Seagoing Vessel Design

[BlackBat242]

Like Striker was a set of equipment creation rules only loosely connected to the starship construction rules, your "wet-ship" rules need be only loosely connected, as (unlike bad Japanese manga) they will never be going into space.

Here is a computer program which designs wet-navy ships.
http://www.springsharp.com/

Welcome to the home page of SpringSharp.

What if the German, Japanese, Royal Navy and US super Battleships were built for WWII?

What if there was a 19th century Navy the equal of the Royal Navy?

What if there was no Washington or London Treaties after the Great War?

SpringSharp allows you to design "what-if" and "never built" warships between 1850 and 1950 using little more than the specifications in books like Janes Fighting Ships, Conway's All the World's Fighting Ships etc. It applies parametric formulas as used by professional Naval Architects (Mumford, Parsons, Holtrop & Mennen etc) as well as empirical data based on research on ships (Liners & Warships) of the period to give a soundly grounded and scientific basis to your designs. SpringSharp produces a written report in far more detail than the above resources.

Here is someone's modified version of the German armoured cruiser Scharnhorst (historic ship laid down January 1905):

SMS Scharnhorst ER, Long Range AC laid down 1905

Displacement:
10,926 t light; 11,370 t standard; 13,189 t normal; 14,591 t full load
Loading submergence 604 tons/feet

Dimensions:
144.60 m x 21.60 m x 8.37 m

Armament:
6 - 8.27" / 210 mm guns (3 Main turrets x 2 guns)
12 - 4.13" / 105 mm guns
Secondary guns mounted low & subject to being washed down in a seaway
2 - 3.46" / 88 mm QF guns
8 - 0.31" / 8 mm guns
Weight of broadside 2,161 lbs / 980 kg
4 - 17.7" / 450 mm above water torpedoes

Armour:
Belt 5.91" / 150 mm, upper belt 2.95" / 75 mm, ends unarmoured
Belts cover 130 % of normal area
Main turrets 5.91" / 150 mm, 2nd casemates 2.95" / 75 mm
Armour deck 0.98" / 25 mm, Conning tower 5.91" / 150 mm

Machinery:
Coal fired boilers, complex reciprocating steam engines,
Direct drive, 3 shafts, 30,665 ihp / 22,876 Kw = 23.00 kts
Range 8,000nm at 12.00 kts

Complement:
615 - 799

Cost:
£1.232 million / $4.926 million

Distribution of weights at normal displacement:
Armament: 270 tons, 2.0 %
Armour: 2,356 tons, 17.9 %
Belts: 1,434 tons, 10.9 %, Armament: 466 tons, 3.5 %, Armour Deck: 385 tons, 2.9 %
Conning Tower: 71 tons, 0.5 %, Torpedo bulkhead: 0 tons, 0.0 %
Machinery: 4,444 tons, 33.7 %
Hull, fittings & equipment: 3,456 tons, 26.2 %
Fuel, ammunition & stores: 2,262 tons, 17.2 %
Miscellaneous weights: 400 tons, 3.0 %

Metacentric height 4.5

Remarks:
Hull space for machinery, storage & compartmentation is cramped
Room for accommodation & workspaces is cramped
Ship has slow, easy roll, a good, steady gun platform

Estimated overall survivability and seakeeping ability:
Relative margin of stability: 1.26
Shellfire needed to sink: 7,163 lbs / 3,249 Kg = 25.4 x 8.3 " / 210 mm shells
(Approx weight of penetrating shell hits needed to sink ship excluding critical hits)
Torpedoes needed to sink: 1.2
(Approx number of typical torpedo hits needed to sink ship)
Relative steadiness as gun platform: 71 %
(Average = 50 %)
Relative rocking effect from firing to beam: 0.20
Relative quality as seaboat: 1.14

Hull form characteristics:
Block coefficient: 0.500
Sharpness coefficient: 0.38
Hull speed coefficient 'M': 6.14
'Natural speed' for length: 21.78 kts
Power going to wave formation at top speed: 51 %
Trim: 62
(Maximise stabilty/flotation = 0, Maximise steadiness/seakeeping = 100)

Estimated hull characteristics & strength:
Underwater volume absorbed by magazines and engineering spaces: 128.3 %
Relative accommodation and working space: 80.9 %
(Average = 100%)
Displacement factor: 96 %

(Displacement relative to loading factors)
Relative cross-sectional hull strength: 0.96
(Structure weight / hull surface area: 107 lbs / square foot or 521 Kg / square metre)
Relative longitudinal hull strength: 1.44
(for 13.12 ft / 4.00 m average freeboard, freeboard adjustment -2.88 ft)
Relative composite hull strength: 1.00

Same hull, engines and lay down date as historical SMS Scharnhorst.
ER = Extended Range.

 

[Timerover51]

Like Striker was a set of equipment creation rules only loosely connected to the starship construction rules, your "wet-ship" rules need be only loosely connected, as (unlike bad Japanese manga) they will never be going into space.

Here is a computer program which designs wet-navy ships.
http://www.springsharp.com/


Here is someone's modified version of the German armoured cruiser Scharnhorst (historic ship laid down January 1905):

After serious thought, "no comment" seems to be the wisest course.

Edited Note: While "no comment" might be the wisest course, the given ship has a machinery percentage of 40.67% per cent of the light displacement. That does not leave a lot of room below the water line for things like magazines, coal bunkers, and the odd living space.

For comparison, the German battleships of the "Helgoland" class also had vertical triple-expansion engines, output was 28,000 indicated horse power, machinery weight was 1,800 tons. The program has 4,444 tons of machinery weight producing 30,665 indicated horsepower. The additional 2,665 ihp costs 2,644 tons in additional machinery weight. Absolutely fascinating.

The German 21cm projectile weight 238 pounds. The 10.5cm projectile weighed 38.4 pounds. The broadside presumably would be 6 X 21cm guns and 6 X 10.5cm guns. That gives 1428 pounds plus 230.4 pounds for a grant total of 1658.4 pounds. That is a bit lighter than 2,161 pounds. Unless, of course, an 88mm projectile weighs 502.6 pounds. Actual weight is 22 pounds. Maybe the difference comes from the 8mm machine guns.

Oh, one other thing. The Germans did not go to superimposed turrets for heavy guns until 1908, so I am not sure where that third 21cm turret is mounted.

Looks like a program that you would use to design the ironclad battleship, HMS Captain. Such a long-lived and successful ship the Captain was, not.

 

[McPerth]

I'm not sure what perecentage of volume is underwater in a ship

I'm not an engineer, but if half the mass of a ship is underwater, and half above, then the center of mass is about at the water line, and ... doesn't that make it susceptible to rolling over in high seas?

Neither I am engineer, so I began with the quote above. The 50% I gave was just to keep with the example Fritz_Brawn gave and to show where his numbers failed. About exact numbers, we better look at what Timeover51 gives, as he shows to have quite more knowledge about the matter than myself.

In any case, as machinery use to be under flotation line and is heavier than the staterooms above the flotation line, that should lower the center of mass of the ship, giving it stability.

About staterooms, I've been twice in cruisers (not in so luxurious one and the Freedom of the Seas), and staterooms are nowere 4 dt each. The stateroom were me, my wife and my daughter were in one of them would not have been a small stateroom in traveller. They use to be quite cramped.

Of course, dining rooms, promenades, etc. accounts for more volume, but I guess the fact that you can go to the deck and see the sky over you head also helps to reduce the volume needed (as the fact you're calling a port daily), as there is not the claustophobia sense you'd have in a starship (once again, submarines excluded).

 

[BytePro]

...
Next, the ship is listed as having a passenger capacity of 3634 with an additional crew of 1360.

The passenger capacity is for double occupancy (see link in prior post).

Staterooms (with common spaces) of less than 30% total internal volume for a luxury cruise ship works well enough - and leaves plenty of volume for extravagant entertainment spaces, etc.

For more conservative designs, especially military bunking, double bunked half-staterooms would probably come close given Traveller (CT) stateroom tonnage subsumes life support, common areas and consumables...

 

[PFVA63]

The passenger capacity is for double occupancy (see link in prior post).

Staterooms (with common spaces) of less than 30% total internal volume for a luxury cruise ship works well enough - and leaves plenty of volume for extravagant entertainment spaces, etc.

For more conservative designs, especially military bunking, double bunked half-staterooms would probably come close given Traveller (CT) stateroom tonnage subsumes life support, common areas and consumables...

Hi,

I realize that the ship has double occupancy (as I noted in my original post) but since the ship has a lot more interior passageways and common spaces, I believe that the 4dton per passenger (from Traveller) would be a much more reasonable number to use.

Looking at the info for the Freedom of the Seas on its website it notes that:

a standard inside cabin is 150.7 square feet of deck space
an accessible interior stateroom is 264 sq ft
a promenade stateroom has 160.4 sq ft
an accessible promenade stateroom 264 sq ft
a family interior stateroom 323 sq ft
and a promenade family stateroom 300 sq ft.

Assuming the ship were laid out in nominal Traveller deck squares 50 sq ft of deck area is very close to 1dton (assuming a 3m/10ft deck height from Traveller). Thus you would end up with:

a standard inside cabin is just about 3dtons
an accessible interior stateroom is about 5.28 dtons
a promenade stateroom is about 3.21 dtons
an accessible promenade stateroom is 5.28 dtons
a family interior stateroom is about 6.46 dtons
and a promenade family stateroom is about 6 dtons

While these staterooms can accommodate more than just a single passenger each, you can see that assuming a standard 4 dtons per stateroom is probably not necessarily a good approximation, and once you consider all the other interior stuff needed, like passageways, common spaces, and life support (such as plumbing etc) the space needed for the passengers and crew is likely to be quite high.

 

[PFVA63]

After serious thought, "no comment" seems to be the wisest course.

Edited Note: While "no comment" might be the wisest course, the given ship has a machinery percentage of 40.67% per cent of the light displacement. That does not leave a lot of room below the water line for things like magazines, coal bunkers, and the odd living space.

For comparison, the German battleships of the "Helgoland" class also had vertical triple-expansion engines, output was 28,000 indicated horse power, machinery weight was 1,800 tons. The program has 4,444 tons of machinery weight producing 30,665 indicated horsepower. The additional 2,665 ihp costs 2,644 tons in additional machinery weight. Absolutely fascinating.

The German 21cm projectile weight 238 pounds. The 10.5cm projectile weighed 38.4 pounds. The broadside presumably would be 6 X 21cm guns and 6 X 10.5cm guns. That gives 1428 pounds plus 230.4 pounds for a grant total of 1658.4 pounds. That is a bit lighter than 2,161 pounds. Unless, of course, an 88mm projectile weighs 502.6 pounds. Actual weight is 22 pounds. Maybe the difference comes from the 8mm machine guns.

Oh, one other thing. The Germans did not go to superimposed turrets for heavy guns until 1908, so I am not sure where that third 21cm turret is mounted.

Looks like a program that you would use to design the ironclad battleship, HMS Captain. Such a long-lived and successful ship the Captain was, not.

With regards to a program like Springsharp it is my understanding that it would likely be too convoluted for use for something like Traveller as there are a number of items within its programing that are not necessarily well defined and subject to a fair bit of interpretation (especially with respect to the survivability and seakeeping stuff in the inputs and output).

 

[PFVA63]

With regards to modern naval vessels, here is some additional information that I have accumulated over the years, including data on volume requirements.

http://www.mnvdet.com/Post-Processor Vol.htm

With respect to personnel volume, there is a plot from that website showing the growth in personnel on many modern warship designs in terms of cubic meters/person versus year built. For ships built after 1970 or so you can see that one recommendation for volume is about 21.2 cubic meters per person, and this has likely gone up a bit since that time.

In addition to the specific volume for just the personnel, there would also be requirements for things like passageways, heating ventilation and cooling equipment, plumbing, water tankage and drainage tanks, offices, stores and supplies and other such items some of which would likely fall into the definition of "life-support" for modern vessels (currently I can't remember were stuff like galleys and mess decks and such are included but they too would also need to be accounted for).

From the data on that website it can also be seen that a rough estimate for passageway volume is about 10.5% of the ship's total enclosed volume +/- a small constant.

Other info on another pages of this website provides further info on volume requirements for other things like weapons and sensors, machinery and other such items.

 

[Timerover51]

If you want to spend the time working up some sort of design system for modern and post-modern wet naval vessels, go ahead.

 

[PFVA63]

Hi

I've been considering trying to do something along those lines, but right now I've misplaced some of my data.

In the mean time, here is a plot that I put together from an article I recently ran across that compared naval ship designs over a period of time. It shows total vessel weight (hydrostatic displacement) divided by total volume (in dTons) versus year built. It seems to kind of show that back in the mid to late 1800's a weight of just around 7mt per dTon may have been typical, with this value starting to drop off around 1900 or so, reaching about 4 (+ or -) in modern modern times. (One specific item of note also being that the lowest point on the graph I believe represents an early weight for the USN's FFG-7 class, which over time grew in weight a fair bit, with its weight per dTon increasing a bit accordingly, putting it even closer to the value of the other two more modern ships shown on this graph, of about 4mt/dTon.

I figured such a graph might be useful in helping a player in getting a rough idea of how big (in terms of dTons) to make a ship given the listed hydrostatic displacement of similar real world known vessels.

I had hoped to take some of the data I had in my other files and fill this curve out a bit, but I can't find my original spreadsheet that contained that data right now.

 

[Timerover51]

Galley and Mess Area Dimensions

The following dimensions are taken from some high-quality general arrangement drawing of a US Coast Guard 180 foot buoy tender that I have. They should give an idea as to the space required for the same facilities on a Traveller starship. The crew size of the ship was about 55 or so personnel.

Galley: Fore and Aft, 15.5 feet
Abeam, 15 feet

Crew Mess: Fore and Aft, 22 feet
Abeam, 10 feet

CPO Mess: Fore and Aft, 14 feet
Abeam, 8 feet

Wardroom: Fore and Aft, 17.5 feet
Abeam, forward 17.5 feet
Abeam, aft 15.5 feet