WesWorld

Here is a Mexican Patrol Boat, probably the first ship to be laid down. 16 planned.


Sonora, Mexico Patrol Boat laid down 1930

Displacement:
489 t light; 507 t standard; 608 t normal; 688 t full load

Dimensions: Length overall / water x beam x draught
250.00 ft / 250.00 ft x 27.00 ft x 7.00 ft (normal load)
76.20 m / 76.20 m x 8.23 m x 2.13 m

Armament:
1 - 5.00" / 127 mm guns in single mounts, 62.50lbs / 28.35kg shells, 1930 Model
Breech loading gun in deck mount
on centreline forward
2 - 1.85" / 47.0 mm guns in single mounts, 3.17lbs / 1.44kg shells, 1930 Model
Dual purpose guns in deck mounts
on centreline, all aft
Weight of broadside 69 lbs / 31 kg
Shells per gun, main battery: 150
4 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.00" / 25 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 7,850 shp / 5,856 Kw = 25.00 kts
Range 4,000nm at 15.00 kts
Bunker at max displacement = 181 tons

Complement:
60 - 79

Cost:
£0.241 million / $0.964 million

Distribution of weights at normal displacement:
Armament: 9 tons, 1.4 %
Armour: 3 tons, 0.5 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 3 tons, 0.5 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 238 tons, 39.2 %
Hull, fittings & equipment: 224 tons, 36.9 %
Fuel, ammunition & stores: 119 tons, 19.6 %
Miscellaneous weights: 15 tons, 2.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
431 lbs / 196 Kg = 6.9 x 5.0 " / 127 mm shells or 0.3 torpedoes
Stability (Unstable if below 1.00): 1.34
Metacentric height 1.2 ft / 0.4 m
Roll period: 10.5 seconds
Steadiness - As gun platform (Average = 50 %): 69 %
- Recoil effect (Restricted arc if above 1.00): 0.12
Seaboat quality (Average = 1.00): 1.19

Hull form characteristics:
Hull has low forecastle
Block coefficient: 0.450
Length to Beam Ratio: 9.26 : 1
'Natural speed' for length: 15.81 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 58
Bow angle (Positive = bow angles forward): 0.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 15.00 ft / 4.57 m
- Forecastle (20 %): 10.00 ft / 3.05 m (11.00 ft / 3.35 m aft of break)
- Mid (50 %): 11.00 ft / 3.35 m
- Quarterdeck (15 %): 11.00 ft / 3.35 m
- Stern: 11.00 ft / 3.35 m
- Average freeboard: 11.20 ft / 3.41 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 140.4 %
- Above water (accommodation/working, high = better): 89.0 %
Waterplane Area: 4,306 Square feet or 400 Square metres
Displacement factor (Displacement / loading): 108 %
Structure weight / hull surface area: 29 lbs/sq ft or 142 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.67
- Longitudinal: 2.20
- Overall: 0.75
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is cramped

at 25knots, doesn't she fall into "B class DD" territory?

Shes smaller than 600tons and Mexico never signed the CT so it really doesn't matter.

Quite: if you're a surface ship under 600 tons, you can go as fast as you like or be as heavily armed as you like and the CT regards you as unlimited. And with Mexico, like Denmark, being unrestricted by the Treaty, it, as RA says, doesn't matter anyway. Mexico could, unlike Canada, mount 5.5" guns on it's destroyers without anyone batting an eye (well, other than the US firms that thought they were going to be supplying the guns, anyway).

I've been working on the principle that Denmark will one day join the Treaty, and therefore obeys the design rules, and quite forgot that I don't have to!!