Ship Design

Ship Design


Age of Sail ships are different enough that several changes need to be made to the Gurps: Spaceships design system to accommodate those differences, although the same general system can be used. Those changes are detailed here.

Firstly, Age of Sail vessels need not use decade-scale HP, damage, DR etc. All systems below use normal scale.

Secondly, since all vessels use the Design Switches: Hidden Batteries, Lacks Automation, Nautical Lines, Top Deck (Spaceships 7, pages 19 to 22) and the Design Features: No Computer, Pre-Radio (Spaceships 7, p24), these are assumed in system specifications.

All Age of Sail ships are elongated boxy vehicles, so take the +1 for SM noted in Basic (p19). This shifts SM one place in comparison to the table in Spaceships 1 (p9).

All vessels are built of wood, limiting maximum size. At over 225 feet long, the ship’s timbers flex greatly in any kind of swell, allowing water into the ship and potentially sinking it if the water is not continually pumped out. Historically, the answer to this was to use steel cross-braces and keel struts to reinforce the ship, allowing lengths of up to 330 feet, but that didn’t begin until around the 1820s. Ships in Arcanum are limited to the lower ranges of SM+11, with lengths of up to 230 feet and displacements of up to 5,400 tons. Vessels below SM+4 are generally too small to have systems in the same sense and can be thought of as boats rather than ships.

Spaceships ship designs have three hit locations. For sailing vessels, the front section would be the Fore section – forecastle and foredecks; the central section would be the Mid decks plus a Core section; and the rear would be the Aft section – quarterdeck plus aft decks and a Core section. Each section will have a Top Deck open to the air, with any sails above it. It will help to produce a standard format for showing where and how systems are distributed.

Thus, for a full-sized 1st Rate or 2nd Rate warship or a large cargo ship, the slot distribution would look like this:

Fore Mid Aft
Sails Sails Sails
Forecastle (open) Upper Mid-deck (open) Quarterdeck (open
System System System
Foredeck Middle Mid-deck Afterdeck
Lower Foredeck Lower Mid-deck Lower Afterdeck
Fore Orlop/Hold Mid Orlop/Hold Aft Orlop/Hold
Core Core

The “System” slots above could be for Armor, Batteries, Small Boats etc. It should be noted whether these sections are Open Decks or not. All this plus judicious use of split systems, whereby a section can be split into 3 systems each one SM smaller, should allow for modelling of most Age of Sail ships.

For this design system, we’ll be introducing the concept of an “Empty Slot”, a section with nothing in it – that actually doesn’t exist for that vessel. Empty Slots can denote less than 3 masts for Sails or less than the maximum of decks, effectively introducing variable section numbers instead of always having 20 sections. They give reductions in overall Loaded Weight as well as bonuses or minuses to speed, handling etc. – see the individual system descriptions for details.

Hull Size Table
Length SM Max. Loaded Wgt ST/HP Hnd/SR
15-21 feet +4 3 tons 100 0/2
21-30’ +5 10 tons 150 -2/3
30-45’ +6 30 tons 200 -1/3
45-60’ +7 100 tons 300 -2/4
60-90’ +8 300 tons 500 -3/4
90-150’ +9 1000 tons 700 -3/5
150-210’ +10 3000 tons 1,000 -3/6
210-230’ +11 5400 tons 1,500 -5/6

System Descriptions

Not all systems described in the Spaceships volumes are applicable to the design of Arcanum ships, and the applicable ones are different enough that it is worth detailing the differences below.

Armor, Wooden [Hull]
SM +4 +5 +6 +7 +8 +9 +10 +11
DR 6 7 10 15 20 25
Cost ($) 0 0 2K 6K 20K 60K 200K 600K

1. See Spaceships 7 (p5). Only locations with an armor system are protected by the armor rating in that location.
2. SM+4-5 Ships without armor, or locations without armor systems, have DR equal to SM/2 round down.

Cargo Hold [Hull]
SM +4 +5 +6 +7 +8 +9 +10 +11
Tons 0.1 0.3 1.5 3 9 30 90 150

1. See Spaceships 1 (p13).
2. Special Options: Smuggler’s Cargo – Each ton of cargo capacity sacrificed provides 0.5 tons of concealed cargo capacity and costs $4K.

SM +4 +5 +6 +7 +8 +9 +10 +11
Control Stations 1 1 1 2 3 4 6 10
Workspaces 1 1 1 1 2 2 4 4
Cost($) 6K 20K 60K 200K 600K 2M 6M 20M

1. Replaces “Control Room”, see Spaceships 1 (p14).
2. Because Age of Sail ships only had a wheel or tiller, not complex control stations, Control Stations represents the number of people – usually officers or NCOs – needed to command the vessel effectively while Workspaces represents the crewmen manning the actual wheel or tiller. For targeting and navigational calculations officers rely on their own abilities and charts, slide rules, books of logarithmic tables and so forth. Gunnery attacks are made at a -5 penalty.

Ship Design

Arcanum 1780: A New World Cernig