* @param navalUnits the ships to put land units on
     * @param random a PRNG
     * @return a list of units left over
     */
    public List<Unit> loadShips(List<Unit> landUnits, List<Unit> navalUnits,
                                Random random) {
        List<Unit> leftOver = new ArrayList<Unit>();
        Collections.shuffle(navalUnits, random);
        Collections.shuffle(landUnits, random);
        landUnit: for (Unit unit : landUnits) {
            for (Unit carrier : navalUnits) {
                if (carrier.canAdd(unit)) {
                    unit.setLocation(carrier);
                    logger.finest("Loading " + unit
                        + " onto carrier " + carrier);
                    continue landUnit;
                }
            }
            leftOver.add(unit);
        }
        return leftOver;
    }