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Wednesday, January 16th 2008, 5:11am

Springsharp Guidelines for Ships

Carriers. Spring Style is designed for ships armed
primarily with guns, but carriers become important from the
end of World War I on. Here is a method for simming carriers:

Design the ship as you normally would. Put in as much
"miscellaneous weight" as you can - that will usually
determine how big an airgroup your CV can carry. Now,
get out your pocket calculator. You'll make two pretty simple
calculations, each of which gives a possible airgroup limit.

1) Take the square root of miscellaneous weight; e.g., if
miscellaneous weight is 10,000 tons, the weight-based limit
for your carrier is 100 aircraft. (In addition, allow at
least 25 tons per aircraft, i.e., if miscellaneous weight
is just 100 tons, your ship can carry 4 planes, not 10.)

2) Multiply length x beam (both waterline) and divide by 750;
e.g., if your CV is 900 ft x 100 ft, the space limit is 120

For the metric gang, divide by 70 instead; if your CV is
280 metres x 30 metres, the size limit is also 120 aircraft.

Use waterline dimensions (if available), NOT flight deck
dimensions; they can vary a lot more, and we want a
consistant rule.

Your carrier's airgroup is whichever number is LOWER.
So in the example above, your CV has an airgroup of 100
aircraft. (That is for WW II or earlier planes. For postwar
CVs with jets, I'd estimate about 2/3 of the airgroup
calculated by this method.) Usually, the weight rule gives
a lower number of planes and thus sets the limit; the size
limit will usually apply to CVEs converted from merchant
ships with a great deal of miscellaneous weight.

Use a word processor, etc., to adjust your ship
report. I list the air group above guns, since it is
obviously a carrier's main armament!

Conversions: If you convert a battlecruiser, etc., to a CV,
follow the same basic procedure. Start with the original
ship, modify main guns, armor, etc., put in miscellaneous
weight (i.e., the flight deck), and there is your carrier.

Note: This rule works pretty well for American and Japanese
carriers. British-type carriers with armored flight decks
may require a lower airgroup limit, perhaps 2/3 the number
generated by this rule.


Submarines: Spring Style is designed for surface
ships, and isn't really suited to sub sims. (Rolf
Hoffman has created an excellent pencil-and-paper sub
sim rule, which will be added to my website once
formatted.) However, a fairly decent approximate sub
sim can be done using Spring Style:

You will sim your sub in awash condition, just
about to go under. Specify depth as about 2/3 of
beam; this seems typical for subs of pre-nuke era.
Provide "miscelleneous weight" of about 1/4 to 1/6
of normal displacement - this is your ballast tank.
(Some nations' real subs had closer to 1/3, but
this will not sim well.)

For freeboard, enter zero. (To avoid computer
error, the program will adjust this to 0.1 ft
(0.03 metre). You'll get a "horribly cramped"
warning - ignore it. However, if your sub has
stability less than 1.0, you'll have to redesign
it. Always enter steadiness of 50 pct. (If you cheat
to get more stability, whoever re-runs the sim will
catch you!)

Multiply composite hull strength times 100 to
get operational diving depth in feet. (Multiply by
30 for depth in metres.) Emergency diving depth
is 1.6 times operational depth; crush depth is 2.5
times operational depth.

You will find that the smaller the ballast
tank, the deeper your sub can dive. However, the
ballast tank is your reserve bouyancy, and will
determine how much depth-charging you can take
and still make it back up!

Adjust your report file. Just delete all those
warnings about lack of seaworthiness - a dived sub
obviously isn't seaworthy by surface-ship standards.
Specify crew as about half the listed minimum.
Don't forget to list operational diving depth.


Monday, February 22nd 2016, 10:25pm

Guidelines for how to sim ocean liners.


Ocean Liners: These are a special class of merchant ships, which obviously carry mainly people, not cargo. In wartime they may serve as troop transports or as fast armed merchant cruisers. For liners, miscellaneous weight may include some cargo capacity, but mainly represents the weight of the passenger accommodations - cabins, dining saloons, promenade decks, and so forth.

To sim a liner, provide miscellaneous weight for passenger accommodation as follows (in addition to any miscellaneous weight used for cargo, perhaps 10-20 pct of the total). Required miscellaneous weight can be estimated as follows:

Liners laid down up till 1900: 4 tons per cabin-class passenger, 1.5 tons per steerage passenger (i.e., immigrants to America).

After 1900: multiply the above figure by 1 plus (date - 1900) / 25. Thus, for example, a liner laid down in 1910 will require 1.4 times the miscellaneous weight needed for one laid down in 1900 or earlier; a liner laid down in 1925 will require twice as much.

For liners used as troopships, assume they can carry one soldier per 2 tons of miscellaneous weight. When simming a liner, allow plenty of freeboard - at least half the beam, or even 60 percent. When you compute gross registered tonnage, add 10-20 percent - this allows for the extensive superstructures of liners. Displacement + (freeboard x loading submergence) / 2.5 is a handy formula to use, and adds 14 percent to the standard cargo ship figure.

The gross registered tonnage of a liner should be at least equal to her displacement, typically about 20 percent more (the Normandie had a registered tonnage close to twice her displacement).

The baseline gross registered tonnage of a liner built in 1900 or earlier should be 15 tons per cabin passenger and 5 tons per steerage passenger. Multiply this by the same formula as above for ships built later than 1900.

Note: In practice, when you sim a liner you may have to use the formulas in the other direction - your ship will have a given miscellaneous weight, and you'll have to determine how many passengers she can carry.

Suppose you lay down a liner in 1910, and she has 8000 tons of miscellaneous weight. You allow 1000 tons for cargo, leaving 7000 tons for passengers. Divide by 1.4, the multiplier for 1910 to get 5000. If 4000 tons of that is alloted to cabin passengers, she can carry a thousand cabin passengers, the remaining 1000 tons of date-adjusted passenger weight capacity allows her to carry 667 steerage passengers. This liner should have a gross registered tonnage of at least 25,669 tons.