public void readOption(){
    	
    	String choice = null;
    	boolean validChoice = false;

        do {
            displayShipyardMenu();
            try {
                choice = sc.nextLine().trim().toUpperCase();
                System.out.println();
                if(choice.equals("M")){
                	validChoice = true;
                	processBackToMainMenu();
                } else {     	
                	int input = Integer.parseInt(choice);
                	if (input >= 1 || input <= shipList.size()){
                		validChoice = true;
                		displayShipDetail(input);
                	}
                }
            System.out.println("Invalid Input!");
            } catch (InputMismatchException e) {
                // display error message
                System.out.println("Please enter a valid option!");
                sc.nextLine();
            }
        } while (!validChoice);

    }