kayak seat instructions

[Doug Canada]

Greetings I am looking for instructions for making a kayak seat out of minicel foam.
Any good instructions out there?
I am looking for hip & knee bracing as well.
(Its for my cedarstrip kayak, Endeavour)


Thanks,
Doug


.

[JimD]

I cut mine with a bent hack saw blade and then sanded it smooth. Used a belt sander, random orbital, and by hand, as required. Got a perfect custom fit.

[P.I. Stazzer-Newt]

You can just "carve to fit"
Suitable pics here
http://www.roho.co.uk/acatalog/Robin_Hood_WS_Perception_Kayaks_966.html
Veneer sprint boats used to se the seat on a pair of stringers so as to spread the load - visible here http://www.struerkajak.com/The-kayaks/Competition-kayaks/K1-Stranger.aspx


Knee/hip/back bracing is intensely personal - and what I'd do for a Slalom boat is very different to what I'd do for a sprint or marathon boat.

[Cuyahoga Chuck]

It's art not technology. If you're smart enought to build a strip kayak you have everything you need fiddle with minicell.
The big trick is coming up with something that is orthopedically correct so that you avoid the dreaded "numb leg" syndrome.

[Tom Robb]

I've no answer, but I think he's looking for how to get the fit right, not so much as how to carve the foam. For instance would sitting in a tub of plaster of paris and then copying the shape work? HOW do you know where and how much to cut?

[P.I. Stazzer-Newt]

Have a look here (http://oneoceankayaks.com/Wshophtm/Shop18.htm).

I have tried the large-plastic-bag-and-pour-in-place-foam - with poor results.

[Jim Ledger]

Tom, only a strict traditionalist would sit in a tub of Plaster of Paris.

It's all digital, nowadays.

For example....http://www.youtube.com/watch?v=ykhSLNlx3n0

[Spokaloo]

Doug, its really simple.

ROS or grinder is the fastest. Cut for a minute or two, place ass in form. If it doesn't feel good yet, cut for a minute or two, put ass in form, rinse repeat.

Its definitely not rocket science. Just take your time, and use the form thats attached to you above the thighs and below your back.

E

[DDan]

Don't overlook the Thermarest(r) seat pad. This is a seat size version of their sleeping pads. Inflate it, sit on it in boat, and let out air until your butt bones just begin to touch the bottom. I think because the air moves around some, it keeps a bit more circulation going in your backside. Plus - it's easy. In my Pygmy Queen Charlotte, I sometimes place the Thermarest on a wedge-shaped bit of closed-cell foam that came with the kit. I do wish sometimes that I had more back of thigh support than this gives.

Last summer, I completed a West Greenland skin-on-frame boat. I haven't figured out what to do to make it really comfortable. Because it's so cramped, I sometimes just need to get out and stretch. Any seat or braces has to not impede getting in or out, so there's less that can be done than in a modern/larger cockpit boat. I use the Thermarest with it. I need to shave some off the masik for a better fit with my shins. I've wrapped some foam around the deckbeam my back rests against. Any other ideas?

[JimD]

... Cut for a minute or two, place ass in form. If it doesn't feel good yet, cut for a minute or two, put ass in form, rinse repeat...

E

Yup

[LeeG]

Doug, I'd suggest getting a block of minicell wide enough to extend beyond the hip plates so you can lock it into place fore/aft with notches. That will provide a bit of thigh support to the side and forward of the hip plates. Then make sure it's long enough that the aft end extends a couple inches behind where it's carved out, maybe an inch behind the back band. Depends upon how you've set it up. I've extended them back far enough to make soda can holders or provide just enough space for a dry box/tow belt if the bulkhead is close to the coaming.

Make a template of the inside curve of the hull so you don't end up carving a flat block and try and fit it in a curved bottom. That way you start carving the bottom/sides and hip plate notches first.

It'll probably still be too stiff to fit in the kayak but it's a beginning.

Ok,,get a marker and draw a flattened semicircle a few inches from the back of the block to about an inch from the aft end of the hip plate notch. This is a vague representation of the back curve of the seat. Get in/out of your kayak a few times so you know where you're hips/butt are located with regard to the hip plates. The back of the carving is a bit forward of the backband, maybe an inch to start.

Go ahead and sit on the block with your knees rotated out as you'd sit in the kayak. With marker in hand draw a V from your groin to the forward edge of the seat marking the inside edge of your thighs.
This is where you discover that the block needs to be kind of long to provide more than under the butt support. If the hip plates are 17" wide that means the block should be at least 18"-19" wide,,and probably 18"-22" long depending on how much thigh support or aft filling you want.

Ok,,so there's a rectagular block with notches on the side, rough carving on the outside edges/bottom, v drawing and semicircle for back edge of seat. Now draw lines roughly parallel to the V from a point about an inch in from the hip plates at their forward edge. This is the outer edge of your thighs,,maybe just sitting and tracing the outline will work.

Ok,,,now roughly connect the semicircle in the back to the lines marking the outside of your thighs at the front. All these lines will get torn up shortly.

Get a utility knife and set the blade about 3/8 deep and make a mess of hash marks IN THE MIDDLE of the lines starting where your sit bones would be then going forward under your thighs,,don't make many cuts near the foreward edge of the seat.

I'm not a fan of using power tools, esp, rotating discs but maybe I'm chicken and just didn't find the right technique.

Get a 3 1/2" hole saw and use it like a gouge by hand tearing out 1/4" size chunks of minicell from the deep sections. DON"T try and do it all with the hole saw. You have to finish about 1/4" deeper than the hole saw to remove the rough surface, likewise a 3/8" utility knife cut is more like a 5/8" deep cut once everything is finished. So get a sense where a 1" thickness is and DON"T go there untill you're using the next tool.

Which is a rough 16-32grit sanding disc also handheld. It'll smooth up what the hole saw started.

After carving down an inch in a 3" block it's time to experiment with fitting it in the kayak,,if you can. This will get the outside fit better and get you sitting in the seat for further carving.

It took me four hours to make my first seat and about an hour now.

"shark skin" doesn't work well, it breaks and cuts. The sanding discs make smooth curving lines. Then smooth out further with dry wall sanding screen.

If you want to get slick you can glue on stretch fabric or whatever this fellow sells www.kayakfit.com

If you want a semi-hard semi-smooth surface you can paint on a rubberized coating with the stuff in the tall skinny can called "tool dip". But make sure you make it smooth or it'll be like varnish on 80grit scratches. Some folks mentioned using a flame carefully to remove fuzzy edges, I haven't done it.

another thing,,this is kind of a mondo big seat so it's got a lot of flotation,,if it's NOT secured it will find it's own way out. That's why it needs to be wedged in by the hip plates,,and if your hip plates are too wide apart so much the better to install some Salamander hip pads which can wedge/press down on the seat. I would NOT rely on velcro to hold it in nor would it be good to glue it in. I've had the seat stay in as described but relying on velcro resulted in a floating/moved seat. Not good.

Don't do this in the house,,or anywhere you don't want a billion bits of grey fluff

[Ocean Spray]

What is minicell used for in the real world?

[Spokaloo]

Many whitewater padding and flotation applications.

E

[Robert W. Long]

OK: Here's what I did for a true ass fitting seat. 1. put some kind of dry mixed up morter in a black plastic trash bag. 2. close bag with twist tie and put in kayak with tied side down. 3. sit on bag and wiggle around to get a custom assed shape to the morter mix. 4. lift your ass out of the kayak. 5. when dry, remove bag from hull and remove trash bag.6. Lay up a couple layers fiberglass cloth on top of form, saturate with epo then top with a cloth layer of your choice. {I used a piece of camo t shirt from cabelas. 7. when cured, make a template of inside bottom of seat area in hull. 8. prop your glassed ass print up over the template and fill a couple inches or so in between with insulating foam that you squirt out of an aerosol can. I used 2 cans. 9. trim sides to shape and contact cement a layer of naughahyde on bottom side of seat. I trimmed mine{the seat, not my ass} to press fit in between the thigh supports in my pygymy arctic tern. Enjoy. The job was easy, and the seat works very good. If any one is really knocked out by this method, I can post a pic or 2 of the seat.

[Robert W. Long]

Hi: I'ts me again. I forgot to say that before I made my custom seat I had used a thermarest, and had made a great looking minicell foam seat, and they both still gave me numb legs and sciatic pain after a few hours paddling. The seat made over a cement form was the answer to those problems. Took the pressure off the nerves and gave good under thigh support. Eneough from me on this subject. bye

[LeeG]

about 1/6 folks have a sciatic nerve that routes through the piriformous muscle in a way that makes a pinched sciatic nerve more likely. This corroborated with my observation in kayak classes that about 1/5 beginners immediately got numb legs in 15minutes. That described me 15yrs ago first getting in a kayak.

You can also use expanding foam to make a mold for a glass seat but honestly for all the effort you can make as good a seat with minicell.

What a custom seat gets you that you cannot get from a production seat is better support in the immediate area radiating out from yr sit bones. Most folks think underthigh support will reduce numb legs and pinched nerves but it's not as important as the shape of the seat supporting the muscle/fat of yr butt to raise the sit bones up off the bottom.

The other area a custom seat works better than production is when you lean a kayak you can get better support on the outside edge of the downhill hip/thigh and downhill edge of the uphill thigh. It's something that's obvious with molded seats and worth carving out on the minicell one. Not that you should be locked into position but better support when the kayak is leaned 45+ degrees as it will reduce the pressure on the knees for bracing/rolling.

I had a Mariner Express with a flat angled seat, not comfortable at all, tried all manner of thermarest seats and underthigh supports for incremental improvements but it just wasn't right. Made a foam mold and glass seat. The effort on my knees to hold the kayak near the capsize angle was about 1/3 as much with a LOT more control.

It's not the squish under the ischial tuberosities that makes a good seat, it's the shape around the ischial tuberosities that supports the fat/muscle and lifts those bones up a bit that makes a comfortable seat. My hard fiberglass seat is more comfortable than any squishy seat simply because it removes the point pressure off the sit bones.

Basically yr trying to make a tractor seat with better hip/butt support,,what happens forward under the thighs isn't as significant to lifting the sit bones up.

[George Roberts]

I myself prefer to use 1/8" wood strips and build a flat seat (perhaps a bit of dish).

---

What ever you decide, make the seat as low as possible. Makes for more stability.

[Tom Robb]

Ya found me out, Jim.
Nice info.
I knew you guys had it in ya.

[Tom Robb]

Lee,
Say what?
You don't happen to have some sort of drawing/diagram for those Latin named thingys?
Can't seem to find my old Grey's Anatomy.

[LeeG]

maybe my observation in kayaking classes that 1/6 beginning paddlers get numb legs in 15 minutes is purely coincidental but it coincides conveniently with that bit of data

http://en.wikipedia.org/wiki/Ischial_tuberosity


http://en.wikipedia.org/wiki/Piriformis


Main article: Piriformis syndrome
This syndrome occurs when the piriformis irritates the sciatic nerve, which comes into the gluteal region beneath the muscle, causing pain in the buttocks and referred pain along the sciatic nerve. This referred pain is known as "sciatica." 15% of the population has their sciatic nerve coursing through the piriformis muscle. This subgroup of the population is predisposed to developing sciatica.

[Tom Robb]

So, is this related to the dread Numb-Crotch one gets from narrow bicycle seats?