Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?

Bob Swarts

On Sun, 16 Oct 2005 08:01:04 -0700, Robert or Karen Swarts wrote:

Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?

Bob Swarts

There could be weight and righting moment issues.

Maybe it will be OK, but I guess I would at least want to do the math
before I poured the foam...

There could be possible corrosion problems.

Hollow masts are pretty resistant to oxidation. If you fill it with foam
it could easily develop pockets of poor drainage, and therefore corrode.

--Mac

I would guess it all depends on YOUR defilation of 'foam'.

When this question comes up there are usually references to ' . . .pouring
foam . . .'. I would absolutely NOT use any of the 2-part 'Pour-in-Place'
foams. Your are really in it, as regards solutions to 'What if . . .?'
problems.

What I think of in this situation is the foam 'Swim Noodles' or big blocks
of Styrofoam. Cut to roughly 'rod shape' about the ID of the mast. Just
shove them into place with a long piece of 1x1 or lengths of 1in PVC.

The reasoning behind ANY foam or flotation material is to fill AIR SPACE. It
is the AIR that gives the actual buoyancy. That's why they designate the
'Marine' foam as '2 pound', '3 pound', etc. That means that for each cubic
foot, the foam weighs 2 pounds, etc. Therefore, when calculating buoyancy .
.. . a cubic foot of water {there is a slight difference between Salt and
Fresh}weighs about 62 pounds MINUS the weight of the foam EQUALS the ability
to support 60 pounds per cubic foot of that particular material.

Regards & Good Luck,
Ron Magen
Backyard Boatshop

"Robert or Karen Swarts" wrote in message
...
Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?

Bob Swarts

I give up ... why would anyone fill a mast with "foam"?

"Robert or Karen Swarts" wrote in message
...
Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?

Bob Swarts

Primary reason is that it increases righting moment in the event of a
capsize. I suppose it might also keep the mast from sinking in case of a
demasting.

Might make the mast marginally stronger if completely filled.

I also misspoke in this area in that what I was envisioning was plugging the
mast with foam rather than completely filling it.

BS

"Bowgus" wrote in message
...
I give up ... why would anyone fill a mast with "foam"?

"Robert or Karen Swarts" wrote in message
...
Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?

Bob Swarts

Robert or Karen Swarts wrote:

Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?


About the only foam you would ever consider placing inside a mast would
be blocks of soft furniture foam for the purpose of quieting any wires
inside the mast that might be slapping the mast.

IMHO, the result is almost the biggest PITA on the planet.

Been there, done that.

A good messenger cable makes the problem go away.

Lew

On Sun, 16 Oct 2005 15:39:19 -0700, "Robert or Karen Swarts"
wrote:

Primary reason is that it increases righting moment in the event of a
capsize. I suppose it might also keep the mast from sinking in case of a
demasting.

Might make the mast marginally stronger if completely filled.

I also misspoke in this area in that what I was envisioning was plugging the
mast with foam rather than completely filling it.

Bingo...

An inversion may cause the mast to fill with water, and depending on
the diameter and lenght of mast, the the leverage weight at or near
the masthead would be significant. I think 1square foot of water is
about 64 lbs. Or about 1 gallon of water is about 8lbs...

Anyone know what the leverage force would be needed to lift 64lbs at
30ft of leverage from the folcrum point? That may not be exactly the
right question...

I would not recommend filling the complete void in the mast, but
sealing of the mast might be considered. As this was a suggestion by
someone making their boat 'bluewater' ready as just one of the things
they would do.

Also if the mast is buoyant then it could help the righting momentum.

BS

"Bowgus" wrote in message
...
I give up ... why would anyone fill a mast with "foam"?

"Robert or Karen Swarts" wrote in message
...
Assuming one makes provision to access and mechanical or electrical
components within the mast, are there any compelling reasons NOT to foam
fill the mast?

Bob Swarts

An inversion may cause the mast to fill with water, and depending on
the diameter and lenght of mast, the the leverage weight at or near
the masthead would be significant. I think 1square foot of water is
about 64 lbs. Or about 1 gallon of water is about 8lbs...

Cubic foot. One square foot of water has a weight of zero.

Anyone know what the leverage force would be needed to lift 64lbs at
30ft of leverage from the folcrum point? That may not be exactly the
right question...

Approx. 3000Nm, but that's irrelevant:
Assume inversion. The mast will first be underwater. Then the water in
the mast has neutral buoyancy. To get out of the inversion, the
boat uses hull shape and keel weight, if not a racer designed to
remain stable in an upside down position. But these have escape
hatches on the bottom.

Once the mast is parallel to the water surface, the keel has the best
angle of attack to righten it. Much more than during strongly heeled
sailing, i.e. a few gallons of water at the mast top won't do anything.

Not even a few hundred pounds. If you want easier proof: You can hoist
a person up the mast of even small keeboats witout inverting them.

Chris

On 26 Oct 2005 23:23:21 -0700, "Chris" wrote:
///
Not even a few hundred pounds. If you want easier proof: You can hoist
a person up the mast of even small keeboats witout inverting them.

Chris


Can you hoist a person up a mast at 60 degrees to the vertical,
without a capsize?

Brian Whatcott

Several years ago, at the first Atlantic City Sailboat Show I think, there
was a 'solution' to this problem. The Geougeon Brothers {the WEST System
people - forgive the spelling} were manufacturing a 'large' catamaran {I
don't know if they still are} at the time.

Anyway, as I was walking about the hall I noticed what looked like a
miniature 'blimp' {about 3-4 feet long} above the field of masts. It had
their name on it and that's what I thought it was - an airborne
advertisement. As I got closer, I saw that it was actually attached to the
top of the mast of their catamaran . . . but still thought of it as an
advert.

I soon found out that it was really a piece of 'Safety Gear'. The shape was
for aerodynamic reasons. A catamaran has 'Ultimate Stability' at TWO points
.. . . completely upright AND completely upside down!! Having a sufficient
quantity of extremely buoyant, and light weight, material at the end of a
long attached moment arm reduces this to ONE. While you may experience a
'knock-down', you shouldn't be able to 'turtle'.

OBVIOUSLY, it takes a great deal more material {or even air} then can be
contained in the volume of the mast itself.

Regards & Good Luck,
Ron Magen
Backyard Boatshop

"Chris" wrote in message
oups.com...
An inversion may cause the mast to fill with water, and depending on
the diameter and lenght of mast, the the leverage weight at or near
the masthead would be significant. I think 1square foot of water is
about 64 lbs. Or about 1 gallon of water is about 8lbs...

Cubic foot. One square foot of water has a weight of zero.

Anyone know what the leverage force would be needed to lift 64lbs at
30ft of leverage from the folcrum point? That may not be exactly the
right question...

Approx. 3000Nm, but that's irrelevant:
Assume inversion. The mast will first be underwater. Then the water in
the mast has neutral buoyancy. To get out of the inversion, the
boat uses hull shape and keel weight, if not a racer designed to
remain stable in an upside down position. But these have escape
hatches on the bottom.

Once the mast is parallel to the water surface, the keel has the best
angle of attack to righten it. Much more than during strongly heeled
sailing, i.e. a few gallons of water at the mast top won't do anything.

Not even a few hundred pounds. If you want easier proof: You can hoist
a person up the mast of even small keeboats witout inverting them.

Chris