MODIFYING YOUR KAYAK FOR COMFORT, PERFORMANCE AND CONVENIENCE
By Ken Rasmussen
Finish and Appearance
Velcro Verses Glue The Seat Back
Bands and Seat Backs Hip
Braces Knee Braces Other
Customizing Options
Conclusion Acknowledgements
(Click on links in the article to view related photos. Click the back button to
return to the article)
What follows is a method I have used to build foam seats for kayaks. Please
don’t presume that this is THE method. It is just a way of doing things. I
suggest you read this and use the techniques that appeal to you. Read the entire
text of these instructions, even if you’re not making a seat, hip braces and
knee braces. I have included a number of hints and tips that are apply to all
foam fitting, and I have not always bothered to repeat the information a second
and third time if I’ve mentioned it previously. (I know this is a lot of
reading. I wrote it!)
Making a complete custom cockpit is a big job. Allow plenty
of time. Have extra glue and foam on hand. Your skills will improve and your
ideas may change as you work, and it is frustrating to run out of material
when the creative fire is burning bright
SITTING PROPERLY IN A KAYAK
It is best to paddle your kayak sitting very erect, even
leaning forward at the hips slightly. By paddling in this manner the lower back
does not rest against the back band, or seat back with much pressure so the
torso is free to rotate. The arms hold and control the paddle, but much of the
power comes from the large muscles in the torso. The footrests should be
adjusted for this posture so that with the legs straight, and the feet
perpendicular to the legs, you can feel solid contact with the foot rests. When
the knees are lifted into position beneath the deck there will still be solid
contact with the foot rests with the feet inclining naturally forward. When
paddling, the legs alternately bend and straighten to apply pressure to the
footrest on the paddling side. The leg on the paddling side of the boat comes
fully straight at the end of the stroke. Getting the footrests adjusted properly
makes this easy and natural.
It is often necessary to practice this posture frequently, for short periods of time, to make it natural and comfortable. Many
paddlers, accustomed to bucket seats in cars or easy chairs, paddle in an unathletic manner, leaning heavily backward, and paddling entirely
with the arms. It is not an easy habit to break, but it is worth the
trouble it takes, since paddling speed, efficiency, and comfort all benefit.
You will want to sit conscientiously and correctly when you
create the foam components of a custom cockpit. Otherwise you'll be creating a
water-going easy chair, not a real paddling craft. Back to Top
It is possible to do a very effective job of customizing a
cockpit without taking much trouble about the appearance. That is perfectly
satisfactory. If a finer appearance is desired, spend extra time sanding for
appearance. It is also possible to cover foam surfaces with 1/16th inch self
adhesive foam or upholstery fabric for improved wear resistance and a more
finished look. The only place covering the foam is really important is on the
hip braces. When squeezing past the hip braces there is a tendency to tear or
abrade them, so they should be covered.
The self adhesive foam is the easiest covering to apply, but
it can’t adapt to tight compound curves unless darts are cut into it. The
fabric is easier to fit to complex curved surfaces. The fabric also increases
the amount of friction between you and the boat, so it is helpful for staying
put. I have even used fabric over self adhesive foam to hide prominent seams in
the underlying gray minicell foam by means of the self adhesive foam, and to
hide and protect the darts in the self adhesive foam by means of the upholstery
fabric. It was a lot of fuss, but I was very gratified by the overall effect
when it was finished. Back to
Top
I’ve never used velcro to attach pads or a seat to a kayak but others have.
It is a very good idea if people of dissimilar size are sharing a boat, or if
the boat is a folding boat that needs to be dismantled.
When attaching pads with velcro, upholster the pad with
fabric and attach the velcro to the upholstery fabric. Use industrial grade
velcro for best results. It would be a good idea to run removal straps beneath the pads in order to keep from doing damage to the pads while
removing them. Rex Roberton made his removal tabs by extending the velcro
beyond the foam, and doubling the end over, so the excess velcro is a removal
tab.
You can also temporarily attach pads by spot gluing them. They can be easily
removed with an icing spatula.
SKIN BOATS
The framework of a skin boat complicates the attachment of a seat and hip and knee braces. It is easy to place foam squares between the framework of a seat boat and cut them flush with the top of the frame. These can be glued to the skin of the boat, and provide a good surface for attaching the seat and braces. You may wish to end the floor boards at the seat in order to make the seat lower. Most skin boats are round in the bilge and narrow, which makes them tend to be tippier than many paddlers might prefer. By putting the deepest part of the seat below the height of the floorboards, the stability can be increased significantly.
FOAM: CHOOSING, PREPARING, AND CUTTING
IT
We prefer to use
Voltec M200 minicell foam for customizing kayak cockpits. We pay more
money for it because there is too much labor in making a cockpit to use a
material that might wear out. Most sellers of foam, even if they sell Voltec foam, sell L200, which is more compliant and less costly. It's not
bad stuff, but it isn't as structurally strong. In our opinion, the amount of labor
one invests in the project outweighs the economy of using cheaper
material. When you buy foam it may have a skin on it. The skin is
very tough, and does not rasp or sand well. Any surfaces that will require
rasping or sanding need to have the skin sawn off first. An ordinary
carpenter's crosscut handsaw works well.
When cutting foam, cut as close to the layout lines as you
dare with a crosscut saw, serrated knife, bandsaw, or what-have-you. Use a
Stanley Shureform 21-115 to rasp to the lines. The Shureform has one side
that is straight, and one side that is serrated. By angling the blade as
you draw it toward you, you can use the serrations for aggressive roughing, or
the straight edge for a better finish. A spare blade for the Shureform can
be modified for cutting concavities. To modify the blade, determine which direction
the blade cuts and break (or grind) off the back mounting tab, leaving a tab on
the front to pull from. (Wear safety glasses when breaking or grinding the
blade.) Grind or break off the corners at the back of the blade so the back edge
of the tool is rounded. You will find this tool indispensable for making concavities. I use
it as much as the blade that is mounted in the handle. Take the work as
far as possible with the Shureform, then finish with Dragonskin (metal
sandpaper) or 40 grit sandpaper. I use a strip about 7/8" by 2
1/2" with rounded ends. Take the faster cutting tool as far as you
dare before switching to the slower cutting tool.
The seat is the basis for comfort and control in your kayak. A custom foam
seat gives more comfort and control than any other type. The weight
you can save by using a foam seat instead of a plastic or fiberglass seat could
be as much as the weight you might save by spending a few hundred dollars extra
to get a kevlar or carbon fiber boat. Making a foam seat is a less costly way to
save weight (or to save even more weight!). Since you can make the foam seat
lower than most other types, you can increase the stability of your kayak. What
follows is a step-by-step method that will allow you to build a custom foam
seat.
1. Sit on the floor with your right hip adjacent to a wall. Pull a box up
against your left hip. Stand without disturbing the position of the box. Measure
the distance between the box and the wall. This will be the approximate width of
your seat.
2. Depress a couple of dents into a block of foam by sitting on it. Measure
the center to center distance between the dents. Later, when you carve "butt
dimples" into the surface of your seat, you’ll need this dimension.
The material I use is gray mini-cell foam, 3 inches thick, 2-pound density. I
have noticed a difference in the ease of carving and in the strength of
different types of gray mini-cell foam. I prefer Voltec M200, which is a fine
cell, crosslinked "polyolefin" foam with a polyethylene base that
weighs 2 lbs per cubic foot. Back to
Top
3. If you already have an existing seat in the boat, learn all you can from
it. The fore-and-aft position of your weight affects the trim of the boat: If
the seat is too far forward the boat may not track well when paddling without a
rudder due to too much immersion of the bow, too far aft and the stern may drag
when paddling fast. The seat position also has an effect on weather cocking. You
can reduce the tendency of the bow to veer into the wind by moving the seat
back. Lee helm—the bow swinging away from the wind--can be reduced by moving
the seat forward.
If you want to mount your new seat in the same location as
the old one, remove the seat back and install a back band before you remove the
seat. Then when you install the new seat you can adjust the position of the seat
relative to the back band, and you will be in the same position as before.
Mark a line
across the hull where you want the deepest part of your seat (the butt
dimples) to be. You can get this location from your old seat if the paddling
characteristics are good, ask the manufacturer of the kayak, or use trial and
error paddling to find the best spot. Now make lines across the inside of the
hull 5 inches aft and 7 inches forward of the "butt dimple" line.
These lines represent the front and back edges of the seat. The fore and aft
dimension furnished is not empirical. A friend made his seat two feet long so he
could gain additional support beneath his legs in order to reduce pressure that
was causing his legs to become numb.
Remove the old seat. Fiberglass seats that are suspended from
the cockpit combing can be sawn off a little below the bottom of the combing. (I
once ran my bayonet saw through the side of my boat. Now I use a handsaw, and
run the blade at an angle so as to miss the boat!) The rough edge of the saw cut
can be smoothed with sandpaper. Start with coarse sandpaper and work through
finer grades. Remove whatever foam and adhesive remain in the hull from the
previous seat. "Goof Off", a paint remover, is useful for removing old
adhesive.
4. Make cardboard templates of
the inside of the hull where the front and back of the seat will be. Mark
vertical centerlines on both templates. These templates will be used to trace
the contour of the front and back edges of the seat. Hint: To minimize
trial-and-error trimming of cardboard, use a flex
curve (sold by engineering supply shops) or a length of heavy soldering
lead. Press the flex curve or solder into the hull along the lines drawn,
bending it into the correct shape, and then trace the curve onto
cardboard. Alternatively, you can hold a series of stiff paper cards in
place and tape or staple them into alignment to create a curve. Back to
Top
5. Next you will need to locate the upper edge of your seat on the
template. Your seat will need to be at least as wide as your bottom in front
(see step #1). Make a horizontal line two and one quarter inches above the
bottom of your front template and extend it until it intersects the edges of the
template. This line should equal or exceed your butt width from step #1. If you
need to, you can increase the height of the line a bit, up to 3". In order
to save foam you can make the seat narrower than the full width of the boat, as
long as it is still wider than your bottom. On the other hand you may prefer the
appearance of a seat which spans the width of the boat. It is an aesthetic
choice. Trim the template along the line you've created, which represents the
top of the seat. Subtract one and one sixteenth inch from the maximum height of
the front template. The resulting dimension equals the height of the rear
template at center. This will cause the seat to slope back at an angle of about
5 degrees. (Giving the seat a 5 degree slope is not essential since the top of
the seat will be sculpted to fit the paddler anyway. It does reduce the amount
of material that will have to be removed in order to make a comfortable seat.
Some people like to make an extra tall seat and carve their imprint deeply into
it, but it does increase the labor significantly.) Draw a horizontal line across
the rear template at this height and cut along it. Making the back of the seat
lower will also make it narrower. It will usually be a little narrower than your
bottom, but since the entire width of your bottom does not contact the seat it
will be OK.
If your cockpit comes too high around your body you can make
the seat taller, as long as that won't make your boat too unstable. Conversely,
if the cockpit is not too high and the boat is unstable, you can increase the
stability by making the seat lower, or by carving the curves to fit your butt
more deeply.
6. Lay out the foam. Start with a block 12 inches by the width of your front
template (see step #5). The 12-inch dimension is the fore and aft length; the
front template dimension is the width. Label the top, bottom, front and rear
edges of the foam. Make a centerline on the foam perpendicular to the front and
back edges of the seat. This line will follow the keel of the boat. Make a line
5 inches from the back of the seat, perpendicular to the keel line, to give you
a fore and aft location for your sit bones. Mark the
butt dimple centers on the "sit bone line" equidistant from the keel
line (see step 2 for the dimension). Hold your front and rear templates level
with the top edge of the foam and mark the cross-sectional shapes on the front
and rear of the seat block. Be sure to keep the centerlines of the foam and the
templates in alignment. On the top of the seat connect the lines from the
corners of the front and rear templates. These lines represent the sides of the
seat and will be used as cutting guides when roughing out the foam. Make two
more lines parallel to the sides of the seat so that they run through the butt
dimple centers. These will be useful as guides when sculpting out the butt
dimples because as soon as you begin sculpting, the centers will disappear.
However the lines you have drawn on the top of the seat will give you a set of
"cross hairs" so you will be able to judge where the butt dimple
centers were, so you can carve on center and keep things
symmetrical. Back to
Top
7. Rough out the foam with a carpenter’s
hand saw or serrated bread knife. Refine the contours with a
Stanley Shureform Shaver 21-115. Finish
with dragonskin (metal sandpaper) or coarse
sandpaper, either on a block, for broad surfaces, or a narrow strip held over
thumb or forefinger to finish small areas and concavities. Use faster cutting
tools like the hand saw and the knife as much as possible before progressing by
stages to progressively slower cutting tools like the Shureform and the
sandpaper. One of the virtues of working with foam is that you can glue scraps
on to give yourself a second chance if you cut too much. It is very difficult to
avoid making mistakes, so relax: Buy some extra foam and glue, and don’t worry
about the inevitable mistakes. You can still get excellent results.
First contour the underside of the seat to match the bottom
of the boat. A straight edge is helpful for determining whether the surface
between the layout line on the front of the seat and the layout line on the back
of the seat is straight. When the seat fits the boat properly you can begin to
sculpt the top surface. Begin with the butt dimple centers. Rough out the butt
dimples with a modified spare blade for a Shureform
21-115 gripped in the fingers.
With the boat supported on something soft, sit on the seat
wearing thin pants and observe any sources of pressure or discomfort. (I have a
bean bag chair that I rest my boat on when I wish to sit in it. It keeps me
from beating the boat up. It is also a good surface to rest the boat on when I
am working on it. The usefulness of the bean bag chair can’t be overstated.
Get one if you can.) Gradually contour the seat until the pressure is uniformly
distributed and there are no uncomfortable spots. I call this part of the fit
process "The Princess and the Pea", after the fairy tale about the
princess who was so sensitive that she couldn’t sleep because there was a pea
beneath the 16 mattresses that she slept upon. Cultivate your sensitivity when
fitting your boat to yourself, and later, on long trips, you’ll be glad you
did! Most of the contouring consists of cutting gradually deepening ovals
beneath the "sit bones". The ridge between the two depressions will
also need to be cut lower. The stability of the boat improves markedly as the
seat is lowered. You can make the seat lower by removing additional material
from the bottom (as long as you don’t make the seat too narrow) or by cutting
the butt dimples deeper into the top of the seat. I like deep butt dimples
because they tend to anchor you in place on the seat better. Be aware of the
height of the deck of the boat. It is possible to make the seat too low. If the
seat were made too low, the combing and the deck might be too high relative to
the paddler, and could interfere with the stroke of the paddle. Take lots of
time and test frequently as you sculpt the seat into its final
form. Finish with dragonskin metal sandpaper or 40 grit sandpaper. I cut a channel
along the keel line on the underside of the seat to allow water to pass beneath
the seat (in order to make bailing and sponging easier).
8. After you have tested the seat for proper fit, you may wish to upholster
the top of your seat for a longer wearing, better looking, higher friction
surface. I use a fabric that is often used to
cover speaker grills. To apply fabric to the surface of your seat (or any fit component) use spray contact adhesive. (Make
certain that you get an adhesive that is compatible with the foam--like Dap
Multi Purpose Spray Adhesive or 3M General Trim Adhesive 08088).
Spray a thin coat of adhesive to the seat top and the underside of the fabric,
followed by 3 successive thin coats, each perpendicular to the previous coat. If you spray too
heavy a coating it will penetrate the fabric and make an unsightly mark on the
surface of the seat. (If you do get some adhesive bleeding through you can make
it less visible with a permanent marking pen after it dries.) Allow the adhesive
to dry briefly (follow manufacturer’s instructions), then stick the fabric
onto the seat top and trim with scissors. Always cut the fabric
oversize and trim after bonding. Once the glue on the fabric contacts the glue
on the foam, it sticks, never to be moved again! It is much easier to trim the
fabric accurately after it is in place than to try to cut it exactly and then
align it while gluing. Back to Top
9. Place the seat in the boat using the fore and aft location lines from step
#3, and trace the outline of the seat into the bottom of the boat. Hint: It is
often helpful, when gluing foam seats or pads into a kayak, to create
"witness lines" by holding the foam part in place and making several
marking pen lines which begin on the foam and cross onto the boat. By
positioning the part so the lines all connect, the location will be nearly
identical each time you fit the foam into the boat. Before applying glue,
"dry fit" the part to the boat as if you are placing it on contact
cement. Make certain you have a good strategy for correctly setting the part
into glue before you apply the glue. Contact cement bonds permanently as soon as
the surfaces touch, so you need to be well rehearsed in order to get the
position correct on the first try.
Lightly sand the fiberglass within the outline of the seat
and wipe it clean with acetone. Use a waterproof contact adhesive to attach the seat to the
bottom of the boat within the outline. (Kayakfit no longer sells contact
adhesive due to shipping difficulties. Most hardware stores carry Dap
Contact Adhesive, which works well.) Follow the manufacturer’s instructions
for the best results. I usually apply 2 coats to the boat and 3 coats to the
underside of the seat, allowing each coat to dry until tacky. I apply the first
coat of glue to the foam, then the first coat of glue to the boat, then the
second coat on the foam, alternating, and finishing with the final coat on the
foam. Don't apply the glue too thickly. More coats are better than thick coats.
Porous surfaces like foam need more coats than smooth surfaces like fiberglass.
(Put your adhesive in a ziplock bag and store it in the freezer for a longer
shelf life.) Take care when placing the seat in the boat. Once it touches it
sticks. Put it down where you want it--it will not be possible to slide it into
position. Clean up glue spills with Goof Off. Your seat base is done!
BACKBANDS AND SEAT BACKS
Most of us use a padded back band for the seat
back. Back bands give excellent support and control, and are less apt to be an
impediment when doing rescues, rolls or braces than the rigid seat backs used in
many kayaks.
The installation is straightforward. We usually bolt the attachment straps to
the underside of the deck just above the hull/deck joint. If you plan to leave a
suspended seat in the boat you may find it more convenient to bolt the straps to
the sides of the suspended seat. Some boats have vertical panels on either
side of the seat. If you decide to leave these in the boat you may wish to
mount the back band to the back side of the vertical panel.
Back bands usually have grommet holes so they
can be secured by means of screws on either side of the deck, at points which
will permit the back band to be adjusted into the correct position. Choosing the
points of attachment is the most important concern. The height of the holes
determines the height of the back band. I usually mount as high as
possible. Avoid placing the attachment
points too far aft or you may not be able to pull the back band forward as much
as you wish. When the back band is installed and adjusted, the straps should
angle forward at about 45 degrees if you have chosen your attachment points
correctly. You can reinforce the inner surface of the deck at the attachment
points if it seems necessary, and it is a good idea to distribute the stress
with large washers. Most paddlers use elastic cords to guy the back band into
position, though it isn't always necessary. When drilling holes for guying the
back band aft, choose points (in the deck aft of the cockpit) slightly further apart than the width of the back
band. Always look beneath the deck before drilling to see what you are drilling
into. (I have drilled into the rear bulkhead before. It is most vexing!)
Important note: The
attachment points usually occur where the hip braces are going to be
mounted. That isn't a big problem. Cut clearance for the screws and
straps into the hip brace before gluing it to the boat. There will still
be plenty of surface for gluing the hip brace in.
In some kayaks the cockpit combing and the rear bulkhead are
very near to the back of the seat. When that is the case, a good alternative is
to make a foam seat back attached to the bulkhead and the combing. The process
would be similar to the seat making process Back
to Top
Hip braces are used to keep the paddler centered on the
seat and to make it easier to keep from falling out of the boat when upside
down, or from sliding off center when the boat is leaned. The ability to lean
without having to struggle to balance makes previously difficult maneuvers easy
to do. The pads curve inward at the top making it necessary to turn slightly
sideways and drop the aft hip when wriggling in and out. It is unnecessary to
have a tight fit in order to have good control. As with the seat, good fitting
maximizes surface contact and minimizes pressure. (Make certain you can still do
wet exits and rescues in the presence of a spotter.)
We usually make the fore and aft dimension of the hip braces
6"--which is the thickness of two pieces of 3" foam glued together to
make a block of stock. I have my hip braces approximately centered in line with
the "butt dimples" carved into the bottom of my seat. I notice that my
wife has hers a couple of inches further forward. We make our hip braces the
same height as the cockpit combing.
To make templates for laying out your hip braces you can make
pairs of incomplete templates made to the boat, and to yourself, made to overlap
when held in correct alignment. The alignment can be found by sitting in the
boat and putting the templates in place. After the templates are aligned they
can be carefully withdrawn and stapled together to form a single template.
To begin, make make templates of the
side of your right thigh near the hip with cardboard. Sit on a bench. Press a
Flex Curve or a length of stiff solder into the same curve as your body along a
vertical line at the point where the front edge of the hip brace will be. Trace
the shape onto cardboard. Now pick up the line where the aft edge of the hip
brace will be and transfer that to cardboard. Make templates of the right side
of your boat from the inside at the front and rear edges of the place where the
hip brace will be. Sit in the boat with the front pair of templates
(that is: The right to-the-boat template, and the right to-the-human template)
in place and hold them in the correct relationship to each other. Taking care
not to jostle them out of alignment, withdraw the templates from the boat and
drive a couple of staples through to fix them in place so you can use them to
lay out the front edges of the hip brace. Repeat the process with the rear
templates.
Sometimes the front and rear templates are similar enough
that it isn’t necessary to make both. You only need to do one side--after you
get your right hip pad roughed out you can hold it against the stock you will
use to make the left hip pad from, and trace the mirror image directly onto the
stock using a marking pen. I like to extend the hip pads above the height of the
cockpit combing—it is best to make them too tall, and bring them down to the
correct height during the final finish sanding, after gluing.
Lay out the foam--use 3-inch gray mini-cell foam, usually two
layers glued together with the glue plane perpendicular to the axis of the
boat--and rough it out oversize. Use the Stanley Shureform 21-115
to contour the fit to the boat first. When the right hip brace is done you can
hold it up against the foam you will cut the left hip brace from and trace
around it for a pattern. The right
brace is a perfect pattern for a left brace, and vice versa. This makes the
second side very fast to make--about one quarter of the time it takes to make
the first side. Remove just enough material on the surfaces that contact your
body so that you will be able to squeeze in with difficulty.
Prepare the boat for the glue with light sanding and acetone
in the same manner as with the attachment of the seat base in step #9. Be sure
and practice your strategy for fitting the braces into place before you apply
glue. The glue locks into place as soon as the surface touches, so you want to
be certain you can do it properly before you apply the glue. Glue the braces
into position while they are still too tight and do the do the finish work
after they are glued. The braces act as if they lose some of their thickness
when they have been glued because they get pressed tightly into place and then
stay slightly compressed.
Pay attention to centering yourself in the boat as you
contour the inner edges of the hip braces. You don’t want to be positioned to
port or starboard when you are done! Some boats or individuals may not be quite
symmetrical--be aware of the possibility. Finish the surfaces with dragonskin
or 40 grit sandpaper. Sand until you have a nice fit wearing thin shorts, then
sand again until you have a nice fit wearing your immersion clothing. (Remember
the story of the Princess and the Pea. Make the fit as close as you can without
feeling any pressure.) Swing your torso fore and aft and from side to side. Sand
until you have all the freedom of motion you want. Since the hip braces are snug
at the top where they hook inward, it is easy to damage the foam when squeezing
in or out of the boat. Cover the hip braces over with 1/16 inch self adhesive
foam or upholstery fabric for
resistance to abrasion. (See step 8 of the seat building instructions.) I have usually used 1/16 inch self adhesive foam
for this application, but on my most recent boat I had a compound curve near the
top of my hip brace that made the upholstery fabric a better choice. When
upholstering complicated shapes like hip or knee braces it is sometimes helpful
to use a "straw", like the ones that come with W. D. 40 spray
lubricant to control the spray when spraying adhesive inside the boat. You may have to
improvise by borrowing a nozzle from another spray can--a straw won't always fit the standard nozzle.
Allow the thin foam or the fabric to overlap onto the
fiberglass combing to reinforce the glue joint at the top of the hip pad. Trim
the fabric after gluing. Back to Top
Knee braces provide the kayaker with sufficient grip to
torque the boat with power and authority. Many paddlers who have experienced
little success in their efforts to do leaned turns, braces, and rolls will find
their efforts successful when the boat has been properly fitted with support for
the knees. Support should be given to both the inside and outside of the knee
(or thigh near the knee). When torquing the boat, the inner support is needed to
transmit force. Supporting the outer side of the knee improves general comfort
and helps create a feeling of security in the boat. Some people design knee
braces with support for the end of the knee, though that surface is less
important than the sides, and can be omitted with little loss of comfort or
control.
The following instructions presuppose that the deck passes
over the knee and thigh so that there is an adequate surface to glue foam pads
to, the foam acting as the cushioned interface to anchor the knees properly
beneath the deck. If your kayak does not have support above the knees study the
last chapter of Derek
Hutchinson’s book, Eskimo Rolling, for modifications appropriate to your
cockpit. The wide variety of deck heights and contours make it difficult to give
directions for creating a single type of knee brace.
Several methods have been used with good success. You can
take a block of foam and carve it to fit over the top of your knee and thigh,
then fit it to the deck of the boat. You can fit the
block to the deck first and carve the space for your knee second. Either method
gives a good result; do whatever seems easier. If space beneath the deck is very
limited, or if you'd like to work with smaller, less complicated
shapes, you may find it more practical to jam the knee up under the deck and
cut shapes to fit into the spaces beside the knee.
My favorite method is to use a block of foam, approximately
3" x 9" x 10", and fit it to the underside
of the deck so that the 10" dimension runs across the boat, and the 9"
dimension runs fore and aft. I carve off the top of the 3" dimension,
mostly at the gunwale end of the block, allowing the other end to protrude into
the cockpit at its full 3" thickness.
The location of the block is determined by the position of
the knee beneath the deck. I like the end of the knee to be contained within the
front part of the block when the carving is done. To achieve this I sit in the
boat and mark the point where my knee contacts the deck, on the top of the deck.
(Since the knee contacts the underside of the deck the location of the mark on
the top of the deck is a guess, but a close guess is sufficient.) I hold the
block below the deck, and move it fore or aft until the dot on the surface of
the deck is in approximate alignment with an imaginary line three inches behind
the forward edge of the block. In other words, the top contact point of the knee
would be one third of the way aft of the front of the block of foam. Holding the
block in position beneath the deck, I trace onto the underside of the deck along
the front and rear edges of the foam with a marking pen. Then I make templates
along those lines to lay out and carve the block to the deck. Your
front and rear templates are fairly easy to make, but consider the relationship
of the templates to each other when holding them in position on the ends of your
piece of foam. They need to be in alignment. Study the deck and gunwale of your
boat where you are creating the knee brace. Probably the angle of the gunwale
will stay the same over the length of your knee brace. The deck often curves
significantly in that area. If so, you need to hold the curve of the gunwale in
alignment when tracing around the templates.
If you have complicated shapes on the underside of the deck
to fit to, consider filling them with foam before fitting your knee brace
to the underside of the deck. Cut slices of foam thin enough to flex into the
curves of the deck, glue them into place, and carve or sand to make the entire
surface of the underside of the deck into a smooth curve or flat surface where the knee brace
will be. It seems like extra trouble, but it is much easier to get a nice fit
that way. My Eddyline Falcon 16, and my Falcon 18 both have ornamental gutters
around the cockpit combing. It drove me nuts trying to carve to fit the gutters.
I didn’t do as nice a job as I would have preferred, and it took forever. I
wish I had filled the gutters first.
I carve the block to fit the deck, then make fresh lines on
the underside of the deck by tracing all around the block. I also make witness
lines which cross from the underside of the deck onto the foam knee brace in
several places, making it easy to locate the foam in the same place each
time. It is helpful to try to rock the block when doing the final
sanding to fit it to the deck. As you rock the block it is easy to guess where
it is pivoting, and that is where you need to sand in order to get a good fit.
When the block fits the boat correctly, and its location is
marked, I begin to rough it out to receive my
knee. The easiest way I’ve found to do this is to fit the foam into position
beneath the deck, and move your finger beneath the foam until you think it is
directly below the knee-contact dot you drew on top of the deck. Mark that point
on the foam with a marking pen. Now put your leg below the foam with your knee
directly below its correct location. Make a mark on the foam above the center of
your thigh where it passes beneath the foam. Make a line connecting the two
points. Using the line as a reference, sketch the cutout for your leg on the
foam. Draw and cut conservatively, since you can't see what you’re doing very
well. I usually start cutting with a saw or serrated knife, but switch to the
modified Shureform blade (described
previously) almost immediately, since it works well in concavities. When I have
a cavity scooped out that my knee can fit into, I do my drawing by feel: I align
the block carefully on its marks, then try to work my knee into position. When I
feel where the interference is, or undesirable pressure, I drop my knee and
raise my pen into position and scribble or stipple the location where I want to
remove material. Still seated in the boat, I withdraw the block of foam,
and carve until the pen marks are gone. (I wear thin shorts to make it easier to
see and feel, and rest the boat on a beanbag chair to prevent damage to the
hull.) Then I reposition the block, work my knee back into place, and stipple
some more, alternately carving and stippling, until I feel that the carving is
at least three quarters of the way done.
Now consider the question of getting your knee past the brace
when getting in or out of the boat. Fit the block into place, lower your knee
into the cockpit, and try to slip it below the brace into position. It probably
won’t go. Observe where material would need to be removed, and remove it a
little at a time until it appears that you will be able to get in. Don’t
remove any more material than necessary at this time. More can be done later
when finish sanding the knee braces after they have been glued.
I use the first knee brace as a template to lay out a mirror
image part for the opposite side of the boat. Hold the carved block against the
corresponding surface of the uncarved block and trace around it. After all of
the surfaces have been marked, the second part can be carved very quickly. I
mark the location of the 2nd block on the other side of the boat, then glue both
pieces into place (as described previously). Part of both blocks usually
projects into the cockpit. Since most cockpits are almost too large to give
adequate support to the knees, it is often desirable to let the support extend
into the cockpit. Unfortunately foam isn't very strong, so it is important to
brace it up well to give durable support. I often fit and glue an extra piece of
foam into the angle formed by the inner surface of the cockpit combing and the
top of the foam block where it projects into the cockpit. That gives a lot more
support to the brace. (You can glue additional pieces of foam anywhere you wish.
Each boat and individual are different.)
Next comes the final finishing of the braces. There are 4
kinds of remaining cuts: 1) Cuts that make it easier to get the knees past the
braces when entering and exiting the cockpit. 2) Cuts that make the left and
right braces aesthetically pleasing and symmetrical. 3) Final sanding to make a
perfect fit. 4) Sculptural sanding to make a nicely
finished appearance. At the beginning of this process you have a couple of
very clunky looking things sticking into your cockpit making it so you can
barely enter or exit the boat. By the time you're done you've got a couple of
streamlined shapes that you can easily wriggle past, which fit so well that they
appear to be molded to you. It is very gratifying.
Although it is important to design the knee brace shapes for
sufficient support, I have not usually found it necessary to upholster them for
additional reinforcement. However, I am aware of instances of badly designed
knee braces tearing, and if you want to reinforce them with fabric it won’t
hurt. It is important to use good quality foam and design strength into the
shapes when making knee braces.
On my most recent boat I thought the foam was a bit thin in
one spot, and since I had upholstered the seat and hip braces, I was attracted
to the idea of making the knee braces match. I had a prominent seam that I
wanted to hide, so I used a layer of 1/16th self-adhesive foam in that area, and
then covered that over with fabric. The overall effect was very nice. I hadn’t
done any complicated surfaces with fabric previously, and found it challenging.
I scrapped some material while experimenting, but eventually came up with a
workable strategy. I found it helpful to hang the boat in a sling so I could
stand erect and rotate the boat to convenient positions. The trick of using the
W. D. 40 straw in the spray adhesive nozzle was indispensable. I had to mask
some areas while spraying inside the boat, but the W. D. 40 straw helped
minimize the amount of masking needed. I trimmed the
fabric after gluing. A very sharp knife with a curved edge was the most useful
tool I found, though I used a scissors in a couple of places.
Back to Top
The seat is an easier shape to visualize than the hip
and knee braces, and lends itself to an orderly procedure. The skills acquired
in making the seat help in making the hip braces, and making the hip braces
creates additional skill for making the knee braces. This approach is also good
to follow because the seat location is determined by weight placement for
optimal boat performance, and hip and knee brace locations are dependent upon
seat location.
Prove the safety of your work to yourself by having someone
stand by while you test paddle the boat, practice your skills, and do wet exits
and rescues. Don’t presume all is well only to discover that it isn’t at a
more critical time!
Temperaments vary. I am a fussy guy who will take endless
pains to get an exact fit and good appearance. If you aren’t that patient it
won’t matter. Your work will last as long as mine will, and your boat can fit
you as well as mine fits me. Since you will be learning new skills, the project
may test your patience, but if you don’t quit until you are satisfied, your
efforts will be amply rewarded. Remember the Inuit kayaks which were the
precursors of ours? Each was custom made for (and usually by) its owner, and the
learning, making, using, and enjoyment of the boat were all inseparable parts of
the process of becoming a kayaker. That process produced good boats and good
paddlers. It is still a good process. It still produces good boats and good
paddlers. Back to Top
Most sea kayakers need to carry some equipment that has to
be accessible from the cockpit. It is good to make a list of such items and
determine how each is to be stored. Sometimes you may be able to take advantage
of opportunities which present themselves when constructing the seat, hip or
knee braces to create storage for a pump, a flashlight, some flares, or any
other gear your creativity can find a home for.
In my Falcon 16 I took advantage of an unusually deep vee
hull to store the pump beneath the seat. Although the
butt dimples were cut within a quarter inch of the hull, I had enough space to
store the pump without raising the surface of the seat (which would have made
the boat unstable). Most boats wouldn’t have that much room below the seat,
but it might still be possible to fit a flashlight or some flares. Most kayaks
have quite a bit of room on the sides, so looking for space within the hip
braces could often result in a good place to keep a pump or some similar large
object.
Dry storage boxes are handy to use
but difficult to store. I glued a foam scrap to the bottom of one and contoured
the foam to fit the hull of my kayak just below my knees. I put Velcro on the foam
and on the hull so I can store the box beneath my knees where it is safe, handy
and acts as a support for my legs. I didn’t do it, but it would be easy to
attach foam to the lid and contour it for additional comfort as a leg support.
I use a small under deck bag
manufactured by Mark Pack Works which clips to a track made of webbing so that
it can slide out from under the fore deck into the cockpit almost like a drawer.
I am very enthusiastic about that accessory.
On my Falcon 16, I utilized my rear bulkhead, which is foam,
as one end of an ice chest, accessible by means of
the rear hatch. I lined the deck and hull aft of
the bulkhead with foam from half-inch Insulite pads and made a two piece door
out of heavy foam backed with fiberglass. The two piece door easily fits through
the hatch and jams into place against the Insulite, sealing the ice chest
nicely. (The latch for the door is a paint stirring stick with Velcro attached
to one side. The two halves of the door have Velcro also. When the stick is
attached to the two sections of door it all acts as one stiff piece. It can't
slide aft because the interior gets smaller aft, and it can't shove forward
because the side and top insulation pieces restrain it.) All pieces except the
bulkhead are removable for cleaning, or if the space is wanted for other
storage. The method I used to create the curved pieces for the top and sides of
the ice chest was to apply spray adhesive to sections of Insulite pad, and then
glue them together by holding them against the contour of the
kayak. I laminated the pieces together until I had the thickness I wanted,
at which point the material had the correct curves permanently formed into it.
Then I used handsaw and Shureform to finish the edges. I did my forming aft of
the location of the ice chest because the parts need to fit inside the boat, not
outside. By forming the pieces aft of the actual location, I was building on a
smaller form of similar shape, which is exactly what was needed.
My Falcon 18 has ten and one half inch round hatches made by
Kayaksport on the front and rear decks. They are not large enough to enable me
to store long items within the dry storage space. I installed a seven and one
half inch VCP hatch (Valley Canoe Products) in the rear bulkhead, and used a
backband with ratcheting buckles so that I can remove the backband easily.
Although the VCP hatch is smaller that the others, its position at the end of
the storage area enables me to fit many items into the storage area that will
not fit through the deck mounted hatches.
When designing deck rigging I draw on the deck with a grease
pencil for several days before I drill any holes in order to have plenty of time
to think of improvements. I try to make each hole as productive as
possible. Often a single screw can secure a perimeter line and elastic above
the deck, and still function as a tether point for something else below deck. I
like to use three quarter inch nylon webbing to encircle deck lines (as opposed
to plastic or metal strap eyes) because each attachment point uses one screw
instead of two. You have half as many perforations in your boat and cut the
weight of your hardware in half. By using finish washers to fair in the screw
heads the result is very low and trim.
I use 5/16 inch self-adhesive foam
to make pads on the deck beneath the blade and shaft of my spare paddle. This
creates a higher friction base to
secure the paddle to so it is less apt to be carried off in surf, and
prevents the spare paddle from marring the deck. (Of course, since the deck is
covered with a pad no one can see if it has been marred or not.) Back to Top
These ideas all came to me as a result of problems I had, or
had noticed other people having. It was surprisingly easy to address most of
them. Some ideas, like using webbing to form loops as a substitute for strap
eyes, I borrowed from other sources. Some people, having been influenced by me
and by my friends, have gone on to produce imaginative, beautiful, and practical
variations on our ideas that outstrip our work. It is very satisfying to spend
time in your own unique boat, adapted to your needs with your hands, directed by
your creativity. If you do a nice job you'll get a lot of compliments, which
you'll enjoy, and you'll inspire others. The sport will continue to evolve and
advance, and you will have helped direct its progress.
Copyright © 1999 [Kayakfit]. All rights reserved.
Revised: April 28th, 2001. Back to Top
A number of people have helped with this website. My wife, Kathea, is
the person who introduced me to kayaking many years ago. She has also
helped to put on a number of workshops and seminars, and took many of the photos
which appear here. She bought a computer and created this website with no
previous computer experience,
Tom Derrer, of Eddyline Kayak works, drew me more deeply into kayaking and
into the kayak trade, and furnished us with excellent boats. The most
recent, a Falcon 18, had a deeply contoured seat base that was so well designed
that it seemed sacrilegious to take it out. I needed some additional seat
making photos however, so out it came.
Rex Roberton, of Gronseth's Kayak Academy, introduced me to high quality
custom cockpit fitting. Before Rex outfitted his boat I'd never seen good
work, so I had never wanted to fit my boat to myself. When I saw
Rex' beautiful work, and how it improved his control, I was inspired to do
the same. Rex is currently at work making a video on custom outfitting of
kayak cockpits.
Bob Rock, of Bob Rock Photography, is an avid paddler and kayak
instructor. He supplied us with a 26 very fine photographs for this
website.
Chris Cunningham, editor of Sea Kayaker magazine, gave me the writing
assignment on cockpit customizing (February 1998 Sea Kayaker) which
became the framework and inspiration for this website. My thanks to all of
these people for their support. Back to Top
Ken Rasmussen