 30-odd years later when I was growing up. 

I believe the small platform on the front of the chart house may have supported an RDF (Radio Direction Finder) antenna, although not all ships carried their RDF in this position. Many photos show it mounted more centrally on the roof of the chart house.

Along with the door on the aft end of the chart house is a small protrusion with a glass top - I believe this housed nautical charts so that they could be seen from outside without the chart getting wet in adverse weather conditions.

A view of the chart compartment from inside.

The museum was closed during my brief visit, so I don't know if it is known which corvette donated this particular charthouse - I wouldn't be surprised if that information has been lost to time. I'm just glad to see that at least one of these structures (along with some childhood memories) has been saved.

Refitting HMCS SACKVILLE - Progress Report

On Friday, I managed to make my way down for lunch in the Dockyard with the SACKVILLE trustees, and afterwards carted my safety equipment over to visit SACKVILLE herself to view the progress of her refit. Workers have spent several months surveying the condition of the plates and frames that make up the hull, and making plans to remediate the greatest problems in order to keep her afloat for the coming years.

As such, she is surrounded by scaffolding, and the entire hull is currently painted in "red lead". The photos below show her current status.

This was the state of SACKVILLE the last time I saw her, on the day she was hauled into the submarine maintenance building.

SACKVILLE on June 8, 2018. All the hatches are open to gain access, the whaler is missing, and the hull is painted red.

SACKVILLE is completely surrounded by scaffolding, so it is impossible to see the entire hull unimpeded.

My favourite vantage point, because it is such a unique perspective of SACKVILLE.

The scaffolding makes it difficult to get a good view of the hull.

View from the stern.

Repair and restoration work is scheduled to begin soon, and should be complete in time to allow SACKVILLE to return to the water this fall.

Rolling, rolling, rolling - moving HMCS SACKVILLE into the Sub Shed

After being hoisted out of the water on Fleet Maintenance Facility Cape Scott's (FMFCS) Syncrolift platform on February 11th, SACKVILLE's hull was cleaned of marine growth and prepared to transfer into the adjacent Captain Bernard Leitch Johnson submarine maintenance building in HMC Dockyard (hereafter referred to as the "sub shed" or simply the "shed").

By the morning of February 15th, SACKVILLE was ready to transfer into the shed.

Thursday morning was sunny, so I got some better photos of SACKVILLE on the lift. She also looks a bit cleaner.

SACKVILLE points towards the sub shed which she will soon enter. The army of bogeys under the ship can be seen here.

The view from inside the shed, looking out. The bogeys to the right are connected to the tow motor, and straddle inner two of the four rails. The tow motor will push these bogeys, and the attached tow bridle, out to join to the bogeys under the ship. The brow is still fitted in this photo.

An HDR image made from two different exposures - it turned out pretty good, considering I took the two exposures hand-held, and not from a tripod as I should have. Throughout the transfer, I had issues with the different exposures between the interior of the shed and the bright sunny day outside. The tow motor's traction chain is running along the centre of the image here.

A plated-over hull penetration below what would have been the chain locker or store. I'm not sure what it was for - it may have been associated with SACKVILLE's postwar career.

These hull penetrations are just aft of the bow slope transition, and are roughly where the original Type 123 ASDIC would have protruded below the hull. I'm not sure why there are two, though some of the early sonar sets required penetrations for more than one transducer. Again, both of these may not have been original.

Looking forward along the port side, showing the bilge keel, blocking, and bogeys. There are several of these plates on the hull that stand an inch or more proud of the hull surface. Four anodes are also visible.

It is important that the ship's hull be well supported during the move, so workers pounded shims into any gaps between the hull and the blocking.

The system for transferring the ship into the shed is fairly simple. Four rails run from the Syncrolift platform into the shed, and the bogeys which support the ship's weight straddle either the two outer sets of rails, or the inner set. The tow motor that propels the ship along the rails straddles the inner two rails.

The outer end of the traction chain that the tow motor grips to propel itself, with SACKVILLE in the background. During the transfer, the chain will be under considerable tension, and this presents a hazard to people in close proximity to the chain if it were to fail or snap. During the transfer, only FMFCS staff were allowed to remain in the work area.

Unlike a train locomotive, which uses the friction between its drive wheels and the rails to propel the train, the tow motor grips a heavy chain (I will refer to it as the traction chain in this post) that runs between the two inner rails from an anchor post at the inshore end of the shed to an anchor post at the inshore end of the lift platform.

The yellow post at the end of the traction chain is the outer anchor post, which allows the tow motor to pull itself out to the wharf. The tow motor can not go out onto the platform itself, as it can not pull itself beyond the anchor post.

In order to hook itself up to the bogeys under SACKVILLE, the tow motor pulled itself out to the Syncrolift platform along the traction chain.

The orange tow motor, at left, is now in position. It has pushed a series of bogeys and a tow bridle out onto the Syncrolift platform to bridge the distance between itself and the bogeys under SACKVILLE, and workers have connected the two sets of bogeys.

Once everything was connected, and non-essential staff were directed to designated observation areas, the transfer began. I was allowed to view the transfer from the mezzanine platform inside the sub shed, but was not allowed down to the shed floor during the transfer.

The transfer has begun, and the tow motor has moved back inside the sub shed. SACKVILLE is still on the platform in this photo.

There were several pauses during the transfer operation to confirm that SACKVILLE was still well supported by the blocking.

The view looking inward, with SACKVILLE now inside the building.

There are several levels within the sub shed, and this photo was taken from the highest level.

Once SACKVILLE was fully inside the shed, and the tow motor could not proceed further without hitting the end of the building, the intermediate bogeys between the tow bridle and the bogeys under the ship were removed to shorten things, and allow the tow motor to get closer to the ship, in order to bring SACKVILLE in a bit further. There are several overhead bridge cranes that span the width of the shed, and one of these was used to lift the bogeys out of the way.

One of the intermediate bogeys is lifted out of the way.

The tow motor is at the inshore end of the traction chain, which is attached to the inshore anchor post that is just outside the shed, through the dark opening just to the right of the motor. The anchor post itself is cast into a large block of buried concrete. The tow bridle is attached directly to the bogeys under the bow of the ship.

Once the ship was in position, I was allowed back down to the shed floor to get some more photos of the ship inside the shed. 

The tow motor is at the inshore end of the shed, and the yellow overhead bridge cranes can be seen behind the ship.

A view from the mid-level mezzanine platform of the starboard bow.

Compared to the previous photo, this was taken from the upper platform, which is just below the overhead bridge crane track. Some of the photos make the ship look like a model.

Another photo from the upper platform showing the ship from aft, with the brow (gangway) now fitted. It was lifted into place by one of the bridge cranes. The man pulling out the safety net is standing on the mid-level mezzanine platform.

A wider-angle photograph, showing the scale of the shed's interior, including the upper level translucent panels to allow in natural light.

A floor level image from aft.

A wider angle image from floor level, with the yellow bridge cranes visible at the top of the image.

A panoramic image from my phone. Until I viewed her from above, I never realized SACKVILLE's pendant number was painted on top of her radar enclosure.

Two FMFCS staff stand between the transfer rails, alongside the traction chain.

Now that SACKVILLE is inside the shed, her refit can begin, and is expected to last several months at least.

A complete gallery of my processed images of SACKVILLE's lift and transfer is linked here.