Folding Kayaks Forum

The user forum for FoldingKayaks.org
It is currently Wed Oct 17, 2018 8:31 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Fujita
PostPosted: Tue Jan 24, 2006 8:03 pm 
Just redirecting from: viewtopic.php?t=295&start=30 :)


Top
  
 
 Post subject:
PostPosted: Tue Jan 24, 2006 9:35 pm 
Chrstjrn wrote: "The Fujita has a sewn PVC hull. That is where a lot of the weight savings is. Those of us who have used PVC hulls are not sceptical about it's durability.

Having inspected a Fujita frame, I would say that it is second to none. If Klepper or Long Haul tried to "modernize" their frame design, I believe that they would end up where Fujita is. It is extremely solid."

Does anyone have any idea how fiberglass would measure up against polyurothane? Yostwerks seems to use this stuff as a frame material of choice. viewtopic.php?t=348 I suspect that fiberglass might last longer than Poly, but that poly would be more impact resistant. After surfing some of Tom's stuff, I thought of repairing a rib or 2 w/ poly, just to compare it to wood.

I suppose this topic has recently been a Fujita vs. Klepper vs. Long Haul, so I'm not straying by bringing up this comparison. I've recently been constructing a "Used Klepper pricing formula" as a seller/buyer tool to perhaps be included in a "Folding Kayak Bluebook". In constructing this formula, one of the largest factors in Klepper's slow depreciation is the history of frames lasting 50 years on average.
One of the things I really love about Klepper is the repairability of wood. I suspect that wood supercedes both poly and glass in the repair field. Though some wood frame owners use glass for repair, I've avoided it because of the delicate nature and fumes of handling the epoxy. I prefer aluminium splints instead.
Again coming from a road cyclists point of view: Neither poly nor glass has been taken seriously to my knowledge in cycling. Other than a poly saddle I had on my race bike in my teens and derailur pulleys etc. I've never seen poly used much. Glass, I can't think of a single example. Wood however, a lot. Wood frames can still be bought as far as I know and were very common at one time. My mum even raced on wood rims well into the mid 70's. Wood seems to be extremely durable, flexes well, and finally recycles better than poly or fibreglass.


Top
  
 
 Post subject: Pix
PostPosted: Wed Jan 25, 2006 11:07 am 
Can't log in to the gallery to upload a few pix - comes up as invalid user name and password(?)


Top
  
 
 Post subject:
PostPosted: Wed Jan 25, 2006 11:51 am 
Site Admin
User avatar

Joined: Sat Apr 16, 2005 9:02 pm
Posts: 1035
Location: Astoria, OR
Excerpting from the earlier thread:

K. Klepper wrote:
By the by, what are you using for your ribs on your aluminium boats? From the pics it looks like the same sort of plastic used for professional cutting boards. In what colours is it available?


Yostwerks replied: It is High Density Polyethylene ( HDPE) and is the same plastic used by Feathercraft on most of their boats.


Kap, that stuff Yost uses is not polyurethane. Polyurethanes would not be good choices for frame material, as far as I know.

_________________
Dave Kruger
Astoria, OR
--
Folbot Kodiak, Cooper, and Edisto; three hardshells; Mothership: Surf Scoter the Bartender; dinghy Little Blue Duck.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jan 25, 2006 1:25 pm 
K. Klepper Wrote:
Quote:
Does anyone have any idea how fiberglass would measure up against polyurothane? Yostwerks seems to use this stuff as a frame material of choice. viewtopic.php?t=348 I suspect that fiberglass might last longer than Poly, but that poly would be more impact resistant. After surfing some of Tom's stuff, I thought of repairing a rib or 2 w/ poly, just to compare it to wood.



High Density Polyethylene ( HDPE)...

I use "Polyethylene" for cross sections following FC's lead. The reason has little to do with durability, though it has held up fine. The reason for it's use is it's "memory" . It can withstand the "snap-on" of the aluminum tubes over and over again. I doubt that fiberglass would posess such a property.

PVC Skin ( Vinyl / Polyester core)....

On the ongoing issue of skin material. I use PVC because it is inexpensive and available. If hypalon or Urethane were cheap, I'd use them also. As a homebuilder I'm not concerned about the relative merits of the various skin materials. They all work.

For a given weight per yard, they all have more similarities than differences. It's my understanding that Pakboat uses an 18oz PVC. The difference is that they use what is referred to as a one side coating. Meaning that more Vinyl is on the outside than on the inside for durability where it counts. This gives it a pronounced woven look on the inside. Correct me if I am misinformed.

I use Coverlight PVC whose Vinyl ( 2-side) is evenly distributed per side. I tried the Pakboat PVC , but the rougher inside didn't provide as good a glue seam ( I don't weld or sew) on my SeaOtter.

PVC is easy to glue, easy to repair, folds well, and has proven to be more than durable enough for me. I use a lightweight 18oz per yd. skin and that's considerably lighter weight than an FC skin. I use a light weight as it allows me to construct a one piece hull, otherwise I'd have to cut and glue panels and add rub strips. All of which would add work, weight, stiffness, and folded size.

Since it costs me under $100US to make a skin and less than 20 hrs, I can make 15 or so replacement skins for the cost of one FC or Klepper skin.

Aluminum Frames......

Repair of aluminum is easy, in the field or in the shop. However, I can't recall the last time I had to repair a frame. They are tough and forgiving. I make wood frames for non-folders, but don't use wood for a folding frame due to the much greater complexity of homebuilding a folder with wood. This is due to the numerous (mostly metal) fabricated parts required to make a wood frame fold. Aluminum has no such limitations as the tube sections simply plug together and then snap onto the HDPE cross sections.

The FC aluminum frame type is simple to build, and maintain. Corrosion is not a factor with a clear understandinmg of the material and sound preventative maintenance.

Whew !...glad I got that off my chest. :)

Regards,

Tom


Top
  
 
 Post subject:
PostPosted: Thu Jan 26, 2006 5:48 am 
Yostwerks wrote:
If hypalon or Urethane were cheap, I'd use them also.


You wouldn't like using hypalon, I guess. My understanding is that it's heavier and bulkier than comparable urethane-coated skin, and neither lighter nor more compact than comparable PVC skin. Especially if PVC-coated fabric is kevlar mix as in Fujitas - this is probably where they gained some weight savings too, with higher strength per ounce of fabric weight. But this PVC fabric isn't too cheap, I think.


Top
  
 
 Post subject:
PostPosted: Thu Jan 26, 2006 12:00 pm 
Quote:
You wouldn't like using hypalon, I guess. My understanding is that it's heavier and bulkier than comparable urethane-coated skin, and neither lighter nor more compact than ]comparable PVC skin. Especially if PVC-coated fabric is kevlar mix as in Fujitas - this is probably where they gained some weight savings too, with higher strength per ounce of fabric weight. But this PVC fabric isn't too cheap, I think.


The Hypalon skin on my K-Light is a bit heavier but with similar bulk to the Urethane Kahua skin ( allowing for the difference in size of the two skins).

I've used Hypalon for skins, but it was the liquid variety that I brushed on sewn Polyester or Nylon skins. It was durable, but it took forever to cure and had a tendecy to crease when folded over long periods of time. It was quite expensive at an average of $100.00US per gallon ( depending on color). I've also used liquid neoprene, but it was a bit stiffer than hypalon though easier to work with overall..

PVC is a good compromise as it's inexpensive, durable, and easy to use. My Sea Glider ( 19ft X 18.5in) PVC skin weighs 12lbs including it's integral aluminum coaming and deck rigging. The deck to hull seams are glued, and the zippers are sewn / glued.

http://yostwerks.com/NewPage19.html - Sea Glider PVC Skin

Because PVC is used for truck tarps, it's readily available for kayak skins. Urethane is essentially unavailable, and Hypalon ( in rolls ) is expensive and normally has a nylon core, which is much less stable than polyester in a water environment due to shrinkage.

Regards,

Tom


Top
  
 
 Post subject: Hey Tom
PostPosted: Thu Jan 26, 2006 12:46 pm 
I may be able to get you some sea lion skin if you want to try that :+)


Top
  
 
 Post subject: Re: Hey Tom
PostPosted: Thu Jan 26, 2006 4:01 pm 
Site Admin
User avatar

Joined: Sat Apr 16, 2005 9:02 pm
Posts: 1035
Location: Astoria, OR
tsunami von chuck wrote:
I may be able to get you some sea lion skin if you want to try that :+)
Ecovandal!! :lol: :roll:

_________________
Dave Kruger
Astoria, OR
--
Folbot Kodiak, Cooper, and Edisto; three hardshells; Mothership: Surf Scoter the Bartender; dinghy Little Blue Duck.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jan 26, 2006 7:46 pm 
The skins that the Inuit used do not last long south of the Arctic. They also get a funny smell. Thought I mention it just in case...


Top
  
 
 Post subject: Fujita 480 Pix
PostPosted: Thu Jan 26, 2006 11:16 pm 
What photos I currently have of the PMS (Paddle Motivated Ship) Chiquita - not to be confused with a yellow submarine - are now in the gallery. I plan to do a much more extensive shoot, including some mods that I've made, in the not to distant future.


Top
  
 
 Post subject: Re: Fujita 480 Pix
PostPosted: Sat Jan 28, 2006 5:08 pm 
larrybluhm wrote:
What photos I currently have of the PMS (Paddle Motivated Ship) Chiquita - not to be confused with a yellow submarine - are now in the gallery.


I like what I see on the cockpit photo - very accurate frame. Looks like it has sewn-in cockpit rim - good idea. Feathercraft has eventually started dong this on Kahuna, but not on K1 yet. Fujita 500 or 480 could be a cheaper alternative to K1 for lighter/smaller paddlers and for shorter trips. Trips range must be the same as in Kahuna, only Fujita should be faster. Can't help but thinking of Folbot Cooper as very close alternative to Fujita 480 or 500. Slightly heavier and much cheaper. Imported boats of decent quality can't be that cheap, alas. Has some, let's put it that way, "simplified engineering solutions", - perhaps, more than Fujita, but costs way less too.
Possible cons of this 480:
Have some doubts in rib "clamps" holding the long members - they look like simply cut in the plywood. This works in HDPE and Polycarbonate, but in plywood I think Klepper and LH solution (servicable plastic inserts) is better. I didn't notice lower stringer protection strips on the photos - they expand skin life-span and range of conditions.


Top
  
 
 Post subject:
PostPosted: Sat Jan 28, 2006 7:25 pm 
krudave wrote:
Kap, that stuff Yost uses is not polyurethane. Polyurethanes would not be good choices for frame material, as far as I know.


Oops!, Sorry, I was really thinking of polystyrene (sp?) But couldn't for the devil think of what it was called. Cheers.


Top
  
 
 Post subject: Fujita Frame
PostPosted: Sat Jan 28, 2006 10:38 pm 
There are substantial stainless clamps at each rib along the gunwale bars - these are just out of view in the pic. In addition, each rib is pinned permananently to the appropriate sections of both the deck bars and keel bars and swivel into place as each section is added, the bars locking with spring buttons. Only the chine bars ride in cuts in the ribs and are snapped into position after the frame halves are slid into the hull. That cleverly makes the frame halves a bit easier to insert. The inner liners of the sponson chambers extend far enough to additionally serve as wear protection for the gunwale and chine bars. There are many quietly elegant design solutions throughout the boat.

The cockpit rim is indeed sewn in with articulated sections backed by flat plastic stiffeners. The stock spray skirt is less than superb, but an NRS Monterey works very well - I can very nearly pick up the boat by the skirt. I haven't yet found a neo skirt that works - any suggestions?

I've added a quick pic of the frame looking forward from inside the cockpit to the gallery. A more extensive shoot of assembly and details, to share with my fellow fanatics, seems indicated since there are currently so few of these rather remarkable boats around.


Top
  
 
 Post subject:
PostPosted: Sat Jan 28, 2006 11:34 pm 
Anne wrote:
The skins that the Inuit used do not last long south of the Arctic. They also get a funny smell. Thought I mention it just in case...

Week old sea lion skin or week old unbathed kayaker, take your pick but either should suffice to keep the mosquitoes away! :wink:
For good measure, one could even use whale gut for a spray skirt, but that might do more than keep the mozzies away. -And it might attract Green Peace.


Top
  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB® Forum Software © phpBB Group