Folding Kayaks Forum

Big Kahuna polycarbonate frames
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Author:  xeniv23 [ Tue Oct 03, 2017 7:10 pm ]
Post subject:  Big Kahuna polycarbonate frames

Recently bought a used (2001) Feathercraft Big Kahuna. Used it about a dozen times now and I can't say enough good about the boat; now that I have figured out to put it together and have it tuned to fit me.

One surprise, that I have seen hinted at in a few posts, is the seeming fragility of the polycarbonate frames. I just broke the aft frame just behind the cockpit by getting into the boat on my lawn to adjust (fiddle) with the rudder pedals and sea sock. I placed my hands bearing my weight on the cockpit rim adjacent to the frame and started to swing my feet into position when there was a jolt. I got out and saw immediately that the frame had broken and separated just to the port side of the keel, top and bottom. Close inspection with a glass reveals a lot of crazing, like in plexiglass, and that this seems to be the initiating point of the cracks. It's a 16 year old boat so there is bound to be something.....

I had it in mind that I would fabricate a new set of frames from UHMW at some point. That point is now. I have fabricated and shaped parts out of UHMW for other applications and it is easy to work with ordinary woodworking tools so it's just a matter of putting in the time.

Other than the deck being every so slightly faded, the rest of the boat seems to be in very good condition indeed so I have nothing to gripe about....

I have used my WindPaddle and also mounted and used my KayakSailor 1.6m and it does very well with either. A little velcro, a couple of small foam pads and some straps is all that is needed for the KayakSailor. Easy on and off.

Packed for airline transport with all the ancillary equipage its right at 50 lbs and quite manageable. I'm a happy guy.

Author:  Jeremiah [ Tue Oct 03, 2017 9:44 pm ]
Post subject:  Re: Big Kahuna polycarbonate frames

Congratulations on your Big Kahuna. Mine is about the same age as yours and despite the many years of heavy use it shows very little wear. But the ribs were a troublesome area to deal with as they were always chipping and fracturing. I went through three sets (Feathercraft was good at sending me new ones), the final ones being black instead of white. I'm thinking that the color change had more to do with Feathercraft finally solving the problem (so far so good).

I'm curious about UHMW material. Not sure what that is but it would probably be a good thing to know about in case I have to do something similar. Anyways, glad you like your kayak and I hope you get many more years out of it.

Author:  xeniv23 [ Wed Oct 04, 2017 12:31 am ]
Post subject:  Re: Big Kahuna polycarbonate frames

UHMW is a very strong, stable and easily worked material. You may have some in your home as the white translucent and indestructible cutting boards that are everywhere.

I have no reason to believe that Feathercraft won't open the hoped for parts supply shop this autumn.....but who knows? Just in case, I will use the current frames as patterns and fabricate my own. A 24" x 48" sheet a half inch thick should do the trick for the Big Kahuna. A few days leisurely puttering will be fun. Then I should never have to worry about it again.

I often get way out past Bumfield and typically am alone so equipment breakage is to be avoided if at all possible.

Author:  KerryOnKayaks [ Wed Oct 04, 2017 12:33 am ]
Post subject:  Re: Big Kahuna polycarbonate frames

I have heard of someone using commercial sized polypropylene cutting boards as "blanks" to fabricate new ribs for Feathercrafts but I don't recall the source. These seem to cost about a third to half of what the same area of bulk UHMW material costs. Cutting boards are about $25 for an 18" x 24" x 0.500" from various sources vs close to $150 for the size of UHMW you describe, though there would obviously be less waste with a larger sheet (and 24" might be too narrow for the larger ribs).

I started kayaking with a 2001 Kahuna. Had a lot of fun with that little red boat (that's it in my avatar pic).

Author:  xeniv23 [ Wed Oct 04, 2017 1:41 am ]
Post subject:  Re: Big Kahuna polycarbonate frames

Thanks for the suggestion. Cutting board blanks are often HDPE which might be ok but UHMW is much more impact resistant though it is more expensive. I'll look around. 24 x 48 sheet is large enough to make one mistake. I always make a mistake.....

Author:  kidkanektok [ Thu Oct 26, 2017 1:54 pm ]
Post subject:  Re: Big Kahuna polycarbonate frames

I have definitely had this problem, with the most troublesome chips happening (currently) at the bottom of the front small rib where the pin is. I have done a very sketchy superglue and tape repair that won't last.

Is there really a feathercraft parts store? That would make me wicked happy!!

Author:  xeniv23 [ Fri Nov 03, 2017 11:46 pm ]
Post subject:  Re: Big Kahuna polycarbonate frames

So. A few days ago I finally got around to sawing a new set of frames for my Big Kahuna from two pieces of half inch UHMW. For marking I used a Sharpie and cut to the inside of the line. I used a jig saw with a coarse wood scrolling blade running at slow speed to avoid meltage. Mark and drill the holes for the longerons and then cut out the rib. Drill and kerf the slots for the straps that attach to the underside of the deck for the fore and aft large ribs. Drill and kerf the keyhole for the deck bars in the fore and aft large ribs. Where needed I smoothed things up using a router with a straight bit freehand. Smoothed up the cuts with a spoke shave set for a very fine cut. Got about three hours into the project.

Perhaps not works of art but after a while: Who's going to know?

I made the holes in the fore and aft large frames slightly oversize for the chine and gunnel bars. Goes together and comes apart like butter. Bow and stern frames I made the holes the official size as they need to be freestanding and hold together while you slide the whole works into the skin. The fore and aft large frames don't have that requirement. Weight is very comparable, perhaps a touch lighter for UHMW.

I'm not saying that there is very much chance that a tank will run over my new frames. But if one did I'm confident that they will be ok. If through misadventure I happen to break a frame while in the kayak a broken frame will likely be the least of my concerns.

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