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Friday, August 20, 2010

Boat Materials and an email exchange

Today I paddled with a woman who wanted to test paddle my boat, and a friends boat as she is preparing for her first long distance paddle. As the two boats were constructed differently, it prompted the question of what kayaks are made of and how. So I thought I would go over it briefly here.

First, and probably most common material for a kayak is plastic. I had the opportunity to go to a factory near me, to see plastic whitewater kayaks and recreational kayaks manufactured. Plastic kayaks are made from plastic powder, which is poured into a mold, and then placed in a very large oven. The oven is on a gimbal, and moves the mold every which way, after heating the mold to around 500ยบ (If I recall the temperature correctly)

Plastic kayaks are relatively inexpensive, incredibly durable, but comparatively, fairly heavy.

The next most common material for kayaks is fiberglass, and it is the generally preferred material for a high performance boat. More expensive, a bit lighter, a bit stiffer. For all practical purposes each boat is hand made, though I am sure that someone can fill in the blanks of how they are manufactured.

These are, by far the two most common materials for kayaks. There are of course wooden kayaks, skin on frame kayaks, folding kayaks - which I tend to think of as skin on frames younger cousin, and high end carbon/kevlar composites, but the majority of paddlers use Fiberglass or plastics.

Like everything in kayaking there are trade offs of each, and because of the popularity of fiberglass and plastic those are the two I want to focus on.

As I said, the plastic kayaks are incredibly durable, and less expensive, and since a lot of high end fiberglass manufacturers are making plastic versions of their high end boats, it makes it very easy to start with one of these kayaks.

If you do manage to damage your plastic kayak they are not easy to repair. I have seen kits for plastic repair, but I suspect there is always a scar, whereas Fiberglass is easy to repair, and maintain, and repairs often leave no scars whatsoever, though they are a bit more fragile.

Having paddled both extensively, I can say that there is a responsiveness to fiberglass that is incredible. Actually responsiveness isn't the right word. It's a feel. This isn't an accurate description, but some say that paddling plastic kayaks, the boats 'feel dead'. I don't know what that means, but when you paddle both you will understand the expression. There is a snappiness in fiberglass that isn't present in plastic. Plastic kayaks have a 'thud' to them when they come down over a wave. It is really very hard for me to describe.

The big argument between the two is the inherent stiffness that the fiberglass kayaks offer, over the relative softness of the plastic.

And this brings me to my email exchange with the editor of Sea kayaker magazine. It was just before I bought my current kayak, I emailed him to suggest a story idea. The idea was this, since Sea kayaker does all sorts of tests on kayaks to determine drag, and speed, and the like, I felt they were in a position to discuss materials and all the benefits and drawbacks. Over several emails we exchanged ideas and information - in all fairness he gave information, I gave questions! He talked about the stiffness of fiberglass, and how that translates to speed. He talked about the plastic kayaks tendency to gouge, and its effect on speed. The flex of the side of the kayak when you push on your foot braces which he thought would be a big drawback of plastic boats efficiency, and I thought the flex of the paddle blade and shaft would be a big loss of power. (According to Sea Kayakers tests we were both wrong, as the flex of the kayak at the foot braces, and the flex of the paddle shaft are both non-issues.)

After a number of emails I asked what I really wanted to know. In testing, with all conditions being the same, what are we really seeing in actual speed difference between plastic and fiberglass. His response was this, 1% or 2%. I cruise at around 4 knots. 2% of four knots isn't much. So don't let speed be your overall judge in deciding what types of kayaks to paddle.
The outcome of the email discussion was published in the 25th anniversary edition of Sea kayaker magazine.

I have only owned plastic kayaks. Mainly due to cost, but durability is also a factor for me. I started kayaking the shores of Long Island, New York which are essential rock piles. I didn't want to worry about my kayak, so plastic it was.

Of course I haven't mentioned my current kayak, which is thermoformed plastic. Using plastic in sheets, the kayaks are manufactured similarly to fiberglass kayaks. I currently feel that it is the best of both worlds. It doesn't have 'the dead feeling' of plastic, and is lighter than most fiberglass kayaks. You repair it very similarly to fiberglass, but it is priced between fiberglass and plastic. I am curious how the kayak will age, but thermoformed kayaks have been around for quite some time with various names -airalite, and ultralite being the most popular.

So you need to think about use, and care, and cost of the kayaks you are looking at, but most importantly you have to paddle kayaks to get a feel for the different boats. I am a firm believer that once you start paddling different kayaks, just like the paddles, one will sing to you. One will feel just right. One will be 'the' kayak.

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