What does mast rake do?

So, from a 505 perspective (suspect that many other classes will have a different approach) you are essentially attempting to keep the sailshape the same in most conditions.  There are 3 zones.  below 8 knots; below 12 knots; and above

8/9 knots - 12/13 knots or thereabouts is your fully powered sector.  Rig fully upright; max power, no frills.

Less than 8 knots (as the crew comes off the trapeze, and the wind gets a bit holier) you need to replace the mast bend....so more shrouds, and less strut.

Less than 4 knots - the only time when you are seeking to distort the sailshape.  Loads of shrouds - 420lbs - and destrut (upwards) to bend the mast, and make an easier shape for the wind to stick to.

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And upwards from 13 knots:

Steadily rake backwards to depower, following the rake with increasing amounts of strut (down).  If you don't pull enough strut down, you will allow the middle of the rig to "pant", which unbalances the rig, and makes the hull feel twitchy in the water.

In extreme conditions, fully nail the kicker down (we last broke a boom on Lake garda in no waves...!!) to bend the top mast, and flatten the rig....or blade out the trailing edge of the mainsail.

There are other subtleties (jib cars, flatners, cunningham, jib cunningham, centreboard etc) and obviously wave state plays a large role in deciding which gear to step into.  However, rake in this class depowers..!

Chas