SQL String Function Help

Here is the scenario.

I have a 10 position varchar field that holds a project number. The project number is in the form yy-nnn... where yy is the current year (06) and nnn is a sequential number. The project number is displayed on a data entry form so that the next record has the next sequential number.

So when the data entry form first opens the project number field has 06-1 after that record is entered the form is cleared and reinitialized and the project number now shows 06-2. If the form is closed and then reopened the project number would still show 06-2 if that previous record was not entered and 06-3 if it was.

The way I am going about getting the next sequential number is the following:

SELECT MAX(RIGHT(ERFNumber, LEN(ERFNumber)-3)) AS MaxERFNumber From Table1

This approach is working fantastic until record 06-9 is entered. The above line does determine that 06-9 is the MAX record and then creates a record 06-10 but every subsequent time a record is attempted it still thinks 06-9 is the MAX value of the above statement.

I am assuming that since the field is defined as a varchar the MAX function is applying character logic versus numeric logic thus the 9 being treated as the MAX value.

Is there an SQL function that can change the result of RIGHT(ERFNumber, LEN(ERFNumber)-3) to a numeric value so that the MAX function will work correctly.

I know there are many other ways to do this but in the interest of time because the application is almost finished, changing this now is going to be a major undertaking.

Any help or guidence would be greatly appreciated.