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HMS Jason - Alarm class Torpedo Gunboat 1890's

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Ok, so I said I would be out for a few months due to the move and the need to rebuild my workshop, still that doesn't stop me building in my mind and on the computer.


As I cleared the workshop, HMS Jason had to be moved, for the third time now.  I made a decision, this would be the last time I move her.  I'd always said that I would complete her when I retire.  Well, I'm retired now so there are no excuses. 


So, here is the plan.  I've found many pictures I took of the build all those years ago and scanned them so the story so far can be told, it's just 18 years late.  Then while I'm sorting out the new workshop and house actually, I'm going to work on fittings on the computer so that when I get back to being hands on, the process will be faster than before.  Also, this one will probably be for sale at the end.  The house really can't take too many 5 foot models, still that's a decision for next year, on with the story...


As the Victorian navy moved away from steam and sail to pure steam the old hybrid gunboats looked very old very fast, lovely though they were.  The threat of the new fast coastal torpedo boats needed countering, and so these Torpedo Gunboats were developed.   Really they are like mini-light cruisers, not only capable of defending harbours and also colonial duty around the empire.  In general, the idea (like many Victorian naval developments) was not a huge success, mainly due to the locomotive boilers that were used.  However, Speedy, the only one of the class to be built by Thornycroft's, had more modern naval boilers and was faster and far more reliable


The Alarm class was the fourth and last class to be built before the true destroyer type developed, along with turbine propulsion.  These were a step change in vessels for this service and made the TGB's redundant.  However, they soldiered on through the 1st world war, 2 as submarine depo ships and others converted to minesweeping duties.  4.7inch gun mounted minesweepers!!


HMS Jason was laid down in September 1891, launched in May 1892 and lost to a mine in 1917.  She was 230 ft long, displaced 810t and carried 2x 4.7 inch QF Elswick guns on a Mark 1 pivot mounting.  She also carried 4 3prds and 3 torpedo tubes, one in the bow.  As a redundant throwback, she sports a ramming bow, helpful for surfaced submarines...  From a distance, the profile could be mistaken for a light cruiser


Here she is in black, white and buff livery of the Victorian navy.  These are the colours I shall model




And again, dressed for a special occasion




To give you some idea of what I hope this will turn out like, here is a contemporary builders model of a very similar vessel built in Britain for Brazil in the 1890's



I love builder's models.... 


Why did I abandon the project all those years ago?  There were a number of reasons.  I started her too soon after completing HMS Medea (RFI thread coming soon).  That project had taken 4 years and I dived into HMS Jason immediately afterwards, one year on, I was just a tiny bit exhausted with the whole thing and so stopped modelling and built a car instead...  Also, a number of areas were not working out well enough, the bilge keels were rubbish, the deck houses were not crisp enough, my plans for internal lights were too ambitious etc etc.  It all built up in my mind and so I shelved it.


Now I ready to get back, sort out the problems, and get this beast finished.  This is a big serous model, I actually can't wait to get back to it.


Looking forward to sharing the journey



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So, now we travel back in time, to 2003 when I started the build.


In those days, the Brass Foundry (the Maritime Museum archive) sold full size photocopies of their plans.  Jason has a number of sheets available, conveniently at 1/4" to 1ft, 1/48th scale.  There are sections, a GA, below deck, main deck and boat deck plans, the lines of course, a rigging plan and one plating cross section showing where the plates are in and out.  The key drawing missing is the shell expansion, which was a blow, but I will explain how I worked out a reasonable approach to the plate layout later.


The hull is plank on frame, 3mm ply frames and 3mm thick Obeche planks which gives plenty of meat for sanding.  A mixture of 12 mm and 6mm wide plank were used, the narrow planks on the round of the bilge.  The rounded stern is carved from a block and the stem plate is brass as this bow comes to a knife edge for ramming.  Also, embedding a brass stem prevents over sanding.  The keel is "T" shaped with the cross on the "T" being inserted between each frame as they are added.


Here is the beginning of the frame installation, the string line helps make sure the frames all line up at the top




In the stem plate is the angled bow torpedo tube, the plate is epoxied into two wood cheeks, note the admiralty drawing in the back-ground




This process then continues until it looks like this.  The frame encompasses the opening for the forward shelter deck and raised forecastle.  The sheer-line frame plank runs through to the bow to strengthen the join.  Note also the diagonal framing on the main deck that prevents twisting while planking the hull




This is a twin screw vessel, so the prop-shafts were let into the frames and the transition tube turned and mounted before planking.  Note the tube for the forward rudder




The A frames were then made up in brass, here being silver soldered




And here epoxied in place.  Note here I've added the main rudder hinge assembly and the first propeller scratch made in brass.  I never got around to making the second prop, so these may be replaced with a cast bronze props, still thinking that through.  Victorian props had blades that were mu9nted on disks that were bolted to a central boss, I can get that detail into a casting, very hard to do otherwise.




Planking next





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25 minutes ago, Jamie @ Sovereign Hobbies said:

Looks like a copper sheathed hull on the builders model?

I don't think so, these are flush rivetted steel hulled vessels, not timber.  I think that's just the red oxide paint, gone light wiht age





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12 hours ago, beefy66 said:

Look a bit like a miniature version of the Chih Yuen

Zhiyuen is a protected light cruiser, ~50 ft longer but displacing almost 3 times Jason @ 2,300 tones.  Protected cruises had an armoured deck to provide some degree of protection against plunging fire.  I believe armoured cruisers had a side armoured belt to resist more horizontal direct fire.  The debate seems to have raged through the 1880's driven by expectations (or dogma) of engagement distance and fire control/accuracy.


Checking Conway, Britain did not have anything quite like Zhiyen, mounting 8 inch guns on such a relatively small vessel.  The closest I can see is the Marathon class of 2nd class cruisers (1887/8) which mounted 6 inch BL's, though more of them.  (see HMS Magicienne below)




Zhiyen looks a bit like a coastal protection vessel to me, heavy guns but probably not designed for ocean cruises the way RN vessels were...  It's interesting to me that RN warships all had to have foreign service in mind as a key design consideration because of the needs of the empire.  German dreadnoughts for instance were really only designed for short raids and so had many more water-tight doors, crews slept ashore.  Its interesting the way these design considerations impact thinking, but I've wandered way off topic.... 


However, you are right, the TGB's were designed to look a bit like contemporary light cruisers from a distance but were unarmoured so pretty venerable to cruiser fire.  A 6 or 8 inch shell would probably go right through...


But there are lots of similarities in appearance and colour scheme, good spot..







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As I've said, the hull is planked in 3mm thick Obeche working from the bow backwards, first down to the sheerline plank and then onwards




In this shot below, it is easier to see the cut-outs for the starboard 3 pdr which sits behind side hinged hatches and the shelter deck arrangement.  The deck sides have also been added to stiffen the hull before planking the bottom.  Planking is done both sides at once to help prevent twisting, something that is easy to introduce but hard to see until its too late.  Planks just stuck with to the frames and each other with PVA wood glue and pinned to the frames, a pin pusher is the key tool for this job, makes it all pretty fast




Working back to the stern, good shot of the planking progressing.  You can see the use of the narrow (6mm wide) planks on the curve of the bilge that run out before the bow.  Otherwise this is a simple hull to plank. 


You can see some wires in the shot below.  I had a plan to illuminate some of the interior space, in particular the wardroom which would have been panelled in mahogany.  Ah, the energy of youth, daft idea really :doh:, there was no way anyone could have seen the interior and working our a power source with the case etc, what a nightmare....  That bit is now firmly cut from the project




This just progresses until complete, the stern cheek pieces are carved from Jelutong blocks and then the whole hull was sanded and covered with a two part epoxy varnish to add strength and provide a sound foundation layer for the aluminium plating.  Unfortunately I don't have a picture of the completed planking stage, the next post will cover working out of the plating layout without the benefit of a shell expansion drawing.


If anyone is wondering where this is, we used to live in a barn that had a 12 ft square granary on the land, that was my second workshop, hence the oak beams in the background 





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A short discussion on plating of steel hulls.  Firstly, most hulls of this period through to the advent of welding in WW2 were surface (ie raised head) riveted.  In particular, once ships used turbine propulsion, the extra power meant that the parasite drag associated with the exposed rivet heads did not adversely impact performance to the extent to warrant the extra expense of flush riveting.  Hence if you look at close-up pictures of WW1 destroyers, you will see rivets everywhere, but if you look at 19th century torpedo boats, where speed was everything, you will see they are smooth.  Merchant ships were mostly lap riveted with goggled edges, but warships were always butt riveted fore and aft and laid in inner and outer runs vertically (for interest, the outer plate lines require packing pieces to be able to be riveted to the frames). 


Interestingly, the Denny SGB's (as I showed in my build thread) were lap riveted, I think this is because they were constructed at shipyards more used to merchant ships as the naval yards were all full building destroyers.  As ever with rules, there are exceptions.  The Flower class corvettes are another class that have lapped plates as they are really more armed whalers than warships as such. 


By the way, if you are modelling exposed rivets on hulls, remember that all plates were rivetted to each frame they cross and butt joints have at least double rivet lines on each side of the butt, so a minimum of 4 lines per joint.  I've seen commercial model hulls where the rivets have been marked only run round the edge of the plate, a ship built that way would fall apart more or less immediately it was launched....


The butt joints are a weakness so the layout of the plates should be done so that each frame spacing only has up to two butt joints.  Plates were around 4 ft wide on this size of vessel, probably a lot larger on capital ships.  This is to ease handling.  Generally the plates were around 8-10 ft long.  These are only guidelines, each situation has to be considered based on the plate position.  Also, double curvature is avoided as much as possible.  It is fascinating (well to me at least) how mostly flat or single curvature plates can form the complex curves needed for a hull.


What I had to go on to start this process was a cross section amidships which showed the plate runs with widths and the sequence of inner and outer.  If you don't have that, the keel plate is always an inner (logical :doh:it comes first...) and the sheerline plate is an outer.  So, using these rules, you can set up the layout.  Also, not all lines of plating run the full length of the vessel.  In particular the lines that cover the bilge section run out to trapezoidal pieces for and aft.


So, step one is to lay out the inner plate lines onto the hull using tape as shown on the photograph below.  You will see that I'd already marked the location of the frames (actually the lines show every other frame, there are too many frames to show each one), knowing the frame centres is also important.  Butt joints cannot occur on frame lines, no way to build that.  The butt joints all sit between frames so to work out the shape of each plate, you need to know where the frames sit.  Also, the taper to the trapezoidal closing plates doesn't end in a point, it cuts off to a butt joint no less than 2 ft long.  Designing a plating layout is a key shipyard skill I don't have, but using this logic, the model can at least have the sense of the real thing in the absence of a shell expansion drawing




I was lucky this hull only needs a single inset line so getting the inner lines right wasn't too complex.  Here is the run out at the stern, just cut off are the special stern plates




Once the inner lines are marked, the butt joints need to be worked out following the rules and reasonable length constraints.  This takes some time and trial and error to get a layout that makes sense and follows all the rules


Here is the bow with the butt joints marked out in green marker.  Remember, the frame lines here are showing every other frame, so the joints are all set at the quarter point of the space between the lines.  Also shown in this picture is the brass insert at the break in the forecastle, set in flush and edge filled plus a close up of the bow gun cut out and doors




and below is a section amidships, note the way the butt joints march along across the plating lines.  If you see a model with plates looking like bricks in a wall, that is not correct, the joints always stagger. 


That picture in the album behind came from the brass foundry, its not come to light in the move yet, will keep looking because that has details not available on line....  The quality of close up will have shown me where the butt lines were set at the bow, and of course confirmed that she was flush riveted




Proceeding from this layout, the aluminium sheeting is attached with impact adhesive, 0.1 mm thick for the inner plates and 0.2 mm for the outer plate lines.  Here is a shot taken as I worked my way from the bow to the stern.  With no rivets to mark and butt joints, this is really quite a fast process, the sheets are cut with a knife and the finish is flattened with wire wool which also cleans away and stray adhesive.  I use an ordinary wallpaper edging roller to get the sheets firmly in place




And here is the hull completely plated looking very shiny.  It may seem like I fuss over this sort of detail too much, but at this scale, the joints can be seen very clearly and modelling them correctly(ish) adds lightness to the finished model




I hope that long text may help others work this sort of detail out for themselves.  Many commercial models I've seen really let themselves down in this area imho





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28 minutes ago, longshanks said:

I enjoyed that explanation

Thanks Kev, I'm was hoping to demystify this topic.  I've not seen a commercial model hull get this right, and some are plain awful. 


And don't get me started on models that have no openings for condensing water, what do they think happens to the fresh water needed to make steamf??  People spend ages on tiny details on a deck while the hull has no way of sucking in and spitting out the condensing seawater, great big holes are needed or the boat goes nowhere....  :banghead:  In my book, that's up there with sticking out flags....:rofl:.

Edited by Steve D
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  • 3 weeks later...
On 08/04/2021 at 12:11, Alun Gallie said:

following with interest 

It will be slow and somewhat intermittent, but I will continue the thread once our house move needs give me more time





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Fascinating stuff which I shall follow with interest.  Pre-Dreadnought era is not really my thing but this could change that.


BTW, I know it's off topic but I must ask, what car was it that you built?  I'm currently just finishing the strip down on a 1982 TVR Tasmin before I start the full nut & bolt rebuild

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4 hours ago, Chewbacca said:

what car was it that you built? 

Good luck with the strip down, I believe they have rust issues on the chassis


The car I built as a Hawk ACE, MGB running gear with a US spec (i.e. carburetted ) TR6 engine and a removable hardtop.  Here's a few pictures, the car is long gone, sold to provide funds for me to build the plane....










Thanks for the interest





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19 hours ago, Steve D said:

Good luck with the strip down, I believe they have rust issues on the chassis


That's very nice Steve. 


TVRs do suffer from corrosion on the outriggers - the last one I did had no outrigger chassis tube left at all on the nearside just pieces of rust that fell out of the sill panel when I removed it.  This one is better but not a lot and what is left of the outriggers will all need to be cut away and replaced with new.  The rest of the chassis looks pretty solid although I won't know for certain until it's sent away for shotblasting and all of the powder coating is removed.  But none of it is undoable.


The worst issue with this car is electrics - the loom is shot so will need a new one completely.  I'm undecided yet whether to buy a ready made one and fit that or build it myself which means I can custom design it.


But enough of the off-topic stuff - back to the TGB!

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Sorry, I've been preoccupied with stripping out the new house and neglected the forum.  Thanks for the nice comments, I'll post a few more pictures tomorrow.  As a teaser, I drew the 4.7inch QF gun while we were packing and sent it off to Shapeways to print, came back a few days ago, but I've not had time to do anything with it...  My plan was to have it printed in brass, but the cost was over £200....:yikes:


Here is the artwork, it comes in 4 main pieces (3 print models as the carriage and tub are part of the same print job).  I've also drawn the gun shield open, it hinges about the pivot behind the curve, you can see the locking handle in the background


4_7inch 3d 5


This is it assembled.  That shield is thick armour plating, quite weird for an open mount


4_7inch 3d 3


It actually came out very well, all the details you can see printed perfectly

4_7inch 3d 2


4_7inch 3d 1


Really, just a bit of fun to escape packing, I'm getting better with that program, though not in the same class as  @Iceman 29.  The result deserves fitting on something, must get a workshop back....



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