Chuck,

What's the diff between kevlar and fiberglass?

Kevlar is the brand name for an aramide fiber. In itself this fiber
is very strong and tough, but _only_ relatively: according to some
measurements Kevlar is 5 times stronger than steel. BUT according to
that same measurements, fiberglass is 2 times stronger than
steel...!
Using Kevlar in a canoe does help to get a few kilograms lighter and
a bit stronger boat than a canoe made from fiberglass, BUT only when
applied properly.

Problem is that Kevlar has some characteristics that have to be
dealt with, to get a stronger and lighter canoe, than the same canoe
made with mostly fiberglass. To take advantage of the better
strength of Kevlar one must use a better laminating material than
the normally used polyester. Otherwise the bond between the kevlar
and the resin will fail on impact, before the better strength of
Kevlar will be useful... Most knowledgeable canoe builders use
vinylester, and some even use epoxy as a laminating material. Other
'problem' is that using only Kevlar has proven to give problems with
impact and such. The best kevlar laminates have to be combinated
with some stiffer materials like S-glass (a much stronger version of
fiberglass) on the outside, to be really successful.

In order to get a very much lighter canoe (say 5 kg / 11lb. less
than a fiberglass one), using Kevlar alone is not good enough. You
have to combine it with lightweight core materials like foams or
balsa wood, and or carefully use carbon fibers. And then difficult
decisions have to be made regarding stiffnes, strength and
durability. Making a canoe very lightweight without losing too much
strength, means that it will be more flexible. You can make it
sufficiently rigid and very lightweight, but this will make the
canoe less strong, especially when you do not use the right core
materials and building methods, etc.! If a canoe builder is very
good, this compromise will turn out better than with a bad canoe
builder, who will make the canoe either too heavy or too flexible or
not as strong as possible! How will the canoe builder know whether a
canoe is as light as possible but still strong enough etc.?
Ultimately only the customers can tell... And if the company who
makes the canoes has many customers, and listens to them well
enough, then they should be able to produce strong enough Kevlar
boats.

If you really want a very strong canoe and don't care much about
weight, just ask the builder for an all-cloth kevlar canoe with a
layer or two of Kevlar extra in the middle of the lay-up -- it will
make the canoe as heavy as Royalex but almost as strong
and last a lot longer.

Dirk Barends

For weaker paddlers, a short boat will allow them to poke around
with less work. The side effect is more manueverability and less
weight to carry as well. A lot of paddlers, kayak or canoe, tend to
buy boats that are too long.

A shorter boat does not necessarily have to be more maneuverable and
lighter. That depends on design, capacity and displacement I think.
I have experienced several shorter versions of longer boats that
certainly were less maneuverable, with the same (light) load (of
course).

Dirk Barends

I'm starting to like the Penobscot 16. I think it might work for me.


There is one for sale, nicely outfitted with a couple of decent
quality padle too, on the NPMB for sale board:

http://www.npmb.com/dcforum/DCForumID2/5287.html

Michael Daly wrote:
On 6-Aug-2003, (William R. Watt) wrote:


longer canoes are faster.


Self taught in canoe performance too? Here's a _free_ lesson and it's not from a
professional:

(from a previous post on r.b.p.t)

This statement about length is not completely true. The longer kayak/canoe will have a
greater wetted surface than the smaller for the same displacement. Hence, it will have
_more_ resistance at low speeds than the smaller one. If you take a person who is
inherently slow and put them in a longer kayak/canoe, they will likely slow even more.

If you take two kayaks/canoes and plot their speed vs resistance curves, you'll see that the
longer one will have its sharp rise in resistance occur at a higher speed than the shorter.
However, the shorter one's resistance at low speeds will be below the longer one's. If
you routinely paddle at a speed below where the two kayaks'/canoes' curves cross, you should
use the shorter. Otherwise, get the longer. (this data is published with kayak reviews
in Sea Kayaker).

Another seat-of-the-pants observer of canoe dynamics (me).

You are correct on this I think, however a couple of other key design
items make a lot more difference than simply length and wetted area to
how much effort it takes to move a boat thru the water:

- Shape of the hull. A number of canoes widen quickly in the bow and
stern to provide better bouyancy in waves. Great, but it makes for a
slower boat than a hull designed with a very fine entry, and more flare
above the waterline. Also, the bow shape for a composite boat is
usually a much finer entry into the water than a royalex/poly boat - you
can't make as narrow a bow on a molded boat. If it looks like a
johnboat, it will paddle like one as well.

- Depth of the water. Once you get past 10' or so, it isn't an issue.
The real difference comes when you are in 5' or less (suck water). The
faster you go in any condition, the bigger wave a given boat makes until
you get past displacement hull speed and climb over the bow wake. In
shallow water, the bow wave moves further back on the boat and the back
end sucks down and you paddle uphill. (Every boat - even freighters).
Shorter boats hit this point faster, since the wavelength is mostly a
function of the boat's length. The wave amplitude is a function of speed
and depth of the water.
Stability - it takes more effort to make a boat go if you are fighting
for balance. Boat design, load placement and seat height all affect the
center of gravity. However, the higher the seat, the better leverage
you can get paddling.
Paddle style and type. Without starting a J-stroke vs. Sit&Switch war,
any time you aren't pulling the boat up to the paddle, you are slowing
down. Any time you rudder, the boat is slowing down. Any time the boat
slows down, it takes more energy to accelerate it back to speed. Any
time the paddle face is past vertical, you are slowing the boat down.

Now all that said, it doesn't make a hill of beans if all you want is to
throw 2 packs, the dog and your son in the boat and head into Rangley or
the BWCA for a week's fishing and you really don't care about getting
there fast or working hard. It's all OK. *Pick a boat you really like
to paddle and feel comfortable with.* That's the best boat for you.

BTW, if I could only have one 'all around' boat, it would probably be a
Penobscot 16. As close as I've paddled to doing it all reasonably well
- in fact, I just sold our older 16 (and bought a MinnIIG).

Marsh Jones
Minneapolis

This is a pretty wide subject... but some basics: There are one man canoes
out there faster than your kayaks, but they don't carry gear well etc For
solo, a 15' is good for flat water. The longer, usually the faster, but
also heavier. The more blunt the ends, the slower, ( narrow ends cut water a
bit better). If you have to travel 10 miles with camping gear then a light
fiberglass is good. Are you out for cardio workout? of wanting to go
fishing? Plastic is durable, glass is usually more high tech.