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Ship Design Guidelines

Where in doubt, rely on common sense and historical practice. 

This is a "living" document; entries may be added as events or discussions warrant them.

Block-coefficients

0.38 is the absolute minimum.  Coefficients should be reflective of the size and speed of the vessel.

Architecture

Any ship with main guns larger than 7 inches is generally built to the BB/AC "architecture" meaning the technology rules for BBs and/or ACs apply. Any ship with guns 7 inches or less may be built to the Light Cruiser "architecture". Ships may be built to the TB/DD "architecture" rules, provided they meet the minimum requirements for such ships.

Exceptions to architectural classifications may be granted by the Moderators at their discretion. This is to allow for ships of unusual design or concept, and for certain OTL historical outliers that do not fit as easily in this system.

Hoists

Protected cruisers should have hoists with the gun mounts, if the appropriate technology has been researched. Destroyers of WWI had no hoists for individual guns.  A cruiser without hoists has a lower sustained rate of fire, and is more vulnerable due to the ammo exposed on the deck.

Hull Strength

Minimum 0.50 cross-sectional hull strength for ships built to Destroyer/TB tech; otherwise, composite hull strength of 1.00 is recommended.  Ships not meeting this criteria are at risk of moderator-inflicted incidents.

Length to Beam Ratio

Ratios should be reflective of the size and speed of the vessel.

Length to Beam Ratios of 12:1 (smaller, faster ships) or 10:1 (larger or slower ships) or less are reasonable and do not risk moderator-inflicted incidents.  Ships approaching circular shape risk moderator-inflicted performance issues.

Miscellaneous Weights

This will be added to as new items are suggested or become available.

Boats:  Typical ship's boats are part of fittings.  Extra boats, landing craft, or attack craft require 2 t of miscellaneous weight per tonne of boat weight:  the difference accounts for cranes and hull reinforcements.

Coalling/Oiling Gear:  Considered part of ship's fittings.

Depth-charges:  1 t per three depth charges, including rails.  1 t per thrower, once available.

Fire Control:  250 t for ships built to BB/AC Architecture; 100 t for any other ship above the nation's maximum DD/TB size; 25 t for DD/TB and ships of similar size.  Monitors may use the next-smallest system, but will suffer in engagements against moving targets.

Fluff:  Flag facilities, medical facilties, climatization, extra pumps, and so forth are assigned weight as the player sees fit.  Moderators may assign performance bonuses to the ship under specific circumstances if the facilities warrant it.

Mines:  1 t per mine, including associated laying and storage equipment.

Radar and Remote-Hearing Devices:  25 t per installation is recommended, though the effectiveness of these devices is questionable.

Torpedoes: Torpedoes will be assigned a miscellaneous weight value equivalent to the tonnage listed in SS3 for the weight of a given torpedo. The integrated torpedo section does not reliably add in the needed weight into designs, hence the use of miscellaneous weight.

Troops:  1 t per four troops for short-ranged landing craft.  2 t per troop for long-term (> 1 day) embarkment.

Wireless:  10 t for a short-range (100 mile) set, 25 t for a long range (250+ miles) set.  Redundant installations are allowed.  New construction laid down 1/1/13 or later does not require weight to be set aside for short-ranged sets.

Shafts

Four shafts are the most that may be installed aboard a ship.

Speed

For ships not constructed to Destroyer/TB tech, the SS3 reported top speed is just that. For ships constructed to Destroyer/TB tech, the SS3 reported top speed should be considered that ship's top in-service speed in a seaway. To calculate the speed attained by that ship on trials in smooth water, you can use the following equation:

To calculate the trial speed, first find the base bonus derived from it's light displacement, starting with what "band" the ship is in:
<=210: 6 knots
<=250: 5 knots
<=500: 2.75 knots
<=750: 1.5 knots
<=1000: 1.125 knot
<=1500: 0.75 knots
<=1750: 0.6 knots
<=2000: 0.5 knots
over 2000 tons: 0 knots

In each band, then divide the bonus for that band by the value of the light displacement divided by the upper limit of that band..

So for instance, for a 450t (light) dd, do this: 2.75 / (400/500) = the "base" bonus of 3.44 knots.

Then mix in the machinery modifier, which is simply the normal displacement percentage of machinery/0.6 (so that a machinery weight of 60% = 1), then multiply the base bonus above by that figure.

For one example ship:
Displacement: 250t
Mach %: 51.7 (or after divided by 100, 0.517)
Speed: 28.08

Base bonus: 5 / (250/250) = 5
Mach modifier: .517/.6 * = .861667

So the bonus = 5 * .861667 = 4.31 (rounded to 2 decimal places), or 4.5 (rounded to the nearest half knot), giving a new clean water optimal condition trial speed of 32.5 knots (using the half-knot rounded figure).

Or for ease of use, use this calculator:




Springsharp

SS3 is the program we use.  We do not use SS2.  If the ship can not be designed from scratch in SS3 using our design guidelines and naval technology trees, the design is invalid.

Transom Sterns

The utility of this hull form is not yet recognized and is not to be used in designs.

Sailing  Rules

Sailing rigs
A sailing rig to propel a ship, in normal conditions, at a cruising speed of 1/2 the hull's natural speed,  will weigh 5% of the ships NORMAL displacement.  Each additional knot of possible speed, up to the hull's natural speed, will weigh 1% of the ships normal displacement.  Each additional knot of possible speed, above the hull's natural speed, will weigh 2% of the ships normal displacement.  In the proper conditions, a normal ship-rigged vessel can exceed it's cruising speed by up to 5 knots, by setting extra sails and sailing across the wind.

Sailing
Generally, a sailing voyage has to consider the wind.  If travelling east or west around the globe, the savvy captain will make use of the trade winds to push him on his way.  If travelling north or south, the captain will be cutting across the trade winds in the higher latitudes, but must be aware of the lack of trade winds in the equatorial regions and adjust his route accordingly to make use of more coastal winds (with the related risks of shoal waters and hostile shores).   Sailing ships generally cannot move upwind, they can only move  across the wind or downwind.  Also, note that the normal sailing cruise speed is governed not only by the ships capability to catch the wind, but by the wind available: if the wind is blowing at 10 knots, a ship with the ability to cruise under sail at 20 knots will not make 20 knots, because there's not enough wind to drive the ship at that speed.

Steam and sail operation
It is quite possible to operate under both steam and sail power at the same time, should the wind be running in the proper direction and the captain desiring more speed.


Example:
A ship has (in SS3) a natural speed of 18 knots.  If 5% of the ships normal displacement is reserved as above-decks miscellaneous weight and designated as sails and rigging, this ship would have a normal cruise speed, under sail, of up to 9 knots (because that is half of 18 knots).  Up to an additional 9% of the ships normal displacement could be reserved as above-decks miscellaneous weight and designated as sails and rigging, which would bring the normal cruise speed, under sail, up to 18 knots.  If the designer wanted to allow for even more speed under sail, an additional 2% of ships normal displacement could be installed to bring the normal sailing cruise speed up by 1 knot.