| Why not? If the boom can take the torsion in one direction, then unless
| it is a very weird asymmetric structure, then it will take the same in
| the opposite direction.

Capt. Mooron wrote:
This is where you stray from engineering principal... that is not the case
at all nor is it the rule.

Oh? Are you saying that a symmetric structural member is stronger one
way than the other? If you nail a board into a frame, you have to be
careful to put it label side up or something?




| Sure it is. It's exactly the same in both directions.

No Doug... it is most assuredly not the same in both directions if only by
the points of compression

Well, go explain that to Newton. He had a little to say on the subject.

.... forget the boom or assume it indestrutructable and unbendable.

OK


| The max forces are limited by the righting moment of the boat. On a 30
| footer, it doesn't need to be that massive. On bigger boats... take a
| look at the vangs on IACC racers...

Nobody is discussing righting moment here Doug...

Well, if we're not discussing the strength of the boom, nor the limit of
force on the whole system, then the only thing to complain about it the
compressive strength of the vang itself (which with a proper one, should
not be an issue) or the strength of the connections between vang, mast,
& boom.

If you break the gooseneck, then it probably wasn't strong enough
anyway. The vang connections take greater strain than the gooseneck (due
to the greater leverage) and thus they have to be stronger yet. So that
rules them out.

Now all you're left with is the strength of the vang itself.

How about a hydraulic cylinder? Some are. How about a very thick solid
SS turnbuckle with machine threads? Some are. That leaves the little
fiberglass rod ones (which I agree are not going to hold up much load)
and the spring loaded locking kind. I suggest you take a look at the
specs on several and see if you can't find one or two that look strong
enough to hold up a substantial load. They're there.



... we are discussing the
ability of basic mathematics in regards to the placement of the vang and the
loads you expect it to encounter.

Not really. You were trying to obfuscate the basic point that a vang
needs to be strong enough to stand up to hard sailing, and if it will do
that, it is almost certainly strong enough the other way too (unless
it's one of those wimpy hen-pecked little fiberglass rod ones).

| For using the boom as a lifting device.... you will stress the vang
unduly
| with a set-up located that far back on the load arm.
|
| ???

Well come on now Doug.... it's basic common sense engineering principal!

It can't be that basic, I have no clue what you're talking about.
Doesn't seem to pertain to vangs, though.


| ... It's not designed for
| that.
|
| It should be. Anything less would not be safe for sailing IMHO.

No it's not... it's designed as a VANG!

I guess a tackle employed as a vang would not be strong enough to use
for anything else?

I do one thing... you can't push a rope.

DSK