The War Times Journal Home Page


Design Formulas

These formulas were used to establish all of the basic values shown in the Battlefleet 1900 Ship Values pages. Note that despite these guidelines, some ship values may vary slightly due to the complex nature of period naval architecture and the scarcity of information on many vessels. If the numbers seem to vary too much, or there are just too many unknown factors about the design you want to re-create, make sure to have some of the more common technical sources available for reference. These include Conway's All the World's Fighting Ships 1860 - 1905 as well as the Arco Publishing reprint of Jane's Fighting Ships 1905-1906. Both of these titles have some errors in them, but the amount of valuable information they contain far outweighs the minor issues.

Ship size – Normal displacement multiplied by .004. Values of larger vessels (over 25) are rounded, usually to nearest 5.
Speed – Quote actual vessel's speed in knots (nautical miles per hour). The Scales Page supplies formulas for converting actual ship's speed to game scale speed. The game scale speed is not quoted in the ship values lists because there are several different game scales available.
Stability – Either Good or Poor. A vessel is usually considered good unless it was known to have poor stability.
Seaway – Either Normal or Poor. A vessel is usually considered normal unless unless known to be poor for its size. Players should not automatically give small vessels a poor rating, because the seaway effects table (see Optional Rules) already takes vessel size into account. So a typical torpedo boat should still be listed as normal so long as it is normally seaworthy for a torpedo boat.

Thickness Modifiers
Krupp (6" and over only) 1.25
Nickel Steel 1.00
Steel 0.90
Compound 0.70
Wrought Iron 0.50

Armor Values
The two numbers used to express a vessel's armor rating represent the protection for vitals and upperworks respectively. Original armor values used to establish these ratings are all in inches. The various factors used to calculate the final numbers are defined below:

BLT = Thickest belt value
SLP = Average slope thickness of armored deck, only when it slopes down to bottom edge of belt. Vessels without sloping side AD should omit the SLP value.
MAIN = Averaged Thickest Turret and/or Barbette/shield. Do not include thin shields which are 50% or less in thickness compared to the barbette. See optional rule #502.
AMID = Average thickest secondary turret/shield and/or casemate/battery/upper belt. In some cases where there is thick armor over a very small area there are two options: Use half the thick armor value (average with 0) and adjust the upperworks protection accordingly, or use the full thickest armor values instead of averaging and bump the upperworks protection rating down one level from what it otherwise might have been. Check probable combat chart results for most satisfactory combination. Example of later method is USS Albany which gets full benefit of its 4" gun shields but has a "none" upperworks protection.
LowAD = Lower armored deck below the belt. Used on French designs which included better protected machinery and magazine spaces.

Rounding for final armor value of x.2 or over is always up. A vessel whose final calculation total is 15.2, rounds up to a 16. A value of 15.19 rounds down to 15. Minimum armor for both values in all ships is a 1. Unarmored areas of all vessels are a 1/2. Barbette ships with no sloped AD (IE - AD on top of belt) should use formula similar to #4, ignoring the SLP addition. Protected cruisers which have some or all of the largest armament in heavy (4" +) gun shield should have those values included in the Vitals value and as a result, those guns must be considered as mains, not secondaries. Otherwise, general unshielded or lightly shielded weapons grouped in single mounting will usually be considered as secondaries.

Armor Formulas
Type Vitals Formula %
#1 Barbette battleships with wide (10'+) belts [BLT + (SLPx1.5) x .50] + [MAIN x .50] 1.00
#2 Barbette or large turret battleships with narrow (7') belts [BLT + (SLPx1.5) x .45] + [MAIN x .50] 0.95
#3 Turret battleships with narrow (7') belts and sloped AD [BLT + (SLPx1.5) x .45] + [MAIN x .45] 0.90
#4 Turret battleships with narrow (7') belts and top AD [BLT x .45] + [MAIN x .45] 0.90
#5 Turret battleships with narrow (7') belts and LowAD [BLT + (Lower ADx3.0) x .45] + [MAIN x .45] 0.90
#6 Central redoubt ships [BLT x .45] + [MAIN x .45] 0.90
#7 Armored cruisers with large main turrets [BLT + (SLPx1.5) x .45] + [MAIN x .45] 0.90
#8 Armored cruisers with medium main turrets [BLT + (SLPx1.5) x .45] + [MAIN x .40] 0.85
#9 Armored cruisers with small main turrets/casemates [BLT + (SLPx1.5) x .50] + [MAIN x .35] 0.85
#10 Armored cruisers with no turrets [BLT + (SLPx1.5) x .75] 0.75
#11 Protected cruisers w/armored mains [(SLPx1.5) x .55] + [MAIN x .20] 0.75
#12 Protected cruisers w/o armored mains [(SLPx1.5) x .60] 0.60
  Upperworks Formula  
All vessels [AMID] 1.00

There are two "category" modifiers used to help control a vessel's level of protection under fire. They jointly cover the crucial areas of waterline and upperworks protection, and the assignment of each has a fairly important impact on a ship's performance during battle. Below are the guidelines used to establish the use of these ratings.

Type Guideline
Great Ships with two full decks of battery armor or;
Ships with one full deck of battery armor and entirely casemated/turreted secondaries
Good Ships with one deck of battery armor and some casemated secondaries or;
Ships with less than one full deck of battery armor but turrets or entirely casemated secondaries
Poor Ships with less than one full deck of battery armor or;
Casemate/battery/turret protection for some - but not all - secondaries
None Ships with no battery, casemate or secondary armor to speak of. Guns with shields do not count toward next higher level, although their full armor value may still be used.

Type Fore & Aft Waterline Belt Fore Waterline Belt only
Great 4 inches or more
Good 2 to 3 inches 4 inches or more
Poor No 2 to 3 inches
None No belt amidships either ---------------------------->

Size – Original shell weight in pounds divided by 14. Values of larger guns are then rounded to nearest 5 or 10 to speed game play. Most shell sizes under 15 use actual value without rounding.
Rate of Fire – This is a somewhat abstracted figure based loosely on a gun's theoretical rate of fire combined with the probable rate of fire during a battle.

Rates of Fire
ROF Types
2 Light and medium-light QF (quick fire) weapons.
1 Medium and large all-round loading
Medium-light caliber BLR
½ Large caliber end-on loading
Medium-large caliber BLR
¼ Very large BLR (breeching loading rifle)
Old MLR (muzzle loading rifle)

Gun Assignments
Main vs Secondary – Some light vessels that have little or no armor above the AD as well as no real armored main gun positions may have their main gun positions assigned secondary position status. Care must be taken when assigning main, secondary and tertiary weapon status to a ship armament list because it has a dramatic effect on how the vessel sustains damage. However, by manipulating and adjusting these assignments, players have a powerful tool for relating many different types of ship designs.

Boat Guns – Total all light guns of 12pdr or less according to weight and divide by 12. Sum is the number of boat guns. For example: A vessel with 2-12pdr and 8-6pdr light guns would have six boat guns for game play.

Equals average penetration of nickel steel at 2000, 5000 and 8000 meters range. Many guns posted in existing Battlefleet lists will match guns of ships not yet posted, so these are good places to hunt for gun values if penetration data seems otherwise unavailable.
  Copyright © 1996-2003 by The War Times Journal at All rights reserved.
All games shown here may be freely downloaded for personal use only. Not for resale or any other commercial venture not authorized by The War Times Journal.