Hello Dave; I sail on the ocean in Brooklyn & the ocean Southerly winds always pick up in the early afternoon as the land mass heats up. So I frequently use a smaller main with the jib roller furled ! I still can't right the boat solo when it capsizes.
When using a smaller sail to depower the boat the head of the sail will not come out of the mast track if it has the same size rope luff as the regular main.
If you use a tether to make up for the space inbetween head of the sail & the main halyard stop on the top of the mast You WILL NOT BE ABLE to release the halyard from its stop at the top of the mast. It will not release when you turn the mast to align the halyard ring above the stop because a line tether is not rigid enough to move the ring into the release position. LET ME EXPLAIN:
When Using a smaller sail on the P-19 or any boat with the same set up using a halyard ring & stop ,you must use a rigid extension to take up the space in between the top of the sail & the halyard ring stop at the top of the mast.
I use a sail that is 6'shorter than my regular P-19 main . I use a flat piece of aluminum 6'x 1/2"x 1/4" with one hole drilled on each end .One hole to attach a new shackle to the extension & to the head of the sail & one hole to attach the regular halyard shackle & ring to the rigid extension. On the Aluminum extention , I attached 1 plastic mast slide 2" below the regular halyard shackle & ring & 1 plastic mast slide in the middle of the extension. The slides face the mast sail track . When you hoist the sail up, the 2 mast track slides attached to the rigid extention will keep the halyard ring in line with the head of the sail & it will lock & unlock the same way the regular main does .
If you just use a piece of 6' line, ss halyard or strapping to take up the space you will be able to hoist up the sail but you will not be able to release the halyard ring to lower the sail ! I worked this system out by trial & error & it works everytime without fail . If I confused you get back to me & I will try to answer your qs . Bill