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Recycled poly (again)


mitchmellow
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I've now had the FreeB 14 on the water several times.  Mostly its been on small lakes and much of the time there has been a little "walleye chop" (small wind driven waves).  The recycled poly has begun to develop small ripples/wrinkles.  They are especially prevalent around the coaming and between the gunwale and lower chine.  This was my first build and so I am bringing this to the forum for opinions and advice:

 

1.  Is this just the relaxation of the poly?  I think Jeff has said that there is a little relaxation with time.

2.  If it is relaxation, does the original poly look the same?  In other words, is this normal for all or does the recycled relax more?

3.  Could it be that I didn't shrink the poly enough?  I used an iron calibrated to 230 F and went over the entire boat.  It was "drum tight" after.

4.  Should I have used a higher temperature when shrinking the fabric.?

 

I've found that I can reduce the ripples by ironing over a thin damp cloth but they come back.

 

I'd appreciate the collective wisdom of the group.  I liked the recycled poly but this could change my choice of fabric with any future boat.

 

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Hi Mitch:

 

I purchased the recycled fabric for my Firefly but I have yet to cover the kayak.  I bought an extra yard of fabric and have been experimenting with shrinking techniques and various paints on 1 foot square frames.

 

I once rebuilt and covered a small airplane with polyester fabric so I pulled out the manual for a refresher (understanding that aircraft fabric and our recycled fabric are probably two different animals, aircraft fabric is typically 2.7 oz …but polyester is polyester).  The manual specifies an initial shrinking at 250 degrees with a calibrated iron to obtain a uniform tension (prevents warping of the wing and pulling on the ribs).  The final temperature to develop maximum tension is 350 degrees.  The manual warns “…polyester filaments will start to thermo-soften and loose measurable tension at about 375 degrees…”.

 

I used this technique on one of the test panels with good results.  I guess this is my long-winded way of saying, shrinking at a higher temperature may be a solution. Notice I said “may”…who knows, the recycled fabric may give up, over time, some of it’s tension regardless of temperature used for shrinking. 

I hope this is helpful and I will let you know how things turn out with my kayak….

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I thought I sewed it pretty tight following the method in the video for the recycled fabric.  For the fore and aft of the boat I wasn't sure it needed any shrinking.  There were some wrinkles around the coaming that needed to be heated.  I ended up heat shrinking the entire boat but just with the iron at 230 F.

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I thought I'd get a little more on others' experiences from this forum. Is there anyone else who used the recycled poly and experienced this? If you used it but didn't experience the wrinkles, how did you sew and heat shrink? Hotter iron? For those who used the original 8 oz. poly, have you experienced any relaxation that led to some wrinkles?

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I have experienced this relaxation to a lesser extent using the 8 oz original fabric coated with Spirit Line, a two part poly urethane. Heating it up again after its coatings were completed did take out most of the relaxation, but it's only been on the water four times and therefore untested. I am watching re-relaxation. (I think you told me to try reheating with an iron and wet cloth.).

O

I since have looked closer to the photos on Jeff's website of his boats. In see this relaxation taking place in his

Curlew http://www.kudzucraft.com/designs/curlew/index.php

And his Vardo http://kudzucraft.com/designs/vardo/index.php

We builders on this web sight have a great kayak frame building system....I love it! But I sense that we are still in the experimental phase with the covering process?

If I get my next boat started soon, and am skinning it under cold temperature conditions, I will seriously consider nylon. Nylon relaxes when it's cold, and tightens with warmth. I would have concerns sewing up nylon in the hot summer months.

In will be keeping my eye on this topic, it's an important one.

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We builders on this web sight have a great kayak frame building system....I love it! But I sense that we are still in the experimental phase with the covering process?

I don't think the process is experimental at all.  The problem is that the market for material is not great enough to warrant a material designed specifically for our needs.  So what Jeff, and other suppliers are doing is trying to find existing materials that work.  Unfortunately nothing available is perfect.

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Today I manned up and turned up the temp on the iron. My iron (actually my very tolerant wife's iron) at maximum registered about 340 F with the thermometer under a cloth. This time I used a dry cloth between the iron and the boat skin. The Rustoleum seems to take the heat fine. I've only done a portion of one side but the wrinkles in that area are gone. From my admittedly limited experience I believe they will be back after more use. I think there's enough flex in the frame to slowly stretch the skin. Perhaps a fabric that heat shrinks well also more easily stretches. I usually don't worry so much about looks so I'm not sure why they bother me. Perhaps it's because it looked so damn good when it was first finished. This continues to be a most interesting experiment for me and really all the more fun for it.

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VARDO was skinned in 12 oz nylon.  The white Curlew was also nylon. Nylon absorbs water and will relax and wrinkle on the water and polyester doesn't. 

 

If you can sew a polyester skin on tight, it will stay tight. Coamings flex so there will likely be a little wrinkling around that regardless. The new polyester, we know the new 8 oz will stretch out.

 

Calling it experimental is just a word game. At what point does it become normal, accepted or whatever you prefer? You could call it experimental if you wanted but it doesn't really mean or change anything and sure not worth debating on here.

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"So what Jeff, and other suppliers are doing is trying to find existing materials that work."That sounds like experimenting to me.

I didn't say people weren't experimenting with materials.  I said the process was not experimental.  People are always trying new materials for projects.  Each material has different characteristics and each person has to decide which ones are most important. Jeff offers a few options and you choose what you think is best for you.

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I stapled the skin (Jeff's original polyester) on my first - and only - build. I stretched the hull skin as tight as I could, working from the center toward each end, alternating ends and sides, wrapping the skin around the gunwale and stapling on the inside about every three inches. After the initial stapling I went back, rolled the excess into a sorta' neat roll and stapled every inch. The deck was also stretched as tight as possible and stapled on the outside using the same system. There were very few, very small wrinkles left to iron and they have not re-appeared with use. 

 

I've not tried sewing a boat so I can't compare sewing to stapling, but I can strongly endorse stapling. The process used over a thousand stainless staples and took a couple of hours. My electric stapler didn't always seat the staples fully, but a hammer fixed that problem. I covered the ugly line of rolled and stapled deck fabric with a polyester webbing. The webbing looks good (to me) and protects the gunwale from scrapes against docks and storage racks.

 

My hands were a bit sore from pulling the fabric tight, so there's not much advantage in effort, based on comments I've read about sewing.

 

Stapling certainly falls into the experimental category, but my single data point indicates it's worth considering.

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At the Maker Faire here, they had a display of SOF kayaks.  The builder there, suggested a trick for pulling nylon tight for sewing.  They clamped the skin in place and then did a wide cross lacing (like shoe laces) back and forth about 3 inches on either side of the deck beam.  Then you draw that as tight as you can and tie it off.  With that tied off the skin is held tight and  you apparently have to pull very little when stitching to get everything tight.   I know this would never work with the loose weave 8oz poly, but I wonder if the 11 oz or recycled poly have a tight enough weave to try this? 

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