HrMs O-13 by FreekS - 1:50 - RADIO - 1931-1940 - Last Dutch Sub “on eternal patrol”

[FreekS]

I’m just starting this new project. Netherlands started WW2 with 23 submarines, split evenly between Netherlands-based and Dutch East Indies based. Seven of these subs were lost. O-13 first saw action in the Spanish civil war escorting ships, and then escaped from Netherlands to England in May 1040 with many other boats. However, already in June 1940 on her second war patrol in the waters between Norway and Denmark she failed to return. To this day the wreck has not been found, but every few years there are searches with newer equipment. The most likely cause of her loss is being struck by a mine in a (now known) minefield along her route, but also attacks by German aircraft and a collision with a Polish sub are remote possibilities.

 

This model will be radio controlled, and the boat will be in-between my Holland-class O-1 (the first sub in the Dutch navy) and the larger K-XVIII which fought the Japanese in Asian waters. Both those models still sail regularly and well.

O-13 was part of a class of 4, at 60 meters in length and with underwater displacement of 750 tons she was suitable for coastal waters, but also travelled to the Dutch islands in the Caribbean and the waters around Gibraltar. She had 4 torpedo tubes in the bow, one in the stern, and two 40mm guns retracting into buns. No deck gun was installed and some of the 40mm guns were removed as the class had significant stability issues.

 

I have the original build plans (which can be downloaded freely from the Dutch national archives), but photos, especially dock-photos are relatively rare. 
I plan to build a traditional plank on frame wooden hull, impregnated with epoxy and coated with woven glass. Inside will be a watertight compartment made up of several connected tubes to house the technology to fill and empty the dive tank, and to control the two props, rudder and diveplanes. I hope to include running lights in the wet area and also attempt to functionalisme the folding forward dive planes visible in the picture. Due to space constraints I will not aim to make moving periscopes and functioning torpedo’s for this model. In the end the model will be 120cm long, 13cm wide at its widest point, likely weigh 3-5kg, and use tubing of 50 and 75 mm diameter as water tight compartment.

So far, I’ve been doing rough planning of the location of components, closure means, and rough calculations of the required size of the dive tank to achieve a realistic waterline. I’ve also started to convert the build plans to individual frame drawings (taking into account the thickness of the hull planks (2mm) and the need to mount the frames on a build plank). Needless to say - this will not be a quick build!

[Richard44]

Hi,

 

Another one of the Dutch subs, K XII, was wrecked on Fairlight beach, Sydney Harbour, in June 1949 after breaking its tow. It became a RAN vessel in 1943, but never saw service. It was moored alongside a pier at Manly wharf as a tourist attraction, but was being moved to a more sheltered site during a storm when it broke its tow.

 

I well remember seeing it on the rocks - Fairlight was my local beach.

 

Cheers

 

https://www.flickr.com/photos/41311545@N05/5230854984

 

[FreekS]

Started converting the concept drawing into a 1:50 plan. I’ve not made too many plank on frame models, normally I’d mount the frames on a build plank upside down. With this submarine planking has to go all the way around, so a build plank seems not too useful. 
I therefore cut a “keel/deck support plank” (no idea if there is a name for this) and will glue the frames to this plank. 

the keel is 8mm thick and the shown frame 44 also, as that is where the hull will be cut later to have access to the inside, so I need some strength in that area. I’ll likely double that frame at least. . .

this was also sort of a test frame if I can cut the frame from the print, transfer it to both halves of the wood and saw it out accurately. Took quite some time - maybe I’ll try gluing the paper to the wood first.

 

The other frames will be 4mm thick and after all frames are mounted I will connect them first with inserted short wood pieces to end up with a rigid (and hopefully straight) hull. I did that once before and it worked but for a shorter and simpler hull

(so this was the basis of my Holland class sub, with much simpler circular frames)

Edited January 12 by FreekS

[FreekS]

I finished the sawing of the frames, and placed the half-frames loose on the “keel”. It’s clearly a more difficult shape, with the saddletanks in the middle and a suddenly widening keel below them. I also had to take into account the space for the watertight cylinders and for the prop axes as drilling will be harder once the hull is planked. the two thicker frames is where the hull will be cut to access the insides.

[FreekS]

All frames now glued to the keel, and I inserted small sticks between the frames which gives the hull rigidity.

 Before planking, I have to assure myself I can install the rudder/diveplanes assembly in the stern, and the bow planes in the bow. The boat is so narrow at this points (around 2cm), that I have to have a clear idea of the controls on the planes and rudders before closing the hull!!

 

started with the bow planes, which as the photo on the 1st post shows, rotate upwards and then fold back when the sub is on the surface. I made a brass assembly where two cogwheels control the dive angle and the vertical rotation, and then a pushrod can fold the planes against the hull. 

it sort of works, but I have a long list of modifications before I can make a true prototype. And yes, the planes themselves will get shaped!

 

 

[KeithAug]

Interesting model. I'm looking forward to following. 

[FreekS]

I’ve sort of worked out how the front diveplanes and the rear rudder assembly need to work. They will still be a lot of work, but I can get on with planking. To have access to the front and rear planes mechanisms, I’ve decided to split the boat both horizontally and vertically. Vertically with a bayonet which will open the water tight compartment, and horizontally for maintenance. Horizontally the boat will split along the “drainage line” where the bottom hull meets the deck section.

That is the top plank visible in the photo that overlaps the plank below. Those are not glued together so once planking is complete, I will cut the frames along that line.

in the stern, a solid block of wood is mounted that will hold the pushrods for the rudder and diveplanes. 

[Jim Lad]

Just found your log. What a fascinating build - with lots of technical problems to play with!

 

John

[Ian B]

Fascinating, looking forward to this build 😃

[Roger Pellett]

Interesting project! I’m curious.  Where are the ballast tanks?  Submarines that I am familiar with (U S Navy) carried ballast in saddle tanks outside of the pressure hull, or in tanks wrapped around necked down areas of the pressure hull.  This meant that they were Soft Tanks; not designed to withstand sea pressure.  They also have Hard Tanks within the hull.  These were used to adjust weight to maintain required trim.

 

Roger

Edited February 15 by Roger Pellett

[FreekS]

Thanks for your interests - the boat has at least 14 tanks, with the main ballast tanks in the saddles. Well visible on the frame-plan. 

yes lots of technical challenges - these 1931 boat was rather small - and so I will refrain from working torpedotubes! But I’m going to ensure I have spare power and signal wires going out of the water tight compartment so I can later consider moving periscopes and navigation lights.

 

 

[Roger Pellett]

Thanks, I see them.

[FreekS]

Reached a milestone in that the planking of the hull is complete! 
 

I cut my planks myself out of pine, they are 4mm wide and 2 mm thick and were cut from 2m by 5cm by 4mm planks. Just needed to avoid the knots in the wood. 

the keel of the boat has a thicker area, probably for ballast, as these boats suffered from instability, which is why a deck gun was not included in the class. The keel was not, however, detachable which was common in even older subs.

next step is rough sanding, followed by a first coat of epoxy before splitting the boat as described in a previous post to have access to the inside.

 

[Jim Lad]

You've made very fast progress on that hull!

 

John

[Ian B]

It's really taking shape, great contours 

[FreekS]

Yes, it’s really taken shape! thanks for the compliments.

 

now comes the best/worst job in building a wooden radio controlled submarine:

after some playing with a level, a 90 degree angle I managed to draw the cut lines on the hull. A little splintering, but anything wood can be repaired, and I’m still before the big epoxy putty jobs.

 

This vertical cut is between frames 43 and 44, both of which I made thicker than the other frames. This is where the bajonet closure will be installed later that will give quick access to the boats technology at the water front. 
 

to actually build and be able to repair the boat, I’m also doing a horizontal cut that will be closed except for maintenance (with real subs if they need to change an engine they actually cut through the hull). This is where the prop shafts and rudder controls will be built. I’ve done the aft part with a simple jigsaw.

[ccoyle]

Surely there must be at least a little trepidation about cutting apart a hull like that, even if it is a necessary part of the process.

[KeithAug]

Great progress although I winced when you got to the hull separation stage.

[FreekS]

I winced too! 
 

in scratchbuild, I find there is a need to plan in your head these kind of difficult procedures, which I’ve been thinking about for weeks (when to do it, what needs to go first….). Then when you do it, you can move on and think about next steps more clearly - in my case: “ok I’ve separated the hull sections, what’s the best way to fix them together so they come apart easy again”. In my case - the plan is pretty fluid. 
 

 

[Jim Lad]

Ouch! What a brave way to build a model!

 

John

[FreekS]

The four pieces came out OK, I coated each one inside and outside with epoxy sealer - mainly to glue all planks together and stabilise the boat against small chips during sanding. 

There were a few small places with damage from the saw, and I replaced two small pieces of plank. 
 

Yesterday applied first layer of epoxy putty and stated sanding that back. The boat parts now feel really strong and I can focus on getting the outside shape smoothed.

[FreekS]

The four parts of the hull have been sanded and I applied first layer of epoxy filler. The basic shape is now done. I want to get the various holes cut in the hull (for flooding, allowing air to escape, and the rudder, planes and prop holes before I epoxy again - so that all wood becomes sealed. 
 

thus I have to plan all “holes” and one of the difficult ones is for the front dive planes at the bow. These planes fold flush against the hull, and are covered by some plating outside the hull. 
 

so I started designing the functionality with the allowed space (tiny). This is the result:

https://youtu.be/hi7XH0Wy4v0?feature=shared

the two yellow gears rotate the common axle of the diveplanes. The axle has a hingepoint to fold each plane. Underneath each hingepoint is a brass gear that turns a pair of messing wires to apply sideways force on the axis outside of the hinges. This turns the diveplanes  flush with the hull and back. The two brass gears are coupled through 4 more to work in tandem (could have worked with 2 but they would have had to be bigger and cause conflicts). The large yellow cog and one of the 6 brass cogs will be driven by a servo 4-8 inches further back in the water tight compartment of the boat (this gear assembly will be “in the wet”).
 

This took me a good few hours of brasswork (of which I learnt a lot) and 3D design and printing (at which I’m also a beginner). I’d like to replace the printed parts with messing but I’m not at all sure I would achieve the precision on the boreholes to make it turn properly. I anyhow need to make another version of this as there is some play in the yellow cogs.

[Jim Lad]

Very ingenious work!

 

John

[yvesvidal]

Fantastic work. I am following with a lot of interest. Can't wait to see pictures of the sub diving....

 

Yves

[FreekS]

1 hour ago, yvesvidal said:

Fantastic work. I am following with a lot of interest. Can't wait to see pictures of the sub diving....

 

Yves

You mean “surfacing after a dive” ! 
it will be a while….. for O-13, but here is one from my also wooden K-XVIII

 

[FreekS]

Started work on the water-tight compartment inside the wooden hull. The hull will flood when dived, and the WTC will contain the motors, batteries, receiver, two-way pump and a 500ml divetank to dive the boat.
The insides of the WTC can be accessed by a bayonet between the aft 50mm diameter PVC tube and the mid 75mm PVC tube. 

this is the WTC seen from the stern. The white stern endcap will have two shafts driven by a motor inside the 50mm PVC tube. The holes are where the prop shaft and the rudder and diveplanes seals will come. Between the two white parts of the endcap will come a gearbox to counter rotate the two shafts.

Further forward is the bajonet, seen below when opened. 

 

two M4 bolts on the start section fit into the keyholes (strengthened with brass) in the front section and thus the two boat halves can be twisted shut. The bajonet contains O-rings to seal the 50 and 75mm PVC tubes.

 

this picture shows the bajonet shut and the bolts holding the two halves together. 
And finally with the two deck sections attached.

 

now that I know exactly where the WTC and its connections will come, I can start to work on the prop shafts and their outholders, the rudder and diveplanes and the holes in the wooden hull to flood the boat and enable air to escape.

 

[KeithAug]

Its all very ingenious, I look forward to seeing her working.

[Jim Lad]

Ingenious indeed! Looking forward to watching her progress.

 

John

[yvesvidal]

Wonderful job. I like these PVC pipes and the two-ways pumps.

 

Yves

[Canute]

A very nice feat of engineering. 👍