On The Slipway

Category: General (page 3 of 4)

Bridge equipment, part I

Nearly all resources of HMS Hood show the layout of the bridge equipment in the open air, though only as location placeholders. One good image is known of Hood’s Air Defence Position (ADP) showing a series of pedestals and smaller sights and range finders. Finding out which one goes where and what piece of equipment it is was the next challenge. In the end, it appears that HMS Hood is fitted with the same equipment fitted to all battleships, most heavy cruisers and fleet carriers. However, getting a good picture of that equipment is something different altogether as these smaller sights are usually placed in crammed positions that are visually obscured.

Here is a unique image of the ADP of HMS Hood. Some equipment is visible and was an unknown to me before starting doing some research. If you want to learn more about how and why the bridge of a British warship was equipped, I suggest reading The British High Angle Control System (HACS) by Tony Tony DiGiulian at the navweps website or the High Angle Firing chapter in the Gunnery Pocket Book at the Historical Naval Ships Association.

The ADP has a control team consisted of the Air Defense Officer (ADO) and his assistant. He has a special ADO sight that can indicate the to-be-engaged aircraft by relaying a target bearing. Such an ADO sight is thus an aircraft bearing indicator but this sight also functions as a star shell sight at night. The other ADO sight is manned by his assistant, so two of these sights are present. There are six so-called Air-Lookouts (ALOs), three on each side of the ship’s bridge. Each ALO continuously observes an arc of the sky around the ship, watching for aircraft to appear. The ALO uses a position with a pair of binoculars. Once an aircraft is spotted and marked by the ADO, the High-Angle Control System (HACS) will determine the target’s speed and bearing so that it can be engaged by the heavy anti-aircraft artillery. Each large capital ship was typically fitted with three or four of such HACS directors. The model of the HACS is described here. Next to the HACS directors, a series of close-range pompom directors are fitted. HMS Hood was fitted with one such director for each pom pom gun, one Mark I and two mark IIs ). The pom pom and HACS directors in the Royal Navy were all fitted with the Yagi radar aerials later, but HMS Hood was sunk before those radars were fitted. One piece of equipment present on other ships that probably would have been fitted to HMS Hood was the Auto-Barrage Unit (ABU) that determined the range of the enemy aircraft, in order for all anti-air guns to fire a single barrage.

Several directors for the searchlights were also present next to these air-defence positions. There is a single searchlight sight per searchlight, but as the two ADO sights can also act as a searchlight bearing indicators, HMS Hood was fitted with four additional searchlight sights.

The captain himself also has a bearing indicator that was placed on HMS Hood, but not on the inside of the bridge probably due to space constrains. On the King George V class, these sights were placed inside. A final sight, according to John Roberts, is a UP sight placed near the upper ADP of HMS Hood. No information was found on this particular sight.

So, the typical equipment found on RN warships is one pair of captain sights, a pair of ADO sights, two pair of searchlight sights (depending on the number of searchlights), three pairs of ALO sights, a pompom director per gun and a number HACS directors. The latter is the only one that is clearly visible on warships.

This image of HMS Prince of Wales’ bridge shows the ADP most clearly. From this picture follows that the sight on HMS Hood’s ADP is the same. The three ALOs are seen clustered together with the pom pom directors fitted a level lower. The searchlight sight (SLS) is just out of view.

A clear top view of the bridge of HMS Duke of York. The three ALOs are well visible. HMS Prince of Wales and HMS King George V have their ALOs clustered together in a single position, but one of the ALOs aboard HMS Duke of York appears to be placed a but further aft. The searchlight sights (SLS) are seen at left below the main fire control director and are wrapped in covers, as are the pom pom directors (PPD). The captains sight is inside the fore bridge and is not visible.

An excellent top view of HMS Queen Elizabeth, clearly showing the six ALO positions and searchlight sights (SLS). The ADO is not visible, but might be located in the fore bridge, as with HMS Warspite (slightly different bridge layout). The ABU is visible bottom right.

A very clear front view of HMS Queen Elizabeth showing the searchlight sights (SLS) and the ABU.

This schematic of the bridge of HMS Victorious shows the same equipment as on the battleships. Even with everything clearly in the open, I haven’t been able to find a good picture of the bridge of a carrier.

Now that I know what to look for, this equipment is visible on most other larger ships and even on monitors such as the layout above indicates, but the information on bridge equipment of most of these images is poor. If you flip through Raven and Roberts Battleships and Cruisers volumes, you’ll notice many (unannotated) positions of the ADP equipment corresponding to the number of directors I now expect on board these vessels.

So, here’s a clear image of HMS Hood showing the location the Captain’s Sight (CS) and UP sight (UPS) as well. This clear image indicates that it is impossible to see any of the items on photographs as described above and the first image in this post of the ADP is the best there is as far as HMS Hood is concerned.

Part II of this post will show the individual units in detail.

Searchlights, part I

The large 44″ searchlights of HMS Hood were one of the last items of which I did not have good information except for a few pictures. Fortunately, John Lambert issued a series of drawings, L/O/162, although he mentions it’s the Mk VII of 1942-44, while Hood was sunk in 1941. I ordered them anyway and initially thought they were wrong as the frame didn’t match the photographs. However, I found out that nearly all pictures of the searchlights showed their port side and that I somehow thought the unit was symmetrical. On closer inspection it seems the drawing of the searchlights is as good a match as far as I can tell. This picture shows some of the best images of the searchlight. The images at left ware taken of HMS Onslow (top) and HMS Prince of Wales (bottom) with HMS Hood at right.

I intend to build the searchlights in two parts. The frame is mainly built in styrene (can’t see how to make a photoetch part that I can physically fold into the frame shape) and the projector itself mainly as a photoetched part.

I started with strips cut to shape for the frame and gluing them into the shape shown right. The front and rear should angle back about 8 degrees and this first attempt resulted in very uneven parts. It’s not so well visible in this particular picture but when continuing to add the rest of the frame, the part didn’t really work out. On to the Mk II miniature frame! This time, I spent some more time pondering and I eventually took a slightly different approach by cutting triangles first. At the bottom the mould for the chopper is shown. I use this approach a lot to cut angled parts to size. At right you can see a small template triangle in place to position the template. After a few sizes of triangle, you end up with the size you need (there’s always a slight difference in the template and copy size, usually about 0.1 mm.

Top left shows how to prepare large amounts of strip at an angle. Works pretty well, but right shows the easier approach; strips glued to the triangles. Now it’s just a matter of chopping the parts to size using another small mould. I always have large cheap styrene sheets laying nearby to spend on such actions. Two chops later and the front and rear base frames are cut to size much more consistently (and easier) than adding strips cut to size.

The next mould is a small plate angled forward 8 degrees and placeholder strips for the frame. The two blocks are for positioning what’s shown at right; two strips glued to a center block that acts as a spacer (and makes it easier to handle as well). Add a bit of glue and it’s fixed. Next, the part is cut to size and the same mould is used to glue the second frame. All parts were given some superglue in the corners. Now both the front and end plate are at the correct angle. Using a few moulds seems to be a lot of work but in the end the result was less work, resulted in less rejected parts and the parts more consistent in shape than when not using the moulds.

The top half of the frame was built from strip drilled in using my new drill press which I bought for the occasion. The side detail was built from a small ring, a small tube and some triangles.

This part was sanded to size and added to the frame. I made another ring for the searchlight bearing and checked if the part was nicely aligned. The hand wheel was then added, starting from a strip drilled in with a small 0.3 mm drill using the drill press. I start using thicker and slow-curing CA more frequently when bonding metals as the photoetch parts do not allow most of the other glues I have to stick.

The second hand wheel is being constructed from a small ring and strip. It barely survives the chopper! The end result is a small part to be added to the searchlight base.

Here’s the completed frame. The base part is made using my new lathe The lower base part has a conical shape and a 2mm gap so that it can be fitted easily on a disk on the model. The top part of the base is a small disk but with a very small 2mm extension so that it fits concentrically in the lower base part.

This is the design for the lantern which will be nearly all photoetch except for a small disk to close the part off. I couldn’t add all the required detail in a double-layer part, so I made three additional part to be glued onto the main part. The two parts for the side will be aligned using some rod, the top part will be aligned using the small square visible in the middle of the main part. Should be a nice folding exercise!

Go on to part II.

Vents II

For some reason I avoided beginning to build all the mushroom vents of HMS Hood. There are many sizes and shapes and they are both numerous and small. I took the basic measurements from “Anatomy of the Ship: HMS Hood”, drawing I1: Fittings. I brought the total number of different mushroom vents down to about four and tried to classify all mushroom vents on the drawings and photographs. I decided on Large  (2.4mm or 0.095″), Medium Large (2.0mm or 0.08″), Medium Small (1.22mm or 0.048″, a US punch size), and Small (0.8mm or 0.0315″). I tried to do a head count and came up with 13 large, 18 medium large, 32 medium small, and 31 small; 94 vents in total. As these parts are small I might loose them during handling and as I probably missed a few on the drawings or pictures, I had to make a nice supply of parts.

The largest vents are visible here, cut from tube. I added a disk to all rings so that the support of all mushroom vents has the same height; I now need to cut the support to length on the model, paint it, and then add the mushroom vent. This way I know what the height will be before painting the entire ship and I do not have to get the height correct of each vent to what is visible on the photographs after painting . After this disk was placed, a small disk was glued on top of the vent as detail. None of the vents on the photographs have any more detail such as a hand wheel. Too bad, would have looked nice.  The grille of the vent is simulated by an etched part bent into shape and set with superglue. I only had tubes for the largest vents, the two medium sized vents were made from rod with the center punched out as explained here. This was some work with many casualties due to off-center punching, dropping to the floor, misalignment and more dropping to the floor.

I started with the largest vents which I found to be small to begin with, and worked my way down. The smallest vents were really a challenge. I started by cutting up rod in batches of ten. They had their centers punched out by the ten-fold. I decided the smallest vents can probably be put into place prior to painting with little risk showing their white undersides or can be placed on the painted model. So, I put the rod in place. I first slid the rod in (bottom left), dipped the tip into superglue and slid the ring into place. The bottom right shows the result prior to sanding.

These are all the vents; 20 large, 34 medium large, 40 medium small and 58 small, 152 total. At least, 152 are left and dozens more are scattered around in the hobby room. Perhaps casting a few would have been possible, but I didn’t look forward to the prospect of casting several batches of tiny parts with a high failure rate.

Vents, part I

A series of boiler room vents runs through the bridge superstructure and next to the funnels. On all the drawings, two boiler room vents are drawn at the bridge location, but only one of them visibly exist the superstructure on the admiral’s signal platform. So, where does the other one end up? The top left section of the image shows the rear of HMS Hood’s superstructure, with the arrow indicating the exact location of the after boiler room vent. The other vent is seen on the image section next to it. The top right image shows the implementation on the model. I’m not exactly sure if the aft vent is correct, but this is all the material I have. The bottom half shows both vents in detail. The vents on the admiral’s signal platform intersect the base of the 5.5″ rangefinder towers.

There are four large engine room vents on the boat deck, all situated on the center line of the ship. The top left image shows a sailer posing with one of these vents in the background. A little to his right, the vent near the searchlight platform is visible. Notice anything? This vent is considerably taller than the other vent, which is not indicated on any drawing of HMS Hood. The other pics show the same vent in detail. It’s very easy to overlook the height of this vent, until you actively gauge its height from nearby details. It’s nearly twice the height of the sailer standing in the top right image. The top left image shows that a series of hatches are present on the top of the vent, including a small ridge around it.

This image has the location of the vents indicated. Notice that all hatches on top of the vents are opened toward the stern of the ship. It’s difficult to make out the outer right vent and I can’t tell if hatches are present. Probably not, as the main derrick is stored on a crutch on top of this vent, blocking the hatches from opening. The vent near the disinfector house (second from the right) is also blocked by the main derrick, but is built wider with hatches capable of opening when the main derrick is stored. This might be true for the vent at right as well, but I cannot find any picture showing this, with all the boats and launches stored there blocking the view. If hatches are present, I’ll add them afterwards as I’ll have the main derrick in the stored position on the model.

Here are the vent models that took a surprising amount of time to complete. I started by cutting strip to size, added wire mesh, cut the strip to height and width, and glued them to a rectangular base. A small 0.25mm strip was glued to each corner. The roofs are frameworks of 0.25mm strip as well. Small triangles were added to the corners of the mesh (difficult to do) and custom-etched hatches were added later. The hatches are fixed using arced supports, visible when stored in the top left of the previous image (behind the sailor).

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