WesWorld

Soon the Mountain Class sloops will be refitted but they are lacking in misc weight and have little future growth. From 1942 I intend to build these in small numbers at a steady stream (maybe four hulls per year every other year).

It is a Shannon with more range and some goodies the Irish haven't got. I wanted 6x 4.5in guns really but it was too heavy and I wanted to use the Shannon hull. I might build a sub class with 2x2 4.5in and 2x2 6pdr AA later on. Later ships will have ASW mortars and better Asdic sets. Radar is a minimum on these ships as they are intended to work well with little maintainence on overseas stations.

River Class, Great Britain Sloop laid down 1942

Displacement:
1,118 t light; 1,181 t standard; 1,365 t normal; 1,512 t full load

Dimensions: Length overall / water x beam x draught
303.53 ft / 300.00 ft x 38.00 ft x 11.00 ft (normal load)
92.51 m / 91.44 m x 11.58 m x 3.35 m

Armament:
6 - 3.70" / 94.0 mm guns (3x2 guns), 25.33lbs / 11.49kg shells, 1936 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, majority forward, 2 raised mounts - superfiring
2 - 1.57" / 40.0 mm guns (1x2 guns), 2.00lbs / 0.91kg shells, 1941 Model
Anti-aircraft guns in deck mount
on centreline aft, all raised guns - superfiring
4 - 1.57" / 40.0 mm guns (2x2 guns), 2.00lbs / 0.91kg shells, 1941 Model
Anti-aircraft guns in deck mounts
on side, all amidships, all raised mounts - superfiring
12 - 0.66" / 16.8 mm guns (2x6 guns), 0.14lbs / 0.06kg shells, 1936 Model
Machine guns in deck mounts
on side, all forward, all raised mounts - superfiring
Weight of broadside 166 lbs / 75 kg
Shells per gun, main battery: 365

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.00" / 25 mm 0.50" / 13 mm 1.00" / 25 mm
2nd: 0.50" / 13 mm 0.50" / 13 mm -
3rd: 0.50" / 13 mm 0.50" / 13 mm -
4th: 0.50" / 13 mm - -

- Conning tower: 1.00" / 25 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 7,100 shp / 5,296 Kw = 23.05 kts
Range 9,500nm at 12.00 kts
Bunker at max displacement = 331 tons

Complement:
111 - 145

Cost:
£0.525 million / $2.100 million

Distribution of weights at normal displacement:
Armament: 21 tons, 1.5 %
Armour: 16 tons, 1.1 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 13 tons, 1.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 3 tons, 0.2 %
Machinery: 185 tons, 13.6 %
Hull, fittings & equipment: 732 tons, 53.6 %
Fuel, ammunition & stores: 247 tons, 18.1 %
Miscellaneous weights: 165 tons, 12.1 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
3,654 lbs / 1,657 Kg = 144.3 x 3.7 " / 94 mm shells or 1.2 torpedoes
Stability (Unstable if below 1.00): 1.13
Metacentric height 1.5 ft / 0.4 m
Roll period: 13.2 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.34
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:
Hull has low quarterdeck
and transom stern
Block coefficient: 0.381
Length to Beam Ratio: 7.89 : 1
'Natural speed' for length: 20.53 kts
Power going to wave formation at top speed: 54 %
Trim (Max stability = 0, Max steadiness = 100): 35
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 20.00 ft / 6.10 m
- Forecastle (20 %): 18.00 ft / 5.49 m
- Mid (50 %): 17.00 ft / 5.18 m
- Quarterdeck (25 %): 10.00 ft / 3.05 m (17.00 ft / 5.18 m before break)
- Stern: 10.00 ft / 3.05 m
- Average freeboard: 15.76 ft / 4.80 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 71.4 %
- Above water (accommodation/working, high = better): 213.8 %
Waterplane Area: 7,214 Square feet or 670 Square metres
Displacement factor (Displacement / loading): 190 %
Structure weight / hull surface area: 57 lbs/sq ft or 277 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.84
- Longitudinal: 4.54
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Names:

Electronic Equipment
One Type 276 set (search & gunnery)
One Type 274Q (high-definition surface search)
One Type 282M gunnery direction set
HF/DF Type 292
ASDIC Type 141 (later ships will have Type 146)

Misc Weight
20 tons for ASDIC
50 tons for two DCR and four DCT for 60 DCs
15 tons for three radars
30 tons for extra accomodation and crew comfort
50 tons for growth

Quoted

Originally posted by Hood
Radar is a minimum on these ships as they are intended to work well with little maintainence on overseas stations.

Three radars is "a minimum"?

Yes, a search radar is a must for its sloop role. It can double as a long-range gunnery set too. The high-definition search is for smaller objects nearer the ship and for safer manouvering in crowded waterways and convoys. The smaller gunnery set is the OTL Type 282 barrage set for pom-poms etc. Pretty lightweight but useful to have where there is a high aerial threat.

Early ships may not carry all three radars but have the space for them.

Here is the likely refit for the RSAN Alswinn in Iraqi service. Nothing major, the notes at the end cover the main points. I may replace the diesels in a future refit.

HMIS Basrah (ex-Alswinn), SAE Coastal Defence Ship laid down 1926

Displacement:
1,883 t light; 1,973 t standard; 2,176 t normal; 2,338 t full load

Dimensions: Length overall / water x beam x draught
384.28 ft / 377.30 ft x 41.01 ft x 12.30 ft (normal load)
117.13 m / 115.00 m x 12.50 m x 3.75 m

Armament:
4 - 5.91" / 150 mm guns (2x2 guns), 102.98lbs / 46.71kg shells, 1926 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread
4 - 3.70" / 94.0 mm guns (2x2 guns), 25.00lbs / 11.34kg shells, 1935 Model
Dual purpose guns in deck mounts
on side, all amidships
4 - 2.24" / 57.0 mm guns (2x2 guns), 6.00lbs / 2.72kg shells, 1941 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread, all raised mounts
8 - 1.57" / 40.0 mm guns (4x2 guns), 2.00lbs / 0.91kg shells, 1941 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread, all raised mounts - superfiring
8 - 0.03" / 0.7 mm guns (4x2 guns), 0.00lbs / 0.00kg shells, 1926 Model
Machine guns in deck mounts
on side ends, evenly spread
Weight of broadside 552 lbs / 250 kg
Shells per gun, main battery: 140
4 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.76" / 70 mm 210.47 ft / 64.15 m 7.68 ft / 2.34 m
Ends: Unarmoured
Main Belt covers 86 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 3.15" / 80 mm 1.38" / 35 mm 3.15" / 80 mm
2nd: 0.50" / 13 mm 0.50" / 13 mm -
3rd: 0.50" / 13 mm 0.50" / 13 mm -
4th: 0.59" / 15 mm - -
5th: 0.39" / 10 mm - -

- Armour deck: 1.38" / 35 mm, Conning tower: 4.72" / 120 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 12,064 shp / 9,000 Kw = 24.03 kts
Range 6,200nm at 12.00 kts
Bunker at max displacement = 365 tons

Complement:
159 - 207

Cost:
£0.614 million / $2.458 million

Distribution of weights at normal displacement:
Armament: 69 tons, 3.2 %
Armour: 537 tons, 24.7 %
- Belts: 190 tons, 8.8 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 87 tons, 4.0 %
- Armour Deck: 243 tons, 11.2 %
- Conning Tower: 17 tons, 0.8 %
Machinery: 386 tons, 17.7 %
Hull, fittings & equipment: 851 tons, 39.1 %
Fuel, ammunition & stores: 293 tons, 13.5 %
Miscellaneous weights: 40 tons, 1.8 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,994 lbs / 1,358 Kg = 29.1 x 5.9 " / 150 mm shells or 1.0 torpedoes
Stability (Unstable if below 1.00): 1.22
Metacentric height 1.9 ft / 0.6 m
Roll period: 12.5 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.46
Seaboat quality (Average = 1.00): 1.61

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.400
Length to Beam Ratio: 9.20 : 1
'Natural speed' for length: 19.42 kts
Power going to wave formation at top speed: 49 %
Trim (Max stability = 0, Max steadiness = 100): 44
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 21.00 ft / 6.40 m
- Forecastle (20 %): 17.72 ft / 5.40 m
- Mid (50 %): 17.72 ft / 5.40 m (9.84 ft / 3.00 m aft of break)
- Quarterdeck (15 %): 9.84 ft / 3.00 m
- Stern: 9.84 ft / 3.00 m
- Average freeboard: 14.04 ft / 4.28 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 84.6 %
- Above water (accommodation/working, high = better): 126.4 %
Waterplane Area: 9,525 Square feet or 885 Square metres
Displacement factor (Displacement / loading): 114 %
Structure weight / hull surface area: 55 lbs/sq ft or 270 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.73
- Longitudinal: 1.51
- Overall: 0.78
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Refit Changes
B and X 88mm mounts replaced by two twin 6pdr Mk II AA mounts
Both beam 88mm mounts replaced by twin 3.7in DP mounts
All 40mm replaced by 2pdr Mk II L/70 twin mounts
All 20mm replaced by twin 0.661in Vickers HMG
Addition of one Type 270 surface search radio-location set
10 tons of added misc weight for improvements to crew spaces
Refurbishment of internal fittings for life extension

The sloop is fairly similar to the Black Swan Class, but ~20-30% smaller whilst carrying quite a lot more stuff. Is this felt to be reasonable?

As a more detailed comment, the block coefficient is very low for the ship. This'll give limited buoyancy towards the ends of the ship and likely poorer seakeeping.

Essentially this is a slow multi-purpose escort vessel?

Quoted

Originally posted by Red Admiral
The sloop is fairly similar to the Black Swan Class, but ~20-30% smaller whilst carrying quite a lot more stuff. Is this felt to be reasonable?

It's a Black Swan by another name. I build the prototype, the Shannon, for Ireland and I used the Black Swan statistics all around; I'm not sure why you think it's 20-30% smaller, because according to my figures it's actually 100 tons heavier.

Hmm, I thought they were considerably bigger than that.

Quoted

Originally posted by Red Admiral
Hmm, I thought they were considerably bigger than that.

Yeah. They were originally 1,250 tons and later modified to 1,350 tons, according to my info. I used the Black Swan weights for Shannon, and that's why the Rivers have a low BC.

It's unclear as to whether those weights are standard or legend. Deep displacement was 1800-1950t and so quite a bit more.

Quoted

Originally posted by Red Admiral
It's unclear as to whether those weights are standard or legend. Deep displacement was 1800-1950t and so quite a bit more.

I have never seen any more detailed information about the Black Swans, and thus did not have that info when I designed the Shannon.