Marking harness line position?

[Unregistered]

On my old black gripped HPL boom the harness line position markers have rubbed off.

When I switch between sails, I need to move the harness lines. Is there a good trick for marking harness line position between sail sizes? I tried a silver permanent marker but it rubbed off.
Is there a particularly permanent marker that would last?
Any suggestions?

It burns quite a bit of time and energy to rediscover the perfect position for the lines and retighten them especially when sailing overpowered and in choppy water.

[Ken]

There are white felt tip paint marker pens that I have used to mark masts, mast extensions and booms. The paint doesn't last forever, but you can re-paint very quickly.

Try office supplies or hardware stores.

[Unregistered]

Mark the sails with a piece of electricians tape. (centre point of harness lines)