Capt. Mooron wrote:
it's an auxiliary diesel.. 30 HP!

???
What is?

.... The vang holds the boom down not up...

Therein lies your error. A solid vang holds the boom up and down.


yes it has the capacity to hold up a boom up with some weight.... but that
is not it's primary function.

Why isn't it? That's like saying that because a bridge is designed for
cars to drive over it, it won't hold up a person walking across.



Leverage is required at the end of the boom for lifting. I'm certain you are
familiar with fulcrums?

Yes. I fail to see your point though. If the vang holds the boom up,
then it holds the boom up.

If the vang will hold the boom down under heavy sailing loads, then it
will probably hold at least as much in the opposite direction, nyet?

How much leach tension do you think your boat generates in a good breeze?


Where would you fasten the mainsheet to the boom... generally it's 50% of
the length or more. Look where the vang is... at what 15%?

Depends.

It's not a relevant issue though. Wherever the boom vang is attached, if
it will stand up to the load then it will... umm... stand up to the
load. If not, then it wasn't strong enough to begin with and that's true
whether it's a solid vang or not.

|
| A *real* solid vang (and boom) will fulfill all the functions of a
| topping lift, except as an emergency backstay replacement. I've seen a
| lot that wouldn't, but I don't like them either.

No Way Doug!! No for all the tea in China. The engineering is out to lunch
for such a claim.

Actually the engineering is quite sound. If you have problems with vangs
breaking and booms folding up, then that suggests that your engineering
needs a little more beef and less cheese.

Fresh Breezes- Doug King

Doug,

Think about the mechanics of both your statement and mine

By using the topping lift for Hoisting the total strength of the Rig is
used (Shrouds, fore and back stays; In my case double lower shrouds to
keep Mast in line.
With the Rigid Vang in Hoisting, you are putting Max Effort on the end
of the boom, supported at a point about 1/4 of the way back from the
Gooseneck.
That is an awful long unsupported Alum. Pole. (Hollow Aluminium Pole).

In operation, the force of the sail is at least two points on the boom,
with the main sheet countering the force on the boom. Often assisted by
the Vang. Often over assisted by a Hydra. Rigid Vang.

I'm sure, as an Engineer, you can admit to the difference

If you were careening the hull, you wouldn't weight the end of the boom
without the back-up of the topping lift and/or a halyard to call on the
full strength of the total rig. The topping lift is a solid connection.
The halyard is a varying force

Just some things to remind you of.

I'm not knocking the Rigid Vang. I wish I could fit one on my boat but
the Pilothouse makes that impossible. I'm thinking I might be able to
use a KICKER. I'm pointing out that PITA top lift still is a worthwhile
addition.

Ole Thom

Thom Stewart wrote:
Doug,

Think about the mechanics of both your statement and mine

OK

By using the topping lift for Hoisting the total strength of the Rig is
used (Shrouds, fore and back stays; In my case double lower shrouds to
keep Mast in line.

OK

With the Rigid Vang in Hoisting, you are putting Max Effort on the end
of the boom, supported at a point about 1/4 of the way back from the
Gooseneck.
That is an awful long unsupported Alum. Pole. (Hollow Aluminium Pole).

OK

Oh, are you saying that the boom might fold up? You're right, but it
shouldn't unless it was too weak to start with. Is your boom the same
spar section as your mast? If so then it probably isn't strong enough to
use with a solid vang anyway.

Think about this, Thom... the force on the end of the boom is going to
be very great when sailing hard... enough to lean the boat over a lot.
If the boom end can take that force, then it should take that same force
in the form of a weight heavy enough to heel the boat over.



In operation, the force of the sail is at least two points on the boom,
with the main sheet countering the force on the boom. Often assisted by
the Vang. Often over assisted by a Hydra. Rigid Vang.

I'm sure, as an Engineer, you can admit to the difference

Yep. The difference is that in one case, you have put the boom & mast
under compression by tensioning the whole rig. In the other, you have
put the boom under a torsion load, and on a much smaller part of the
mast, and none on the rig (which actually means less stress on the hull).


If you were careening the hull, you wouldn't weight the end of the boom
without the back-up of the topping lift and/or a halyard to call on the
full strength of the total rig.

Probably not to careen the boat, but if I had a solid vang suitable for
hard sailing, I would not hesitate to hoist a weight on the boom that
would heel the boat far enough to put the boom in the water.

... The topping lift is a solid connection.

???

The halyard is a varying force

???


Just some things to remind you of.

I'm not knocking the Rigid Vang. I wish I could fit one on my boat but
the Pilothouse makes that impossible. I'm thinking I might be able to
use a KICKER. I'm pointing out that PITA top lift still is a worthwhile
addition.

In some cases, yes very much. In others, it's just in the way. My point
is that if a boat & it's rig is engineered to take proper advantage of a
solid vang, then you do not need a topping lift. Do not. Period.

If the rig is noodley and engineered to transfer compressive loads
through a series of components, then a solid vang can be added for
convenience but it will not be as useful. If the rig has a very low boom
or a pilothouse, there's not room for a proper vang anyway... but you
can probably do a lot of the same sail trim functions with a wide traveler.

Fresh Breezes- Doug King

Doug,

Your Bridge example is WRONG. Those cables hanging down are for
suspension. Not compression. I think you can remember the Tacoma Narrows
Bridge when the wind got under it. IT FALL DOWN GO KAPLUNK!

OT

Since you're clearly not perfect, I'm going to change my
vote for president... to Willie Nelson.

In article ,
DSK wrote:
Jonathan Ganz wrote:
Doug, I thougth that's what you were saying it would do... as an
emergency backstay. Oh well... my reading comprehension is going
downhill fast.

My bad. I have been in a hurry all week and am probably not writing very
clearly.

--
Jonathan Ganz (j gan z @ $ail no w.c=o=m)
http://www.sailnow.com
"If there's no wind, row."

"DSK" wrote in message

| Yes. I fail to see your point though. If the vang holds the boom up,
| then it holds the boom up.
|
| If the vang will hold the boom down under heavy sailing loads, then it
| will probably hold at least as much in the opposite direction, nyet?

No Doug! No No No!.... look the vang may be able to hold the stresses on a
sail "down"... but it will never hold the stresses of a weight at the end of
the boom "UP". The leverage just isn't there. This is not a hydraulic arm on
an excavator! If it were the vang would be massive ... require an engine to
power the compressor and be attached to the end of the boom.

Look..... I can understand where your assumptions are based but I'm
thinking you have not taken into consideration the engineering incorporated
into the vang and it's intended use. If you have 10,000 lbs of pressure on
the main only a fraction of that force will be utilized to incur lift on the
boom. The vang is not holding down the entire pressure placed on the main.

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. It's not designed for
that. A topping lift to the end of the boom requires much less force to hold
the boom level on a lift than the stresses placed on a vang that is located
at 15% of the load arm length. I don't care if it's a 1/2" I Channel carbon
steel beam for a boom! We are not discussing boom failure here.... we are
discussing load bearing to the vang.

I await your rebuttal... :-)

CM

Thom I can't support your example here because you are bringing in an
ancillary factor of boom strength. That is not the subject... the subject is
the suitability and ability of a rigid vang to support the loads generated
at the end of the boom in a lift situation.

I concur with your assessment that the vang is not up to the task or poorly
positioned and designed to accomodate such loads... but let's not bring the
boom strenght into the equation.

CM

"Thom Stewart" wrote in message
...
| Doug,
|
| Think about the mechanics of both your statement and mine
|
| By using the topping lift for Hoisting the total strength of the Rig is
| used (Shrouds, fore and back stays; In my case double lower shrouds to
| keep Mast in line.
| With the Rigid Vang in Hoisting, you are putting Max Effort on the end
| of the boom, supported at a point about 1/4 of the way back from the
| Gooseneck.
| That is an awful long unsupported Alum. Pole. (Hollow Aluminium Pole).
|
| In operation, the force of the sail is at least two points on the boom,
| with the main sheet countering the force on the boom. Often assisted by
| the Vang. Often over assisted by a Hydra. Rigid Vang.
|
| I'm sure, as an Engineer, you can admit to the difference
|
| If you were careening the hull, you wouldn't weight the end of the boom
| without the back-up of the topping lift and/or a halyard to call on the
| full strength of the total rig. The topping lift is a solid connection.
| The halyard is a varying force
|
| Just some things to remind you of.
|
| I'm not knocking the Rigid Vang. I wish I could fit one on my boat but
| the Pilothouse makes that impossible. I'm thinking I might be able to
| use a KICKER. I'm pointing out that PITA top lift still is a worthwhile
| addition.
|
| Ole Thom
|

| If the vang will hold the boom down under heavy sailing loads, then it
| will probably hold at least as much in the opposite direction, nyet?

Capt. Mooron wrote:
No Doug! No No No!.... look the vang may be able to hold the stresses on a
sail "down"... but it will never hold the stresses of a weight at the end of
the boom "UP".

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.


... The leverage just isn't there.

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

What I'm saying is the same as saying if you can stand on a beam (let's
say a 2x6) between two sawhorses, and it doesn't break, then you can
turn the beam over and still stand on it. You're saying that it doesn't
work that way, if the beam doesn't break one way then it will definitely
break the other...

.... This is not a hydraulic arm on
an excavator! If it were the vang would be massive ... require an engine to
power the compressor and be attached to the end of the boom.

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...


Look..... I can understand where your assumptions are based but I'm
thinking you have not taken into consideration the engineering incorporated
into the vang and it's intended use.

Actually, I have. It's not that complicated. Try drawing out a diagram
of moments. If you need a refresher
http://www2.umist.ac.uk/construction...xp/sfbmdex.htm


... If you have 10,000 lbs of pressure on
the main only a fraction of that force will be utilized to incur lift on the
boom. The vang is not holding down the entire pressure placed on the main.

No, it isn't... but it is holding down 100% of the leach tension, which
is very large. It also takes all the load of the mainsheet when hauled
in tight to go to windward. If it doesn't break when you honk down on an
8:1 purchase, then it should hold at least 8X your honking strength


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.

???

... It's not designed for
that.

It should be. Anything less would not be safe for sailing IMHO.



I await your rebuttal... :-)

If I give you a re-buttal, then who was the butt in the first place?

Seriously, I'm not saying 'all solid vangs are great for lifting heavy
objects' because many aren't. But then remember Sturgeons Law '90% of
everything is crap' and then tell me why it *shouldn't* be.

Some are. I know that for a fact. And if I had a solid vang that's what
I'd insist on. YMMV

DSK

wrote:
Apparently you think the term "rigid vang" means essentially a solid, steel
pipe. It doesn't mean that at all. A Rigid vang "telescopes" and has springs
inside it.

All the ones I've seen also have locks.


...(stupid BS snipped) ...
I'm not surprised you don't know this. Maybe if you were other than an armchair
wannabe sailor...

Maybe if you sailed anything other than a cheap old beater, maybe if you
had some experience with other than obsolete gear, maybe if you hung
around sailors who know how to sail and how to rig their boats properly,
you'd know that solid vangs have locks.

DSK

"DSK" wrote in message

| 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.

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

| 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
|
| What I'm saying is the same as saying if you can stand on a beam (let's
| say a 2x6) between two sawhorses, and it doesn't break, then you can
| turn the beam over and still stand on it. You're saying that it doesn't
| work that way, if the beam doesn't break one way then it will definitely
| break the other...

That's not at all what I said and again you are attempting to introduce the
boom as a factor... that is not good methodology for what we are discussing
here.... forget the boom or assume it indestrutructable and unbendable.|

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


| Actually, I have. It's not that complicated. Try drawing out a diagram
| of moments. If you need a refresher
|
http://www2.umist.ac.uk/construction...xp/sfbmdex.htm
|

No Doug... it's not that I refuse to seek knowledge but this time you had
better be able to logically explain your theory to me without a jaxxian
reflex to google proof that may or may not have bearing on what we are
discussing.



| No, it isn't... but it is holding down 100% of the leach tension, which
| is very large. It also takes all the load of the mainsheet when hauled
| in tight to go to windward. If it doesn't break when you honk down on an
| 8:1 purchase, then it should hold at least 8X your honking strength

No Doug... it is most certainly NOT holding down 100% of the leech
tension... that load is divided with a bigger factor attributed to the
mainsheet.
|
|
| 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'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!


CM