RASMUSSEN’S
RASMUSSEN’SMODIFYING YOUR KAYAK FOR COMFORT, PERFORMANCE AND CONVENIENCE
by Ken Rasmussen
Within our kayak club cockpit modification has become a mania. Members continually strive to outdo one another with creative ideas for cockpit improvements. In some cases the work resembles an art form. We jokingly refer to it as “Foam Art”. The resulting cockpits have had such a transforming effect upon our kayaking that we will never want to be without our custom outfitted cockpits again. Everything we could do before in our kayaks we can now do better. We have learned new skills which would have been impossible formerly. Our level of comfort has exceeded all our expectations. We have found more satisfaction with our boats, the sport of kayaking, and with our own abilities.
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. 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.
The seat is the basis for comfort and control in your kayak. A custom foam seat base 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. Since you can make the foam seat lower than most other types, you can substantially increase the stability of your kayak. Following is a step-by-step method that will allow you to build a custom foam seat.
First contour the underside of the seat to match the bottom of the boat. Then cut down into the top surface beginning at the butt dimple centers. Rough out the butt dimples with a modified spare blade for a Sureform 21-115 gripped in the fingers. To modify the blade determine which direction the blade cuts and break off the back mounting tab with a vise. (Wear safety glasses.) Leave the other tab to pull on--you will use the tool to cut on the pull stroke. 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.
With the boat supported on something soft, sit on the seat wearing thin pants and observe any sources of pressure or discomfort. Gradually contour the seat until the pressure is uniformly distributed and there are no uncomfortable spots. 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 coming and the deck might be too high relative to the paddler, and could interfere with the stroke of the paddler. 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 to make bailing and sponging easier..
9. After you have tested the seat for proper fit, upholster the top of your seat for a longer wearing, better looking, higher friction surface. If the curves aren't too extreme, you can use 1/16” self adhesive foam--The easiest way to apply a good looking, durable surface. The 1/16” foam may wrinkle it you try to follow a compound curve. Deep compound curves are more easily upholstered by means of an upholstery fabric. I use a type commonly used to cover speaker grills. To apply an upholstery fabric use spray contact adhesive (make sure you get one which is compatible with the foam--like 3M General Trim Adhesive #3M 8088). Spray a thin coat of adhesive to the seat top and the underside of the fabric, then spray another thin coat perpendicular to the first. If you spray too heavy a coating it will penetrate the fabric and make an unsightly mark on the surface of the seat. Allow the adhesive to dry briefly (follow manufacturers instructions), then stick the fabric onto the seat top and trim with scissors.
10. Trace around the sides of the seat using the fore and aft location lines in the hull from step #3. Lightly sand the fiberglass within the outline of the seat and wipe it clean with acetone. Use waterproof contact adhesive like Hydrogrip to adhere the seat to the bottom of the boat within the outline. Follow the manufacturers instructions for the best results. Depending upon the type of material to be glued and the type of glue, apply one to three coats to the boat and to the underside of the seat, allowing each coat to dry until tacky. Porous surfaces like foam are apt to require 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 in 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!
11. Most of us use a padded backband for the seat back. Backbands 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. Instructions are furnished by the makers, though you may wish to deviate from the suggested method if it seems easier. The P. D. Designs backband is secured by means of bolts, one on each side of the deck, at points which will permit the backband to be adjusted into the correct position. The Snapdragon backband threads through slots in the side of the seat or coming. Since you have removed your suspended seat you may not have anything to make slots in. The easiest thing to do is double the end of the strap over and install a 1/4 or 5/16” grommet. (An upholstery shop or sailmaker can do this.) Then you can install your Snapdragon backband in the same manner as the P. D. Designs type. (The Snapdragon backband is very good, and worth taking the extra trouble over.) Choosing the points of attachment is the most important concern. You can reinforce the inner surface of the deck at these 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 backband into position, though on my narrow boat it hasn't been necessary.
In some kayaks the cockpit coaming 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 which can be adhered to the bulkhead and the coaming. It would not be difficult for a person who had made a seat to adapt the method for making a seat back.
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. The amount of retention is up to the maker. It is unnecessary to have a super tight fit in order to have good control. As with the seat, good fitting maximizes surface contact and minimizes pressure. (Caution for beginners: Make certain you can wet exit! The retention is helpful in rolling. It is a good idea to learn to roll, but you definitely do not want to entrap yourself. You can always glue in more material later if necessary.)
To make hip braces make templates of the side of your right thigh near the hip with cardboard. Sit on a bench. Press a flexcurve 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 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. I like to extend the hip pads to the height of the cockpit coaming. 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. A 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. Glue the braces into position while they are still too tight and do the finish work in place. 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. Since the braces are snug, it is easy to damage the foam when squeezing in or out of the boat. Cover the hip braces over with denser 1/16 inch or 1/8 inch self adhesive foam for resistance to abrasion. Allow the thin foam to overlap onto the fiberglass coaming to reinforce the glue joint at the top of the hip pad. 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 #10.
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 underside 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 discussion presupposes 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. If there is ample clearance between the knee and the deck 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, trimming off the excess where it intrudes into the cockpit. A keyhole saw or small serrated knife makes a fast start on cutting the big concavity for the knee. Alternatively, you can fit the block to the deck first and carve the space for your knee second. Sometimes is necessary to laminate a couple of layers of material to make a big enough block. Either method gives a good result; do whatever seems easier. If space beneath the deck is very limited, you may find it more expedient to jam the knee up under the deck and cut two or more shapes to fit into the space on each side of the knee. I prefer this method (even when there is plenty of room above the knee) because it is often easier since you don't have to deal with as many contours on a single piece of foam. As previously noted, a right brace is a perfect pattern for a left brace, and vice versa. This makes the second brace very fast to make.
Although it is important to design the knee brace shapes for sufficient support, I have not found it necessary to upholster them for additional reinforcement. However I am aware of instances of poorly designed knee braces tearing, and if you wanted to upholster them it couldn't hurt. Using the best material you can get, and designing strength into your shapes, is most important when making knee braces.
Although the details of how to build knee braces are sketchy, you will discover that the order of operations outlined above should be enough to enable you to do the project. The seat is easier 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 location is dependent upon seat location.
Most sea kayakers need to carry some equipment which 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 kayak I took advantage of an unusually deep vee hull to store the pump beneath the seat. The butt dimples were still cut within a quarter inch of the hull, so 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 it 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 and contour the lid for additional comfort as a leg support.
I use a small underdeck 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 this accessory.
I utilize 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 an ensolite pad 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 ensolite, sealing the ice chest nicely. All pieces except the bulkhead are easily removable for cleaning, or if the space is wanted for other storage.
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 narrow 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 quarter inch self adhesive foam to make pads 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 gel coat on the deck. (Of course, since the gel coat is covered with a pad no one can see if it has been marred or not.)
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, and your boat can fit you just 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 originated our sport? 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.
Rasmussen’s Expert Bicycle Service, 630 Ershig Road, Bow, Washington 98232, phone 360 766-8720. is a source for 3” gray mini-cell foam, speaker grill fabric, 1/16 inch and 1/4 inch self adhesive foam, waterproof contact adhesive, backbands, and instructions.
Kayak shops, especially those selling whitewater kayaking equipment, usually sell foam, glue, dragonskin metal sandpaper, and backbands.
Contact spray adhesive can often be found at auto parts stores and sometimes at upholstery shops.
The 1/16 inch and 1/4 inch self adhesive foam are available from Northshore (800) 800-7237.
Excellent backbands are made by Snapdragon, (206) 957-3575, and P. D. Designs, (970) 241-0312. These are usually sold through dealers.
The Stanley Shureform 21-115 is commonly sold in hardware stores.
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Material Copyright © 1998 Tom Weese