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Sunday, November 3rd 2013, 4:44am

Irish Merchant Designs for 1944

Quoted

[SIZE=3]Donegal Rose, Irish Trawler laid down 1944[/SIZE]
Designed for the Donegal Bay Fishing Company Ltd of Ballyshannon, County Donegal, as a pelagic trawler for Atlantic operations.

Displacement:
359 t light; 370 t standard; 530 t normal; 658 t full load

Dimensions: Length overall / water x beam x draught
155.03 ft / 145.00 ft x 25.25 ft x 8.80 ft (normal load)
47.25 m / 44.20 m x 7.70 m x 2.68 m

Machinery:
Oil fired boilers, complex reciprocating steam engines,
Geared drive, 1 shaft, 970 ihp / 724 Kw = 14.00 kts
Range 5,950nm at 14.00 kts
Bunker at max displacement = 288 tons

Complement:
54 - 71

Cost:
£0.134 million / $0.537 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0 %
Machinery: 53 tons, 10.0 %
Hull, fittings & equipment: 152 tons, 28.6 %
Fuel, ammunition & stores: 171 tons, 32.2 %
Miscellaneous weights: 155 tons, 29.2 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
999 lbs / 453 Kg = 9.2 x 6 " / 152 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.09
Metacentric height 0.8 ft / 0.2 m
Roll period: 12.2 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.576
Length to Beam Ratio: 5.74 : 1
'Natural speed' for length: 12.04 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 35
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 19.69 ft / 6.00 m
- Forecastle (20 %): 18.04 ft / 5.50 m (10.17 ft / 3.10 m aft of break)
- Mid (50 %): 9.51 ft / 2.90 m
- Quarterdeck (15 %): 10.17 ft / 3.10 m
- Stern: 10.83 ft / 3.30 m
- Average freeboard: 11.71 ft / 3.57 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 65.0 %
- Above water (accommodation/working, high = better): 88.5 %
Waterplane Area: 2,550 Square feet or 237 Square metres
Displacement factor (Displacement / loading): 203 %
Structure weight / hull surface area: 29 lbs/sq ft or 143 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.80
- Longitudinal: 7.28
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, rides out heavy weather easily


Quoted

[SIZE=3]Donegal Rose, Irish Naval Trawler laid down 1944[/SIZE]
A proposed ASW trawler variant of the previous vessel, likely only to be considered in rather dire circumstances.

Displacement:
353 t light; 370 t standard; 530 t normal; 658 t full load

Dimensions: Length overall / water x beam x draught
155.03 ft / 145.00 ft x 25.25 ft x 8.80 ft (normal load)
47.25 m / 44.20 m x 7.70 m x 2.68 m

Armament:
1 - 3.70" / 94.0 mm guns in single mounts, 25.33lbs / 11.49kg shells, 1944 Model
Quick firing gun in deck mount
on centreline forward
2 - 1.57" / 40.0 mm guns (1x2 guns), 1.95lbs / 0.88kg shells, 1944 Model
Anti-aircraft guns in deck mount
on centreline aft
2 - 0.79" / 20.0 mm guns in single mounts, 0.24lbs / 0.11kg shells, 1944 Model
Breech loading guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 30 lbs / 13 kg
Shells per gun, main battery: 350

Machinery:
Oil fired boilers, complex reciprocating steam engines,
Geared drive, 1 shaft, 971 ihp / 724 Kw = 14.00 kts
Range 5,950nm at 14.00 kts
Bunker at max displacement = 288 tons

Complement:
54 - 71

Cost:
£0.154 million / $0.616 million

Distribution of weights at normal displacement:
Armament: 4 tons, 0.7 %
Machinery: 53 tons, 10.0 %
Hull, fittings & equipment: 157 tons, 29.5 %
Fuel, ammunition & stores: 177 tons, 33.4 %
Miscellaneous weights: 140 tons, 26.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
970 lbs / 440 Kg = 38.3 x 3.7 " / 94 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.12
Metacentric height 0.8 ft / 0.2 m
Roll period: 12.0 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.07
Seaboat quality (Average = 1.00): 2.00

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.576
Length to Beam Ratio: 5.74 : 1
'Natural speed' for length: 12.04 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 35
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 19.69 ft / 6.00 m
- Forecastle (20 %): 18.04 ft / 5.50 m (10.17 ft / 3.10 m aft of break)
- Mid (50 %): 9.51 ft / 2.90 m
- Quarterdeck (15 %): 10.17 ft / 3.10 m
- Stern: 10.83 ft / 3.30 m
- Average freeboard: 11.71 ft / 3.57 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 68.1 %
- Above water (accommodation/working, high = better): 88.6 %
Waterplane Area: 2,551 Square feet or 237 Square metres
Displacement factor (Displacement / loading): 193 %
Structure weight / hull surface area: 30 lbs/sq ft or 148 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.80
- Longitudinal: 7.52
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Notes:
A Level Three refit to arm these ships and give them ASW sonar would cost 53 tons a vessel.

2

Sunday, November 3rd 2013, 6:06pm

A good looking and thoughtful design in both variants.