WesWorld

As you´ve seen the RSAN is going to get some new toys.

I´ve carefully read whenever designs of small combatants were posted but I´d be curious to hear what you guys think about the one below. The decision is made, the ships are on the slips so feel free to fire away.

These ships are meant to act as escorts. Their speed should allow them to keep pace with the fast majority of all submarines known once those are surfaced. Second they can be used as patrol crafts (smuggle, fishing etc.) and thus are a modern version of my old and somewhat outdated sloops.

What do you think?

River-class, laid down 1925



Displacement:
597 t light; 628 t standard; 856 t normal; 1.039 t full load

Dimensions: Length overall / water x beam x draught
258,98 ft / 255,91 ft x 27,89 ft x 10,50 ft (normal load)
78,94 m / 78,00 m x 8,50 m x 3,20 m

Armament:
4 - 4,13" / 105 mm guns in single mounts, 35,32lbs / 16,02kg shells, 1925 Model
Breech loading guns in deck mounts
on centreline ends, evenly spread
8 - 1,57" / 40,0 mm guns (2x4 guns), 1,95lbs / 0,88kg shells, 1924 Model
Anti-aircraft guns in deck mounts
on side, all amidships
6 - 0,79" / 20,0 mm guns (3x2 guns), 0,24lbs / 0,11kg shells, 1923 Model
Anti-aircraft guns in deck mounts
on centreline, all aft
Weight of broadside 158 lbs / 72 kg
Shells per gun, main battery: 150

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1,18" / 30 mm 121,88 ft / 37,15 m 7,87 ft / 2,40 m
Ends: Unarmoured
Main Belt covers 73% of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1,38" / 35 mm 0,79" / 20 mm -
3rd: 0,59" / 15 mm - -
4th: 0,39" / 10 mm - -

- Armour deck: 0,39" / 10 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 4.021 shp / 3.000 Kw = 20,29 kts
Range 7.200nm at 15,00 kts (Bunkerage = 410 tons)

Complement:
78 - 102

Cost:
£0,183 million / $0,731 million

Distribution of weights at normal displacement:
Armament: 20 tons, 2,3%
Armour: 95 tons, 11,1%
- Belts: 50 tons, 5,8%
- Torpedo bulkhead: 0 tons, 0,0%
- Armament: 13 tons, 1,6%
- Armour Deck: 32 tons, 3,7%
- Conning Tower: 0 tons, 0,0%
Machinery: 131 tons, 15,2%
Hull, fittings & equipment: 316 tons, 36,9%
Fuel, ammunition & stores: 259 tons, 30,3%
Miscellaneous weights: 35 tons, 4,1%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1.667 lbs / 756 Kg = 47,2 x 4,1 " / 105 mm shells or 0,9 torpedoes
Stability (Unstable if below 1.00): 1,39
Metacentric height 1,3 ft / 0,4 m
Roll period: 10,2 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0,19
Seaboat quality (Average = 1.00): 1,56

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0,400
Length to Beam Ratio: 9,18 : 1
'Natural speed' for length: 16,00 kts
Power going to wave formation at top speed: 50 %
Trim (Max stability = 0, Max steadiness = 100): 45
Bow angle (Positive = bow angles forward): 15,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 11,48 ft / 3,50 m
- Forecastle (20%): 9,51 ft / 2,90 m
- Mid (50%): 9,51 ft / 2,90 m
- Quarterdeck (15%): 9,51 ft / 2,90 m
- Stern: 9,51 ft / 2,90 m
- Average freeboard: 9,67 ft / 2,95 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 72,6%
- Above water (accommodation/working, high = better): 102,1%
Waterplane Area: 4.393 Square feet or 408 Square metres
Displacement factor (Displacement / loading): 156%
Structure weight / hull surface area: 42 lbs/sq ft or 204 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,92
- Longitudinal: 2,03
- Overall: 1,00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Good armament for the size. I'd go for 2 or even 1 105mm guns but with huge ammo capacity, >400 rounds. The Flower Class corvettes seemed to manage pretty good iwht only 1x4" gun.

I'm not quite sure why you've bothered with armour.

20.29knts is fast enough for an escort vessel. There is one submarine that is faster underwater, but shes experimental.. The K-class have been retired, and X1 is unlikely to be built.

The range is great.

35tons for misc. weight might not be enough. My similar sized vessels have 75tons. My 1000t escort has 190tons.

I choosed a heavy broadside with 4x 10,5cm guns to give these boats a chance against incoming MTBs or TBs (probably even small DDs). Naval architects of the RSAN plan to deploy these ships to South American waters for example. There they might be forced to defend coastal waters and the estuary of the Rio de la Plata against raiding vessels send there by either Brazil or Argentina. Strategists of the RSAN foresee hit and run tactics in that region - should there every be hostile action - as nobody in the neighborhood could hope to take on the RSAN in open waters.

So given these scenarios a ship with four guns (each of which offers a rate of fire of about 12 shots per minute but has only 150 shells per barrel) provides much more firepower for a short period of time than one with just a single gun that could fire said gun over a longer period of time. If a clash between small and fast combatants happens every single shell that can be fired within the very first minutes could make the difference.

Similar logic as above applies if those units are used in coastal waters at Cameroon.

I bothered with armor because I thought gun crews as well as boilers/machinery should have at least some protection - even if it is splinter protection only. Might also help against ice if those units are used way south...

35ts of misc weight should be suffice. With ~250kg per depth charge such a units can carry a total of 140. These ships are not meant to carry any staff or other heavy equipment.

Thanks for your input...

HoOmAn

I can't help but think she's going to be over-crowded with that many guns - though your sketch suggests that it can work.

If you're expecting mostly light-caliber, flat trajectory fire, any thought of deleting the deck armor and adding an upper belt as some folks do with their cruisers?

They should work well as ASW/AAW escorts, and I think your miscellaneous weight is more than sufficient for the mission.