Personal Handicaps

I am from a small boat club on the Murray Lakes in South Australia
called Clayton Bay Boat Club. We only have a around a half dozen
races a year as the major races on the lakes are run by the larger
clubs in neighbouring towns (such as the Milang to Goolwa with 300 to
500 entrants each January)

I have taken on the task of running our club races this summer and
have been very pleased with the response. Last year we had trouble
getting a fleet but this year most races have had at least 15 and our
best has been 33 entrants.

With the final race of the series in a fortnight I have been looking
at how I can introduce personal handicaps to "spice " it up a bit.

As an absolute dummy when it comes to computers I need help.

Is there some formula I could use to adjust the handicaps based on
the the previous race results?

Kind regards
Ken