WesWorld

A yet-to-be-determined number of this class of sub will be constructed beginning in Q4/29.

Torpedo tube arrangement is 4 forwards, 2 aft, and 2 in a trainable casing on the deck (patterned after a historical Dutch design).

Filipino Rémora-class submarine, laid down 1929

Length, 242 ft x Beam, 21.4 ft x Depth, 12.9 ft
950 tons normal displacement (831 tons standard)

Main battery: 1 x 3.94-inch / 100mm (1x1)
Secondary battery: 2 x 0.98-inch / 25mm (1x2)

Weight of broadside: 32 lbs

8 TT, 21.0" (6 submerged)

Hull unarmored

Maximum speed for 1435 shp = 15.00 knots
Approximate cruising radius, 6000 nm / 12 kts

Typical complement: 86-111


Estimated cost, $605,000 (£151,000)

Remarks:


Distribution of weights:
Percent
normal
displacement:

Armament ......................... 4 tons = 0 pct
Machinery ........................ 44 tons = 5 pct
Hull and fittings; equipment ..... 561 tons = 59 pct
Fuel, ammunition, stores ......... 140 tons = 15 pct
Miscellaneous weights ............ 200 tons = 21 pct
-----
950 tons = 100 pct

Estimated metacentric height, 0.6 ft

Displacement summary:

Light ship: 809 tons
Standard displacement: 831 tons
Normal service: 950 tons
Full load: 1041 tons

Loading submergence 93 tons/foot

+++++++++++++++++++++++++


Estimated overall survivability and seakeeping ability:

Relative margin of stability: 1.09

Shellfire needed to sink: 584 lbs = 19.1 x 3.9-inch shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not counting critical hits)

Torpedoes needed to sink: 0.3
(Approximates number of 'typical'
torpedo hits needed to sink ship)

Relative steadiness as gun platform, 1 percent
(50 percent is 'average')

Relative rocking effect from firing to beam, 0.00

Relative quality as a seaboat: 0.00

+++++++++++++++++++++++++


Hull form characteristics:

Block coefficient: 0.50
Sharpness coefficient: 0.32
Hull speed coefficient 'M' = 7.51
'Natural speed' for length = 15.5 knots
Power going to wave formation
at top speed: 37 percent


Estimated hull characteristics and strength:

Relative underwater volume absorbed by
magazines and engineering spaces: 86 percent


Displacement factor: 297 percent
(Displacement relative to loading factors)


Relative cross-sectional hull strength: 3.87
(Structure weight per square
foot of hull surface: 113 lbs)

Relative longitudinal hull strength: 1.44
(for 0.1 ft average freeboard;
freeboard adjustment -9.4 ft)

Relative composite hull strength: 1.85

+++++++++++++++++++++++++

But the range is a bit low. This translates to a limited time on station, as well as range.

Quoted

Originally posted by AdmKuznetsov
But the range is a bit low. This translates to a limited time on station, as well as range.

not really. 6000@12knots is more or less similar to the range of the WW2 German TypeVIIC class (it had a range of 8400@10 knots). I'd say that what the design has is a quite limited emergency diving depth, but for restricted and shallow waters of the Phillipines, is good enough.


The external training torpedos is something I almost included in my two last classes of submarines, the ocean going O-1 and the coastal defense tipe K-17, but I decided to go with a six internal forward torpedo tubes configuration because of the ability to reload.

These training tubes are something I'm not overly familiar with. Just how common were they historically, and how useful were they compared to internal tubes?

I don't think they were very common and I'd expect them to get little use. I suspect thats why we didn't see them much. Anything thats rarely used on a ship is usually dead weight to be removed in the next refit/repair.

I think the huge French sub had them. Surcouf or something like that.

Seems like they would be of limited use. Like as a threat to freighters or destroyers that catch the sub on the surface, as that is probably the only place they can be used.
Might be interesting for training subs though. Use a blackout hood and small periscope on a position between the tubes and use them for officer training maybe?

Several historical French designs carried external torpedo tubes.

The Saphir class had 2 x 21.7" in the bow, and an external triple mount aft with 1 x 21.7 and 2 15.7".

Surcouf had four 15.7" in a quad trainable mount, with 8 torpedoes, in addition to her 8 x 21.7" mounts.

The Requin, Sirene, Redouable, Argonaute, and Aurore classes also had external mounts. They could be trained and fired even submerged.

In Surcouf, and I assume in the other submarines, the idea of the smaller tubes was that they would be used against merchantmen.

Regards,

Big Rich

As noted, historically both the French and Dutch used external trainable mounts on their subs...so there must have been something to it, at least theoretically.

As for the range, these boats will primarily be operating in the South China Sea, so extreme range isn't really necessary.

It finally dawned on me that a 242' submarine will not fit in a 230' Type 0 slip.

So I put 'em on a diet...


Filipino Rémora-class submarine, laid down 1929

Length, 230 ft x Beam, 21.4 ft x Depth, 12.9 ft
904 tons normal displacement (789 tons standard)

Main battery: 1 x 3.94-inch / 100mm
Secondary battery: 4 x 0.54-inch / 13.7mm (1x4)

Weight of broadside: 32 lbs

8 TT, 21.0" (4 forwards, 2 aft, 2 trainable)

Operational diving depth: 194 feet
Emergency diving depth: 310 feet
Crush depth: 485 feet

Maximum speed for 1399 shp = 14.97 knots
Approximate cruising radius, 6000 nm / 12 kts

Typical complement: 82-107


Estimated cost, $579,000 (£145,000)


Distribution of weights:
Percent
normal
displacement:

Armament ......................... 4 tons = 0 pct
Machinery ........................ 43 tons = 5 pct
Hull and fittings; equipment ..... 521 tons = 58 pct
Fuel, ammunition, stores ......... 136 tons = 15 pct
Miscellaneous weights ............ 200 tons = 22 pct
-----
904 tons = 100 pct

Estimated metacentric height, 0.6 ft

Displacement summary:

Light ship: 768 tons
Standard displacement: 789 tons
Normal service: 904 tons
Full load: 993 tons

Loading submergence 88 tons/foot

+++++++++++++++++++++++++


Estimated overall survivability and seakeeping ability:

Relative margin of stability: 1.06

Shellfire needed to sink: 519 lbs = 17.0 x 3.9-inch shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not counting critical hits)

Torpedoes needed to sink: 0.2
(Approximates number of 'typical'
torpedo hits needed to sink ship)

Relative steadiness as gun platform, 1 percent
(50 percent is 'average')

Relative rocking effect from firing to beam, 0.00

Relative quality as a seaboat: 0.00

+++++++++++++++++++++++++


Hull form characteristics:

Block coefficient: 0.50
Sharpness coefficient: 0.32
Hull speed coefficient 'M' = 7.27
'Natural speed' for length = 15.2 knots
Power going to wave formation
at top speed: 38 percent


Estimated hull characteristics and strength:

Relative underwater volume absorbed by
magazines and engineering spaces: 91 percent

Relative accommodation and working space: 1 percent


Displacement factor: 285 percent
(Displacement relative to loading factors)


Relative cross-sectional hull strength: 3.77
(Structure weight per square
foot of hull surface: 110 lbs)

Relative longitudinal hull strength: 1.55
(for 0.1 ft average freeboard;
freeboard adjustment -9.3 ft)

Relative composite hull strength: 1.94

+++++++++++++++++++++++++

Trainable torpedo tubes have some advantages. Like being able to fire on just about any bearing. The 400mm TT on Surcouf could be reloaded, the ones on other ships couldn't.

Or you could go for fixed external tubes like on the British subs. Not possible to reload, but they don't take up internal space.

The main disadvantage of trainable mounts is that they kick up a lot of bubbles to the surface. So you can see where the submarine is.

The Italian experimental submarine SX1 has 2x450mm trainable tubes.(I couldn't fit a smaller calibre) They have been found to work reasonably well.