lookupSearchlight = type2Id => {
			this.ship().find((ship, shipIndex) => {
				if(!ship.isAbsent() && ship.hp[0] > 1) {
					const equipMap = ship.findEquipmentByType(2, type2Id);
					const equipIndex = equipMap.indexOf(true);
					if(equipIndex >= 0) {
						result[0] = shipIndex;
						result[1] = equipIndex;
						// stop on first occurring
						return true;
					}
				}
				return false;
			});
			// return true if no any found
			return result.every(v => v === -1);
		}
Estimate possibly activated searchlight from current fleet ships.
Night battle only 1 searchlight of current fleet can be activated,
the rules and priorities are following:
@see http://wikiwiki.jp/kancolle/?%C1%F5%C8%F7%B9%CD%BB%A1#c3e3dd4e
     - priority: Large > Small, look up from flagship to escorts.
@see https://twitter.com/KanColle_STAFF/status/438561513339498496
     - ship HP < 2 does not use searchlight.
@return a tuple: [ship index, equipment index], both starts from 0.
        return false if no searchlight can be used.