PlanetsCentral

Ships with the Boarding ability (generally, all Privateer and Tholian ships) can board fuel-less enemy ships by towing them, and thus obtain control over them. Uncooperating enemy crew members are jetissoned and replaced by own crew.

New_crew_on_boarded_ship =
   Traitors + Crew_beamed_over
New_crew_on_boarding_ship =
   Crew_on_boarding_ship - Crew_beamed_over
   ...where
      Traitors =
         Crew_on_boarded_ship
                     ...if boarded ship is Privateer
         Trunc(0.9 * Crew_on_boarded_ship)
                     ...if boarded ship is Fed
         Trunc(0.7 * Crew_on_boarded_ship)
                     ...if boarded ship is Colonial
         Trunc(0.4 * Crew_on_boarded_ship)
                     ...if boarded ship is Empire
         0           ...otherwise
      Crew_beamed_over =
         Min(Boarded_ship_full_crew - Traitors,
             Trunc(Boarding_ship_crew / 2))

As a special exception, if these formulas would reduce New_crew_on_boarding_ship below 2, PHost uses Traitors at least 2 and Crew_beamed_over = 0.

(4.1f) PHost before version 4.1f would have given exactly 2 crew, even if the original Traitors were more.