Has anyone replaced the white EPS foam in a windsurfing board?
danc...@gmail.com
Waterat Pat
the hardware store. You have to open up the board first shoot it in
then sand it down and laminate over it. A really good resource is the
Board Lady.
http://www.boardlady.com/index.htm
Cheers Pat
Dan Weiss
> IF so, I would like to hear about it .. Thank-you.
Yes. The key is to closely match the new plug with the old hole.
Flat surfaces make it a much simpler job and require a lot less
epoxy. Using as little epoxy as possible is critical to reducing the
chance of exothermic reaction that would otherwise melt the foam. You
must use true 2-part epoxy as well, not polyester resin or anything
elese that contains a solvent. Again, you do not want to melt your
board.
Many people on rec dot, including me, have performed sucessful styrene
surgery. What is your specific situation?
-Dan
danc...@gmail.com
> surgery. What is your specific situation?
Hi Dan:
I am thinking of cutting open the tail end of a 1996 AHD 310 board,
removing the old soggy EPS foam core, and replacing with fresh
dry EPS foam.
The goal is to save 1 lb of weight, and maybe to replace foam that
might have plankton and barnacles growing inside. :-) But
I don't have a clue if the interior is actually in this condition.
I'm not sure if it is worth the effort for a measely 1 lb, but
I want to discuss so that I can educate myself on the
pro's and con's of such a repair, and learn from the
guru's on this forum.
At present, I have a 3/8" hole drilled into the tail end, and the
board is positioned in a vertical position to allow graviity to drain
any remaining water out of the tail end of the board. I don't
have access to vaccum bagging techniques like discussed
on the board lady web site.
Looking into the 3/8" hole at the rear of the board, the white
EPS foam beads look nice and white, and there are
no ugly green grimy pictures like seen on boardlady web site.
-ddd
Charles Jutkins
. See the boardlady.com for description of repairs.
<danc...@gmail.com> wrote in message
news:54a8c0c4-6b10-4d76...@x35g2000hsb.googlegroups.com...
Bob T
all styrofoam and replacing with closed cell urethane foam to just
removing styrofoam where delams occur and replacing with urethane
foam. I'm traveling right now, but will be home soon and then I will
write you on how to do the work. Be patient for a couple more days
and I'll get you the answers you're looking for. Bob T.
Charles
> There are other ways of removing water either buy vacuuum or a board spinner
> . See the boardlady.com for description of repairs.
>
Gravity is nice, but there is a better way. Remember your high school
science class and the old Bounty paper towel commercials, " Bounty the
quicker picker upper"
Osmosis. The water would have a greater affinity for the paper than
the EPS. I know its not technically osmosis, but I thought that would
be the best way to describe this method.
Start with a stack of newspapers positioned under the hole, They must
be touching the hole so that water will be drawn out of the board and
into the newspapers by osmosis. Change the newspaper stack
frequently. When the newspapers stop absorbing water, switch to paper
towels. Again change the paper towels as soon as they are saturated.
If you have an incandescent shop light. point it at the tail of the
board. The heat from the light will also help with the process. No
need for fancy board spinners or vacuums.
Dan Weiss
>
> - Show quoted text -
Great tip, Charles! ddd, the fall may be your friend as the relative
humidity can be quite low and aid in evaporation, whether directly to
the ambiant air or using the osmosis method. In either event, simply
placing into a room that is air conditioned a.k.a cooled or -even more
ideally- a small room that is dehumidified via a room dehumidifier.
I just used the latter method after repairing a board that had been
open for over a year about 1.4 mile from the ocean. It seems the
board lost a TON of weight. Remember that the best deal occurs when
the foam is evenly dry. That's why time can appear as friend or foe,
as the case may be.
-Dan
Indrek Aavisto
>> <dance...@gmail.com> wrote in message
>> news:54a8c0c4-6b10-4d76...@x35g2000hsb.googlegroups.com.
>> ..
>> Hi Dan:
>> -ddd
C> Gravity is nice, but there is a better way. Remember your high
C> school
C> science class and the old Bounty paper towel commercials, " Bounty
C> the
C> quicker picker upper"
C> Osmosis. The water would have a greater affinity for the paper than
C> the EPS. I know its not technically osmosis, but I thought that
C> would
C> be the best way to describe this method.
C> Start with a stack of newspapers positioned under the hole, They
C> must
C> be touching the hole so that water will be drawn out of the board and
C> into the newspapers by osmosis. Change the newspaper stack
C> frequently. When the newspapers stop absorbing water, switch to
C> paper
C> towels. Again change the paper towels as soon as they are saturated.
C> If you have an incandescent shop light. point it at the tail of the
C> board. The heat from the light will also help with the process. No
C> need for fancy board spinners or vacuums.
I think the term you are looking for is "capillary action", or "wicking".
Plants use the phenomenon to draw water up through their roots to their
leaves.
Check out this link
http://en.wikipedia.org/wiki/Capillary_action
Cheers,
Indrek Aavisto
--
Criticism is easy; achievement is difficult. W.S. Churchill
Bob T
history. I had a Bassett wave board which had mast box and fin box
issues and had taken on a lot of water. The 8'-5" board weighed 25
lbs. I tried the vacuum idea for a couple days and got poor results.
It lost about 1 pound. I then opted to take the fin box out of it
(because I wanted to put in a Tuttle box) and put the board in the
attic, tail down, and let it sweat drain. It spent six months of hot
Texas summer up there in the attic and lost about 3 pounds. At this
point, the board weighed about 21 pounds, which is still too heavy.
So...... I got the idea to pull out all the styrofoam and replace it
with much stronger and closed cell urethane foam. This board was made
with styrofoam with a density of 1 to 1.5 pounds per cubic foot. I
estimated the volume and how much it would weigh if I used 2 pound per
cubic foot urethane foam ( http://www.shopmaninc.com/foam.html ) and
it came out to about 22 pounds. If I was to replace the styrofoam with
urethane foam, I would have to cast it with hollow tubes if I was to
reach my target weight of 17.5 pounds. I decided to proceed. First, I
would have to get the styrofoam out. I cut three equally spaced access
holes in the bottom of the board, each hole being about 8"x12". I
saved these bottom pieces for later re-attachment. Next, I dug out all
the styrofoam using screwdrivers, grinders, etc. and a shop vac until
the inside was devoid of any styrofoam. The hollow hull weighed about
11 pounds.
During this process, I discovered some mis-conceptions about wet
styrofoam. In my case, the water had dispursed throughout the
styrofoam. It was wettest right at the mast box and near the fin box
area where the water leaked into the board , but at 24" away, the
water was fairly dispersed and the styrofoam was only slightly damp.
You can check dampness by pressing a piece of styrofoam to your lips
which are extremely sensitive to moisture. First mis-conception, if
you try using some of the conventional methods mentioned, you will
eventually get all the water out. Totally false! You might get some
of the super saturated water out, but the dispersed water is there to
stay! It is even difficult to squeeze out when pressing a piece of
styrofoam between your finger. Even afte squeezing really hard the
piece of styrofoam is still damp!
Tomorrow, recasting the interior foam with 2 lb. per cubic foot closed
cell urethane foam.
Bob T
the styrofoam has just as much draw of capillary action as the paper
placed under the board to draw out the water. At best, you might
achieve an equilibrium where the foam wants to retain the water more
than the papers can draw it out.
Bob T
times stronger in compression, many times stronger in flexural
strength, and it bonds to just about anything it touches. To cast
the hollow tubes, I first experimented with with balloons, which
weren't tough enough, then with PVC pipe which were too difficult to
pull out after casting. I finally settled on lexan tubes used to
protect 4' fluorescent bulbs. I bought them at Ace Hardware. The
urethane foam bonded to the lexan tubes so I developed a system of
wrapping the tubes with polyethylene (like a condom) which doesn't
bond well to the urethane foam. The next obstacle to overcome was the
need to control the swelling of the foam so it wouldn't alter the
shape of the hull. To do this, I made a press by cutting two 1x6
boards about 3" longer than the width of the hull. I would place one
board crossways on top of the hull and one on the bottom of the hull,
then I used threaded rods to connect them together at the ends. I
would tighten the threaded rods just enough to make firm but not
distorting contact with the board top and bottom. Starting at the
nose, with the board standing vertically, nose down, I would position
the tubes, mix and pour the expanding foam, allow it to harden (which
takes about 1/2 hour) then I would pull out the lexan tubes, then the
polyethylene condoms and repeat the process, I tried to size the
pours to fill the voids for about a distance of 12"-16". Once the
foam hardened, I would reposition the tubes/condoms, hold them in
position, move the press to the new position and make another pour.
When I got to the point where the holes had been cut out to provide
access to the interior of the hull, I masked around the holes to
reduce the clean up mess, but I would also just let the expanding foam
ooze out the hole. One of the things I learned early was that right
after I would pour the mixed and expanding urethane foam, it helped to
pick up the board and tilt it back and for to slosh spread the foam
around the bottom of the void to be filled. This helped it to expand
evenly and vertically without unintended voids. I repeated this
process until the hull was filled with urethane foam.
I learned to watch the hull as the foam expanded, adjusting the press
as needed and pressing with my hands in areas I thought were being
pushed outward too much.
Imagine now that you are looking at a hull filled with foam and foam
bulging out from the four holes in the bottom which were used for
access. I then used a hacksaw blade to cut the bulging foam flush with
the bottom, then I used a router to rout out a recess in the urethane
foam deep enough to receive the bottom piece(s) used for access. I
mixed up a slurry of epoxy with enough thickener to give it the
consistency of jam then I would spread this in the recess, followed by
reinserting and pressing in the original piece of the bottom. I then
would use a weight to hold it down till the epoxy hardened. Once the
epoxy set, I would use epoxy and fiberglass to cover the joint created
by the jig saw where the original piece was removed. A little filler
and some Imron and it was back looking like new.
I wouldn't say this attempt was a success because the board weighed
nearly 20 pounds when I was done. A lot of careful wet sanding got it
down to about 19 pounds but it still felt too heavy. What seemed to
have gone wrong was the density of the urethane foam after it
expanded. I learned that If everything was ideal, meaning correct mix,
pre-warming the foam components to about 110 degrees F., and working
conditions of about 90 degrees, and then pouring a big enough volume
to get nice even bubble distribution, I could get foam with an
approximate density of 2 to 2.5 pounds per cubic feet. Let one of the
variables get altered and the foam would come out approximately 2.5 to
3 pounds per cubic foot.
To top it off, after finishing the board and sailing it several
times, I discovered I really didn't like the board at all. It had a
tendency to chatter badly when pushed really hard in short steep chop.
I gave the board to a beginner and he thought he had hit the lottery!
Tomorrow, how to use what I learned above to effect some very decent
repairs for serious major delams and mast/fin box problems.
Bob T
shows the problems of working with closed cell urethane foam. There
are several ways a mast box can fail from delams to pulling the box
loose by lever action of the mast. From a repair standpoint it is much
the same. First set up a work table w/ a piece of carpet on it and
place the board on the carpet, bottom down. Use a pencil and a
straightedge to mark on the deck the centerline and ends of the
mastbox. This will be used later to position the mast box on re-
installation. From the centerline, mark lines on the deck 1.5" either
side of the centerline and 1.5" beyond the ends of the mast box.,
creating a rectangle roughly 3"x13" for a 10" box. Jig saw cut
following the lines at the perimeter of this rectangle, then take a
screwdriver and pry out the mast box with the rectangular portion of
the deck exposing the styrofoam core of the board. If the mast box is
reusable, extract it from the deck piece/foam, and clean it up for
reuse.
Back to the hole in the board, inspect the styrofoam for moisture by
squeezing a chunk or pressing it to your lips. If wet, remove wet
foam back to dry foam by using screwdrivers, etc. and shop vac. It is
time consuming, be careful not to damage the deck or board bottom.
The objective is to create a void to be filled by urethane which is a
little longer than the length of the mast box and which extends all
the way to the bottom of the board. Make the void about 1.5" wide at
the bottom, and tapering up and outward to the deck opening. At the
deck, the void should extend at least 2.5" beyond the edges of the
rectangular cutout. Filling the void will structurally connect the
deck with the bottom making it much stronger. Casting Part 2 to
follow.
Bob T
process gives off heat and which can DAMAGE your board by heating the
materials which softens them and allows them to distort if the heat
becomes too concentrated, especially the bottom of the board. To cast
the foam, mask around the perimeter of the deck opening to prevent
getting urethane on the surfaces. To protect the bottom from heat
damage, you will cast a small batch of urethane foam which won't
generate a lot of heat but will act as an insulator for the bottom to
protect it from the larger batch(s) to follow. To prepare, bring the
temperature of the foam components up to at least 90 degrees (this
usually produces better bubble distribution). Usually I set the foam
cans in a pan of hot water to warm them up. Once warm, use 2 paper
cups to precisely measure equal parts of the components which when
combined will produce a liquid volume of about 1/3 cup. Pour the
contents of one cup into the other, use a stir stick to rapidly mix
them. You have about 40 seconds of mix time before the foam starts to
expand rapidly. At about 35 seconds, pour the contents into the bottom
of the board and use a foam or acid brush to quickly spread it around
so that it evenly coats the bottom of the void. This foam will expand
about 25 times it's original volume creating a blanket of foam about
3/4" thick to protect the bottom from the heat to follow. If your
board has a fairly thin skin, like 1/16" thick, reduce these volumes
by half to create a ½" blanket then do it a second time. Thin thermal
formed skins are the most susceptible to heat distortion. It will take
about 45 minutes to fully swell and harden. I prefer to cast the
remaining void in 2 passes, doing one side then the other. I have
someone stand the board on its edge then I mix a batch with a
unexpanded volume of about 5/8 of a cup and pour it into the void then
I grab the board and gently rock it back and forth to spread the foam
out around the side to be filled. As the foam expands, I carefully
watch the deck opening to make sure the foam is not pushing it up and
out of position. About ¾ thru the foam expansion I set the board back
on it's bottom. It is ok and even encouraged to allow the urethane
foam to ooze out the deck opening. IF the deck is being push up, I
gently hold it in place until the foam stops expanding and hardens
enough to no longer distort the deck. I repeat for the second side.
With the foam hardened and oozed out the opening, I use a hacksaw
blade to trim it flush with the deck. Next, I want to repair the
opening. I like to use structural core foam such as: ¼" Core-Cell
Structural closed cell foam which I get from Defender Marine
http://www.defender.com/ This is more like klegecell than it is like
divinycell and it seems to be well suited. I use my router to create a
¼" recess at the deck opening to receive a piece of the Core-cell the
same size as the opening. I bed in a layer of 6 oz fiberglass in the
recess then I mix a slurry of epoxy and filler about the consistency
of jam, spread it in the recess then press in the filler piece of Core-
cell. I use weights to hold it in place until the epoxy hardens. Next
I position the mast box using the centerlines and end lines drawn
earlier, I trace around the mast box then use my router to create a
recess for the mast box so the top of the box is flush with the top of
the core-cell. To prevent the track of the mast box from bonding with
epoxy, I apply a layer of petroleum jelly with a Q-tip. I bed in a
layer of 6 oz fiberglass in the recess then I mix a slurry of epoxy
and filler spread it in the recess then press in the mast box allowing
the excess epoxy to ooze out around the edges. Once the epoxy hardens,
I sand it flush with the deck then glass over the top of the mast box
and Core-cell, then apply fairing filler and Imron. Once dry, I use a
¼" flush router bit I found on Ebay to route out the track of the mast
box, then a little edge sanding of the track and removal of any resin
which may have found it's way into the track and it's ready to use,
only now it is much much stronger than before.
Tomorrow, I'll use this process to correct major delams!
danc...@gmail.com
Bob:
Instead of the closed cell polyurethane foam,
would it be better to packing board with open cell beads
which are enclosed in water tight bags? That's
what the LASER sailboats use in their interior (from what
I've read)...
The idea would be to keep the density lower than the
closed cell polyurethane foam that you mentioned.
The enclosing plastic bags would prevent water from getting
into the foam again, if there is a future leak, and would
hopefully minimize weight gain.
By the way, how many liters was your 17.5 LB board?
-ddd
Bob T
making it a monocoque assembly. The urethane foam ads significant
structural rigidity to the board over styrofoam. making the board more
durable. Bags of beads would allow the board to flex and twist. Lasers
would use the beads purely for safety flotation in the event of a leak.
Bob T
> By the way, how many liters was your 17.5 LB board?
Somewhere around 115 plus or minus 5 liters.
Charles
> No, the urethane foam bonds readily to the inside of the board hull
> making it a monocoque assembly. The urethane foam ads significant
> structural rigidity to the board over styrofoam. making the board more
> durable.
The styrofoam isn't used to provide rigidity. It's used as a plug to
hold the shape (rocker/rails/width/thickness) while the board is
skinned with fiberglass/carbon/etc. and epoxy. The entire strength of
this board is provided by the skin. If you could remove the styrofoam
after the skin was laid up the strength would not be significantly
different than with the stryofoam in place. The urethane foam will
definatly add more weight to the board and I doubt it would provide
much difference in strength.
Bob T
of my test where I removed the styrofoam from a Basset wave board you
would have deduced that the empty hull was somewhat flimsy, flexible,
and very crushable if you stepped on it. Understand that I ride and
own Doyles which are hollow and are incredibly tough because of their
construction of 1/2" thick divinycell and s-glass. The Basset was
built a lot tougher than most modern boards with1/4" divinycell, but
without the styrofoam, it would be unusable. Many modern boards are
manufactured with a skin thickness 1/16" and 3/32" thick and without
the styrofoam would barely be able to support their own weight without
the styrofoam let alone be able to be sailed.
As for weight, most boards are made with styrofoam which weighs
between 1 and 1.5 pounds per cubic foot. The urethane foam I have been
using has a density of from 2 to 2.5 pounds per cubic foot or roughtly
twice the weight of styrofoam or 1 more pound per cubic foot. A 112
liter board would have a cubic foot volume of 4 cubic feet at 28
liters per cubic feet. So replacing the styrofoam with urethane foam
would add 4 pounds. To get the weight down, it is necessary to cast
"hollow" spaces in the board. See my Basset example.
When using the urethane foam to do the mast box repair, the total
volume of styrofoam removed was about 4 quarts and there are roughly
30 quarts per cubic foot so the dry styrofoam would weigh about 4
ounces. The same volume of urethane foam would weigh about 8 ounces
so the weight increase would be about 4 ounces when using the urethane
foam to replace the styrofoam in this example. Four ounces is more but
isn't likely to be noticable to the kind of sailor who would choose
this method of repair, especially if it gave his favorite board a new
life expectancy.
Bob T
1 lb/CF styrofoam has a compressive strength of about 7 psi. while 2
lb/CF urethane foam has a compressive strength of 40 psi or roughly 6
times stronger.
See: Urethane foam 2# Physical Properties: Parallel Compressive
Strength: 40 psi,
Tensile Strength: 30 psi, Shear Strength: 30 psi, Flexural Strength:
50 psi
Bob T
problems getting it to recognize my ISP. Shouldn't take too long to
work the bugs out then I'll post more.
danc...@gmail.com
Is the product below the one that you used for your foaming?
http://www.defender.com/product.jsp?path=-1|10918|16458|970853&id=21724
Also does 1.75 density mean 1.75 lb per cubic foot ?
Froth Pak Polyurethane Foam
Density: 1.75, 1.0 cu. Ft. Yield
Item #: 752550
Manufacturer: FROTH-PAK
Model #: 12 kit
Shipping Weight: 3.30 Lbs.
Our Price: $36.99
Bob T
Defender. I don't know anything about the Froth Pak Foam. Yes, the
1.75 is their advertised density per cubic foot.
Bob T
area. Usually it is in the area where the feet are placed during a
jibe. Some delams I have fixed are as large as 18” in diameter. Put a
piece of carpet on a table and place the board on the carpet. Use your
hand to press down in the area where you suspect a delam and see if it
deflects downward. Try to determine the perimeter of the delam. I try
to access a delam by going thru a hole created under one of the deck
pads. By doing this, I’m able to conceal the access hole when I
replace the deck pad. Detach the deck pad(s) closest to the delam.
Sometimes I use lacquer thinner to soften the glue which holds the pad
down. When the lacquer thinner is ineffective, I use a sharp razor
blade or matt knife. For this example, lets assume there is a 13”
diameter delam in the center of the board between the front and rear
footstraps. And lets assume there is one deck pad for the front foot
straps and another deck pad for the rear foot straps. I prefer to work
where access is easiest, so I would remove the front foot straps and
the front deck pad. Next, I would determine how big of hole I will
need to cut from the deck to access the delam area. In this case I
would use a pencil to trace in the area where the deck pad was removed
an ellipse about 7”x11”, but I would stay back at least 1” from the
edges where the deck pad had been. The reason for this is to give
myself room to glass over the cut I’m about to make in the deck when
I re-attach the deck piece. Next I use a jig saw to cut the ellipse
then I use a screwdriver to pry out the piece of deck. The deck piece
will come up with Styrofoam attached. I remove the Styrofoam from the
deck piece and set the piece aside. Next, I use screwdrivers,
scrapers, grinders and a shopvac to dig out the Styrofoam from the
area of the delam down to a depth of about 3” from the underside of
the deck. Crush type delams usually are distinguished by a horizontal
void in the Styrofoam. See the Board Lady’s website:
http://www.boardlady.com/softdeckanalysis.htm Remove the Styrofoam
wherever there is a void. Then taper the void up to the deck for
about 3” beyond the limits of the original void. You should now have a
piepan shaped void about 3” deep and about 19” in diameter in the area
of the original delam. You could stop here and recast the foam, but I
like to make the board stronger by using the urethane foam to connect
the board bottom to the board top. To do this I dig the Styrofoam out
all the way to the board bottom in 2 round patches. Each patch is
about 3” in diameter and located about 5” left and right of the
centerline of the board. Each patch is tapered upwards and outwards in
the Styrofoam. With the void smoothed and fairly even, it’s time to
cast foam.
Like the mast box repair, this next part is VERY IMPORTANT! When
casting foam, heat is produced and this heat can DAMAGE your board by
softening them and allowing them to distort as the foam expands if
the heat becomes too concentrated, especially at the bottom of the
board. To cast the foam, mask around the perimeter of the deck
opening to prevent getting urethane on the surfaces. To protect the
bottom from heat damage, I cast a small batch of urethane, enough to
fill each recess when expanded, to a level of about 3/4”. This small
amount won’t generate a lot of heat and will act as an insulator for
the bottom. To prepare, bring the temperature of the foam components
up to at least 90 degrees like before, use 2 paper cups to precisely
measure equal parts of the components which when combined will produce
a liquid volume of about 1/3 cup. Pour the contents of one cup into
the other, stir rapidly, then pour about half of the liquid into each
3” diameter recess. Then pick up the board and keeping it reasonably
level, slosh the liquid around in the bottom of the recesses trying to
evenly spread out the expanding foam. Then set the board back on the
carpet and let the foam set up for about 30 minutes. For the remaining
void I would cast it in 3 loafs, doing one side then the other side
then fill in the middle.
I have someone stand the board on its edge then I mix a batch with a
unexpanded volume of about 5/8 of a cup and pour it into the void then
I grab the board and gently rock it back and forth to spread the foam
out around the side to be filled. As the foam expands, I carefully
watch the deck opening to make sure the foam is not pushing it up and
out of position. About ¾ thru the foam expansion I set the board back
on it's bottom . It is ok and encouraged to allow the urethane foam
to ooze out the deck opening. IF the deck is being push up hold it
gently it in place until the foam stops expanding and hardens enough
to no longer distort the deck. I repeat for the second side. Then cast
the center loaf. Like before I use a hacksaw blade to trim the oozed
out foam flush with the deck, then I use my router to create a recess
to receive the original deck piece I removed earlier, I bed in a
layer of 6 oz fiberglass in the recess then I mix a slurry of epoxy
and filler about the consistency of jam, spread it in the recess then
press in the deck piece and use weights to hold it there until the
epoxy cures. Then I use my small grinder to make a tapered v-joint
from the jigsaw cut extending 5/8” either side of the jigsaw cut and
to a depth of about 1/16”. Then I use long 1” wide strips of 3 oz.
fiberglass and glass over this v-joint with epoxy. Usually it takes
about 5 layers of 3 oz. fiberglass to fill the v-joint. Once hardened,
I sand somewhat smooth and re-install the deck pad with contact
cement. The best contact cement is: 3M Scotch-Weld Neoprene Contact
Adhesive 10. It also works great for boom regripping. Then put the
footstraps back on and the board is ready to use. The beauty of
making your access hole under the deck pad is you don’t have to do
fantastic job of the deck repair like you would if you made the hole
in the non-skid area.