Shrike, a lightweight sea kayak for home construction.^

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

Post by ChrisJK »

Thank you Nick I'm fairly regularly reading the manual but trying to avoid making a mess up, which just might have occurred here if the subject hadn't come up. I'm away from my Shrike just now and thought uh oh but by the sound of it the depth of foam I would have on the foot bulkhead is probably around 100 mm and will just go behind me and the amount of leg room remain the same. I don't fancy chopping out the bulkhead and moving it back towards the bow but if I must then so be it. At present I have the back beams ready to epoxy and the gunwhales just about ready to take the decks with the front deck nearly seating properly. Edging gradually towards a launch.

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

Post by PlymouthDamo »

Oisin wrote:
Sat Jul 24, 2021 8:42 am
Having had a bad day after not reading the manual earlier in the build I picked up on the seat position measurement Image

I found this link in the ukriversguidebook almanac that goes through how to turn a sea kayak in different conditions, with diagrams etc

http://www.ukseakayakguidebook.co.uk/sh ... urning.pdf
I've had a hungover Sunday morning to read that article, and I'm glad I did - the guy gives a really clear explanation and the technique makes sense. I've never had a problem turning towards/away from the wind, but I've never been taught the theory, couldn't really explain how I do it and I genuinely don't know whether I'm employing the technique he's describing, which basically amounts to using your paddle blade as a bow or stern skeg/rudder as necessary to allow the wind to do the turning work for you. I suspect I've ended up, by default, doing my own cobbled-together version of what he's describing, but I reckon I might be able to do things with a bit less effort by applying that technique in a more pronounced way.

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

Post by ChrisJK »

Thank you both for this Info. I have downloaded the pdf to read again. This is where I find that Greenland paddles score highly in counteracting a kayak weather cocking as they can be used as a long manoeuvrable lever particularly considering that those early Inuit SOF kayaks may not have had the luxury of a retractable skeg.
It also underlined the importance of placing the center of the seat at the correct point of balance.
Thankfully I found on after unpacking my return from an excellent UK camping holiday that though I had inadvertently reckoned on the -50 bulkhead as acting as a back rest and brought aft the foot bulkhead accordingly despite having read the instruction on where to place the seat and looked at the photos that when moved forward and placed correctly I still had (within mm) sufficient legroom.
Nick politely put but perhaps if and when you revise the manual and if Plymouthdemo's analysis of photo's is correct that you stamp in a second STOP at a considered point to accentuate the fact that the seat must be central otherwise there may be folks who after expending the effort but not paying attention have made a Shrike and are paddling round like those fellows on the recent thread who were paddling double kayaks solo.

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

Post by DavidDeWitt »

Bryan Hansel of Paddlinglight.com wrote an interesting article a while back on kayak seat placement which includes a discussion of calculating a paddler’s center of gravity and how it should be aligned with a boat’s LCB

https://www.paddlinglight.com/articles/ ... ent-rules/

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

Post by Sparl2021 »

I have decide that I am going to take the plunge and build a Shrike!
As I cannot get plans printed locally that I’m prepared to pay the amount that they are asking, how do I ensure that if I get my plans printed and posted to me that that the horizontal and vertical 50cm reference lines are correct? Any advice is appreciated.

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

Post by nickcrowhurst »

On the paper plans, you measure them with a ruler. If they're not within a millimetre or so, then reject the plans. It's worth telling the printers that you need to ensure that the scale is correct. Ask them to print the minimum amount of paper to show the reference lines, and to measure them before churning out 25 feet of paper.
Welcome to our world of sawdust and epoxy. We are delighted that you are taking the plunge. There is a large quantity of information and advice available to you. But first, RTFM :) - twice! , and highlight any parts that are not clear to you.
Do keep us informed of your progress. We love photos.
Best wishes, from Nick.

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

Post by Sparl2021 »

Thanks Nick.
I will say to them about the need for accuracy when I contact the printers.
I live in a world of sawdust most of the time! As il like to potter with making garden furniture/planters etc but never anything that needs to float!
I have read the manual numerous times already and read most of the pages here too!
I will take photos but I will need to have a tidy up first before making more sawdust!

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

Post by darylf »

sparl2021 if you are in the UK check my post above about getting the plans printed, it was no problem and i got them the next day, cheers

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

Post by Sparl2021 »

Hi darylf

Thanks for the heads up I think I’m sorted with plans via Servicepoint in either Southampton or Aberdeen.
Cheers
Mike

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

Post by darylf »

Mike,
ideal!! I got my ply from fyne boat kits, and epoxy and cloth etc from east coast fibreglass, long lengths of timber for the sheer clamps and other odds and sods came from my local builders merchants a long length of door lining material and I just ripped the best two bits out for the clamps, and used other bits of it for the beams, probably some kind of spruce or pine I guess. Enjoy your build!
cheers, Daryl

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

Post by PlymouthDamo »

I'd be interested to hear how much a Shrike or Vember build has cost someone who's started recently. The news is currently full of horror stories about the inflation in raw material prices - wood in particular. Would be useful info for anyone trying to decide whether to build one.

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

Post by darylf »

I will attempt to have a tot up having built mine over the last few months, all I can say for sure at the moment is it cost more than I thought it would! PS having looked I reckon around 600 quid.

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

Post by ChrisJK »

I am midway through and including the full kayak sport skeg and most of the disposables I have spent around £600 plus I have needed a craft drill and sander the two cost around £80.
Ah yes plus another £80 ish I think for PPE

I can't foresee other expenses

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

Post by nickcrowhurst »

For comparison, I built the prototype Shrike 8 years ago, and published the Build Manual in early in 2014. On pages 9 and 10 :

Costs
Build a Shrike not to save money, but to obtain a lightweight kayak fitted to your needs, while gaining immense satisfaction from constructing and paddling your own sea kayak.
In 2013 the prototype Shrike, in the photos, the cost about £320, including over £50 of delivery charges. We already had various materials, such as trash timber and plywood for temporary forms, softwood for sheer clamps (inner gunwales), superglue, disposable brushes, webbing tape and line for deck outfitting, a workbench, a full complement of hand and power tools, disposable gloves, etc. Costs, in pounds Sterling were:

Three 2440mm x 1220mm (8ft x 4ft) sheets of 3mm thick Robbins Elite BSS 1088 marine plywood £130
4 kg epoxy resin and hardener (Probably 6kg are required if panels are coated with glass cloth.) £69
50m of 50mm wide woven fibreglass tape £17
West filler and fairing powders £10
Rollers and brushes £10
Glass cloth for cockpit floor and cockpit coaming top surface £3
Paint £6
Minicell foam for seat and backrest £20
Hatches £25
Skeg slider (also known as a glide box) and wire, tube and brass compression fitting from Kari-Tek. £30
Total = £320

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six new Shrikes

Post by nickcrowhurst »

Today, at the Archipelago Folk School, six new Shrikes took to the water, taking the total we know about to 341:

Image

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

Post by ChrisJK »

Hi NIck

Thank you for this project and for UKRGB for introducing me to it. Last year I hankered for a new kayak but didn't want to spend loads of cash to aquire one but a self build wasn't on the horizon.

The hull number seems to correspond to the build start time which may not correlate to it's completion date which is possibly a maritime convention?

Thank you to Yourself, Plymouthdamo and Daryl for information,help and encouragement with my build. Plus of course all the contributors to this thread for info and pictures.

The guys at Archepelago folk school will I think have started with a CNC crafted kit. which perhaps gives them a head start. eg https://selkiekayaks.co.uk/boatkit

I am not being critical here as I have a friend who built a Guillemot kayak Petrel from kit in a lorry container at their Cumbrian base in the midst of winter over a week whist sleeping in a camper van. He described that as being "Intense"

Today I passed a land mark and have seated the front deck ready for fixing.
My next tasks are to secure the masik and the aft deck beams with epoxy and then epoxy the front deck.ff

My timescale is less intense so Shrike 275 is at this stage.

All the best to spar2021 who may overtake me.
Image

Image

This is being built by someone who finds it a challenge to set up a shelf in the house!

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

Post by nickcrowhurst »

Chris, good work. Ben at the Folk School adapted our plans to create a kit, which is how the kayaks are built in one week to a basic stage. However, there's unlimited time that can be spent on finishing the job.
Putting up a shelf, level and square, can be tricky, particularly on old houses :)

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3-piece Shrike from Singapore

Post by nickcrowhurst »

Charles from Singapore says: Another Shrike on the water. Thank you for a lovely design.


Image

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Searching this thread

Post by nickcrowhurst »

A couple of builders have mentioned that the length of this thread makes it cumbersome to find particular items of interest. Not all readers may be aware of the facility to search ONLY the one thread. A the top of each page there is a box labelled "search this topic". Just to the right are two options: "search" and "advanced search". For example, a search on this thread for "skeg" gives 47 hits, listed in full so as to be easy to read.

On the subject of skegs, it is common for any kayak, made of whatever material, to suffer a skeg with a cable that is excessively stiff to move. Here's the solution I use:

1. Turn the kayak upside down on the ground..
2. Lift the stern about one metre onto a saw horse, chair, step ladder, fence, car bonnet, etc.
3. Pull the skeg blade out of the box so that it is sticking up in the air. If one finger doesn't suffice, I use a screwdriver or a narrow stick.
4. Use a torch or head torch to peer into the box and locate the hole into which the wire disappears.
5. Take a spray can of silicon lubricant and inject fluid into the hole until fluid runs out of the finger control. (Easier with a can that comes with a thin tube.)
6. Slide the control back and forth, adding more lubricant until you are content with the movement of the skeg.
7. Smile.

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

Post by ChrisJK »

Thanks Nick

I will lodge that advice.

I have just installed my Kajaksport skeg kit from Argyle kayaks, I had a few issues with it which got overcome when I got a pdf of the contents and installation instructions.
I needed to lightly file the lower parts of the ribs in the box so that the skeg emerged.
At Plymouth Damo's advice I wiped the wire with furniture polish before installing which will hopefully act as a prophylactic for a while.

I have just tried the search facility on the thread and typed in 'roof bars' nothing appeared . At present I have J bars which are 1200mm and 730mm apart on my Peugot van and Vauxhall Meriva respectively. It suits my Capella but will the more V shaped Shrike be ok here or need a different approach?

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

Post by fergus_finn »

Good morning all. Planning the next shrike build and/or retrofitting the first one with Maroske deck fittings. There are a multitude of ways of doing this using tubes & fibreglass etc. but by far the most elegant I have seen are the 3D printed ones. I did price these with a commercial 3D printing company one time and it was going to be 1/2 the price of the kayak so that never happened. I quite like the idea of getting into 3D printing anyway but before taking the plunge I thought I would consult the forum to ask A) has anyone already got a reasonably priced source of 3D printed maroske fittings and B) if you have your own 3D printer setup do you have any pointers for the sort of minimum spec setup needed to be able to do this job ? I can appreciate that this may be a bit off topic but 90% of the kayak build activity which I see on this forum is in this thread anyway so chose to post here.

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

Post by nickcrowhurst »

Fergus, the only reasonably priced ones came a few years ago from a friend of Damian (PlymouthDamo). I believe nylon was the chosen material. We may be able to get some technical advice from that source.
In your position, I might invest in a 3D printer, if only because it's a fun and fascinating technology.
Some readers will not be aware that the data files for printing the fittings are contained in the plans download.
I expect Damian will comment here.

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

Post by DavidDeWitt »

I don’t mean to hijack this thread on 3D Maroske fittings but I wanted to share a picture of the Vember tandem I have been working on for a while. Progress is slower than I had expected - largely a result of family visits and travel during the too short lull in covid cases in the NE area of the U.S. As usual I have relied heavily on Nick and Chris at various stages of this project but for the most part building a tandem is just a little more work than a normal Vember. I am about ready to install the cockpit rims
Image

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

Post by nickcrowhurst »

David, well done. She's looking good. I'm a big fan of Tandems when partners are very different sizes, strengths, or skills. I'm a lot bigger than my wife, and not so pretty. When paddling in separate singles, my day would be spent worrying about her safety, particularly when the wind increased. An efficient tandem changes all that. We have an effective method of capsize recovery, although we've never needed it. One can paddle while the other takes a rest, or arranges drinks. (A plank temporarily across the cockpit acts as a table) Tandems can be very stable. We were once peering hopefully for a tiny island. It wasn't in sight. I stood up (it was a calm day) and the flash of a beach winked over the horizon. I took a bearing with my hand-bearing compass, sat down, and we paddled off to our island. (Don't try that in your Nelo Inuk.)
We've written a book "Sea kayak Day paddles on Florida's Hidden Coast". It describes our 16 favourite trips in the north east of the Gulf of Mexico, with maps and GPS waypoints. Every trip was in our tandem. The free book can be read or downloaded here: https://cnckayaks.com/kayak-hidden-coast/
Tandems rock, but get that lightweight bow paddler some goggles or a face mask. There's a shed load of spray up close to the bow.

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

Post by fergus_finn »

Just got an online quote for 10 maroske fittings using the .stl file from the cnckayaks website. 110 ukp. Not dissimilar to what I got first time around. Looks I will be headed down the 3D printer route. How hard can it be :-) If I ever get it working will post the results.

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

Post by Chris Bolton »

You could buy one of these. Should be big enough. Even when you add the consumables it might be cheaper than the quote for the fittings!

Check it out for yourself, as I haven't used one but the reviews are reasonable. The PLA filament it officially supports is biodegradable, so not good for a kayak, but PETG sounds suitable for outdoor use and users say it works - that might need more checking.

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

Post by nickcrowhurst »

Chris, that's a good find. The manual is understandable, a rare bonus with Chinese products. On first skim-reading, it's not obvious why there are two types of printing: online and off-line. The list of possible materials is comprehensive, and the filament of the correct size and material is available on eBay: https://bit.ly/3mah5Jv
The first issue we found when prototyping version 1 is that the material would allow water to pass through it. Not the best result for a sea kayak :)
That was sorted in version 2.
Damian might be able to find out the details from his friend with the printer. It's Sunday morning, so he'll be examining the inside of his eyelids for a while yet.
Fergus, we don't know if this machine is kosher. 3D printing is very slow with "entry-grade" 3D printers.

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

Post by Chris Bolton »

Nick (and Fergus) I have done some more checking and am not convinced that PETG will work well in that machine. The melting point is 250-260ºC, compared to 170-180ºC for PLA. It would certainly need careful tuning of the settings. I've also read that the degradation agent for PLA is UV, so maybe it would work, as the paint or varnish on the deck would protect it.

I have no expertise in 3D printing, but have read up on it as I do intend to try it. I also intend to build a Shrike, but dare not start either yet as I have too many projects already.

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

Post by fergus_finn »

No real knowledge of 3D printing (which is why I am asking the questions :-) ) but I think PLA is not the right stuff. I would say that ABS would be the minimum material spec and work upward from there. This introduces complexity & cost but if it produces a usable part vs something unsuitable or with a short life then of course it is worth it. Thanks for the tips so far gents.

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

Post by PlymouthDamo »

fergus_finn wrote:
Sun Aug 15, 2021 1:49 pm
No real knowledge of 3D printing (which is why I am asking the questions :-) ) but I think PLA is not the right stuff. I would say that ABS would be the minimum material spec and work upward from there. This introduces complexity & cost but if it produces a usable part vs something unsuitable or with a short life then of course it is worth it. Thanks for the tips so far gents.
I've asked my mate about printing out some fittings for you or advice on buying a printer yourself. Apparently, his 3D printer is on its last legs, but I've asked how much he'd want if it could knock out 8 more fittings for you before it died - still waiting for a reply, which I suspect is because he's currently trying to print them. As far as I can remember, he previously wanted something like £6 per fitting, i.e. £48 to kit out a boat. (It's a tricky thing to price as wear-and-tear on the printer is as much a consideration as the cost of the filament. Plus, we'd originally told him that we'd put him down as an option for Shrike builders, so he'd have a steady flow of 'customers' but that never happened so he's just done the odd one or two here and there, which I guess isn't so attractive a proposition to him.

As far as buying a 3D printer is concerned, he said that a half-decent one would be in the £200 to £300 range. I don't know whether that means that the one Chris linked to above is going to be of poor quality, but it's more likely that it's just one of those cases where you can get good stuff at remarkably low prices if you get it non-branded direct from China. As always, the trick is to try and find some reliable user reviews.

Re. the material to use. I know bugger-all about 3D printing, but we've jumped through a few hoops making these things over the years, so I've got experience of how they fare in practice, plus my mate has experimented with a few different filament types. So here's what we know:

1. A 3D printed fitting is probably going to leak, regardless of the design or what it's made of. All mine have, despite looking like solid lumps of plastic. Apparently, that's down to the way the material is laid down in layers, leaving microscopic cracks. So far, I've sorted all mine out by pushing a bit of epoxy through the tube section - this works, and the fittings in all my boats haven't given me any problems. My mate was also experimenting with using acetone (and maybe heat?) to chemically melt the surface, but I can't remember how well that experiment worked.

2. The UV resistance isn't really a concern as these fittings are mainly under the deck, with only a tiny bit showing through on the surface. I always varnish my boats after I've completed them with all fittings installed, so that gives everything a tough UV resistant coating.

3. There are at least 3 designs knocking around. Nick started with one, then my mate developed it to be more compact and less prone to being snagged/damage by your luggage and then someone else came up with a further refinement (which combine the light weight of Nick's version with the strength/compactness of my mate's version) which I think Nick has the files for.

4. In terms of materials, I've scoured my old emails and here's what my mate's said in the past:

"If your mate can find a printer that prints nylon, that would be ideal. Mine doesn't, at least I've never tried yet and nylon filament is quite expensive (for some reason). Otherwise PLA or ABS, doesn't really matter if you're going to cover it in resin anyway."

(My mate's a ridiculously qualified research chemist, so I just go along with what he says when it comes to this stuff.)

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