Blank – Clark 6’3”C
Glass Cloth – 60 yds of 4 oz, 30" width / 2 yds of 7.5 oz, 30” width
Polyester Resin – 2 gal
Wax Additive – 2 oz.
Acetone – 2 gal.
Hand-Pour Polyurethane Foam (8 lb) – 1 qt.
"SunCure" – 1 tube
Sureforms (1 flat 6”, 1 flat 10”) & Extra Blades (2- 6", 1-10") – 2/1
Safety Razor Blades – About 10
Aluminum Foil – l lg box (200 sq ft) of 12”
Masking Tape (strong 1.5" best) – 1 roll
Duct Tape – 1 roll
Bathtub Caulk (cheap latex) – 1 tube
Sandpaper Discs (5") – 6 of #40, 6 of #80
Sandpaper Sheets – 4 of #40, 10 of #80, 10 of #120
Wet n Dry Sheets – 6 of #320
Spray Paint (Rustoleum appliance epoxy) – 2 cans
Spray Lacquer (Rustoleum) – 1 can
Saw Horses or equivalent
Circular Saw or Handsaw
3’ Paint Brush
Felt Marker (med. or fine tip)
Note: The 60 yds of cloth will cover your board, your fin and more. Maybe you can buy it by the roll and save some money.
DRAW YOUR TEMPLATES
Here’s my estimate of appropriate sizes for this type of board:
125-150 lb — 5’0 x 22”
150-175 lb — 5’3” x 23”
175-200 lb — 5’6 x 24”
200-225 lb — 5’9 x 25”
225+ lb — 6’0” x 25”
Remember, everything that follows in these notes is for a 5’6”. Adjust the measurements up or down for a different size board.
If you’ve never done a template, you need a piece of paper wider and longer than your board. Fold it lengthwise (and straight!). Mark a tail point on the fold, and make and mark the following measurements: 3.5” from the tail point and perpendicular to your fold, mark 9” (your tail corner); at 6” mark 8-3/4”; at 12” mark 10”; at 18” mark 10-3/4”; at 24” mark 11-3/8”; at 30” mark 11-3/4” ; at 36” mark 11-7/8”; at 42” mark 11-5/8; at 48” mark 11.0; at 54” mark 10.0”; at 60” mark 8-1/2; at 66”, nose point. Gracefully connect the dots using pencil, then marker, adding curves where they belong. Cut your template an inch wider and a couple of inches longer even if you’re not making a bigger board. Open and check the shape. Trim it till you’re happy with what you see, or just cut along the line I’ve given you.
Time to draw the part that’s still looking for a name. They’ve been called pontoons, chines, sponsons (UK), the wishbone, the toilet seat, etc. I’m calling them simply “the rails,” as opposed to the “rail line,” which is the outside edge of the rails. Mark the following pairs of measurements, the first one right on the centerline (the fold) and the second one to the right of the centerline at a right angle (use your t-square): at 8” mark on the rail line itself (start of the rails); at 12” mark 8-1/4”; at 18”, 8-1/4; at 24”, 8-3/8; at 30”, 8-3/8; at 36”, 8-1/4; at 42”, 7-5/8; at 48”, 6-3/4; at 54”, 5.0”; and at 59.0”, mark the centerline. Connect the dots, adding the curves. Adjust the shape of the rails to your liking. Go over everything with a marker. Now cut out the entire rail (you’ve been doing the right rail), fold the template, and draw the left rail off the pattern. Open the template and tape the right rail back on loosely–you’ll be removing it again.
This is for a single fin that is to be permanently glassed on. If you buy a fin like the Greenough IV-A from True Ames, just saw off the base and you’re done.
Take a basic fin shape you like, draw it out, print it out, blow it up on a copy machine or otherwise mess with it until you have something you like about 11” high with a 7” base and a 2-3” rake (measuring from the back end of the fin base to a spot on the deck directly below the tip of the fin). These measurements are not all that critical. They’re large enough to let you modify as you go along. Mine ended up being 10.5” x 6.5” with a little more lean to the rear than originally.
SHAPE THE BLANK
The Clark 6’3”-C will be perfect for a 5’6” or less. For a longer board, it’s going to be tight, maybe impossible. The problem is getting a blank that will give you that back 3 ft of dead flat rocker without giving you too much kick in the nose. Also, the 6’3”-C is 25” wide, fine for this board but maybe not enough for a 6’0”.
Place your template on the deck 3-4” forward of the tail. That will leave about 6” up front. Tape the template into place. Trace the outline with a pencil. Remove the template. If it still looks OK, trace it with a marker. Cut the outline with a skill saw or a handsaw. Sureform off the bumps and bulges, keeping everything perpendicular.
Turn it over. Remove the blank “skin.” (There must be a planer for this-I just used a handsaw.) Sureform the stringer dead flat from the tail to 36”. Check it with a long straightedge. Put the rocker into the rest of the stringer. The amount of rocker from that point forward is: at 42”, 1/8”; at 48, 3/8”; at 54, 7/8”; at 60, 1-3/4”; and at 66, 3-3/4”.
Sureform the whole bottom flat and even with the stringer. Don’t put any bowl into it yet–you haven’t drawn your rail line. I also used a 30” long 2 x 4 with sheets of 40 grit wrapped around it to help get the bottom flat. You don’t want any unevenness or twist here, so you be constantly checking your work with a straightedge, and something else wide and flat, like a bookshelf, and possibly a level. Also, assuming you cut the template symmetrically, you can measure the thickness all along both sides of the blank and they will be identical.
Draw your rail line. Mark these points along both sides of the blank from back to front. At 6” from the tail (not from the rail corner), 0” or dead flat; at 12, ½”; at 18, 5/8”; at 24, 7/8”; at 30, 1”; at 36, 1-1/8”; at 42, 1-3/8; at 48, 1-5/8; at 54, 2-1/4; at 60, 3”; and at 66”, 3-3/4”. Connect the dots. As you can see, the rail line is not a straight line but a parabolic arc. Carefully sureform the bottom, blending the contour up to the rail lines. Your hull area can have either more belly toward the center or more bulge toward the rails. I chose the latter because I was interested in planing area.
Hand sand lightly with 80 grit. Check it for smoothness in side light and shadows. During the whole shaping process, be careful not to take foam away from around the stringer. You want to keep that area level and flat.
MAKE THE HULL
Cover the bottom laterally with aluminum foil, overlapping well onto the deck, stretching it tight and taping down the ends. Do a good job–you don’t want the aluminum moving while you are glassing. Around the curves, flatten the foil gently with your hands. Wrinkles will not hurt your glass job. Just make sure that they are as flat as you can get them and that the foil fits the bottom and the rail line like a glove. When the foil is as tight, secure and immovable as you can make it, draw along the rail line with a marker. This will help you as you trim.
Cut your glass cloth. You are using 30” wide sheets, which means 3” of overhand on each side at the widest point, but that’s a lot. 2” is better, so cut it that way for the whole board, the only exception being the tail area, where it is all glass and you need only a slight overhang, 1” or less. You don’t have to snip the cloth around curves because you won’t be glassing it to the other side. Let it hang straight down naturally when you glass. You are cutting 7 full-length sheets. The first will be that one 2-yard piece of 7.5 oz. cloth. Then you will cut 5 partial lengths in 4” increments. The first partial will fall 4” short of the nose; the next, 8” short, etc. etc., till your last sheet, 20” short. You want the deck of your board to be a foil, not a plank, thickest under your knees and tapering both ways.
Plan on 8 days to glass the hull. No rush. Like laying the first few tiles on a floor, you must get this part right or you will pay. Give the laminations time to cure and make sure they cure straight. The blank has to remain in its natural position on the horses. If you see a twist or bow developing, take measures to counterbalance while it’s still early. If you do the hull right, the odds of wrecking the rest of the board decrease.
Your first full-length lamination is important. You’re only doing one sheet. You will use your one and only sheet of 7.5 oz. By putting this one down first, you will have a thickness guide later on when you grind the deck.
You don’t want this one gelling on you. You don’t want air bubbles. Easy on the squeegee. Don’t get it too dry this time. When it gels, trim. Be careful not to cut through the foil into the blank. Let it cure well. I would wait 48 hrs.
Do the next two lams together. Mix it cool, give yourself time. You want the resin to fill any pinholes and air bubbles in the first layer. Squeegee these two layers very dry. Same for the rest. Excess resin shatters. Trim after every session; don’t let the layers accumulate. Cure for 24 hrs after each session.
You can do the rest of the lams a little hotter, including the partials. Doing them two at a time, you’ll be left with one at the end. Give that last one 48 hrs to cure.
The hull is hard enough to pop off now. Untape the deckside foil. Gently pry up the edges of the hull with your fingers till it begins releasing and finally pops off. The foil will stick to the glass, not the blank. You have the pleasure of peeling the foil off the glass and seeing your work. The foil will stick in some of the tiny wrinkles. Pick the foil out of the wrinkles or get it when you sand. Sureform off the sharp edges.
POUR THE RAILS
Paint a thin gloss coat (resin + wax additive) on the hull deck to take away the tackiness. Sand with 80 grit down to the weave. Wipe down with acetone.
Use a keyhole saw to cut the rails off your blank in one piece and set them aside. Cover the edges you just cut on the blank with tin foil, taping it down top and bottom and smoothing out the wrinkles. Place the hull on a level surface. Place the blank in the hull. Use towels to prop up and cushion the sides, belly and nose of the hull so that the hull is hugging the blank and the rail line is as it should be. Check for a snug fit everywhere, no gaps. Seal the hull-rail joint with caulk so that your hand-pour foam won’t seep under the blank.
Follow the hand-pour foam instructions. You’ll probably mix it for 30 sec. and have 60-90 secs. to get it where you want it. It pours like pancake batter and then heats and rises. It’s better to pour long and shallow than short and deep. The directions will tell you the minimum time between batches (20 min., in my case). As soon as permissible, mix and pour the following batches, layer after layer. It’s good if it oozes over the rail line a bit, but don’t let it run over onto the top of the blank. You can finish the pouring of the rails in one session. You should have some leftover.
Let it cure for 24 hrs. Carefully cut along the sides of the blank with a keyhole saw. Lift or gently pry the blank out of the hull. There are your rails, ugly but ready to be shaped. Put the blank back together and secure with tape. It can be used for another spoon, or reshaped and glassed. Scrape the caulk and any foam seepage off the hull surface. Sand that area with 80 grit to get a clean surface.
SHAPE THE RAILS
Shaping high-density foam is like going through sedimentary layers of the Grand Canyon. Some areas will have a sand consistency, some will be granular. There may be small air pockets. Your two sureforms will work for the sanding.
Gradually reduce the volume as you work toward the tail. The rails should have a slight round or ledge. Don’t sand them flat from the deck to the rail line or you will lose spring. A cross section of the rails at any point should reveal a foil.
Leave a slight lip along the hull edges. Don’t remove too much foam. You don’t want to have to glass around a sharp edge.
As you get close to finishing, you can check the evenness of the rails by putting the hull on a flat level surface, laying a 4’ straightedge sideways across the rails, and measuring the distance from both ends to the ground.
GLASS THE RAILS & DECK
Remember that every time you glass now, you run the risk of changing the rocker or adding twist. Check the board position before and after every lamination. If you need to, use weights inside the hull or padding around the outside to maintain the original shape.
Cut 12 layers of cloth just like you did the first time. Make sure you allow for the extra contour. Use a 2-3” overhang everywhere except the all-glass section of the tail; that can be short again. You can glass the overhangs straight onto the hull bottom. You don’t need a tape line. You’ll be sanding and tapering all of that later. You will have to make snips along the curves so that the flaps can overlap and lay flat on the hull surface, the only exception being the sides and trailing edge of the glass tail area. Cut the cloth close there before glassing.
The first layer is the big one. Mix the resin cool. Don’t worry about squeegeeing this one too dry. When it sets up, you’ll be able to see any air holes or bubbles. After it’s hardened enough, come back, slit with a blade, and fill those areas with SunCure. Let this first lam cure for 48 hours.
Do the rest of the layers in two’s,as before, leaving 24 hours between them. Do the partials the same way. Keep them all dry, which means more resiliency and less weight for your board. Trim the tail area after each session. Don’t let the layers accumulate. Keep checking the shape.
Paint a thin gloss coat on the bottom. Use the sureform and/or disc sander with 80 grit to flatten and blend those flaps into the hull surface and rail line. Warning: do not sand too close to the rail line “seam”, that original hull edge under the glass. I would stay a good inch away. That area needs all the strength it can get. Use 120 grit paper and #320 wet n dry on the whole bottom to smooth it out and remove the rest of the gloss coat.
Now strengthen the deck in the knee area by adding 8 partial layers rail to rail but not over the edge onto the hull. The length of the first layer is 2 ft. Each of the next 7 layers is 2” shorter than the one before it. Use 33” from the tail as your center point. Glass the first 4 layers; cure 24 hrs. Glass the last 4 and cure. You can glass all of these very dry.
Next, add strength to each rail deck-side by cutting 10 strips of cloth a little narrower than the rail at the 33” point. The first strip is 4” long and each succeeding strip is 1” longer than the one before it. Do a set of these for each rail. Using the 33” point as your center on each rail and starting with the shortest strip on the bottom, glass both sets down (dry). Cure 24 hrs.
Paint a thin gloss coat on the deck. Disc sand with 80 grit to blend all edges and ridges. Sureform the glass tail edges smooth. Use 120 grit and #320 wet n dry on the whole deck. You’re getting close.
The fin is a lot of work. You can be doing it in between sessions on other parts of the board.
Cover a 15” x 15” sheet of ½” or ¾ “ plywood with aluminum foil. Cut 80 squares of cloth with the following dimensions: 40 squares of 12” x 12”; 20 of 12” x 9”; and 20 of 12” x 5”.
It is important to glass all fin layers dry.
Glass 10 squares of 12” x 12”, watching for bubbles on the foil with the first layer. 24-hr cure then 10 more, same size. 24 hrs and 10, same size. 24 hrs and 10, same size. You’ve now used up all 40 layers of your 12” x 12”. Next, do 10 layers of 12” x 9”, matching the bottom edges. 24 hrs, then 10 layers of 12” x 5”, matching the bottom edges.
Cure for 24 hrs, then turn the whole fin lamination over. Sand that whole side with 40 grit till you can see the weave everywhere. Now, glass down your last 10 layers of 12” x 9”, matching the bottom edge, as you did on the other side. Wait 24 hrs, glass down your last 10 layers of 12” x 5”, matching the bottom edge, as before.
You now have a fiberglass sheet 5/8” thick from base to 5”, ½” thick from 5” to 9”, and 3/8” thick from 9” to 12”. Draw your template with felt marker. Clamp the sheet down. Cut with a jigsaw. Draw a thin marker line down the front center and trailing edge center so you always know where the edge is during the foiling. Also mark your estimated foil “bulge” line (thickest part of the foil) from base to tip, and respect it. You want to preserve most of that thickness. If the fin gets too flat, it bends instead of springing.
Paint a thin gloss coat on both sides of the fin. Clamp down the fin, taper it top to bottom and foil it front to back using the disc sander and 40 grit, then 80 grit. Hand sand with 80 and 120. Make sure your trailing edge has the edge trimmed off of it. Gloss coat and wet n dry.
Tape a string from the nose center point to the tail center point. Draw a light pencil line where your fin will go in order to line it up. The back edge of my fin base is 6” from the tail. Put a few drops of catalyzing resin on the fin bottom and set it in place, running masking tape from the fin tip and front edge to both rails to hold it in position. When the resin has hardened, remove the tape.
Fin rope is no longer available. You have to make your own. Cut about 60 very very thin 10” strips of glass cloth . Also cut two 7” x 9” pieces; two 6” x 9”; two 5” x 9”; two 4” x 9”; and two 3” x 9” pieces. One of each will be glassed on each side of the fin over the rope, beginning with the largest piece.
Place 30 strands along one side of the fin base and 30 on the other with 1.5” left over at each end. Mix your resin cool, because this part takes a while. Work the resin into the “rope” with your fingers until all the strips are clear. Smooth them in tightly with your thumb along the base of the fin, following the foil shape. Now lay a 7” x 9” piece of cloth on each side, with the 9” going horizontally and the 7” divided equally 3-1/2” up the fin , 3-1/2 out onto the bottom. Glass both pieces on, making sure the resin penetrates everywhere there is contact. Do the same with 5” x 9” pieces, centering them, and so forth with the rest of the pieces. Squeeze as much resin out of the rope as you can, using your thumbs. Cure 24 hrs. Thin gloss coat. Sand and blend all edges with disc sander and 80 grit. Roll up a sheet of 40 grit and another sheet of 80 grit to use along the curve at the fin base. Hand sand the entire area with 120, then wet n dry.
GRIND THE DECK
Draw two light pencil lines from the rails at 33” back to the center point of the tail. You have a V. Don’t sand anything within the V. You will be sanding perpendicular to the V lines (not the center line). Use the disc sander and 40 grit to carefully thin the trailing edge and glass corners of the tail to about 8 layers. You will know you’ve hit the 12-layer mark when the larger 7.5 oz. weave appears. Continue grinding along the inside edge of the rails (without touching them) up to the top of the V, grinding less deeply as you move toward the nose. Now go back and blend, thinner to thicker, from where you sanded to the V-line. Go back over it all again lightly with the 80 grit disc. Hand sand with 120.
Decide on your pattern and tape it off using masking tape and newspaper. I used Rustoleum appliance enamel because it sounded harder. After both sides had cured, I sprayed Rustoleum lacquer over everything. It may be anathema to the experts but I’m willing to sacrifice 1 mph on a 12’ wave to have that transparency at 100%.
Congratulations, you made it. It can all be modified, if need be. Investigate the use of carbon graphite laminations if you ever need to strengthen the rails.
Riding a spoon is a long-term commitment-you never stop learning. When you hit 5th gear, let me know.