Assurance Class Tug

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Assurance class tug

IVOR WARNE reviews the Model Slipway kit – Part One

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Introduction

The Assurance class tugs were built from 1940 to 1943 by Cochrane and Sons Shipbuilders Ltd of Selby, Yorkshire. They were designed for convoy escort and rescue, especially in the Western Approaches and there were a total of 21 in the class. They were steam driven with a single screw so their operation would be immediately familiar to merchant seamen of the day.

They were armed with a 12 pounder gun mounted on the deck above the towing hook and on the bridge wings were 20 mm Oerlikon guns for anti-aircraft protection although a PAC launcher was initially mounted on top of the bridge. This was not the greatest weapon invented and speedily replaced by the more effective Oerlikon. The PAC system is worthy of attention, if only because it is so weird. PAC stands for ‘Parachute and Cable’. A rocket would launch the device, reaching a height of 600 feet, into the path of oncoming aircraft. A cable would then deploy and parachutes would open. In theory the aircraft would fly into the cable which would foul the control surfaces making the aircraft crash. This was the plan, but in practice the only fatality using this system seems to have been a Wellington bomber being used to test the system!

After the war the surviving tugs were sold into commercial service and some worked well into the 1960s.

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The kit

The model is to a scale of 1:43 (O Gauge, 7mm to the foot) and is 43.5 inches (1108cm) long and 9.75 inches (248mm) beam with a displacement of approx. 25lbs (11.5kg) which makes the model a reasonable proposition for transport and lifting. The contents of the kit box are as you would expect from Model Slipway, being of high quality and very complete. The model follows their tried and tested formula of a GRP hull with styrene deck and superstructure pieces, both CNC cut and printed, Photo 1. The model is fitted with superb white metal fittings with minimal flash, thus very little fettling is required. There is plenty of wooden dowel and wire for masts and railings, but what really got my attention was the etched brass sheet which includes the stanchions, Photo 2. This really sets the kit apart from its rivals. The layout of the printed sheets is logical. Each particular build item has all its parts together with a box drawn around them and a clear label, e.g. Compass Platform to tell you what you are building. I cut out all the boxes and put them into the packing box that the white metal fittings came in. When I subsequently made up an item I would then store it along with its label in the clear plastic boxes I use for the purpose (Ferrero Rocher boxes are my favourite, although the latest rounded edge ones are not so good, but the contents still taste perfect!).

Die cutting of styrene is okay but it does tend to distort the material, so Model Slipway use a very expensive CNC cutter to create the parts. It is extremely accurate, so if the part does not fit then it is your fault and not that of the kit. The CNC machine just does not make mistakes as the computer will not allow it. On that subject should you ever have the opportunity to view such a machine in action, it is quite spooky and surreal to see it at work.

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It is still necessary to separate the parts from the mother sheet and I usually do this complete for the section of work that is in progress. You must remember to mark each part with its number, using a soft pencil so as not to gouge the surface, or chaos will reign later in the workshop.

A sharp Stanley knife can be used to score round the parts. I do not even attempt to cut to the exact shape of the part, preferring to extract the part first and then trim it to size using a combination of scalpel and sanding. Those that still have sharp eyes will be able to see a milled edge half way down the cut created by the tool bit that marked out the part. I now use a magnifier light to spot this and sand the edge of the piece until the milling mark just disappears. The piece is then at the correct dimensions as ordained by the Model Slipway computer! The point is that time taken at this stage by the model builder will ensure that all the parts fit together properly.

A word here on sanding styrene as it does tend to clog files and sandpaper. The best tools for the job are the abrasive products made by Permagrit, website: www.permagrit.com, coarse grade to start and then fine to finish. Their tools come in all manner of shapes and sizes. The other method I use, is to plane long straight edges using a small block plane with a freshly sharpened blade, Photo 3.

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Let me also say that this is not a stick ‘Part 1’ to ‘Part 2’ review, more a series of notes to enhance the very comprehensive instructions supplied. Also, where I have deviated from the kit contents, this is not because of any inadequacies but for personal reasons. Everything you will need apart from paints, glues, motor, coupling, battery, esc, r/c and a stand, is within the box.

Before you start…..

Yes I know you want to start plundering the big box and start building, but patience is a virtue, so do yourself a favour and make the stand first. I used 20mm thick pine plank that I already had, but plywood or MDF will do equally well.

The dimensions of the stand are included on the plans and in the instructions and this makes for a good fit on the hull. The ends were cut to size using a jig saw. Rather than screwing the stand together, it was held together using 6mm dowels glued into place with PVA. Two holes were drilled at each end where the side pieces would go, then I slightly countersunk the side pieces into the ends to locate them and drilled into these using the existing holes as a guide. A blob of PVA applied to the dowels provides lubrication for the interference fit whilst they are hammered home, Photo 4 Once the glue had set, the stand was perfectly rigid.

Using proper wood rather than MDF or plywood does have a disadvantage in that the upright parts that cradle your precious hull can be accidentally whacked off, or in my case snapped off when I once carelessly dropped the stand. This gave me the idea of drilling a 6mm hole down through the narrow part of each of the end uprights and reinforcing with dowel glued with PVA. It seems to work as none have since broken off.

Hull construction

No matter how good a kit, the GRP moulding will never be 100% consistent and so some slight adjustment work will always be required. For example, where the inside of the hull is exposed as a bulwark then it needs to be smoothed. The best time to do this is before any other work is done on the hull. I just get in there with a power sander to blast off all the irregularities. Usually there are some pits and holes that need some car body filler blended into them. The inner face can then be finished off with grade 400 wet and dry paper. A bit of effort at this stage means that you don’t need to make the bulwarks good while the styrene deck is in place which will impede access for the sanding block or power sander and there is always the possibility, indeed certainty, of damaging the fitted deck. If dry sanding, then do wear a mask please.

I also had to trim back some of fibreglass matting where the deck supports were to go, to ensure that the 2 x 3mm support strips around the hull were properly seated. None of this is unusual with a GRP hull.

The hull deck supports are 6 x 3mm strip. On the foredeck section their positions are self evident and they just need to be placed the deck thickness below the top edge of the hull and this can be tested with a piece of scrap plastic from the deck sheet. With the after deck they need to be positioned to align with the outer moulding of the hull. To draw an accurate positioning line round the inside of the hull it is best to create a simple template to mark the deck support position.

The deck support strips were then added, a layer at a time with each layer being well glued to each other and the hull. This gives added strength to the hull should your model suffer a sudden impact.

Mine was an early production kit, with a tiny error on Page 13 of the instruction manual, but this has now been corrected. At the stern it showed the bulwark supports going all around the stern which cannot be so if the tiller flat hatch is to fit into the stern as shown on Sheet One of the plans. The solution was simple and was not to fit the four bulwark supports in the stern. Before continuing with fitting the decks, it is handy to install the propshaft, rudder, its servo mounting and the motor.

Propshaft

As always, a bit of attention as to how the shaft fits into the hull will be repaid once the boat is finally on the water. An 8mm hole needs to be drilled in the boss on the hull moulding before the rudder is fitted, and then filed slightly oversize for the propshaft. Make sure that the propshaft runs down the centre line of the boat and parallel to the keel. It is as well to roughen the outside of the shaft where it goes through the GRP hull as this will give a good key for the glue.

Before fitting the propshaft tube, it is also a good idea to drill a 5mm hole in the top of the propshaft tube 80mm from the inner end. Solder a length of brass tube into this hole taking care to file a radius in the base of the tube so that it clears the moving shaft. To protect the joint from knocks I fitted some half round plastic tube as a saddle epoxied to the propshaft tube with the brass tube sticking up out of its centre, Photo 5. To make putting lubricant into the propshaft less messy, a length of aquarium pipe slipped over the oiler tube gives a flexible greasing connector that can be capped off with a plug.

Motor and propshaft alignment

Over the years I have developed an idiot proof method of ensuring these line up perfectly. An interference length of brass tube is simply slid over the flexible joint to make it rigid, Photo 6. Set up like this, the propshaft tube can be slow epoxied into the hull along with the motor mount. To make sure all is watertight, pour resin around where the propshaft tube comes into the hull. It is best to put closely fitted masking tape around the outside of the hole to stop the resin flowing outside the hull.

Propeller

The kit comes with a splendid brass propeller which does not need to be finally fitted until after painting the hull, but I found that its shaft lock nut took up too much of the thread and so removed it. The propeller boss was thus not locked in place, but some thread lock between it and the shaft thread locks it all into place, particularly as the propeller is crewed up tight against the end of that thread.

Rudder assembly

The rudder came as a combination of white metal and styrene. The printed styrene parts make up the blade of the rudder. I cut one part exactly and glued it to the other which was just roughly trimmed. Once the glue had thoroughly dried, I sanded the roughly trimmed half of the rudder to match the precisely trimmed half and that way got an exact fit, Photo 7.

As all mariners should know, rudder movement is vital and so it is wise at this point to dry fit the rudder and its hinges on to the pintles and check that everything turns as it should. Then, and only then, dot the hinges with superglue to permanently fit the rudder in place as it will not then come off without major surgery.

At the top of the rudder is a combined white metal and brass fitting that joins the rudder and its shaft together. The shaft should be upright and totally in line with the line of the rudder hinge. I was having a bad day and it took me ages to get this right, the hole for the rudder post ending up much bigger than I would have liked resulting in some judicious use of resin and filler.

Epoxy was used to glue the rudder tube in place and the rudder and its shaft were moved to double check that they could indeed move!. Only when the rudder tube was firmly glued into the hull was the base of the shaft superglued to the top of the rudder. Photo 8 shows how it all should look when finished. On the real ship there would have been a leather gaiter over the hole through which the rudder shaft moved.

Bilge keels

It is always worth taking time over these as they are easily damaged by handling and the odd underwater obstacle. They can be added either before or after the decks are in place. The bases of the keels are styrene and these need to be superglued into place and masking tape will make sure they stay put whilst the glue sets. To make the joint between the bases and the hull nice and smooth, the application of Humbrol Model filler around the edges and then lightly sanded when hardened makes for a perfectly blended finish.

The curved bilge keels need to be glued to their bases and this can be difficult as they need to be correctly aligned and not move whilst the glue sets. It is best to draw a centre line down each base and mark five evenly spaced points. At these marks drill 0.8mm holes and into them insert and superglue lengths of brass wire. Yes, the hull now looks like a hedgehog!

It is now possible to put the hull on its side and lay one of the bilge keels on to the line of wires and check that it fitted precisely to the hull, adjusting as appropriate. The keel can now be glued to the base using liquid poly or polystyrene cement and the wires superglued to its underside. When all is set hard, the excess brass wire can be trimmed and filed flush so that it is out of sight, but still be there to support the bilge keels, Photo 9.

Tidying up the interior

This is also the right time to mention that before the decks went on, I painted the inside of the hull dark grey. You can see what this looks like in Photo 10. Why? Well, the paint seals the inner surface of the GRP hull plus it makes the inside look nice and anything dropped into the hull shows up better and is therefore easier to retrieve. The deck edge supports can be clearly seen together with the geared MFA Torpedo 600 motor that is eminently suitable for this model tug.

Rear deck

There was much dry fitting of both deck pieces until I was satisfied that the fit was right and here the small block plane came into its own for whittling it to fit the hull perfectly. Only then did I use a tube of styrene cement to place adhesive on the top of the deck support strips and slide the stern section into place. To ensure proper contact between the deck, support strips and glue, use clamps resting on pieces of scrap wood to hold the deck in place, Photo 11. It is worth noting that the rear deck will not drop into place as it needs to be slid in from the front of the hull to rest on the deck supports, so don’t go fitting the front deck section first.

Cheating….

There is an area of hull fibreglass on show between the break in the deck line and where Part 19 is fitted. To get an instant perfect finish in this area, measure 50mm back from the break and glue a piece of sheet styrene in place, Photo 12. This was done before the foredeck was added, but the picture also shows the foredeck edge supports and pencil marks to aid positioning.

Foredeck

The side rails, Photo 13, are clamped in place on the underside of the foredeck. At the front is a curved piece that in its natural state wants to stay straight. To overcome this it is best to use masking tape to attach the piece to a wooden block so as to ‘bow’ the piece more than it needs. Left for a week the piece will stay bent without the tape and is a lot more amenable to be fitted around the curve of the hatch, Photo 14.

Also, be careful here as Part 30 is curved to give an upward sweep to it and you are building the deck and coaming upside down, so make sure it curves up in the right direction. Needless to say I got confused and had to do what they call ‘corrective dismantling’ before the plastic ‘welding’ had fully set!

The foredeck needs to be trimmed so that there is 170mm between the bow and Part 27 at the front of the main hatch opening. At the rear of the deck there should be a 3mm overhang above the tow hook assembly. Somehow I wound up with 0.5mm, so I must have trimmed too much off the deck when fitting it into the vee of the bows. It still looks okay but be careful and learn from my mistake.

While we are up in the bow it is worth mentioning the bow plate, which is worth cross drilling for the fitting of the turnbuckle before it is mounted in the bow. The white metal fitting that is the bow plate has mounting pins which are potentially vulnerable, and yes you have guessed it, I managed to snap one off. If it happens to you, then just drill out the stump and substitute 1.5mm brass rod. You might wish to head off the disaster at the outset and drill out both white metal pins and replace them with brass just to be on the safe side.

Once this is sorted, the bow of the hull can be marked off along the centre line and holes drilled to take the pins of the bow plate.

Meanwhile back on the deck, it is eventually painted both black and green which could look a mess without forward planning. To lessen the mess and get a sharp line between the two colours I drew the lines on the deck that represent the border between the two colours. Once the lines looked right, 0.75mm square section styrene rod was glued along the lines. This made it easier to hand paint the deck at a later stage and get a sharp demarcation line between the two colours, Photo 15.

Portholes

The instructions state that the white metal portholes should be 1mm proud of the hull. This can be achieved by making a hole in a 1mm thick piece of styrene sheet and placing this over the hole for the porthole and then pushing the white metal part into place until it is level with the surface of the styrene, then the glue can be applied. This simple template will give a consistent exposure to the portholes. However, whilst testing this method I was not happy with the way that it looked, even though it is quite tidy. Therefore I resorted to some research to try and get my head around the porthole question. I looked at some pictures and film of the real tug and it seemed to me that the portholes were actually recessed into the hull. Therefore I sanded the hull portholes flush with the side of the hull. Of course what you do with your kit is entirely your choice, but I will now have to go and see Mr. and Mrs. White of Model Slipway and explain my actions and no doubt get my knuckles rapped!

On any project like this there is always somewhere when through stupidity or over enthusiasm you can find yourself pushed into an engineering corner. This time around it was the hull portholes. How was I going to glaze them? Well certainly after I had painted and varnished the hull, but then what? So, slightly out of sequence, here is the solution that required exterior grade white PVA glue and masking tape. How does this work?

Put masking tape on the inside of all the portholes to seal them, then put the hull on its side and use a small spirit level to make sure that the portholes are level. Now for the cunning bit! Use a cocktail stick to drip PVA glue into the porthole until it is full to the brim and leave until the glue has set clear and this may take from 24 to 36 hours depending on the depth of the porthole, the volume of PVA and the temperature. Turn over the hull and repeat on the other side, Photo 16. This comes under the heading of a ‘lucky escape’, as the job looks okay when finished. A word of warning though. Do not use interior grade PVA as it is not water resistant and your portholes may drop out! The glazing should also be done before final overall clear varnishing as that will provide extra protection for the PVA.

Mooring eyes

Whilst we are on the subject of holes in the hull, here are some more. The mooring eyes in the bow have a nice white metal fitting to complete them on the outside of the hull, but just a hole on the inside. Real tugs have a strengthening ring on the inside of the bulwark to stop the bulwark from being damaged. This was represented by gluing 5mm brass washers onto the inside of the bulwark which look just great when painted.

Bulwark supports

These are cut from printed sheet. When cutting them from the carrier sheet, a ridge forms where the blade has cut. This looks untidy on a completed model and so there is the fiddly job of sanding off all the ridges before gluing the parts in place. Go on, make the effort as you know it’s worth it, and at the end you will have no fingerprints either which could be useful for some of us I suppose!

All these supports will be oversize to a greater or lesser extent and will need to be trimmed. They were glued in place using poly cement for the deck joint and superglue for the bulwark joint. When the glues are set, these supports can be cropped off to the top of the hull and then sanded level with the top edge now ready to receive the bulwark capping.

Bulwark capping

Okay, you have guessed it! I deviated from the kit parts and for the straight runs, Evergreen (a brand of styrene) strip was used. This was personal choice, the material for all the capping rails is included in the kit, however at the bow and stern, the kit parts were indeed used. It is best to cut the parts with at least 2 to 3mm extra away from the line as no hull is exactly the same and the capping will need to be adjusted to fit.

These oversize parts were simply superglued in place and then sanded to shape on their outer edges and any blemishes made good with Humbrol plastic filler. The inner edge can be marked off with dividers to give an even width and then sanded to shape accordingly.

I had an attack of the ‘clumsies’ with the stern capping and in desperation cut it in half and fitted it in two pieces rather than one, but once the centre joint is filled and sanded you cannot tell the difference.

I could not get the bow cap, Part 38, to fit properly and so used it as a rough template to make another from scrap material. I think this was a case of me being a bit pedantic as it would have been okay as supplied with some slight adjustment.

Main deck access hatch

The joint between the main deck and the main deck access hatch was rather visible as the deck levels were not quite in line, sorry, my fault! Therefore, by gluing 0.75mm square strip along the edge of the deck next to the main opening and running it on to the end of the main deck solved two problems. It masked any discrepancy in deck and hatch levels and also provided a physical break between the grey and green deck colours thus ensuring a sharp line between the two.

Hull fittings

The roller fits under the break of the deck on the left side and is best fitted before the main deck goes on but I had already fitted it, which goes to show what a great kit reviewer I am! This was circumvented by putting a brass locating pin in the base of the roller and drilling a hole in the bulkhead so that it could be wiggled into place with a pair of tweezers.

Twelve pounder gun

This kit within a kit is a little beauty and just like the real thing, I happen to have an example of the real thing at work, Photo 17 (Duxford Imperial War Museum). The model gun is a kit in its own right and a nice thing to build while other stuff is drying and setting. However, it is a heavy piece to have on deck and it will inevitably get knocked and we all know how aggravating that can be, especially at the pond side when the item somehow somersaults into the water and sinks without trace! So to avoid potential disaster, drill a 3mm hole up the centre of the base (Part 3) and through the centre of the mount base (Part 13). Cut a piece of 3mm brass rod so that the gun can still be inserted into the gun shield (there is a height restriction) and the rod also goes through the base and then into the deck, thus making it secure.

There are two wheels that are used to train the gun. If you look carefully on the rim you will see a dimple, that needs to be facing outwards. Superglue a 3 x 1.5mm brass rod into each dimple and these will represent the crank that is used for fast training of the gun. Most people will not even see this detail, but it is nice if you know it is there.

For modellers who want to superdetail the gun there is one outside my office at the Imperial War Museum, Duxford. The Duxford example has no side armour, but here are some pictures, Photos 18 and 19, and Photo 20 is of the model example.

Anchor winch

This is another nice casting and something else to build up while waiting on other parts to dry. The winch is different to the one shown in the box art but do not panic as you do have the correct winch. The box art was of a prototype model and had another winch fitted just to get the boat completed. Parts 11 and 12 are not part of the winch body but are the anchor chain stoppers. They did have me puzzled for a short time, but it is all is obvious once you sit and think it through.

To get an even spacing between Parts 6 and 7 on the main shaft, 4mm spacers were inserted made from brass tube, an undetectable way of getting all the cogs to line up. I think it is perhaps true to say that if you spend enough time making model boats you will go quietly mad and I think I may not be alone. Madness exhibits itself in many ways, not least putting in detail that no one else is able to see. Fitted to the base plate of the steam winch are the valve chest and cylinders. There should be rods between these, impossible to cast in so they were left off the master, but if you drill the faces of these parts and carefully insert 2 x 4mm brass rods between them as they are glued to the base plate you have successfully super detailed the winch even if you can’t see it.

Capstan

This is a really nice fitting, but it really needs three hands to assemble it. Starting off, it was like one of those infuriating puzzles that you get from an Xmas cracker. It would just not go together, or rather it would, but not all at the same time! So, to preserve my sanity and keep the capstan’s circular cross section I built it round a length of brass tube, which acts as a former, holding the pieces in place with an elastic band, Photo 21.There were some minor gaps that were filled with Milliput and sanded to a smooth finish. The brass tube is over long so that it can be inserted into the deck through the capstan base.

Funnel

Some early decisions need to be made here and yes, I blundered on without making them and that made for more extra work. You need to decide if your funnel is to be a ‘smoker’ or remain dormant. If it is to smoke, then you will need to make a hole in the deck. If it is to be a dormant, then leave alone and just drill a hole in the centre of where the funnel is to be located. Being indecisive, I cut the big hole in the deck and then went for a non-smoker funnel!

The top bands of the funnel Parts 146, in early kits were printed as parts for the wheelhouse capping rail, but current kits have a corrective addendum to keep you on track. However, there is plenty of scrap to create the necessary strip, unless you are idle like me, so once again, Evergreen strip styrene 0.75mm x 3.2mm was utilised which is just the job for this and saves cutting.

Cut a piece of strip over length and then drill a 1mm hole in the centre of it and the funnel at the desired position on the moulding. The strip can then be accurately located on the funnel with a 1mm brass pin. Now wrap the strip around the funnel to double check that it is definitely in the right place and then clamp half of it in place so that droplets of thin superglue can be run along the strip to permanently secure it, Photo 22. When this half of the strip is dry the other half can be bent around the funnel and a scalpel used to trim it to length before being clamped and glued. The joint in the strip should of course now be perfect after all this effort. Mine wasn’t, but with a little Humbrol filler and some sanding the joint became invisible.

Towing stage

The towing stage assembly at the break in the deck will be difficult to paint precisely to get a crisp line between deck and superstructure colour. So how can this be made possible?

The answer yet again is to use lengths of 0.75mm x 0.75mm Evergreen strip styrene along the joint between the deck and the superstructure. This strip has two functions. First, it will conceal any bad joints and create a sharp border between the deck and superstructure; second, painting will also be simpler as the brush with a little care will run along the edge of the 0.75mm strip and not flip up and put the wrong colour paint on the other surface. Trust me, it really works.

Oil filler pipe

This runs around the tow hook platform. Do the side pieces first and dry assembly the whole thing before final gluing. The height of the pipe is decided by the two etched parts which rest on the deck. Drill the base of both of these to take 1mm locating pins.

Stanchions

These are beautifully etched and after some experimentation I found that they liked to be fitted into 0.7mm holes in the deck. Once the decks are in place, gaps filled etc., you can assemble the railings into the stanchions when you wish, perhaps as a deviation from gluing styrene.

It pays to cut the stanchions out of the sheet only as you need them as surplus ones tend to grow legs and disappear. The best way to work with these fine parts is to cut them out of the etched brass sheet using sharp miniature side cutters over a small black plant gravel tray. The black tray catches the parts that fly off in a bid for freedom(!) and being black the small brass pieces show up nicely in it as well.

The edges of the stanchions have a slight step in them created during the etching process and this can be removed with gentle filing.

Dry assembly the railings into the stanchions (not yet glued to the deck) checking that they are all upright and only then superglue the railings in place using a cocktail stick to apply the glue. Any surplus glue can be speedily removed with a piece of kitchen towel. The assembled railing sections can be painted off the model and glued in place later, remembering of course to have all the stanchion bases in place.

The forecastle stanchions and railings will need to lean forward a little to be at 90 degrees to the keel, or at least in alignment with the navigation light box support rod. At the back end of this railing run there is a 90 degree turn inboard followed immediately by another stanchion. This fits next to the superstructure, so make sure that the end of the rail does not foul the front of it.

That’s it for this issue and next month will see the superstructure built, the model completed, painted and rigged, plus sea trials!

The kit is available from: Model Slipway, Unit 8, Grange Lane Industrial Estate, Barnsley, S71 5AS. Website: http://www.modelslipway.com/, tel: +44 (0)1226 770008, price £309.


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