Shrike, a lightweight sea kayak for home construction.^

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The estuary of the River Camel, North Cornwall.

Post by nickcrowhurst » Thu Jul 18, 2019 3:39 pm

Who wouldn't want to share this beach with Peter?
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The prototype Shrike just loving the chop

Post by nickcrowhurst » Sat Jul 20, 2019 12:18 pm

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Photo Peter M.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by charleston14 » Sun Jul 21, 2019 4:14 pm

Anyone got any photos of a shrike alongside an Anas Acuta? I’d like to compare the hull designs, and get a sense of how they differ.

Considering a shrike build with plans altered for a more upturned stern, like the Anas.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by PlymouthDamo » Sun Jul 21, 2019 4:33 pm

I don't have any photos, but I know that, for the Shrike, Nick used the dimensions from the same historical boat that was the basis for the Anas Acuta. Nick's got a very early Anas Acuta which I've paddled and it felt very similar to a standard Shrike, but with an ocean cockpit. Nick's been poorly for a few weeks so it might take a while if he hasn't already got a Shrike v. Anas Acuta photo to hand. In the meantime, here's an informative load of info which MikeB has collected about the boat which the Shrike and Anas Acuta were based on:
https://www.ukseakayakguidebook.co.uk/t ... _kayak.htm

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by nickcrowhurst » Mon Jul 22, 2019 2:54 pm

Charleston14, the differences between one West Greenland kayak and another are not ones that will be seen in photographs. The differences are too subtle. The way to appreciate the subtleties is to get hold of Harvey Golden's remarkable book "Kayaks of Greenland", ISBN 0-9787221-0-8, White House Grocery Press. The book is known in the Greenland kayak world as KOG(n) where n is the number of the kayak in KOG. Each kayak is described in detail in the text and illustrated with scale lines drawings sufficient to produce a replica. There are 104 kayaks detailed.
The original Keith Taylor/John Heath Illorsuit Kayak is KOG72. My inspiration is KOG65, which has a good strong rocker confined to the front half of the kayak, giving a sparkling responsiveness to every paddle stroke, and also producing a particularly attractive sheer, IMHO. Our website shows the line drawings of KOG65, as shown here: https://cnckayaks.com/shrike/origins/
Shrike adapts this slightly for thin plywood to follow the shape, and I placed the cockpit a long way forward. (Simpson's rule for integral calculus is an important tool in many calculations for boat design). KOG65 had to cope with the weight of dead animals carried on the stern deck without the stern being submerged. This is not a regular issue in Cornwall :)
If you examine the first post on page 1 of this thread you will see the very low windage of the stern section of Shrike. Just as the very lightweight Shrike is responsive to every paddle stroke, she will also be responsive to unbalanced windage. I have no idea why you would wish to add a more upturned stern to Shrike. One has to consider the horizontal turning moments of the kayak in a 30 knot cross wind. Extra windage on the tip of the stern is in the worst place for this particular design. I would not do this. Do you really want to alter a design that is the culmination of 500 years of development by the world's most accomplished kayak designers, builders and paddlers?
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Re: Shrike, a lightweight sea kayak for home construction.^

Post by charleston14 » Mon Jul 22, 2019 9:32 pm

Thanks for the information..fascinating

Have to say I didn’t realise the peaked stern would have such an effect and so, no,,I’d stick with the boat as per the plan.

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Claude Lechasseur from Canada

Post by nickcrowhurst » Wed Aug 07, 2019 11:39 am

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Another six from the Archipelago Folkschool

Post by nickcrowhurst » Sat Aug 10, 2019 10:03 am

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Today, Saturday is launch day. I'm so pleased that two ladies are taking part.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by Spikeedog » Sat Aug 10, 2019 10:59 am

A truly global movement

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The six completed today at the Folkschool

Post by nickcrowhurst » Sat Aug 10, 2019 4:49 pm

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A kit to build a Shrike

Post by nickcrowhurst » Wed Aug 14, 2019 9:37 am

Chris Tipper of Selkie Kayaks, Newhaven, has produced a kit of machine pre-cut parts to build a Shrike. Shrike kits have been available in the U.S.A and Canada for several years, but this is the first in the U.K that is available for purchase. Chris Tipper is a craftsman trying to set up a small business from scratch, so we wish him every success. He's also a really good bloke. The Archipelago Folkschool Shrikes in the above picture were built in six days using a kit of pre-cut parts. Here's the link to the Selkie Kit: https://selkiekayaks.co.uk/boatkit
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Re: Shrike, a lightweight sea kayak for home construction.^

Post by Spikeedog » Wed Aug 14, 2019 11:22 am

That's a really welcome development. I can see a lot more people building their own with the assurance that the panels are all correctly sized and ready for assembly. I think the residential workshop is a also a great idea. I'm a trustee of a men's shed charity locally and we're about to build a brand new community shed so this would make a great group project in association with our v.successful local canoe/kayak club. My vision is kayaks first then maybe a community boat. Men's sheds might be a good market for him.

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Kits may be suitable for you.

Post by nickcrowhurst » Wed Aug 14, 2019 12:17 pm

Spike, that's a great plan. I build from scratch because I'm a retired old geezer, well past my three score and twenty, and a with a big enough shed, but for many folks a kit saves getting unwieldy full sheets of plywood delivered, and then cutting them into strips before cutting out the component parts. That's in addition to the time saved with accurate pre-cut components, so if you'd rather save the time and hassle than the money, a kit can make sense. Without a kit, I reckon on 100 hours for a first-time builder to finish a Shrike with a skeg, seat, deck-lines etc. but the Folkschool has shown that a 6 day course is feasible with a kit. The builders will still need to spend a few hours sorting out the bells and whistles.
Either way, building your own lightweight high-performance Greenland-style sea kayak is great fun, and a source of pride. I know of no commercially available full-size sea kayak weighing as little as Shrike's 32 pounds (14.5 kg), no matter how much it might cost. Weight is not only a matter of handling a kayak on the shore or onto a car roof. It also dramatically changes the handling when afloat. Try grabbing a pair of kids (it might be better to first get the parents' permission:) ) and sitting them on the ends of a see-saw. Now get hold of one end and start to lift it, and feel the initial load. Now get the kids to crowd together over the pivot point and again feel the initial load. It will be much less. In maths-speak, the moment of inertia has reduced. (The same occurs with a playground roundabout) Now imagine you are trying to make small directional changes in response to wind and wave action when paddling your kayak. A light bow will respond more quickly than a heavy one. Inertia occurs independently of gravity, so even a satellite in space needs a good shove to change to start to change direction. That's why, combined with pronounced rocker in the front half of the keel, the Shrike with its lightweight ends has such sparkling performance. The Inuit are a smart bunch.
Nick.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by Spikeedog » Wed Aug 14, 2019 1:10 pm

Agreed. I built my own from scratch. The only manufactured part on it is the foam seat. It carves a line and a turn as well as (probably better than) any other kayak I've tried.

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Received today, from Adam May in Ireland. another beauty

Post by nickcrowhurst » Wed Aug 14, 2019 2:44 pm

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Mikko Linna proudly presents......

Post by nickcrowhurst » Fri Aug 16, 2019 9:17 am

Mikko is from Finland, the 50th country to host the building of Shrikes and Vembers. This a Shrike-R, the rolling version, produced simply by reducing the height of the standard Shrike gunwales by up to 60 mm. All else is standard Shrike with the ocean cockpit option. The Shrike-R only weighs 23 pounds. It's great fun - if you can squeeze into it. I hand rolled ours first try. It's so easy. An interesting aspect for me is that because the Shrike-R is even easier to roll than anything else I've paddled, this ease makes it the best way to learn the complex bodily movement to learn any particular roll. The aspect I found to be quite surprising is that this skill transfers directly to any other kayak. A common remark would be that "anyone can roll that submarine. You just try it in a normal sized kayak." Well, in my experience, the skills transfers directly. Heavier and bulkier kayaks may be slower in the rolling movement, as they have a higher angular momentum to overcome, but the body movements are the same.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by mcgruff » Fri Aug 16, 2019 3:22 pm

Aha! A rolling version.

Was wondering how I could ask why it's so low in the water without casting aspersions towards the paddler..

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by Beryl » Fri Aug 16, 2019 10:38 pm

Can you use the paddlers weight to calculate where the Shrike will sit in the water? At 160lbs I’m planning a 95% starting point, then trim the boat down whilst keeping my size 9 feet un-squeezed. I like the look of low freeboard but perhaps not quite as much as Mikko!
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Re: Shrike, a lightweight sea kayak for home construction.^

Post by nickcrowhurst » Sat Aug 17, 2019 8:25 am

From pages 7 and 8 of the latest version of the 48 page Build Manual (dated March 1st 2018), which comes with the free plans download at https://cnckayaks.com/shrike/downloads/:

Vary the design to suit the weight of the paddler and the total planned maximum load.
This can be achieved in two ways. First, Low Volume (LV) or High Volume (HV) designs can be created by varying the printer instructions to produce paper plans at any scale between 90% (LV) and 110% (HV). The first Shrike LV (90%) is described under the "kayaks" tab at www.cnckayak.com. A graph of printer output % related to total planned load is in the FAQ section as the answer to the first question. Producing a design in this way scales the underwater sections, thereby creating a genuine "LV".
The second way to adapt the design is to adjust the freeboard (the height of the sides). This preserves the full 100% Shrike hull. The Shrike-R, a specialised rolling variant, was produced by lowering the freeboard 60 mm.
These two methods could be combined. The plans show the lines for a range of freeboards.

Lower or raise the freeboard (height of the deck above the waterline) by 1 cm (0.4”) for each 15 kg (33 pounds) below or above 80 kg (176 pounds) total load.

You should bear in mind that reducing the scale from 100% and reducing the height of the topsides will each individually reduce the stability of the kayak, albeit in different ways.
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This is how sheet 2 of the Selkie kit is sent to the CNC machine.

Post by nickcrowhurst » Sat Aug 17, 2019 9:24 am

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by Spikeedog » Sat Aug 17, 2019 2:44 pm

Beryl wrote:
Fri Aug 16, 2019 10:38 pm
Can you use the paddlers weight to calculate where the Shrike will sit in the water? At 160lbs I’m planning a 95% starting point, then trim the boat down whilst keeping my size 9 feet un-squeezed. I like the look of low freeboard but perhaps not quite as much as Mikko!
I made a 95% with reduced height and a little on the length. I struggle to get size 8 feet under the deck so cannot wear shoes or boots while paddling. Check that your feet with whatever you wear on them fit on the foot bulkhead with a little to spare before you fix it in.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by nickcrowhurst » Sat Aug 17, 2019 3:27 pm

A specific rolling kayak will normally be used for short periods, so pointing the toes can be acceptable. My shoes are size 10 and I can use a 60 mm reduced freeboard Shrike-R. For a day trip one needs a more relaxed pose. If you want lower freeboard and you want more foot comfort you can emulate Plymouth Damo, who made more toe room by using a three-piece section of foredeck close to the specially shaped masik. I thought this would look horrible, but you can see the effect on a Shrike he helped a friend to build. The small triangles are subtle, and do not spoil the looks of this Shrike-R with a 30 mm reduction in freeboard:

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The First Shrike in Taiwan (to our knowledge)

Post by nickcrowhurst » Sun Aug 18, 2019 9:30 am

Eagles Wang has built his Shrike (number 209)in Taiwan, our 51st country.


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Launch day for six Shrikes at the Folkschool

Post by nickcrowhurst » Sun Sep 01, 2019 8:08 am


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Two Vembers at Spring Lake, Minnesota, USA

Post by nickcrowhurst » Fri Sep 06, 2019 10:37 am

Vember on the right with raised topsides for a paddler who likes plenty of room in the cockpit, and a 110% scale lengthened Vember Expedition with the ocean cockpit option on the left:

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Terry Taylor from Scotland celebrates his new Shrike

Post by nickcrowhurst » Tue Sep 10, 2019 8:58 am

Terry shortened his Shrike by removing 4 inches from the topside panels at each end, leaving the bottom panels untouched. This could be a useful modification for someone whose garage is too short to build full-size, but who wishes to preserve the stability of the full-size Shrike.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by mcgruff » Tue Sep 10, 2019 3:53 pm

Do longer, pointy ends influence the way the boat handles (ie in waves - rest of the time they're not in contact with water) or are they more about aesthetics?

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Greenland kayaks and pointy ends

Post by nickcrowhurst » Tue Sep 10, 2019 5:33 pm

My reading tells me that the long overhangs enable the kayak to rise up onto an ice floe when the kayak is paddled firmly towards the floe, either forward or astern. I guess the the long overhangs will also soften the motion through waves, as the buoyancy of the bow increases rather more gradually than with an upright stem as a wave is negotiated. In the Shrike Gallery and in this thread you will see photos of modern Shrikes on ice floes in Russian waters:
https://cnckayaks.com/2018/04/30/%d0%b5 ... sk-russia/
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Re: Shrike, a lightweight sea kayak for home construction.^

Post by mcgruff » Tue Sep 10, 2019 6:32 pm

Thanks :) That makes sense.

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Re: Shrike, a lightweight sea kayak for home construction.^

Post by Oisin » Thu Sep 19, 2019 1:03 pm

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The local 3d printing route hasn't worked so I've been looking at surfboard leash plugs, mock up in the pictures above. 20 of those are very inexpensive.

I can drill the hole with a forstner bit and have a backing plate under the deck I think

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