Boom Length / arc of boom to clear backstay or kicker to hold down?

[ianabc]

Mast taken from house and lowered into boat by expensive crane ...

Just completed first sail with small jib,
Now to build boom......

 

[ytd]

Re: Boom Length / arc of boom to clear backstay or kicker to hold down

that's not much clearance. If the main has any roach it will hit the backstay when tacking. A kicker (vang) will hold the boom level so long as you always remember to have it on. I have seen the solid vangs pull apart with over zealous use of a topping lift.

 

[Robin2]

Re: Boom Length / arc of boom to clear backstay or kicker to hold down

Been there ... done that ...

Peace of mind only comes when the boom cannot touch the backstay at any angle. I shortened my boom twice - once so it would just fit the sail - but that was not enough and I had to get the sail modified. (Boom was originally too long because I was trying to squeeze in maximum sail area - I won't try that again).

 

[chuzzlewit]

Re: Boom Length / arc of boom to clear backstay or kicker to hold down

draw it to scale

 

[Norman_E]

If you are sloop rigged it sounds as if your mast is a long way back, leaving a large fore triangle. If this is the case then a large main may move the centre of effort too far aft. Have you checked that the rig design is correct? I do not have a book on yacht design with me but remember seeing that the centre of effort needs to be carefully calculated, and (if I remember correctly) just ahead of the centre of lateral resistance otherwise it will make the boat hard to control. Most sloop rigged boats seem to have the mast well forward of the centre of the hull length, and a boom which stops well short of the transom.