On Tue, 22 Jun 2010 06:24:55 -0400, W1TEF
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Casady

"Richard Casady" wrote in message
...
On Tue, 22 Jun 2010 06:24:55 -0400, W1TEF
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Casady
That's correct. 35 lb pull will be felt at the bitter end of the tackle.

In article ,
says...

On Tue, 22 Jun 2010 08:00:09 -0500, Richard Casady
wrote:

On Tue, 22 Jun 2010 06:24:55 -0400, W1TEF
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Show me where I'm wrong.

Is he saying that by using the tackle the weight on the boom will be
decreased? Who said that, Tom?

--
Rowdy Mouse Racing - We race for cheese!

In article ,
says...

In article ,
says...

On Tue, 22 Jun 2010 08:00:09 -0500, Richard Casady
wrote:

On Tue, 22 Jun 2010 06:24:55 -0400, W1TEF
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Show me where I'm wrong.

Is he saying that by using the tackle the weight on the boom will be
decreased? Who said that, Tom?

Now, if you hung the top block off the bow you might be able to use the
boom help pull in...

--
Rowdy Mouse Racing - We race for cheese!

In article ,
says...

On Tue, 22 Jun 2010 09:28:10 -0400, I am Tosk
wrote:

In article ,
says...

On Tue, 22 Jun 2010 08:00:09 -0500, Richard Casady
wrote:

On Tue, 22 Jun 2010 06:24:55 -0400, W1TEF
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Show me where I'm wrong.

Is he saying that by using the tackle the weight on the boom will be
decreased? Who said that, Tom?

No - he misunderstood the nature of the answer. Yes, the weight is
still 350 pounds. What you are effectively doing is reducing the
amount of energy required to move the 350 pounds by the use of
mechanical advantage. It seems like you are only lifting 35 pounds.

Yeah, I got that... I thought he was talking about 35 pounds on the boom
holding the tackle..

--
Rowdy Mouse Racing - We race for cheese!

On 6/22/10 11:49 AM, I am Tosk wrote:
In ,
says...

On Tue, 22 Jun 2010 09:28:10 -0400, I am Tosk
wrote:

In ,
says...

On Tue, 22 Jun 2010 08:00:09 -0500, Richard Casady
wrote:

On Tue, 22 Jun 2010 06:24:55 -0400,
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Show me where I'm wrong.

Is he saying that by using the tackle the weight on the boom will be
decreased? Who said that, Tom?

No - he misunderstood the nature of the answer. Yes, the weight is
still 350 pounds. What you are effectively doing is reducing the
amount of energy required to move the 350 pounds by the use of
mechanical advantage. It seems like you are only lifting 35 pounds.

Yeah, I got that... I thought he was talking about 35 pounds on the boom
holding the tackle..


Oh, sure you did. After all, you studied physics...somewhere.

On Tue, 22 Jun 2010 12:22:12 -0400, W1TEF
wrote:

No - he misunderstood the nature of the answer. Yes, the weight is
still 350 pounds. What you are effectively doing is reducing the
amount of energy required to move the 350 pounds by the use of
mechanical advantage. It seems like you are only lifting 35 pounds.

Yeah, I got that... I thought he was talking about 35 pounds on the boom
holding the tackle..

I'd have to ask Wayne, but I think he uses the boom for the rib and
that whole rig has to weigh in at or around 350 lbs - maybe not.

We use a block and tackle arrangement to lift the boom (tilt it up)
with the RIB dinghy attached. The RIB with full fuel tanks, two
small anchors, security locks/cables, safety gear, etc., weighs
somewhere around 400 pounds. Because the block and tackle is pulling
diagonally from the top of the trawler mast, the actual initial force
required is greater than 400 lbs if you solve the vector diagram. For
discussion purposes, let's call it 500 pounds. The block and tackle
is in two parts: a 7 to 1 pulling a 2 to 1 for a theoretical total
mechanical advantage of 14 to 1. Our old nemesis friction steps into
the picture however and reduces the advantage by some significant
amount, probably around 30% which results in a real advantage of
about 10 to 1, requiring a 50 pound downward pull to lift the boom. As
the boom rises above horizontal the vectors add up more favorably so
that by the time the boom is at 45 degrees, the pull required is less
than 30 pounds.

On Jun 22, 11:22*am, W1TEF
It's really a question of dislodging and moving a heavy object
attached to another heavy object using a heavy object. *:)

Interesting question though and a fun one.- Hide quoted text -

- Show quoted text -


But... that reminds me.

What happens when the unstoppable object colides with the imovable
object?


Or is that for a seperate thread?

?;^ )

On Tue, 22 Jun 2010 11:24:29 -0400, W1TEF
wrote:

What you are effectively doing is reducing the
amount of energy required to move the 350 pounds by the use of
mechanical advantage. It seems like you are only lifting 35 pounds.

Wrong. The energy is one foot pound per pound per foot. Duh.
Mechanical advantage can reduce the _force_ while incrieasing the
distance, with the total energy required remaining the same.

Casady

On Tue, 22 Jun 2010 11:56:24 -0500, Richard Casady
wrote:

Wrong. The energy is one foot pound per pound per foot. Duh.
Mechanical advantage can reduce the _force_ while incrieasing the
distance, with the total energy required remaining the same.

Actually the total energy required increases because of the friction
inherent in the block and tackle assembly.