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[Bob K]

H.M.S. Polyphemus (1881),  not quite a submarine

I am hoping that someone on Mayhem can help with information to help build this model, using the 1/60 scale hull from Deans Marine.  Unfortunately the only plans available are with the N.M.M. and I am advised these could cost around £400.  What I am looking for is someone who has built this ship, may have plans & detail photos for it, or may be willing for me to take detail photo's of their model.

I realise this is a long shot.



HMS Polyphemus was possibly the weirdest ship ever to be commissioned by the Royal Navy.  A Protected Torpedo Ram capable of a then-stunning 18 knots, and partially submersible in attack trim for maximum stealth where the waist was almost awash.  Twin additional rudders under the bow.  The first use of underwater beam torpedo tubes, plus a 5th tube inside the huge ram.  Building one has certain challenges.  To properly simulate attack mode construction has to be treated as a surface running submarine. 

[Liverbudgie2]

John Hollis built the original model of HMS Polyphemus, he in turn sold to Ron Dean and it is from this model, I presume, that the mould for your hull has been taken. As far as I'm aware no other model of this vessel has been built and the only available plans can only be obtained from the NMM.

You could approach Ron Dean to view John's model I expect if you want to photograph the detail.

LB

[Bob K]

Thank you LB.  I had spoken with Ron this morning, who no longer has the orginal John Hollis model.  He suggested I asked on the Forum as there should be several either built or under construction out there.  He also suggested a back issue of Model Boats magazine approx 1970's, and Maritime Books.
Online pics are few and poor quality.  I would be prepared to travel to take some photos.

[Bob K]

Searching on Mayhem this question has come up twice before, in 2006 and 2010, without success.  I have emailed Royal Greenwich Museums print agency requesting if they have plans available to purchase.  A0 paper prints are £29.99 ea, and I don't need the whole set, just details of the decks and superstructure.  Maybe 3 sheets will be enough.  I wish I could find better pics on Google, or even of the original model.

Just to show how unusual this ship was, here is a photo of her in dry dock.

[rob]

PM sent Bob.

[Bob K]

Many thanks Rob.  Appreciated.  I have sent PM in reply.

[unbuiltnautilus]

One of our members built one of these in the early nineties, I will find out if he still has plans for it. I purchased the hull originally from Ron Dean, at The Sandown Park show in about 1989, got as far as putting two staggered motors and shafts in it, then sold it. The model is still in the ownership of one of our members, in a box, in the loft. However, I may be able to get some photos of it, if needed.

[Harquebus]

Are you going to name it HMS Thunder Child?

You'd even have a theme song for it.

[JohnH]

Hi Bob
Ron Dean's mould is the one I made many years ago. I also gave him my copies of the NMM plans so unfortunately I no longer have them. As you already have the hull, you would only need the plan of the upper deck, main deck and arrangement plan which should not cost anything like the £400 mentioned, I would give the NMM a call and go & see them, I have found them very helpful for all of the plans I have needed from them in the past.
NMM also have a number of pictures of the vessel, the two best ones being a starbord bow and stern shot whilst alongside a dock - they give a good idea of the deck fittings.
I sold my model a long time ago but I may still have a few pictures of it under construction if they would be of interest. I also wrote an article which appeared in Model Shipwright No 70 in December 1989 which described the build and had a few pictures of the model.
Please drop me a line if any of this is of interest to you
John Hollis

[Bob K]

    unbuiltnautilus   
Thank you, but someone unconnected with this Mayhem Thread has kindly PM’d me offering to let me see his NMM plans and photos. 

    Harquebus   
No, I am not going to name it that, although H.G. Wells credited this unique RN Torpedo Ram with the only known destruction of a Martian Tripod Machine in “War of the Worlds”.

     JohnH 
I am hoping to get the Deans hull this weekend, and hugely appreciate your input here.  Thank you also for telling me the issue number of the Model Shipwright magazine which will greatly help in my finding a copy of it.  I had already emailed the NMM’s Greenwich print agency for information.  Any pictures you still have of your model would be hugely appreciated.  Either PM to me, or post them here.  I know very many people would love to see your multiple award winning model.

For any not familiar with John Hollis’ incredible work see this awesome Russian ship “Lavadia” I found whilst searching on Google.


With sufficient info I hope I can do Polyphemus justice !

[Bob K]

Firstly, some sincere Thank You’s.

• To the gentleman who has been in touch by PM, very kindly loaning me his research file, and hopefully plans too.
• To John Hollis who built the original model, who has emailed me very helpful information.
• To Ron Dean who at short notice made up a hull in time to bring down to Beale Park on Sunday.

Starting with an accurate detailed hull makes a big difference, and with the wealth of information supplied this project has been made possible.  I understand that this ship will require about 20 lb of ballast, and that the bow rudders were not very effective.  Due to the waist being almost awash when underway construction technique will be as if a surface running submarine.

The Hull.  In a rare burst of bright sunshine the super hull detailing is hard to see here:
  Note:  Massive submarine-like side bulges.


Intended Methodology:
Even at 1.27m long, freeboard in attack trim is only one inch. !!!   So . . .  Watertight compartments.
Build in two longitudinal ballast ‘bulge’ bulkheads, intended to trim waterline for either ‘safe’ sailing or in full stealth low freeboard attack mode.  Next build a series of transverse watertight compartments each with gasgetted screw down hatches.



Sectional diagram of side bulges


Working out displacement: 

• Place hull level on suitable stand.  Fill with water to the normal waterline.  Drain and weigh water.
• Refill to attack mode trim.  Drain and weigh water.  The difference between the two figures determines the water ballast required to trim down.
• Mount hull on side.  Fill one ballast bulge with half this volume of water, and mark internal waterline.  This determines the shape and profile of one ballast tank side bulkhead.  Use same profile for other bulkhead.

[TailUK]

With a row of oars sticking out of each side, she'd look like a Greek Galley!

[Bob K]

You are not far off there     In fact I've seen a neat video of a radio controlled galley 

[Bob K]

Measuring Displacements:

Strange that filling a boat with water requires it not to be raining.  In this case I needed a dry day to take reasonably accurate ballast volume measurements, using water.  I had marked two internal waterlines, one for a 'safe sailing' trim that could be used in conditions other than no wind millpond, then another for the more realistic low freeboard attack mode.

Mounting the hull on a stand, checking with a spirit level, gradually adding water to the lower waterline.  7.0 Litres.
Carry on filling to the upper waterline took an extra 2.7 Litres, therefore each side ballast tank needs to be 1.35 Litres, almost exactly 1.35 Kg although not measured at the S.I. defined 4 degrees C.

Mounting hull level on side, 1.35 Litres was added to one side bulge with position of centre of mass estimated from hull profile.  Resulting waterline marked with a waterproof marker.

Using water means the side bulkheads can be made from flat sheet, with a max ballast capacity of 1.35 Kg each.

9.7 Kg total displacement (21.4 lb) including weight of internals and upper-works.  Ties up closely to the 20 lb used for the original model.

[Bob K]

Due to home and work pressures dockyard activities have been a bit limited recently, but progress is being made.  I now have a set of scaled working plans, plus loads of detail photos.  Many many thanks to people who have helped.  This community has been truly amazing.  I would also like to nominate Ron Dean for a customer service gold medal. 

Whilst collating this wonderful wealth of data I am working out the internals.

Materials:
Watertight compartments worked out and materials obtained.  I will be using 3mm clear Polystyrene sheet for the WTC side chambers, and 5mm Marlon cellular Polycarbonate for the bulkheads and under-deck.  The later has corrugated internals, is strong light and should give ample epoxy resin inclusions on cut edges for bonding.  Each of the six WTC covers will be screw down and gasgetted. 

Ballast system:  Air or water pump?
I am weighing up whether to use an air pump with cam operated valve or a large capacity peristaltic water pump.  Most peristaltics only shift around 200ml/min, and these ballast tanks total 2.7 litres.  Using air I only have to watch for bubbles from under hull vents to know they’re full, but with a water pump it will need to vent excess water over the side or fit a pressure cut off switch.

Keeping transport weight down:
10 kg of deep draught boat will take a bit of lifting in and out of the water.  I am contemplating making two of the six internal chambers free flooding to save static mass, (labelled ‘B’ & ‘E’ in earlier diagram)  Either that or chuck in several extra SLA batteries.

Motors & props
I need to research suitable motors for twin very large three bladed props:  I have been recommended geared motors such as the Marx Monoperm or belt drive MFA Torpedo.   Even finding scale props that look like the originals will be challenging.

I have my eye on some watertight prop shafts from Cornwall Model Boats that can be run through into compartment 'C'.

[dreadnought72]

    Harquebus   
No, I am not going to name it that, although H.G. Wells credited this unique RN Torpedo Ram with the only known destruction of a Martian Tripod Machine in “War of the Worlds”.

Not quite! 

Early in the novel a gun crew manage to hit a tripod which crashes, uncontrolled, into Shepperton Church.

</pointless trivia>

Right - on with the build. She's a lovely (if not somewhat insane) vessel. 

Andy

[Bob K]

Right - on with the build. She's a lovely (if not somewhat insane) vessel.  

Andy

<pointless trivia>
Sanity is not my best point of sailing
</pointless trivia>

Thanks for the H.G. Wells update.  I must read it again  

[Bob K]

R&D

After a lot of searching around and comparing options I am leaning towards using an air system for the ballast tanks, rather than pumped water.  Peristaltic water pumps tend to max out around 200-300 ml/min unless you get a really massive one.  The largest snort pumps shift up to 0.7 l/min, and 12V aquarium air pumps a lot more.  Only 85 mm head maximum, this is not a submarine.  Air inlet via hollow main mast.

Rather than a Schrader tyre valve and cam, I have been trying out a pond type air manifold ball valve.  I’ve tried it down to half a metre and it’s water and air tight.  The Blagdon valve arm takes minimal effort to turn, so should work well with an extended arm like a rudder servo.  Some lateral thinking!



Open valve to release air and trim down to minimum freeboard mode.  Close valve and pump air to blow ballast, returning to high freeboard mode.

[Bob K]

Propellers and shafts were a bit unconventional.  Thin bladed and 60 mm dia at this scale, they projected so far outside the hull that fending booms were fitted for docking, not to be confused with dry dock shoring shown below. Sourcing props like this will not be easy. I will need big slow RPM geared-down motors.  Suggestions for both most welcome !


A view in Malta showing how deliberately low the freeboard was.  A Victorian stealth ship.


The principal function of the ram was to break through harbour defence booms. She proved her worth in the Berhaven raid, an exercise in 1885 meant to simulate a sneak atack on the Russian fleet base at Kronstadt

Once inside the boom she could fire her underwater torpedo tubes at point blank range.

[tonyH]

Hi Bob,
Try George Sitek for the running gear. He made the ones for Arquebuse from the builders plans and for Ambrakia from a photo of the builders model and a sketch from me. I've also ordered ones for the current project (Descartes - French Cruiser 1894)

Lovely project by the way.

Tony

[Bob K]

Thank you Tony.  Found their web site on Google.  Not sure which country they are based in though, but I have contacted them bt email

[Liverbudgie2]

Thank you Tony.  Found their web site on Google.  Not sure which country they are based in though, but I have contacted them bt email

It's England, Crewe in fact. 

LB

[Bob K]

Gradually moving from design to procurement phases.  This model will be as unusual in construction as the original.  I am grateful for the wealth of information that colleagues have assisted me with.

Two 50 mm special Victorian ‘crocus’ propellers plus custom A frames are being produced by George Sitek.  Thanks again Tony for your recommendation.  Huge props for a 1.27 m model that project far out from the hull.  I note that prvious models have opted for smaller non-scale props.

To complete the running gear I have Raboesch 301-13 watertight shafts with bearings, and twin Kondor motors -  high torque low RPM.   Double headed ‘bar’ UJ’s with connections to match shafts and motors.  These from Deans.

On board electronics just arrived from ACTion include a P94 twin ESC’s with mixer, a P19 5V BEC unit, and a P64 multi-cylinder steam sound unit plus 2.5 inch speaker.

I was very impressed with the MMB mister smoke unit at Alfold, so this is now on order plus various batteries.  I need to lay out the internals and static ballasting before construction of internal bulkheads.

This will be a long build, with what you can’t see below the decks a major part.

[Subculture]

Bob, you can get snort pumps- basically low pressure diaphragm pumps that will shift loads of air.

Have a look at this links to see a pump that will evacuate your tank in about 15-20 seconds-

http://www.sparkfun.com/products/10398

[mikearace]

Try George Sitek for the running gear

Well recommended.  To me Sitek is to Running Gear what AcTion is to ESCs and Mixers etc.