Builders’ Tips

Deck line fittings

The standard low-cost and simple deck line fitting is to use short lengths of folded tape screwed into the sheer clamps, as described in the Build Manual. There are other options:

We use the 3D printed fittings whose printer files are included in the plans download:

Another simple and low-cost solution from Alec Naneti in Romania uses two copper plumbing bends:

Another option is to create Maroske fittings:

I like the simplicity and elegance of Maroske deck fittings, but they are anything but simple to construct. Google “Maroske fittings”.  if you are not familiar with the standard procedure. It can be a struggle to pull the PVC tube out after the epoxy has set. To make it easy to extract the tube I first put the wire inside the PVC tube, then wrap the PVC tube with PTFE tape, and then insert the PVC tube into the fibre-glass sleeve. This entire assembly is then threaded through the deck. I use fiberglass tape over and under the sleeve to spread the load, and then thickened epoxy smoothed over the entire assembly. The PTFE tape makes the PVC tubes easy to extract after removing the wire. I use a bottle cleaning brush to remove any remnants of PTFE that stick to the epoxy.

One way of producing lightweight Maroske fittings is to bond in a semi-circle of 3 mm plywood. This minimises the use of the heavy epoxy, and also produces an even curve, thereby facilitating the eventual withdrawal of the inner tube.

When positioning the fittings near the cockpit, bear in mind the need for foot-room. Those in the photo are a little too close for comfort.

Key to open screw-in hatches

Screw-in hatches are light and simple to install, and they don’t interfere with the elegance of the kayak. However, they can be difficult to undo, particularly if subject to temperature changes. This is only exacerbated by having cold wet hands. I made a simple HDPE (bread or chopping board) key. One side opens the large hatches, and the other side opens the day hatch. I use both hands on the key, pushing and pulling, for maximum leverage. There are a couple of holes for a lanyard to attach it in the cockpit. (No, not inside a compartment…….)

Weighing Epoxy

We use the excellent Smart Weigh digital scales to weigh the epoxy resin and hardener. The scales have an accuracy of 0.1g and a maximum capacity of 1 kg. They are equipped with a “tare” button, which re-sets the scale to zero after the container is placed on the scale. This is a great feature. The scales cost £6 in the U.K on eBay.
In the USA, eBay has the scales for $18 including shipping. Try “Smart Weigh SWS100” and Amazon.com has them for $10 – try “Smart Weigh SWS1kg”
Using the scales for weighing epoxy is described here.
One disadvantage of the scales is that they have a 60 second time-out, which can be inconvenient.

The importance of sheer clamps

Some kit manufacturers omit sheer clamps, and rely on taping the seams between hull and deck. We strongly advise against this. The sheer clamps produce fair smooth curves and enable a very strong joint. We’ve spent too much time mending these joints on $3000 glass fibre kayaks where glass tape has been the sole method of joining the hull and deck.

Tethering Barton-style hatch covers

Peter M. from Cornwall, UK, used ½” 6g A4 s/s pan head screws and suitable washers to attach a nylon R-type cable clamp to the central moulding on the underside of the hatch cover. Knotted shock cord (3mm) joins the cover to another R-clamp inside of the hatch fitted to one of the bolts holding the hatch cover rim in place. This means that when the hatch cover turns, the central R-clamp turns freely and the shock cord is not wound up.

Finishing the edges of fiberglass cloth

A clean finished edge is sometimes required on an area of glass cloth. This can be when, for example, just the floor of the cockpit is given an extra layer of glass cloth for abrasion resistance, or when a tapered extra keel strip is added. An elegant solution is to use dark coloured masking tape around the perimeter of the area, and laminate the glass over the desired area, overlapping slightly onto the coloured masking tape. After a few hours, when the cloth is set, but not hard, cut at the inner edge of the masking tape with a craft knife, and remove the surplus cloth and tape. The next day seal the cut line with resin.

Repairing a hole in a compartment

Let’s suppose you were rock-hopping, and holed the Vember’s hull. You did, of course, have a buoyancy bag filling most of the compartment, enabling you to get home…… The challenge in repairing a hole in a bow, stern or day compartment is that there is no easy access to the inside to facilitate a simple patch repair, unless it is close to a hatch. In an emergency, just cover the hole in repair tape, but, when back in the workshop, here’s how we do it: 1. Remove the damaged area by sawing round it with a jigsaw, or a hacksaw blade held in a rag. Make any corners well rounded, to reduce stress concentration. 2. Prepare a patch of 3mm marine ply (left over from your deck construction) to be the same shape as the hole, but about 25mm (1″) larger all round its perimeter. Drill a hole of about 3mm diameter in the approximate centre of the plywood. 3. Coat both sides and the edge of the patch and the hole with epoxy resin, and let it set. 4. Lightly sand one side of the patch, and draw a conspicuous pencil line on this side about 1.5″ (40mm) in from the perimeter, and all round it. Sand the first inch or so (25mm) of the inside of the compartment around the hole. 5. Pass about a foot (300mm) of 1/8th (3mm) cord through the hole in the patch, and put a bulky knot at the end of the cord on the un-sanded (inner) side, of the patch. Tie a one inch diameter loop in the cord on the outer side of the patch, and leave the excess cord intact. 6. Check that you can now “post” the patch through the hole in the hull, and pull it back by hand until it is firmly pulled into the correct position and orientation inside the compartment, as shown by an even view of the pencil line around the hole. The patch can be manipulated into position with one hand, while putting tension on the cord with the other. A temporary knob hot-glued into the centre of the outside of the patch can aid this procedure. Don’t lose the patch inside the compartment! Tie a large tool to the other end of the cord to make sure. Remove the patch and cord. 7. After the rehearsal, generously coat the outer inch or so of the perimeter of the sanded outer face of the patch with epoxy resin thickened to peanut butter consistency. The resin must hold its shape when the patch is vertical. 8. Delicately feed the patch through the hole, and pull the patch into its correct position and orientation. Slide a large screwdriver or piece of timber through the outer cord loop. Rotate the screwdriver to twist and thereby shorten the cord until the patch is pulled snugly against the inside of the hull, and an ooze of epoxy is visible. Maintain outward tension on the cord with one hand while rotating the screwdriver with the other. (This is known as a Spanish Windlass technique.) Tape the screwdriver to the outside of the hull when the desired tension is achieved, remove any excess epoxy, and leave the epoxy to set. 9. Remove the Spanish windlass system, cutting the cord and allowing the inner knot to fall into the compartment. 10. If the kayak has a painted finish, fill the resultant void with epoxy thickened with lightweight fairing compound, then sand and paint. If clear-finished, then use pieces of the hull stripping material to make a careful cosmetic repair. Then:
Mark an inch (2.5 cm) or so around the damaged area
Sand down to the wood within the marked area
Apply twill over the marked area, overlapping onto the non-sanded bit by about a cm. (NB – make sure you’ve sanded the bit that’s being overlapped to remove any varnish and key the epoxy without damaging the existing twill)
Lightly sand the edge of the twill patch to feather in any hard lines
Epoxy over it once or twice so it’s buried
Hand-sand the patched area so it has a matt finish.
If you varnish your boats, then cover the matt patch in varnish. If you don’t use varnish then cover it in carefully-applied epoxy. NB – for a perfect finish, you could re-sand your entire kayak and completely varnish/epoxy her.

What can I use to remove excess uncured epoxy?

The best solvent for cleaning up uncured epoxy is white vinegar. The cheaper the better! It is non-toxic and readily available. Sure you can use nasty solvents like acetone but vinegar works. Never use solvents of any kind to clean epoxy off your skin. Many solvents make it easier for epoxy to penetrate the skin which can increase the risk of reactions to the epoxy. We recommend wearing gloves and protective clothing and avoid getting epoxy on the skin in the first place. The best advice we have heard to clean epoxy off skin is to use friction (wipe it off), or soap (emulsifier), or let it dry and peel it off.

Black Keel strip

When the hull is left with a clear finish, it is difficult to spot when the keel has been scratched from contact with the beach or rocks. Water can then pass through the scratch and soak the plywood. This issue with a clear finish can be avoided by applying a coat of black pigmented epoxy (10% epoxy pigment) in a strip down the most vulnerable part of the keel, entirely below the water-line. If you taper the ends it can even look elegant. Good quality masking tape is worth the extra expense for this task. I use the blue 3M 50mmn (2 inch) wide tape.

Knee tube for pump

It seems a shame to spoil the lines of a beautiful kayak by having an ugly plastic pump on the deck, however sensible and practical that may be. I install a knee tube under the deck. The knee tube construction is very basic. I use a length of 100mm diameter sewer plastic pipe as a mould, and laminate two layers of whatever glass cloth I have handy round the pipe, using either polyester or epoxy resin. I cut it to length and width when set, and glue some split plastic flat wire sheathing round the ends to protect feet, etc. I now angle the front of the tube for maximum foot clearance. I install the tube with the kayak upside down, using a few blobs of 5 minute epoxy, and later put a fillet of thickened resin down each side. I then install a piece of elastic shock cord across the mouth to stop the pump falling out. Note that you may have to shorten your pump. By removing an end cap this is usually possible. On some pumps I also temporarily remove the handle to shorten the rod.
Reed will supply spray skirts (decks) with bale tubes to enable access to the pump without removing the skirt, if you consider this necessary: https://www.chillcheater.com/aqshop/catalogue.php?id=2911

Thickening epoxy resin when used as a coating.

Occasionally one needs to place a coat of epoxy resin on a sloping surface, or on an exterior corner. One example is filling the weave on an existing keel strip, where the angular keel line makes the resin flow away from the apex of the upside down hull, which is exactly where one wants the thickest resin. Another example is filling the weave on parts of the cockpit rim and upstand. On all these I use 10% black pigmented epoxy resin with just sufficient West 406 Colloidal Silica filler powder added to make a “paint” that will still brush out smoothly, but will not run and sag as much as pure resin. This gives a very hard and shiny finish. I first mix the resin and catalyst very thoroughly, then add the pigment with much stirring, and then gradually add the powder until I obtain the desired consistency.

Ensuring the skeg box does not leak

Two builders have reported water leaks from the top corners of the standard plywood skeg box. The plywood and inner solid wood framing of the box have simple joints at these points, so there is potential for leaks. We recommend special care to ensure the skeg box is water-tight. Do not use excessive clamping pressure which would exclude all epoxy adhesive from the joints. Apply glassfibre tape and resin over the outside perimeter of the box. Spoon a small amount of warm thin resin into the upside down box while it is on the bench, before the hole is drilled for the skeg wire fitting, and tip the box so as to run the resin into the joints. Leave the box upside down until the resin is set. Fill the box with water if you wish to check for any leaks. Taking extra care at this stage is less trouble than attempting to cure such a leak after the kayak has been completed and launched.

Installing a commercial hatch system

Instructions from Damian, in Plymouth, U.K:

Buy a large oval hatch rim.  I found the 42/30 Kajaksport hatch fitted my standard Shrike perfectly.

  1. Make an approximately 4cm-wide oval ring out of 2 layers of 3mm ply so that the bottom lip of the hatch rim just locates inside it.  (You do this in the same way as you manufacture the cockpit rim for a Shrike.)
  2. Decide where you want the hatch to go on the front deck.  Then draw the outside edge of the plywood ring onto the deck.  (NB: when you sit the ring on your curved deck, the left and right sides will be dangling a few inches above the deck.  Trace round the ring keeping it horizontal, and your pencil vertical to get the right shape on your deck.) Draw a line approximately 4cm outside the rim outline and cut it out, e.g with a jig-saw.  (NB – I am saying 4cm here, but it’s your choice: whatever distance you choose will determine the angle of the recess from the deck down to the hatch rim.  You’ll probably want to have different angles at different points on the rim to make it look nice – that’s fine.)
  3. Put the plywood oval ring into the hole in your deck.  On a standard Shrike, the edges of a large hatch rim should be sitting on the port and starboard shear clamps.  (If not, you’ll need to support it while you do the remainder of the work.)  Use sandpaper/files/plane/etc. to make sure everything is neat and symmetrical and that you’re happy with the angle of the slope down from the deck to the hatch rim.  Then use superglue and accelerant to stick the plywood ring in position on the shear clamps.
  4. Cut out lots of pieces of plywood to fill the gap between the oval ring and the deck.  This gap will start at zero by the shear-clamps and get bigger as the deck rises.  I used about 20 pieces in total.  Shape them with a plane and sandpaper.  Don’t worry if it looks a bit rough-and ready: you’ll fill gaps with epoxy and sand them smooth later.  Bevel the edges of these pieces so they butt up against the deck and the cockpit rim.
  5. Use super glue and accelerant to fix the gap-fillers in place.

6.Apply an epoxy fillet around the underside of the top joint (i.e. where the gap-fillers meet the deck) and fill any gaps between the gap-fillers.  NB: if you have any big holes, then cover them with masking tape from above, turn the boat upside down and fill them with thickened epoxy from underneath.  Remove the tape when the epoxy has gone off and sand it smooth.

  1. Put a layer of fibre-glass over this fillet – either glass tape (cutting the edges to allow it to go round corners) or cut glass cloth to shape.
  2. Put a fillet on top of the bottom joint (i.e. where the gap-fillers meet the plywood ring) and use thickened epoxy to fill in any remaining gaps.
  3. Once this fillet has hardened, smooth off the underside of this joint with sandpaper and then apply fibreglass to it – either glass tape or glass cloth.
  4. Finally, sand the top surface of both top joints smooth and cover both in glass – either tape or cloth.  I used 160 gram ’twill’ cloth which will lay flat over curving surfaces, so I was able to easily cover both joints with one piece.  At this point, make sure you’ve painted any exposed plywood with epoxy.
  5. When the epoxy has just gone off, cut the corners off the glass with a Stanley (craft) knife, apply more layers of epoxy (to bury the fibreglass weave) and then sand it smooth and flush with the surrounding deck.  Then finish it however you prefer – varnish, epoxy or paint.
  6. Fit your hatch rim to the plywood ring using adhesive.  I used a silicone sealant, and then drilled/bolted it in place.
  7. Buy a cover to fit your hatch rim.  Tie it on to your deck-lines (so it doesn’t fly away if it comes off while you’re driving.)  Fit it.  Job done.
Modifications to the skeg

Paul Krysik from the UK did not use the Kari-Tek skeg wire, but instead used a stiffer variety. To help maintain the ease of motion of the skeg cable he altered the orientation of the skeg wire as it entered the skeg box as well as the angle of the slot to hold the wire in the skeg. In the image below you can see how in images a and b (the original design) the wire has to travel through some tight curves as the skeg moves through its full range of motion. These curves can cause tension and unnecessary friction. Paul altered the angles as shown in figures c and d. His approach substantially reduced the curves the wire moves through with the aim of producing a system where the wire is less liable to kink. The bracing for the skeg box in this modification could with advantage be placed astern of the metal fitting, easing access for maintenance.
skeg
Other variations on skeg design are:
From Etienne Muller in Ireland: http://www.etiennemuller.com/SkegProject.pdf
From Erik Frantzen in Denmark: http://justerbarfinne.blogspot.dk/ and links to about twenty here: http://www.kajakbyg.dk/justerbar_finne_skeg.htm

Low profile skeg box

The skeg system shown in the Shrike plans works well with full-sized Shrikes and also with Shrike LVs where the plans are all scaled down, including the size of the skeg box and skeg. However, if only the height of the decks is reduced, as in the Shrike-R, there may be insufficient space between the top of the keel and the underside of the stern deck to accommodate the system. The deck may foul the compression fitting on top of the skeg box.
This can be avoided by installing the compression fitting in the front of the skeg box as shown in the photo below. The following instructions should be read in conjunction with the accompanying photos, and the appropriate section of the Build Manual in the download.

1. Print the paper plans for the skeg box and skeg at 90%, thereby reducing the deck clearance height by about 13mm.

2. Increase the width of the inside of the box to 15mm by using 15 x 12mm cedar internal framing. The overall dimensions of the 90% box are 346 x 122mm.

3. Make a 9mm thick skeg blade from three layers of 3mm plywood, instead of the standard two-layer 6mm thick blade. Before gluing the three layers together, the top curve of the middle layer is profiled to accept the 3mm stainless wire cable in a groove, where it is later epoxy bonded. Cut the inner layer of plywood to accept the wire by reducing the radius of the curved end to a circle centred on the pivot point, and meeting the bottom of the straight slot for the wire, as shown in the area coloured red, which should be removed:

After the three layers are bonded together, taking care to remove excess glue, shape the groove with a round file to accept and guide the free wire over the range shown in the photos, and epoxy glue the wire into just the straight section of the groove:

4. Round the leading edge of the blade and taper the trailing edge in accordance with the NACA 0012 profile, a good shape for optimizing lift at normal kayak speeds: (C.A Marchaj, “Sailing theory and practice”, 1964, pp 281 – 284 & airfoiltools.com)

Give the skeg and box a coat of epoxy, sanded hard, and then a second coat, to ensure smooth contact surfaces.

5. Fit the compression fitting horizontally, with its centre line 95mm above the bottom of the box.

6. When the outer 6mm O.D/ 4mm I.D plastic tube is inserted into the compression fitting, the plastic outer tube should extend into the skeg box by 25mm. With the compression fitting I used, this gave a measurement of 60mm from the outside of the compression fitting to the end of the tube. A pen mark or piece of tape 60mm from the end of the tube helps to position the tube correctly.

7. Fit nylon spacer washers as necessary on the pivot, and complete the box.

The box, when slotted through the keel, will require a height clearance of 119mm from the top of the keel to the underside of the stern deck. A skeg system to this design operates very smoothly, but disadvantages of this design are that the compression fitting and tube are more vulnerable to damage from stowed equipment in the stern compartment, and the available storage volume is reduced.

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