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41

Wednesday, September 30th 2009, 4:31pm

Quoted

Originally posted by HoOmAn
I´m curious to see how you managed all that on 2000 tons. I expect a design not in line with our rules here but probably you can suprise me. :o)


After double-checking the Design Rules for Gentlemen, I found that I did break a rule. Cross sectional strength is 0.48, just below the 0.50 allowance. D'oh!

Quick question: are the rules based on standard tonnage or normal? I assumed standard, but thought I should double check.

This post has been edited 1 times, last edit by "Eidolon" (Sep 30th 2009, 4:52pm)


42

Wednesday, September 30th 2009, 4:58pm

OK, let me have it. Just don't laugh too loudly.

Quoted


DBL39 class, Large Destroyer Leader laid down 1939

Displacement:
1,864 t light; 2,009 t standard; 2,982 t normal; 3,759 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(416.00 ft / 410.00 ft) x 42.00 ft x (15.00 / 17.47 ft)
(126.80 m / 124.97 m) x 12.80 m x (4.57 / 5.32 m)

Armament:
6 - 5.00" / 127 mm 38.0 cal guns - 59.33lbs / 26.91kg shells, 320 per gun
Dual purpose guns in deck and hoist mounts, 1939 Model
3 x Twin mounts on centreline ends, majority aft
1 raised mount aft - superfiring
12 - 1.57" / 40.0 mm 56.0 cal guns - 2.12lbs / 0.96kg shells, 1,500 per gun
Anti-air guns in deck mounts, 1939 Model
4 x Triple mounts on sides, forward deck aft
4 raised mounts
8 - 0.50" / 12.7 mm 62.0 cal guns - 0.07lbs / 0.03kg shells, 2,500 per gun
Machine guns in deck mounts, 1939 Model
4 x Twin mounts on sides, evenly spread
4 raised mounts
Weight of broadside 382 lbs / 173 kg
Main Torpedoes
10 - 21.0" / 533 mm, 24.00 ft / 7.32 m torpedoes - 1.615 t each, 16.155 t total
In 2 sets of deck mounted centre rotating tubes
Main DC/AS Mortars
24 - 65.00 lbs / 29.48 kg ahead throwing AS Mortars + 6 reloads - 0.871 t total

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 1.00" / 25 mm -
2nd: 1.57" / 40 mm - -
3rd: 0.50" / 13 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 33,259 shp / 24,811 Kw = 31.00 kts
Range 8,550nm at 20.00 kts
Bunker at max displacement = 1,750 tons

Complement:
201 - 262

Cost:
£1.292 million / $5.168 million

Distribution of weights at normal displacement:
Armament: 110 tons, 3.7 %
- Guns: 76 tons, 2.6 %
- Weapons: 34 tons, 1.1 %
Armour: 32 tons, 1.1 %
- Armament: 32 tons, 1.1 %
Machinery: 900 tons, 30.2 %
Hull, fittings & equipment: 783 tons, 26.3 %
Fuel, ammunition & stores: 1,117 tons, 37.5 %
Miscellaneous weights: 40 tons, 1.3 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,379 lbs / 1,079 Kg = 38.1 x 5.0 " / 127 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.42
Metacentric height 2.5 ft / 0.8 m
Roll period: 11.2 seconds
Steadiness - As gun platform (Average = 50 %): 77 %
- Recoil effect (Restricted arc if above 1.00): 0.37
Seaboat quality (Average = 1.00): 1.54

Hull form characteristics:
Hull has a flush deck,
a normal bow and large transom stern
Block coefficient (normal/deep): 0.404 / 0.437
Length to Beam Ratio: 9.76 : 1
'Natural speed' for length: 23.45 kts
Power going to wave formation at top speed: 60 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 15.25 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 16.00 %, 22.00 ft / 6.71 m, 20.00 ft / 6.10 m
- Forward deck: 30.00 %, 20.00 ft / 6.10 m, 18.00 ft / 5.49 m
- Aft deck: 42.00 %, 18.00 ft / 5.49 m, 15.00 ft / 4.57 m
- Quarter deck: 12.00 %, 15.00 ft / 4.57 m, 14.00 ft / 4.27 m
- Average freeboard: 17.70 ft / 5.39 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 109.9 %
- Above water (accommodation/working, high = better): 146.6 %
Waterplane Area: 11,027 Square feet or 1,024 Square metres
Displacement factor (Displacement / loading): 138 %
Structure weight / hull surface area: 39 lbs/sq ft or 192 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.50
- Longitudinal: 1.84
- Overall: 0.57
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Miscellaneous weight reserved as torpedo reloads and growth potential.

43

Wednesday, September 30th 2009, 5:02pm

Quoted

Originally posted by Eidolon
Quick question: are the rules based on standard tonnage or normal? I assumed standard, but thought I should double check.

Any time we discuss build rules, it's light tonnage; any time we discuss design rules, it's standard tonnage.

Design looks decent albeit slow. IMHO, good enough for an escort.

44

Wednesday, September 30th 2009, 5:54pm

You've got masses of fuel onboard which is screwing the sim up somewhat. Bunkerage currently is 1750tons whereas Gearing for example had around 700tons. Really I wouldn't go much above 20% of the displacement as fuel.

Aside from that, it doesn't look too bad.

HoOmAn

Keeper of the Sacred Block Coefficient

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45

Wednesday, September 30th 2009, 6:30pm

31kn is very, very low speed for such a vessel. Every light cruiser can easily catch her, the higher the waves the better as the larger ship will be a better seaboat anyway. She is not made to fight a CL, isn´t she?

So I´d add 3-4kn minimum.

I also agree with RA - you´ve devoted way too much weight on fuel which helps to explain why your vessel has such a low standard displacement compared to full load conditions.

46

Wednesday, September 30th 2009, 8:32pm

Roger that. I was worried that it was a case of too good to be true. Like I said, she became a product of design insecurity. Aside from speed and fuel, how is it looking? Am I designing within acceptable limits? Is the armament looking balanced?

47

Wednesday, September 30th 2009, 8:48pm

I'd say that if you dumped fuel down to, oh, 3,000nm @ 20kts (which I feel is quite good), and raised speed to 33-34 knots, you'd have a competent and well-balanced fleet DD on about 2,300 tons light / 2,700 tons normal.

HoOmAn

Keeper of the Sacred Block Coefficient

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48

Wednesday, September 30th 2009, 8:53pm

For a ´39er design she is rather heavily armed. Have you tried a deck plan to see if you can find enough deckspace for all those guns? Those large TT tubes eat up a lot of room and you have quite some AA mounts to place too. Add (two?) funnels, boats, searchlights, masts, bridge and enough room for her crew....

I think she is not too bad a design to start from. However, you will learn that increasing her speed will quickly eat up tonnage currently used for other things AND add an issue with seakeeping. As a result you will either have a deisgn with a freeboard quite high compared to historical DDs or you will have to accept a rating as "poor seaboat" even though this will only be true for bad weather environment.

49

Wednesday, September 30th 2009, 9:06pm

Quoted

Originally posted by HoOmAn
For a ´39er design she is rather heavily armed. Have you tried a deck plan to see if you can find enough deckspace for all those guns? Those large TT tubes eat up a lot of room and you have quite some AA mounts to place too. Add (two?) funnels, boats, searchlights, masts, bridge and enough room for her crew....


I have not drawn a plan view, but having taken inspiration from the Keeling Isl class (bottom of page), I assumed there would be room.

50

Friday, October 2nd 2009, 4:59pm

When filling out the AS Mortar/Depth Charge fields, does Number and Reloads mean systems and system reloads, or the actual number of mortars and depth charges?

For example, if I want a single Hedgehog mortar, would that be one or twenty-four, since that is how many mortars it carried? Would the reloads then be six sets of twenty-four, or the actual two hundred eighty-eight individual mortars?

51

Saturday, October 3rd 2009, 9:57pm

Given the need to specify the weight of charges, I'd conclude that it means individual projectiles in a salvo, i.e. that the Hedgehog is a 24-'gun' mount.

Which would be silly with normal guns, but there you go.

Following from that, you'd require 288 individual charges as your reloads. Bear in mind that ahead-throwing A/S mortars weren't particularly commonplace in 1939 in reality, though I'm behind the curve for WesWorld so they might not be unusual here.

8550 nautical miles at 20 knots is a very long range for a 1930s destroyer, and would even be considered quite a long range for a modern ship. Admittedly, the modern ship can RAS, but even so, that sort of range on a small vessel is demanding far too much.

I'd also be skeptical whether it will all fit on a 410 foot hull, although the ship would need a sketch general arrangement to come to a definite conclusion. My hunch is that you need to lose either a five inch mount or the A/S mortar. And, as has been mentioned, the speed is really inadequate for a destroyer in this timeframe: Royal Navy tactics called for a ten knot margin above the battle line.