Sweet Composites, 6211 Ridge Drive, Bethesda, MD 20816-2641 USA
301-229-2201  –  9:00 a.m. to 5:00 p.m. Eastern, Mon.-Fri.

Last Update: 13 February 2010

How-To Tips

This page has just five subjects for the moment. We’ll add more tips as time permits. If anyone has new or improved methods, please tell us! These tips are not intended to be detailed, step-by-step instructions. The goal here is to provide some ideas to start from so each user can work out his own methods.

Gougeon Brothers has produced several manuals on boat repair, vacuum bagging, and other subjects. We keep all of these in stock. They are listed on the WEST SYSTEM page.

Cutting & Shaping Minicel® Foam

Minicel® is a very fine-grained, closed-cell foam used for canoe and kayak outfitting, flotation, padding, insulation and many other purposes. For most purposes it must be cut and/or shaped. Cutting can be done with a bandsaw, hot-wire cutter, or a knife. A bandsaw is fast, assures a cut perpendicular to the face, and leaves a good surface for glueing but it is messy and many smaller shops do not own a bandsaw. A hot-wire cutter is less messy than a saw and allows very intricate cuts. Since it melts the surface it leaves it less suitable for glueing. A cutter can be built with a length of NiChrome or similar heating-element wire, a spring to maintain tension, and a Variac to control voltage. There are a number of web sites offering hot-wire equipment. One I have looked at offers a “hotknife.”   I provide the link here only as a possibility, without endorsement, not having tried it myself. I recently tried a hotknife from a different manufacturer with quite unsatisfactory results.

For backyard builders or even many commercial shops, the easiest method is just to cut Minicel with a knife. The knife must be kept very sharp and even then will require several passes to get through a 3" bun. Use a straight edge if you want a straight cut and be very careful to hold the knife vertically so the cut is perpendicular. This is how we cut full buns in half for shipping. I recently tried cutting Minicel with an electric carving knife, such as one might use on a Thanksgiving turkey. It worked very nicely for trimming and cutting small pieces but it does not have the power to make a long cut across a bun in any reasonable time. I have not tested it sufficiently to know how the blades will hold up with time either.

For many applications, Minicel must also be shaped. Once large pieces are cut away with a knife, final shaping is usually done with a disk sander or just sandpaper. Typically one would use a very coarse paper, whether with a power tool or by hand. Open coat #36 or even coarser works well. With a power sander be sure to anchor your work and use a light touch. If pressed into the work, the disk could easily dig into the foam and throw it across the room. Wear a dust mask and work outdoors if possible because of the messy dust created. If two buns are to be glued together, the skin must be removed from the surfaces to be glued. This is most easily done with the disk sander held nearly flat and very carefully controlled to avoid gouging.

A Stanley Surform® tool or Red Devil Dragon Skin® are alternatives to sandpaper for some applications. They are available from most hardware stores. The former are made in a variety of shapes and sizes for different uses. They work like a plane with many small cutting edges. As with a knife, a Surform must be sharp. Once it is used to any degree on wood or fiberglass it is no longer effective on foam. Buy a spare blade for each tool and reserve it for foam only. Dragon Skin is just a piece of sheet metal with many small holes punched in it leaving sharp points. It looks like a very fine-grained cheese grater and grates away foam with remarkable speed.

Customized Canoe or Kayak Outfitting

Walls for kayaks kayak or decked canoes are made from full 3" buns of Minicel®. Draw a pattern from your boat, make a rough cut as described above, then shape for perfect fit. I use a 12" Surform plane for smoothing the long cuts to fit the deck and hull. If the lines are not close to straight, some other tool might be better. Once a good fit is achieved, paint the edges of the wall with epoxy or vinylester resin and jam it into place. Placing some weights on the deck will help hold things in place while the resin cures. Contact cement cannot be used to install walls because it does not permit the wall to be slid into position. A wall that is not carefully fitted and glued into place is unsafe and likely to fail when it is needed most.

Saddles for canoes are also made from full-thickness foam, usually two layers glued together to form a 6" wide saddle. The skin must be removed from the glueing surfaces as described above. Leave the skin on the outside as it helps protect the foam. The completed saddle is glued to the bottom of the boat with resin or contact cement. For a decked canoe, the saddle should be keyed into and glued to the stern wall for added security. The top of the saddle can be shaped to fit the user. A nice finishing touch is to add a layer of wetsuit neoprene for an even cushier seat [see below].

Kayak seats can be constructed entirely out of the 3" foam, glued together, carved out, and glued into the kayak. Molded fiberglass seats can be customized by glueing in the ¾" foam as needed and then shaping as described above. Seats can also be customized and padded using neoprene, either the wetsuit or kneepad type, depending on the wishes of the user.

I recently came across a web page with detailed instructions for customizing the seat and entire outfitting in a sea kayak. There are a lot of tips there that can be adapted to other similar jobs as well.

Kneepads and other outfitting can be done with neoprene or Minicel as desired. A large piece of ¾" Minicel or ½" neoprene glued to the inside of the hull of a canoe protects both the boat and the paddler's knees. Minicel is softer but it is somewhat slippery when wet. Neoprene provides better traction under one's knees and is more durable. The ultimate kneepad for a one-user [or same-sized users] boat is a fitted cup carved out of Minicel and glued into the boat, then covered with wetsuit neoprene, nylon side up. To glue wetsuit neoprene in this manner, it is best to scratch up the skin side with coarse sandpaper, just enough to make small tears in the skin, then wipe the dust and any other residue off with acetone or lacquer thinner. Glue the cleaned surface to the Minicel or fiberglass surface with contact cement or neoprene glue. With any contact cement, coat both surfaces to be joined, allow to dry tack free, and then press together. If one must glue down the nylon side of wetsuit neoprene, coat once with cement and allow to dry, then coat and dry again before pressing the parts together.

Another use for Minicel is to make blocks for supporting an open canoe on a car top without the use of racks. Typically, the 3" foam is cut into four roughly triangular pieces, 8" to 10" wide at the base, the upper apex of each is cut off and in the resulting flat a notch is cut to fit over the gunwale of the canoe. With four of these blocks in place, the canoe is set upside down on the car roof and tied in place across the roof and both ends secured to the bumpers.

Making a Neoprene Sprayskirt

I did not have to do much work to set this one up. My good friend Bob Putnam has put together a page on how to make a kayak or canoe sprayskirt. This is one method and it looks like it ought to work just fine.

Installing Yakima Footbraces

Yakima footbraces are attached to the kayak with two 1/4-20 stainless screws. They are usually placed on or close to the seam line but the exact location depends on the type of boat and your personal preference. First decide where you want them so that the adjustment range will cover all intended users. Using the holes in the aluminum rail as a guide, mark two screw holes on one side of the boat and drill 17/64" holes. Measure back from the bow to set up the other side so it is symmetrical and drill the other two holes. The rubber gaskets should be stuck to the rails at each screw hole to make the installation water tight. Be sure the sand slots in the rails (on all but 7" length) are on the lower side, install the screws, adjust the foot pads and you are ready to go!

If you are installing touring footbraces to use with a rudder, everything is the same except that you attach the plastic tracks to the boat using the screws and nuts. The gaskets should be stuck to the tracks. Cables from the rudder are attached to the aluminum rails, which slide freely in the tracks. I cannot tell you exactly how to hook up the rudder and cables but instructions for that should come with your boat or rudder kit.

If you are installing fixed touring footbraces but think that you might want to add a rudder sometime later, we advise using the 14½" version. The holes in these are exactly the same as in the plastic track so the rails can be removed and the tracks added without drilling any new holes in the boat.   Happy Paddling!

Installing Kevlar Skid Plates

Skid plates are commonly installed on the bow and stern of Royalex® canoes to reduce wear and damage from scraping over shallows. They are made from Kevlar® felt and applied with epoxy or some other type of resin. In our catalog we list style 4580 Kevlar felt and WEST System epoxy resin for this purpose. Either fast (205) or slow (206) hardener can be used but we advise inexperienced users to stick with the slow hardener to be sure of having enough time to do the job.

Royalex is a vinyl-ABS-foam sandwich. There is a thin vinyl layer on both sides, then the ABS layer, which is colored and provides the strength, and finally the foam core, which is there for thickness, stiffness, and flotation. Skid plates can be put on other types of canoes but they are mostly used on Royalex. We have been telling people that epoxy will not bond to polyethylene canoes and kayaks; however, recent conversations with Gougeon Brothers assure us that it is possible to apply skid plates to these boats if the flame treatment, described below, is done with care. See Gougeon’s Epoxyworks #16, p. 21, for their discussion of this procedure.

First, decide what area to cover. The usual shape for the felt is an elongated teardrop, with the skinny end going up the stem or stern of the canoe. Typically the full width of the felt (40") is used for the length and the wide end of the teardrop is about a foot. Mark this area on the boat, then use coarse sandpaper to remove the vinyl layer if it is not already scuffed off by river rocks. Sand just enough to bring up colored sanding dust — do not remove the ABS! Brush off the dust, then use acetone or paint thinner on a rag to remove any traces of dirt or dust. Cut the felt a bit smaller than the prepared area as it stretches slightly when applied. Mix up your epoxy, at least a cupfull. The exact amount will depend on the size of your patch of course.

One more thing should be done at the last moment before applying the resin. (Be sure the acetone or other solvents have been taken away to prevent fire.) Using a propane torch, brush the prepared area of the canoe lightly with the flame for a few seconds. The idea is not to burn it or even heat it but only to allow the molecules in the flame to contact the ABS surface. This somehow improves the bonding of the epoxy to the ABS. (This step is advised but optional for ABS boats; for polyethylene boats it is essential.) Turn off the torch and spread epoxy on the boat with a paint brush. Lay the felt into the epoxy and saturate it fully, adding as much epoxy as necessary to achieve saturation. Allow it to cure and you are ready to go!

Two other thoughts:   If you mask around the working area with tape and newspaper it will keep drips and runs off the boat and make a neater job. If the boat is already pretty well beaten up [You should have done this job last year!] the dents and gouges should be filled first to make an even surface. Small bits of the felt can be used or a putty can be made using epoxy and a filler such as microspheres or milled glass. A little of this can be done and the main felt piece applied in one operation. If there is a lot of patchwork to do it is probably better to do that part, allow it to cure, sand it smooth and then do the skid plate.

John R. Sweet

Please contact us for more information.