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navigation_skill

Navigation (Skill)

Use this skill to prevent yourself from becoming lost, to plot a course, or to identify your location by checking the stars, landmarks, ocean currents, or a GPS device.

Check: Make a Navigate check when you're trying to find your way to a distant lo-cation without directions or other specific guidance. Generally, you do not need to make a check to find a local street or other common urban site, or to follow an accurate map. However, you might make a check to wend your way through a dense forest or a labyrinth of underground storm drains.

For movement over a great distance, make a Navigate check. The DC depends on the length of the trip. If you succeed, you move via the best reasonable course toward your goal. If you fail, you still reach the goal, but it takes you twice as long (you lose time backtracking and correcting your path). If you fail by more than 5, you travel the expected time, but only get halfway to your destination, at which point you become lost.

You may make a second Navigate check (DC 20) to regain your path. If you succeed, you continue on to your destination; the total time for your trip is twice the normal time. If you fail, you lose half a day before you can try again. You keep trying until you succeed, losing half a day for each failure.

When faced with multiple choices, such as at a branch in a tunnel, you can make a Navigate check (DC 20) to intuit the choice that takes you toward a known destination. For instance, if following paths through a mountainous region, you can choose the path that takes you toward a village that you know lies to the northeast. If unsuccessful, you choose the wrong path, but at the next juncture, with a successful check, you realize your mistake.

You cannot use this function of Navigate to find a path to a site if you have no idea where the site is located. Your GM may choose to make the Navigate check for you in secret, so you don't know from the result whether you're following the right or wrong path.

You can use Navigate to determine your position on a familiar planet without the use of any high-tech equipment by checking the constellations or other natural landmarks. You must have a clear view of the night sky to make this check. The DC is 15.

The complexities of space travel and drivespace are such that each requires special applications of the Navigate skill.

Astrogation: Plotting a course through drivespace for a ship’s stardrive is known as Astrogation. The process of calculating a course from one star system to another generally takes 2d4 minutes, provided a comput-er of at least PL 6 and a sensor array class II (or better) are available to assist. Without an adequate computer or sensor system, the check takes 2d4 hours and incurs a +5 in-crease to the DC. The time required to plot the course can be decreased by one step (hours to minutes, or minutes to rounds) by taking a +5 increase to the DC. See the chart for check DC’s.

The astrogation check is generally rolled in secret by the Gamemaster, as the character doesn’t know until starrise how well the course will work out. The exact results of the check depend on how high the character’s check is compared to the DC.

Whenever starrise is off-course by any distance, roll on the following chart to deter-mine direction. All given directions are relative to the ship’s facing upon arrival at the tar-get destination. Roll d12 to determine direction. On results of 10 and 12, roll again, ignoring further results of 10 or 12, and add the new direction.

For example, a character with a +8 Navigation skill bonus is plotting a course be-tween a familiar and an unfamiliar system (base DC 15). Unfortunately, corsairs have been detected on an intercept course with her vessel, so the astrogator rushes the course (+5 DC). To further complicate matters, the system from which the vessel is star-falling is currently experiencing massive sun-spots, wreaking electromagnetic havoc (+5 DC). The total DC for the course is 25 (15+5+5) and the GM rolls a 9 for the astrogation check, resulting in a check of 17 (9+8). Because the check is more than 5 below the DC, but not 10 below, the ship starrises 3d10 light years off course. The GM rolls 14 on 3d10 for the distance, then rolls a d12 for direction. The resulting 10 means the vessel appears “above” the destination, and the GM rolls again, getting a 1, meaning the vessel is “up” and “forward” of its target destination by 14 light years. This will probably just mean the ship has to make an additional starfall to get to its destination, unless something is going on where the vessel starrises…

Note that many interstellar voyages will require multiple starfalls, especially for smaller ships. This requires the astrogator to make separate checks for each starfall, each to be resolved individually. Despite the seeming uncertainty of stardrive travel, it is the only (relatively) quick way to travel from star system to star system, and the risks can be minimized. Taking adequate time to plot a course, and buying library files of regularly traveled routes can make an enormous difference, and there are computer programs and special abilities that can provide bonuses to astrogation checks. Characters can also take 10 on astrogation checks, but cannot take 20.

Space Travel: Traveling through space within a star system is not quite so simple as moving in a straight line from one point to another at a given speed. Gravity, congested space lanes, and any number of other compli-cating factors can not only make a trip take longer, but can also give a savvy navigator a chance to shave time off the trip by taking advantage of conditions in the area.

In general, navigating through space is much like navigating on a planet. A character can use a Navigate check to plot a course or to determine his location. Determining lo-cation works exactly as it does on a planet. When plotting a course through a star system, however, a good enough check can not only get you where you’re going on time, but get you there even quicker than normal travel would suggest. In order to plot a course through a star system, determine the base travel time normally (distance divided by cruising speed), then take a full-round action to make a Navigation check (DC determined by base travel time, as shown below).

If the check fails, you still reach the destination, but it takes twice as long. If you fail by more than 5, you get halfway to the destination in the expected travel time, then must make another Navigation check or be lost. If the check succeeds, you reach the destination on time. If the check succeeds by 5 or more, you arrive at the destination in 10% less time than expected per 5 above the DC that the check was.

Special: You can take 10 when making a Navigate check.

You can take 20 only when determining your location, not when traveling.

A character with the Guide feat gets a +2 bonus on all Navigate checks.

Time: A normal Navigate check is a full-round action. Astrogation takes longer; 2d4 minutes with the right resources, 2d4 with-out.

Length of Travel DC Short (a few hours) 20 Moderate (a day or two) 22 Long (up to a week) 25 Very Long (more than a week) 28

Conditions DC Familiar route 10 Unfamiliar route 15 Inadequate/no computer +5 Electromagnetic or gravitic interference +5 Per time step decrease +5 Per 10 LY over 30 traveled +5

Check vs. DC Result +5 or more Within d4-1 AU of target Success Within d12+2 AU Failure Arrive at edge of system -5 3d10 LY off course -10+ Special (GM’s discretion)

  • Roll Direction
  • 1 Forward
  • 2 Fwd./Right
  • 3 Right
  • 4 Back/Right
  • 5 Back
  • 6 Back/Left
  • 7 Left
  • 8 Fwd/Left
  • 9 Up
  • 10 Up/(roll)
  • 11 Down
  • 12 Down/(roll)

Length of Trip DC Short (a few hours) 20 Moderate (a day or two) 22 Long (up to a week) 25 Extreme (more than a week) 28 Very Complex (gravitic anomalies +2 to +6 heavy traffic, etc.)

navigation_skill.txt · Last modified: 2021/12/04 00:39 (external edit)