[C320-list] Correct Dutchman line tension?

[Koen Bennebroek]

I recently had to replace the mono-lines on our
Dutchman system as they had broken. How do I figure
out the optimal tension on the topping lift and the
optimal length of the mono lines (adjusted at the
bottom)? (we have the adjustable system on the topping
lift with the continuous line through the cam cleat)

I initially had the topping lift setup such that my
boomvang could still pull the boom down, but it seems
I have the topping lift too loose now as it sometimes
catches on the backstay triangle, where it never did
before. I also think my mono lines are too long, but
I'm afraid trimming them too short with the hazard of
putting stress on them during sailing.

Any tips on optimal 'trim' ?

Thanks, Koen