Frequently asked questions
Do you want (a) A day tripping or expedition kayak? Or (b) a specialist rolling kayak? If (a) then, then select (c) keyhole cockpit – this is a standard Shrike or (d) ocean cockpit – this is a Shrike Too If (b) the specialist rolling kayak is Shrike-R Now that you have selected your basic model, Shrike, Shrike-Too or Shrike-R, decide whether you wish to vary the scale of the kayak to suit your bodyweight, as determined by the graph below under “Will the Shrike work for my weight?” Finally, select your desired height for leg clearance at the front of the cockpit, between the keel and bottom of the cockpit rim. Experience in other kayaks will guide you in this.
Will the Shrike work for my weight?
As described in the free downloadable Build Manual, the height of the gunwales can be varied to suit differing paddler and equipment loads. However, the scale of the plans can also be changed during printing, so that every dimension of the kayak is adjusted by the same percentage. Below is the graph we use to relate the printer/plotter percentage scale to various loads of paddler plus equipment, in pounds. Because of the length limitations in the pdf specification, the pdf is downloaded at 50% scale, so percentages taken from the above graph must be doubled. For example, a load of 137 pounds (62.1 kg) suggests a 90% plot, doubled to 180% if the pdf is downloaded at 50%. The resulting “LV” version for a 137 pound (62.1 kg) total load would have a beam of 19.3″ (491 mm), and a length of 15ft 8 inches (4773 mm). Feel free to experiment with your planned design. Bear in mind when scaling the design that all linear dimensions must be changed to the same scale. That includes all the measurements relative to the datum line, such as paddler seat centre, position of temporary molds (exterior and interior), and position of bulkheads
If I increase the height of the topsides to cope with higher loads, will that change the cutting layout on the ply wood?
To construct the standard hull we cut two full sheets of ply each into five equal width strips (1220mm divided by 5, less saw cuts) . The topsides, in particular, are a close fit for width on these strips, because of the rise of the gunwale towards the bow and stern. If you increase the topsides height you may need to nest the curves of the bottom panel chines into the gunwale shapes of the topsides when devising a cutting plan for the plywood. This may require you to devise an alternative layout and cutting procedure for the full sheets. Cut round the paper templates and lay them on the full sheets before cutting into them.
Why do you not fit the sheer clamps (aka carlins, sheer clamps, inwales or inner gunwales) to the topside panels before assembly? This seems simpler, and is recommended by most kit suppliers.
With the steep rise and double curvature of the gunwale near the bow of Shrike, and the required kerf sawing (of unknown extent – it varies with the timber) to enable this without stress to the timber, we decided not to use the usual simpler method of prior fitting. If the topsides plus sheer clamps are stressed excessively into position, this can distort the desired final shape of the gunwales, and unnecessarily stress the whole structure.
How do I know that my plans are printed accurately?
The plans include two lines, each 500 mm long, one along and one across the print-outs. These lengths should be checked with a steel rule to ensure accuracy. Our comfort level is plus or minus 0.5 mm.
How do I make sure my 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. Taking extra care at this stage is less trouble than attempting to cure such a leak after the kayak has been completed and launched.
Why do you use temporary screws to hold down the deck? Other designs and kits do not suggest this is required.
Shrike was a prototype. The design emerged during the construction, an organic process to ensure elegance, rather than computer designed in advance. Computer aided design can have constraints on complex shapes. The Shrike foredeck is high and strongly arched, creating high stresses in the plywood. While prototyping and experimenting, temporary screws enabled a tighter control of the shape. Christopher designed Shrike Too with a lower, less arched, foredeck, and only used straps to fit the decks, thereby enabling a construction without temporary fastenings, and a larger forehatch. We no longer use any temporary screws when fitting the decks.
Does the Shrike need the skeg?
Whether or not a skeg is necessary very much depends on the area you paddle, what are the wind and sea conditions in which you paddle, and your own physical state. For example, Nick has a chronically damaged right shoulder. He can’t afford to edge and sweep for long periods to counteract weather-cocking. The worst conditions for weather-cocking are flat sea and strong winds from the quarter. If you always aim to paddle in light winds, and you are fit and strong, then you may never need to deploy a skeg in a well balanced kayak. If you are in doubt, you can build a Shrike without a skeg, but with a stern hatch and the stiffening structure for a skeg. You could then retro-fit a skeg if you decide one is desirable, although this is more awkward than fitting one during the initial construction. In the end though, we have not yet paddled a sea kayak that, ultimately, and in certain conditions, did not benefit from the deployment of a skeg.
Can I omit sheer clamps, and rely on glass tape inside and outside the deck to hull joint?
We strongly advise against this when building with the 3mm plywood. 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.
I read via the Origins page on your website that hard chine kayaks like Shrike balance quite differently from kayaks with a flatter hull. During the time I am building a Shrike, are there any exercises I can do to train for this type of balance?
In addition to maintaining your flexibility and core strength, just follow the Inuit practice. Build or buy a simple “kayak balance stool”, and build up the time you can maintain your balance, perhaps while watching a DVD. Searching the internet for “kayak balance stool” will bring up simple directions for building one from scrap timber, or there are commercial suppliers.
Can I use cheaper plywood?
The recommended BSS 1088 3mm okoume plywood is usually of superb quality. It is consistent in that we have experienced no voids in the inner ply, and it bends evenly without splitting. We have experimented with cheaper plywood, with conspicuous lack of success. It is possible that poorer quality plywood would take the bends in the hull panels, but not the contorted shape of the foredeck, particularly if a high foredeck is constructed. Low building cost is one of the aims of the project, so we would like to hear of any successful use of cheaper plywood. Top quality BSS1088 okoume marine ply is such a joy to use.
In the U.K, Seaworld hatches have proven to be 100% watertight, as claimed:
How do you repair a hole in a compartment?
Let’s suppose you were rock-hopping, and holed the Shrike’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 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 unsanded (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 the kayak is clear finished, take a rubbed pencil tracing of the hole on paper, and prepare a repair patch to this shape from 3mm plywood. Fix the outer patch by using superglue with accelerator to hold it in position, then finish with thickened epoxy in the visible joint. Sand and coat the area with epoxy resin until satisfied with the finish. This procedure will take much care to produce a satisfactory result, and one option for such a repair in a conspicuous position is to convert to a painted hull, and/or deck.
What can I use to remove excess uncured epoxy?
The best solvent for cleaning up uncured epoxy is plain, old, 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.
I dont have enough clamps, what can I use instead?
If you are using the screw-less approach to fitting the carlines you need a lot of clamps. If you don’t already have enough you can make some simple alternatives using plastic plumbing pipes cut lengthways. The longer the tube section the greater the force they apply. Here is a video that demonstrates this approach.
Can I get the AutoCAD DWG or DXF files?
The Shrike templates were drawn using AutoCad®. The original CAD (DWG and DXF) files are now included in the plan and template download file that you can receive using the download page. We encourage you to alter, enhance, experiment and improve upon every aspect of our work. If you want to make money making kits and selling them, or constructing kayaks derived from this work you are free to do so.
Can I buy a Shrike Kayak built for me?
We don’t build kayaks for money but we can recommend builders who do. In the USA Clear Stream Custom Water Craft have offered to build the Shrike design. In the UK Ram-Leisure have offered to build the Shrike design to your specifications. (If you would like to add your kayak building business to this page please email us your details and website.)
Why the name Shrike?
We could say that a shrike is a bird with a pointed beak, just as the Shrike kayak has a pointed bow. However, the truth is that Nick first came across Shrike as the name of an extreme rock climb on Clogwyn d’ur Arddu, a cliff on the north face of Yr Wyddfa, the highest peak in Wales. A photo of this climb appeared in the rock climbing guide to the cliff (1960’s ??). The climber in the photo, Hugh Banner, was shown in a wonderfully dramatic position on a very steep wall. Nick was inspired to climb the route, and the name, Shrike, had just the right tone to emphasize the dramatic nature of the route. Fifty years later, when Nick saw the finished kayak with its flowing lines accentuated by black paint, he knew it had to be called Shrike.
Why the name CNC Kayaks?
We like to play with words. CNC is, of course, widely used as an abbreviation for “Computer Numerically Controlled”, which describes the method by which computers take over from humans in much of industry. However, a main tenet of the Shrike project is that the design should evolve organically from the way the very thin plywood actually wrapped around the craft during the prototyping, rather than be constrained by the limitations built into the controlling software. Have you ever wondered why some stitch and glue kit kayaks look boxy and slab-sided? We only used computers to receive the manual measurements of the completed kayak, and output these measurements to plans. So, CNC is used tongue-in-cheek, knowing that it is likely to be misinterpreted. The truth is that Christopher & Nick Crowhurst is the reason for the label.
How many hours does it take to build a Shrike?
How many hours does it take to build a Shrike? Obviously this depends on one’s experience but an estimate, including some thinking and reading time, would be 100 hours. A friend who is an experienced professional builder states he would put the kayak together in 40 hours, plus outfitting and coating. In seven weeks in the Spring of 2015 I built a full-size Shrike with Maroske fittings , a keyhole cockpit, a knee tube, and a skeg, so it was a comprehensive build. At an average of two hours a day for 47 days, this took 93 hours:
|1||Cut ply strips and epoxy tape one side.||3||3|
|2||Tape other side of joins on strips||0.5||3.5|
|3||Cut out bottom panels||1||4.5|
|4||Cut topsides, assemble panels, superglue joints||7||11.5|
|5||Fit and glue sheer clamps||1.5||13|
|6||Install bulkheads, fillet and tape interior||7||20|
|7||Laminate masik, glass cockpit & foot bulkhead both sides||3||23|
|8||Fair, fill and tape hull, + first epoxy coat all over hull||4.5||27.5|
|9||Fair sheer clamps and fit masik||2.5||30|
|10||Make skeg and box||6||36|
|11||Rough cut deck profiles||2||38|
|12||Maroskes on foredeck panel||2||40|
|13||Finish Maroskes on foredeck panel||1||41|
|15||Prepare stern deck, start Maroske fittings||3||47|
|16||Fair skeg box in keel, tape top of foot bulkhead||1||48|
|17||Progress Maroskes, prepare stern deck for fitting||2||50|
|18||Complete Maroskes and fit stern deck||2||52|
|19||Trim stern deck, fit cockpit upstand||6||58|
|20||Cut out and epoxy cockpit rim and begin thigh braces||3.5||61.5|
|21||Fillet and tape under cockpit rim, kayak upside down||1.5||63|
|22||Shape and glass cockpit rim top||3||66|
|23||Cut and shape thigh braces||0.5||66.5|
|24||Epoxy first coat decks and apply tape to deck/hull joint||1||67.5|
|25||Carve foam back rest, modify foot pegs ready for fitting||1||68.5|
|26||Install foot pegs and hip plates, laminate knee tube.||3||71.5|
|27||Install knee tube, tape round skeg slot||1.5||73|
|28||Sand hull and the tape edges, epoxy second coat on hull||4||77|
|29||Apply tapered keel strip tape with clear epoxy||0.5||77.5|
|30||Trim masking tape from half-hard keel strip tapers||0.25||77.75|
|31||Final shaping of thigh braces and first install stage||1.75||79.5|
|32||Thigh braces under-deck taping.||0.5||80|
|33||Sand hull, apply final coat of epoxy||1.5||81.5|
|34||Install skeg slider and foot braces||0.5||82|
|36||Sand and epoxy coat deck, glass top of thigh braces||2.5||86.5|
|37||Epoxy on cockpit rim, trim and coat thigh braces||0.5||87|
|38||Install skeg and wire||1||88|
|39||Install hatches in deck, fit deck lines and end toggles||3||91|
|40||Outfitting – fit seat, back rest, foam for thighs||1.5||92.5|
|41||Black epoxy on keel strip||0.5||93|