1) Once the laminated board has been sanded (either before a fine sand or a finish coat stage) draw a pencil line between the two shapers fin dots 4 1/2" apart. 2)Lamination: Place a round shaped 4 oz patch on the bottom deck over each box area (larger round shape than boxes), this will strengthen the area around the fin box. 3) Draw an extended line (A) through the shapers fin markings (dots preferable) (Fig 1). Draw a line across the rear fin mark (B). This will guide the "rear" position of the positioning sponge.
4)General Left, right and centre is referred to when viewing the board with the bottom deck facing upwards and from tail to nose. Also note that the actual left and right fin will always rest on the outside of the shapers vertival line.
4.1 Using the placement card Examine the placement card (Fig 2). Using the stepped "cut-away's" as guidance use the left (shorter) vertical (top & bottom) "cut-away" line for the right fin box. The vertical line in the centre is for the centre fin box and the right (longer) vertical (top & bottom) "cut-away" line is for the left fin box. Using the placement card provided (same shape as the positioning sponge), note the rear fin mark position (B) in (Fig 1) and (Fig 2.1).
Position the placement card to align the vertical "cut-away" with each fin positioning line (A) (Fig1). Using a sharp pencil draw the inner & outer lines following the shape of the card. This will help place the positioning sponge accurately. Peel away the gummed backing paper and carefully place the positioning sponge along the lines drawn from the placement card (taking care not to stretch the sponge).
On a practical note it is more than adequate to only remove the 4 corners of the backing paper and the paper of the thin inner oval ring of the sponge. This makes removal easier after complition of the installation.
Remove the round centre sponge cutout (use later, see step 12). Often the inner oval pop out is also removed. This allows any overflow resin to dispurse over the small exposed area of the board, rather than into the box/disc. However where no excess resin mixture is expected, the oval pop out should remain within the main sponge and will be widend during the routering process. Any resin overflow will disperse onto the sponge and not the board, making removal easier.
4.2. Using the fully marked sponge for round box installations Examine the placement sponge (fig.2.2) and note the rear fin position (B) in fig1 and fig.2.2. The placement sponge should always be placed such that the dotted line is at the bottom and therefore corresponds with the shapers rear fin marking; the letters "R","C" and "L" will always appear correctly and not upside down. The sponge right fin marking will align with the extended vertical shapers line and rear right fin marking when viewed through the exposed holes on the sponge. The same principle applies for the centre and left fin markings.
Remove the larger round pop-out centre of the sponge (use later - see step 12) and peel away the 4 corners of the backing paper to expose the gummed area. Carefully place the placement sponge such that the shapers dot and extended vertical line arealigned and visible through the centre of the relevant holes on the sponge, taking care not to stretch the sponge whilst continuing to ensure that the sponge is securely in place.
5) Prepare the router with a router bit comprising no more than a 25mm (1") cutting surface length (any longer and it will cut into the router jigs provided). The depth of the bit must be extended to 33mm from the router base plate.
Take note that the total depth of the cut for the box will be just over 18mm (3/4") so be advised to measure thin tail surfboards first before using the router.
The router bit sizes are as follows: Router bit cutting surface length: 25mm or 1"inch width of cutting surface & top-bearing: 12mm or 1/2" inch with a 1/2" TOP BEARING!
Shaft thickness: 6.5mm or 1/4" inch or 13mm or 1/2" depending on the type of router used. which allows for a very tight fit, as the cutting width is the same width as the shaft. Nevertheless to allow for more resin around the oval box, you can use a wider "undercut" of the cutting surface relative to the shaft width; however once very familiar with the routering procedure you may want to stay with the tighter and neater fit... 6)Router jig: Round = 170mm x 120mm x 15mm Place the router jig (Fig 3) over the placement sponge, pressing firmly down to ensure that the router jig is flush with the surfboard's surface. If required wiggle the jig in the direction required until the jig fits firmly over the sponge. Applying the set router depth, router the deeper circular hole(Fig 3).
7)Box Strengthening Procedures It is recommended that one uses a standard hole saw +- 1" to 1 & 1/2" wide to cut a "ring-hole" through to touch and bond with the top-deck of the board, as used in other fin system procedures. By adding the circular "ring hole" you are strengthening the bond between the box and the "nappy" to the top deck.(Fig.5) In addition it is also recommended that an "undercut" is created just under the glass of the bottom deck, completely around the routered hole (Fig 4).
This provides yet another anchoring point for the resin and nappy. This undercut can be created using a standard panhead screw (10mm diameter head).
Note that for tow-in, kite and twin fin boards it is advisable to pre-install (prior to lamination) small high density foam blocks (approx. 10mm larger than the round box ) in the area where the fin box holes will be routered. Then install the boxes in the usual manner over the glass. The high density foam blocks are capable of withstanding the unusual pressures associated with these high impact boards.
8) Dip the outer surface of the boxes into old/dirty acetone or styrene monomer to improve the bond between the box and resin. Once all the holes have been cut, set the 3 completely assembled fin boxes onto the 3 weighted fin alignment jigs supplied (Fig 6).
Slide the fin jigs into the boxes accordingly. The weighted jig ensures that the boxes won't "float" and that the 4 stabilizing tabs are touching the surface (Fig.8/9). Use finger pressure to ensure that the boxes are pushed down completely.
9)The "Nappy" method (Fig.5): Using the round sponge "pop-out" as a guide cut 3 round 6oz fibreglass patches 1" larger than the round sponge and make a slow mixture (+- 15-20 min.) of +- 100 ml resin with pigment (polyester resin for polyester boards / epoxy resin for epoxy boards). Pour +- 20 ml of resin into each circular cavity, place the 6oz round fibreglass patches over the recesses and position assembled fin jigs with boxes (noting the position of the box markings) with NO additional SPLAY/CANT (splay/cant is built into the fin).
10) Place the fin jigs with fitted boxes over the positioning sponge and into the recesses provided, noting the location of the 4 positioning tabs on the boxes and positioning sponge. Place the assembled fin jig such that the 4 positioning tabs are resting on the surface of the surfboard and NOT "raised" (Fig.6/7/8) - DISREGARD wether the ends of the weighted alignment jig are touching the board or not. Use finger pressure to ensure that the boxes are pushed down completely.
As the fin jigs are pushed down, place the front & rear sections of the fin jigs within the recesses available in the placement sponge. As the fin jigs/boxes are pushed down, the resin in the cavity will surface pushing air bubbles out. Be careful NOT to get resin on the inside of the walls of the boxes where the discs are located. With the remaining resin in a squeeze bottle, top up as required.
Note: For deep concave boards, tape may be required as well, to stop fin-jigs "leaning inwards", lifting the boxes off the surface. 11) Once the resin has "jelled" peel the positioning sponges away from the surfboard. This will leave a neat resin "wall" and lip to sand. Using a rough fibre-disc (36-60 grit) grind down the excess, taking care NOT to OVER-HEAT the plastic (as this causes weakening of the bond between the resin & box), until the box is sanded to the level of the surfboard's surface. Using a coarse sandpaper (80 grit) and a hard sanding pad, sand the surface of the box, finish off with finer grit paper as required. Take note that not more than 1mm or 1/16" should be sanded off the surface of the box.
12) Finish/gloss- coat the surfboard, cover each of the sanded round boxes with the round shaped sponge-cut-outs from the 3 placement sponges. Peel off when the resin has "jelled". 13) After sanding, blow all plugs and screws free of any dust and grit that may have accumulated, and tighten the pan-head screws of the disc as well as unwind the grub screws to allow the customer to insert their fins freely.
Note: Please ensure NOT to over tighten the screws at any time, to avoid stripping the screw heads.
Tip: Where the fin lugs are difficult to insert into the interdisc slot, use vaseline or an alternative oil lubricant on the lug to assist in the insertion process.
8 Key Installation Points
Due to the nature of varying foam densities and strength we suggest applying the following 8 primary installation procedures:
1. Use a high density foam block in the blank prior to lamination to strengthen the fin box mount in high impact boards such as tow-in, twin fin and kite-surfing boards.
2. Laminate an extra fibreglass patch around the fin box areas during the initial installation process.
3. Create a 5mm undercut just under the glass of the bottom deck completely around the routered hole.
4. Dip the outer surface of the box in old dirty acetone to improve the bond between the box & resin (Making sure NO acetone comes in contact with the interdisc!)
5. Create a moderate resin & catalyst mix that is not too hot.
6. Use a 40oz fibreglass "nappy" together with the resin when inserting the box into the routered hole.
7. Avoid heat build-up when sanding down the boxes by:
a) using initially a rough grit sanding pad (24/36 grit) b) rotating the sanding between boxes and c) not sanding too fast