On Thu, 19 Aug 2004 06:23:51 GMT, "Bart Senior"
wrote:

So how do you like the Offshore Spares solid vang? Could you live
without it, or is it a major plus having it?

I like it, but if I were buying another one I would get the Garhauer.
Mine is strongly built but that spring does have a somewhat awful
sound, like a rusty spring in a car suspension. Probably the most
annoying thing about it is the series of holes for the quick release
pin, which is much like the Spinlock. While this is not an issue for
most (all) of the rest of you, down here we have these annoying mud
wasps that love nothing better than holes like that. They must think
of them as birdhouses. In two weeks time they could completely fill
my vang tube with mud, which is not easily removed and really screws
up the ability of the vang to be adjusted. I'll bet you didn't expect
that in my report, did you? I have to keep the holes covered with
rigging tape.

It is a nice thing to have and it is very strongly made. I would
definitely want to have a solid vang, but I would be just as happy
with a Garhauer, which, while inexpensive, *might* be on the heavy
side for serious racers.



"felton" wrote

I am no engineer, but my boat does have a well built boom (Hall) and a
solid vang (Offshore Spars) and a topping lift. I am not worried
about any of the three under any conditions. My vang does have a
means to "lock" it with a quick release pin and a number of holes into
which it can be placed.

On Thu, 19 Aug 2004 06:28:38 -0400, DSK wrote:

You have 'way too much common sense. WTF are you trying to do, stop an
argument?

Who, me? Nope, I love an argument but I was getting lost in the
engineering jargon


BTW is your Hall boom a box section?

No, but it does seem to be strongly constructed. My spar is quite
bendy but my boom can handle anything my vang or my mainsheet tackle
can generate. Even my friend out on the end was no cause for concern.
It could be because my boat wasn't built as a weight saving racer. It
seems much more solidly built than the C&C it replaced, which was
obviously built with a greater emphasis on performance/weight saving
construction.


DSK

felton wrote:
I am no engineer, but my boat does have a well built boom (Hall) and a
solid vang (Offshore Spars) and a topping lift. I am not worried
about any of the three under any conditions. My vang does have a
means to "lock" it with a quick release pin and a number of holes into
which it can be placed. Last year I was sailing when the water levels
were VERY low and we managed to find a shallow sandy spot and run
aground. Hey, not the first time or the last, I am sure. We were
able to swing the boom out over the side and my friend climbed out on
the end of it to give us some heel as we had very little wind to work
with. We managed to sail off and enjoy the day. No big deal. I keep
the topping lift because it is quick and easy to lift the boom for
extra clearance above the bimini when the sail is down, rather than
screwing with the vang. Just my preference, but it works well for me.
If my main had more roach to it that was creating a chaffe issue, I
would probably get rid of it as I don't really *need* it, but I like
it, so there

Backing plates are used everywhere on boats--it is a good method and
excellent solution to Loco's problem.

You don't specify how the thru-bolts are drilled horizontally, or
vertically. Most booms have holes drilled horizontally with a bale
attached. That would not work with a rigid vang. You would need
to make a custom wrap-around bracket to thru-bolt horizontally.
You could use a piece of solder shaped around the mast and boom
to transfer the shape to template such a part--Garhauer method.

Machine screws into tapped hole into a backing plate inside the boom
strike me as an excellent method of reinforcement to spread the load
along the axis of the boom.

I've also seen sections of snug fitting tubing sleeved as reinforcement at
places prone to failures like the vang attachment, and sometimes the
gooseneck to increase boom strength. The method is commonly used
to built taller masts in sections. My Ericson mast is the original, was
constructed in three pieces and has not failed in over 30 years of use.
This would be the best solution.

Thru-bolting adds extra holes and can weaken both sides of the boom,
particularly if over tightened, by crushing or dimpling the shape of the
boom,
thus creating a weak spot. This is more common on smaller and lighter
booms, and vang related failure occur where? Right at the thru-bolts!

Reinforcement is common for boom repairs. Loco's method is a good
one to spread the load and secure the vang to the boom. If your boat
has a reputation for failing at a certain place like the vang attachment
at the boom, consider reinforcing it before the boom brakes.

"Thom Stewart" wrote

A fine idea, my ass!!

Any rigger worth his Salt would have drill thru the boom (2 holes)
Through bolted with the proper size bolt, lock washers and nut in place.

Ole Thom

Ah Balls Bart,

Count up the number of holes drilled and tapped with the backing stock
and connection of the vang and then compare it to a full bale.

Ole Thom

"DSK" wrote in message
| In other words, you're saying that 100# on the end of the boom supported
| by a topping lift is not the same as 100# on the end of the boom
| supported by a solid vang?
|
| OK but I'm a little confused... how does the weight know the difference?

Doug.... the weight remains the same that's not the point. The load bearing
forces between those delivered to the topping lift and the boom acts as a
"spreader"... while with the vang all the load is delivered to the boom and
the vang is subjected to the magnified loads.... in other words the load is
delivered to the vang and the leverage is delivered by the boom. That's why
I mentioned the fulcrum earlier.

When the boom is the spreader the force is compressive and much less than
the forces applied to the vang in such a situation. The topping lift bears
the entire load. The vang supports the boom distal to the load point so as
to magnify the bearing force.

Can you see the point of my argument now??

CM

Capt. Mooron wrote:
Doug.... the weight remains the same that's not the point.

Oh.

... The load bearing
forces between those delivered to the topping lift and the boom acts as a
"spreader"...

You mean the boom takes the load as compression... guess what, so does
the mast, and all the rigging, which transfers it to the hull. The load
is the same, the total amount of stress is the same, except that much of
the rigging is pre-loaded. And the compression on the mast is likely to
be a multiple of the weight involved.


...while with the vang all the load is delivered to the boom and
the vang is subjected to the magnified loads.... in other words the load is
delivered to the vang and the leverage is delivered by the boom. That's why
I mentioned the fulcrum earlier.

OK. It's still not a good explanation and tends to muddy the engineering
points.

The weight is the same... check.

With a topping lift, you seem to think that the boom has very little
stress on it. That is not the case.

Imagine this... replace the boom with your arms. Hang a 100# weight from
a long rope, and then try to push it 12' away from hanging straight
down. Depending on the angle to the point of hoist, you could end up
with more than 100 pounds of force.



When the boom is the spreader the force is compressive and much less than
the forces applied to the vang in such a situation. The topping lift bears
the entire load.

No it does not. Do you think the force magically goes away because there
is a topping lift?


Can you see the point of my argument now??

Yes, can you see the error you're making? You should make a diagram of
the forces involved. It will help you visualize the situation properly.

With a solid vang, that the force on the boom vang is greater than the
weight is not (or should not be) a problem, no more than the compression
on an old-timey noodley boom is. They're designed for that. If the gear
is designed & built properly for it's use, then it is fine.

Ever notice how on modern boats, the boom is not just s shorter section
of the same type extrusion as the mast? There are engineering reasons
for that (plus it looks cool).

Fresh Breezes- Doug King

CM

Count up the number of holes drilled and tapped with the backing stock
and connection of the vang and then compare it to a full bale.

The 4 - 3/16" socket head screws that hold the Quick Vang bracket to the boom
are of no consequence when compared to the 3/8" or larger holes that would have
to be drilled for a bail. Plus a bail wouldn't work with a Quick Vang bracket.
And with a 1/2" piece of aluminum bar stock installed inside the boom it's
like da holes ain't even there.
S/V Express 30 "Ringmaster"
"Trains are a winter sport"

"DSK" wrote in message
| You mean the boom takes the load as compression... guess what, so does
| the mast, and all the rigging, which transfers it to the hull. The load
| is the same, the total amount of stress is the same, except that much of
| the rigging is pre-loaded. And the compression on the mast is likely to
| be a multiple of the weight involved.

No Doug.... I believe that assumption to be incorrect... you fail to
incorporate the dispersion of the load from the mast head to compression of
the mast and delivery of portions of the load to the shrouds. When you
transfer the load to the vang alone [ via the boom].. the mast is only
subject to a side load from the vang fitting and all the force is supported
by the boom/vang. None of the load is distributed to the entire mast or the
shrouds. In other words any portion of the mast above the boom is not
utilized in the dispersion of the forces generated by the bearing loads.


|
|
| ...while with the vang all the load is delivered to the boom and
| the vang is subjected to the magnified loads.... in other words the
load is
| delivered to the vang and the leverage is delivered by the boom. That's
why
| I mentioned the fulcrum earlier.
|
| OK. It's still not a good explanation and tends to muddy the engineering
| points.

The only thing muddy here is your refusal to approach this with an open
mind..


|
| The weight is the same... check.
|
| With a topping lift, you seem to think that the boom has very little
| stress on it. That is not the case.

I never stated very little stress.. I stated much less stress by a greater
margin than with the vang based option.

|
| Imagine this... replace the boom with your arms. Hang a 100# weight from
| a long rope, and then try to push it 12' away from hanging straight
| down. Depending on the angle to the point of hoist, you could end up
| with more than 100 pounds of force.

Ridiculous... the force required to push it away would be far less than the
force required to keep the arm level while applying force to a point just
aft of my elbow!
|
|
|
| When the boom is the spreader the force is compressive and much less
than
| the forces applied to the vang in such a situation. The topping lift
bears
| the entire load.
|
| No it does not. Do you think the force magically goes away because there
| is a topping lift?

It does not go away nor did I say it did... I said the load is more evenly
distributed over a greater span.. Mast, Boom, Topping lift, Shrouds... etc.
This of course increases the ability of the rig to undertake the bearing
forces. Gawd forbid you would ever be required to calc break-out forces
generated by excavators.


|
|
| Can you see the point of my argument now??
|
| Yes, can you see the error you're making? You should make a diagram of
| the forces involved. It will help you visualize the situation properly.

I am most definitely not in error here Doug... you are... swallow your pride
and look at this problem with an eye to structural engineering. I am
visualizing the situation and after much thought and further toying with the
idea I came to the conclusion that you are not correct in your theory
regarding forces delivered to the vang. You have yet to present a viable
defense for your position on this while I have offered several sound,
reasoned, and logical counterpoints to your pretense.

|
| With a solid vang, that the force on the boom vang is greater than the
| weight is not (or should not be) a problem, no more than the compression
| on an old-timey noodley boom is. They're designed for that. If the gear
| is designed & built properly for it's use, then it is fine.

No Doug... it's not the case at all.... the vang is badly situated to handle
the loads you intend to place to it. The topping lift offers a much better
and more efficient distribution of the load ... thus increasing it's ability
to handle much greater loads.

|
| Ever notice how on modern boats, the boom is not just so shorter section
| of the same type extrusion as the mast? There are engineering reasons
| for that (plus it looks cool).

Quit toying with the damn boom.... look think of it this way... how many
lifting devices utilize a support located under the boom at less than 25% of
the boom length? NONE!
Now how many utilize a cable [topping lift] to the end of the boom?? MOST!

You are dead wrong on this Doug... really!

CM

"SAIL LOCO" wrote in message
...
| There are engineering reasons
| for that (plus it looks cool).
|
| No, what looks cool are big boat booms with holes in them.

Loco ... Please! Either join this discussion and add to it or stay on the
side lines and refrain from inane comments. I'm not being mean here.... but
I am requesting a modicum of intellectual input on an interesting
discussion.

Now allow me to ask you if you believe a vang as suited to load bearing
ability as a topping lift.

Let's refine this by placing the caveat that the strength of the vang is
equal to the strength of the topping lift in maximum load bearing abilities.
In other words if you beef up the vang you can as well beef up the topping
lift. Assume the loads are well within the stress capacities acceptable to
both the boom and the mast/shrouds.

CM


CM

Loco ... Please! Either join this discussion and add to it or stay on the
side lines and refrain from inane comments. I'm not being mean here.... but
I am requesting a modicum of intellectual input on an interesting
discussion.?

LOL........... As always your too full of yourself.
S/V Express 30 "Ringmaster"
"Trains are a winter sport"