New to SOF boats and new to this forum

[Bernd v. Hoesslin]

Hello everybody,

just bought the plans of a Vardo boat, I want to build in spring next year. I personally don't have any experience in building boats, but there are friends, neighbours and relatives, who are eager to help me with my ambitious project. The skin of the boats usually is from nylon, or polyester. Has anybody experience with cotton? You know, that type, tipis and canvas wall tents are made of? What are the pros and cons?

Looking forward to any answer, thank you!

 

Bernd

[Action Tiger]

I have done several boats in cotton. #10 duck is good to use. It's not as tough as man made fabrics, but you can soak it with pretty much anything to waterproof it.

I have also used nylon.

I would only ever use polyester, given the choice.

[Bernd v. Hoesslin]

Thanks for the answer, I'll think about that and probably order the pölyester when the time has come.

[PAR]

Someone needs to try Spectra fabric.

[Action Tiger]

Oooh, spectra could be nice. The weave needs to be super tight, though, and I wonder what would stick to it?

I just got some 3mm spectra for halyard/downhaul for my little canoe, and it is cool stuff.

[Kudzu]

I am game, got a source? 

 

Little further looking and I found this on Doyle Sails web site;

 

"Spectra® is a highly processed ultra high molecular weight polyethylene (UHMWPE) made by Honeywell. Spectra offers good UV resistance (on par with polyester), very high initial modulus numbers (second only to high modulus Carbon Fiber), superior breaking strength, and high flex strength. More careful testing, however, reveals that it also exhibits a property known as “creep” (permanent, continuous elongation under a sustained load) that results in a change in shape as the sail ages."

 

That fact it is a UHMW makes me wonder how well anything will stick to it?

Secondly I wonder about how much 'creep it has? Will out our skins go slack?

Third issue is find a source. Do you have one?  Only thing I found was probably a bit to  heavy weight and it was $45 a yard! My 11 oz is only $21 a yard.

[Action Tiger]

The sticking stuff to it part had me worried, too, Jeff. Maybe the scmutz they put on nylon would stick to it?

I wonder about the creep in a tightly woven fabric. Don't they use spectra in those laminated filament type sails, or is it stitched up cloth? Maybe the Oxford style weave would change the creep characteristics?

I freely admit I have no experience with the cloth, just the line. I ain't all in it with ICE and spectra and all that. My sails is plain ole Dacron, or maybe cotton if I'm feeling especially fauxnachronistic, and want to sew em myself.

Maybe one day I'll get this firefly ready to skin and have to worry about it. Or, I'll keep getting distracted by shiny things...

It is an interesting proposal, though.

[Kudzu]

I am curious, but if the price I saw is reflective of the something suitable for our use there is not advantage. Unless is way more abrasion resistant since that is the weakest link in the chain. I have only seen one MAYBE two people say they actually put a hole in one of my fabrics.  Rubbing a hole in them is the most common failure.

[PAR]

I don't have a source for Spectra, but they have figured out how to "size" it, much like other fabrics, so things do stick to it. Yep, they do use both unidia and woven fabric in sails currently, with a lot of savings over Kevlar. It took a decade just to develop a machine that can sew the stuff, without the threads breaking the machine. It's not heavy, in fact quite light and given its other attributes an ideal choice for many things. If I had a source, I'd test the fabric right away, as I'm just starting up some new epoxy formulation testing.

[Kudzu]

Fabrics are always hard to find but I will keep my eyes open for this. Google didn't reveal anything but that is normal for fabrics.

[bwhip]

UHMW-PE will creep as long as it's under tension (as in a kayak skin). In other words, it will stop creeping when it goes loose.  It's also a thermoforming plastic, so paint it a dark color and set it in the sun, and the creep will increase. When it cools, it will retain its new shape.

[BruceT]

I'm new to SOF boats too. Just got my FreeB plans. Probably won't start until after the first of the year do to other projects. My first question is attaching the fabric. I'm an aircraft mechanic and have recovered several fabric airplanes. Why does everyone stitch and staple the fabric on. Tradition? It seems using SuperSeam cement or PolyTac could have all the fabric on in an hour. Seems counter productive to punch hundreds of holes in wood thats going to get wet. Can someone enlighten me? Thanks.

[Kudzu]

I have never tried it because the only ones I have seen done were ugly. Probably because of lack of experience in the builders part but the seems always looked like a bad bondo job on a car where they tried to cover the joint.

 

This is something you can answer probably, is how do you get the fabric tight? Aircraft fabric is to light for a seriously used kayak. The fabrics I can get some will heat shrink, the better ones (what I prefer) don't have much shrinkage, and those that do will creep and loosen up over time.  So how would you put it on tight?  That is one reason I stick with sewing, I can sew it on tight and it stays tight. I will shink out the small imperfections but if I depend on heat shrinkage most times it creeps and loosens up.

 

Except for sewn in coamings, there are no holes in the wood to set it on.