MySQL Date insert

Hello, I have the following PHP code:

        $date = date("Y-m-d H:i:s");
        $result = mysql_query("INSERT INTO Boats (Make, Model, Serial, Stock, Extension, Cust_Name, Store, Date) VALUES
                ('$make', '$model', '$serial', '$stock', '$extension', '$name', '$store', '$date'")
                or die("Invalid query: " . mysql_error() . "</body></html>");

The problem is with the Date column. It is of type DATETIME. I get an error on the second line of the insert statement. I assume I'm not putting formatting the date-time variable correctly but I've tried everything I can think of, so any help is very much appreciated. Thanks. Andrew.