Levers at forward end of boom next to sheaves - what are they for?

[Spirit (of Glenans)]

Yes, twin reefing lines (x3) led aft - I have a clutch obsession, 15 currently! Are the levers normally sprung? mine are not.

No need for springs. When the line is under tension and the lever is pulled back hard, the teeth on the cam engage with the rope. The tension then pulls it tight.

 

[Motor_Sailor]

I have a loop of shock cord to hold them 'open' when shaking out a reef out.

 

[Hoolie]

I have bypassed them as I have single line reefing back to the cockpit, but I think they are permanently closed to stop them getting in the way ...