Conference unifix::sailing

If brute force doesn't work, you aren't using enough of it. Try more 
reverse bend. 

:-)

    Careful there.  The conventional wisdom about cold working aluminum
    has a lot of truth to it.  I broke a dinghy mast trying to take
    a slight bend out of it by leaning on it.  A friend broke his Etchells
    mast (40 ft) by trying to induce some pre_bend it with a come-along.
    If you try to bend the boom excessively, it may not break immediately
    but it will fatigue.  This will be apparent the next time the wind
    comes up.  The boom will bend upwards or fall off much more dramatically
    than before.
    
    The boom on the same dinghy was also bent upwards from too many
    seasons of vang sheeting.  Since the sail was loose footed, I was
    able to turn the boom upside down and reverse all the hardware.
    At rest there is still a bend in the boom but now it's pointed down.
    With wind in the sail however, it straightens right out.
    
    - gene ho

re .1 and .2

OK, I'm going to try more force and I accept the risk that I may break the
boom. The question I still have is do I put the reverse bend in and hold it 
for extended period of time or do I put a lot in and immediately release it?

Thx agn, Bob

    be carefull with to much strenght.Do not try to bend it back in one go.
    Put more and more pressure on it until it bends just a little bit back.
    The next time put just  a little bit more,until the boom is straigt.
    
    Peter

    One method recommended to me, which I was too impatient to try,
    is the following:
    
    Support the boom at both ends so that it won't rotate with the bend
    up between two sawhorses.  Pass a strap through one or more cinder
    blocks and tie to the boom at the point of the bend.  The weight
    should be enoough to induce a slight reverse bend.  Leave it there
    for a week or more until the bend is permanently straightened.

    I dont think .5 will work on a metal boom. Metal is an elastic
    substance, and will return to its previous state when bent, UNLESS
    it is bent past the elastic limit. Once past the elastic limit the
    bend ammount can rise VERY rapidly, ie the part can break. 
    
    So the trick is to stress it enough to pass the elastic limit so that
    it will bend, but not so much that it breaks. I suppose this could
    be done very scientifically, with all kinds of calculations, then
    apply the force and hope for the best!

    
    re .0
    
    >>  That is, laid on its side on a flat surface it lifts a maximum
    >>  of 1/4" off the surface.
    
    If it's bent near the middle, that's 1/8" to each end;  does this
    affect sailing performance sufficiently to warrant getting a new
    boom?  On a Digital salary?
    
       - E. Scrooge
    

Thank you Noters! Using your advice and cautions, I now have a straight DN
boom and I can spend my money on different toys instead of a new boom. 

For the record, the DN boom is approximately 9 feet long. Using the legs of my
6 foot workbench as a jig, I used a bottle jack applied at the crown of the
bend to gradually increase the reverse deflection of the boom from 1/2" to 
1 5/8". The operation looked something like the following:


		|<--------- 6 feet ------------>|
		O				O table leg
	=================================================  boom
				^
				| bottle jack
	    __________________________________________	   wood bracing
		O				O

There was no improvement in the alignment of the boom until I reached 
about 1 1/4" deflection, regardless of how long I held it in position. 
Throughout I always increased deflection by 1/8" increments and, happily, when 
I reached 1 5/8" the problem was corrected. 

Thanks again, Bob