Afloat all season. Used to use International's UNO, like Jambo, but the white is grey. Now use white International Paints Trilux 33, because it's white. As a bonus I've found it a better antifouling. Still use UNO on the tubes where they sit in the water because I've still got some navy blue left in the tin.
The TK clear antifouling, which I spray on the engine bracket and TT rams lasts about 4 months before anything starts to grow.
As Jambo said, if you paint the a/f directly on to the shiny hull (remove any wax polish), without 'keying' the gel coat or using primer or undercoat, 99% will stay on until the end of season, there'll be little fouling on the bits where it does come off, and it's easy to pressure wash off to avoid any build up.
My tubes have been antifouled for 10 years with no damage to the material.