From poor memory, diamond tension affects the middle of the sail.
(Top & bottom of sail can be adjusted by other means which is another thread)
going half up the mast I would want about 15% of draft in marginal trap conditions,
down to 8% for double trap conditions. (%Draft = depth of sail / Chord)
which has to coordinated with leech tension, and fined tuned with downhaul & mast rotation.

I would start with the fullest sail possible(loose diamonds wires), then flatten it out, more each day,
until the fine tune controls give you a workable range (to keep the hull down) Two boat testing helps.
(Many sailors start the other way, with a flat sail and make it fuller)

Perhaps, someone has the time to explain the affects of spread rake on dual axis mast bend.