public String getAsHiddenString() {
    	StringBuilder builder = new StringBuilder();
    	
    	for (int x = 0; x < SIZE; x++) {
    		for (int y = 0; y < SIZE; y++) {
    			int value = fField[x][y];
    			if (value == VALUE_SHIP)
    				builder.append(VALUE_FREE);
    			else
    				builder.append(value);
    		}
    	}
    	
    	return builder.toString();
    }