Spectra fiber

I am considering buying a boat made of graphite-reinforced Spectra fiber.

I have googled Spectra and know what it is: a ultra-tough type of polyethylene fiber made by Honeywell, super-light, UV resistant, very flexible, and even stronger than Kevlar.

But I have never heard of a kayak that was made of Spectra, not to mention in combination with graphite.

Have any of you? If so, what do you know about Spectra boats?

Thanks for your input!


It is suppose to be an excellent material. A builder a number of years ago told me that it didn’t catch on becasue it is hard to work with as it would want to float ontop of the resin and this is most likely why you don’t hear about many boats being built with it. As far as its’ properties in terms of strength and wear and tear, it is suppose to be excellent there.

I believe Novacraft has been building with it for several years. As the previous poster mentioned, it tends to float, so the builders usually vacuum bag boats built with it to keep the spectra in the resin.

spectra is some pretty cool stuff. Rope has been made with it for a LONG time. Attempting to cut it with a hot knife like other rope is an exercise in futility, and you will quickly dull a sharp knife if you cut the stuff often. It’s VERY stiff, so it doesn’t make sharp bends well.

I’ve got some spectra cord that holds my vectran ursack closed. A 1,000lb grizz can pull on it all day long and that spectra cord will hold.

If I had the money to spend, I wouldn’t have second thoughts at all about buying a boat that used spectra in its layup.

Two characteristics it shares with “standard” polyethylene are that it’s difficult to bond to, and starts to loose strength at relatively low temperatures(140 - 160F)compared to other composite fibers. Given the difficulty of bonding, I wonder how it’d hold up in a laminate subject to repeated flexing. I’ve only seen it used in cordage where it has the reputation of being very slippery.

spectra is neat stuff
extremely resistant to stretching…QUITE flexible…very light…floats…has a medium melting point…does not like knots…BREAKS down in UV light (long term)…small diameter for its strength…

in the kite industry spectra has been known about for ~20+ years…that is the line we fly our kites on…just the mutli line kites though…not usually single line unless the spectra is jacketed with another fiber to protect it…it does not take much friction and heat to cut spectra lines under tension…but UV does break down the fibers over time…great stuff but from my experience running running a kite shop…

Are you sure it’s Spectra?

– Last Updated: Oct-16-06 1:34 PM EST –

Because what you're describing is nothing like the Spectra I've worked with, and I've made over a thousand bowstrings and cables with it. Spectra is polyethylene. It is iherently soft and flexible. It is very heat sensitive and tends to creep (stretch permanently) if kept under tension. It bends easily and will handle thousands of bending cycles, even when bent over an edge. While it's possible to make a stiff cord out of it, it's the construction method - specifically the type, tightness and stiffness of the sheath material - that makes the cord stiff, not the Spectra fibers themselves.

Regarding it's use in boats, I share Angstrom's concern about bonding. Leaving a boat in the sun on a hot day could easily exceed Spectra's yield temperature. Perhaps it has advantages that outweigh it's downsides, but it doesn't seem like an ideal material for kayak/canoe building. I've also used Vectran quite a bit and it seems to me that it would be a better choice as a boat material.

More on spectra

CD rudder cable?
Sounds like you are the person to ask- my CD speedster has frayed cables. When I contacted Current Designs they didn’t have cables available and said they didn’t use “Spectra” on other models. What size (weight) line would I be shopping for to replace these cables? Can I buy short pieces for this application without having to get an entire spool? I’d appreciate your input. When I googled spectra for purchase it listed kite shops. Thanks.

Thanks everyone …
… that was helpful.


My experience with spectra is limited to its application in climbing rope/cord for the most part, and a little experience with it in Dyneema fabric (linked by someone else below).

I do not know how much spectra fiber is used in climbing cord and I don’t know what other fibers are used with it. All I know is that cutting it with a heat knife is pretty much an exercise in futility so you must cut it with a sharp blade. The ends of the spectra cord on my ursack are capped with metal tabs because you can’t melt the ends to prevent fraying. It’s so exceptionally stiff that it’s difficult to tie many knots with it (some knots work, but some don’t). It wouldn’t surprise me in the least that at least some of those characteristics are due to other factors of the cord’s construction, as spectra climbing cord is intended to be used in very high-abrasion environments.

There’s something else in there then…
…because Spectra fiber is very easy to cut with a hot knife and it melts very easily on the ends, almost too easily in fact. As I said before, it’s polyethylene and has all the characteristics of it. Perhaps the cord you’re using also contains Vectran or Kevlar, which would make sense based on your description.

spectra in the kite industry
is just a smooth thin slippery string…i am unaware of (but this does nto mean much) any version of spectra that would be rod shaped and be able to be pushed like a cable or rod…unles you have the rope skeg like on a romany (which if i remember correctly) you are just pulling the line to pull the skeg up against a bunjy tension.?.?.?.?