you rent kayaks?
What is hull
is hull speed calculated? (or is it measured?)
longer kayaks are potentially faster should I buy a longer kayak so I can paddle faster?
size kayak is best?
kayak is best for me?
Why don't you list weights with the other dimensions?
Why are all your kayaks Swedeform?
sliding seat fits me perfectly. Can I buy one to put in my kayak (or the kit I am
What is initial and secondary stability?
other kinds of stability to consider?
need to replace the chart bungies but how do I get the shock cord through
those little holes?
Do you rent kayaks?
No, our insurance does not cover us for
rentals (nor are we of the right temperament to be kayak renters). However, there is a
rental kayak operation, NWOC, less than a block to the South, hidden out of sight down the
stairs (which helps explain why "Do you rent kayaks" is by far the most
frequently asked question we get in the store). We do have a fleet of demo kayaks our
customers can try out for free at our lakeside store. A paddler can not only compare
between Mariner models, but between many of the other brands of kayaks we also sell. They
can also rent dozens of more kayak models next door to compare kayaks to their hearts
content. We wouldn't have it any other way because we have paddled over 1000
over the years to, among other things, find the best and the best value
for our customers. (1000+ is not an estimate, I take notes on each kayak I
test paddle and have them all listed in several spreadsheets.) We encourage paddlers to compare kayaks head to head so they can
discover what's best for themselves and have no doubts that a kayak they bought from us
was among the best suited to their needs (from their physical size to the size of their
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is hull speed?
Hull speed is the maximum practical speed of a displacement (non-planing) hull.
Since a wave's length is proportional to the square of its speed, the wave created by a
moving hull will at some speed become longer than the hull's waterline. At this speed the
stern of the craft will no longer be supported by any of the following wave crests. You
will feel the stern squat into the trough following the bow wave. You will also notice
that far greater paddling effort yields little increase in speed because to go faster you
must now, in addition to the other forms of resistance, also work against gravity to climb
out of the trough.
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How is hull speed calculated? (or is it measured?)
The formula for the speed of a water wave, 1.34 times the square root of the
wavelength (in feet) equals the speed (in knots), is often used, by substituting the
crafts waterline length for wave length, to calculate theoretical "hull speed".
In reality many other factors including weight, slenderness, and the fullness of the bow
and stern are also involved.
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Since longer kayaks are potentially faster should I buy
a longer kayak so I can paddle faster?
The concept of hull speed often leads to the
oversimplification "longer is faster". This has caused many paddlers and several
designers to buy or build kayaks that are extremely long in order to be faster. However,
because longer, like wider, also means more wetted surface, there will be a length where
all the available power will be absorbed by the increased friction, before hull speed can
be reached. Longer then becomes slower. Unfortunately, the longer kayak will also require
more effort at all lower speeds because friction is present at all speeds. The speed
advantage of a long waterline is only apparent at top speed. Extremes of length (and then
only up to a point) benefit a racing kayaker and few others. If you can't reach hull speed
(squat the stern) when paddling hard that kayak is probably too long and/or too wide for
The above discussion only points out one of the disadvantages of buying a longer kayak, more
work. There are several other disadvantages (other things being equal). It will weigh
more and be more awkward to carry. It will require more storage room. But most
importantly, in strong winds a longer kayak will be more difficult to handle (especially
when not gear laden). This is due to the increased windage, the longer lever-arm offered
the wind, and generally the slower turning speed of a longer kayak. Not being able to
control your kayak in a strong wind could have disastrous consequences.
Note: A few
companies promote the ratio of waterline length (LWL) to over-all length
being a very important factor in sea kayak hull design, a higher ratio
supposedly being better. One company even includes a list of
waterline length to overall length ratios for many different competing sea kayak
models in their advertising. Not surprisingly, that company's kayaks are all
concentrated near one extreme in this regard. [Their
data doesn't include the Loki at 99% and the Epic Endurance at 97%
though. It is also unclear to me where their data comes from. It appears
that they have used data from various sources that may not always have had anywhere
near the same weight added to the kayaks when they were measured or
calculated. This can
make quite a difference in the ratio, especially with a highly rockered kayak. Sea
Kayaker Magazine's original measurement for the Chinook in 1986 were a 150 pound load
might have been from a Chinook with more rocker--like most rotomolded
kayaks, their shapes could vary quite a bit from kayak to kayak) but using that
old Sea Kayaker data I get 95% for
the Chinook rather than the 92% listed. Other data I have has the Aquaterra Chinook's ratio at 98% with 250
pounds added, and 97% with 150 pounds added. Looking at the raw data I suspect this company has used
an estimated Effective Waterline Length
rather than the actual waterline length (LWL) in those calculations. The estimate
for Effective Waterline Length (EWL) appears to also be the basis used for
the Puffin numbers (they get 94% where I get 96% or 97% using two
other reliable sources--one the same source that gives 94% using the EWL
rather than LWL data). I didn't check every kayak on their list
but several other kayaks vary from Sea Kayaker magazine's data (generally
the most reliable source I know for this data) in a similar way. But I'm digressing
here because the reliability of the data they are using is beside the point.
I want to make is that too high a ratio is likely to result in some big
While overall length certainly
is one factor in making a kayak harder to handle in wind it is only one of
many factors that are involved (and overall length is only one part of the ratio). If
the waterline length to overall length ratio was that important, you would probably see a lot more vertical
(kelp pushing) low volume/no flare
(wet riding) bows with flat sides near the bow and stern (that get pinned in and slapped around by waves) on
the full range of sea kayak designs than you actually do. With a very high
ratio it will be hard to eliminate those negative characteristics. One does see quite vertical bows and sterns on racing kayaks but
that is because the artificial rules limiting overall length distort racing kayak hull designs,
creating "rule beaters"
rather than functional seakindly designs capable of handling well in rough
seas (and also being fast). In boat design you are likely to pay a big price
in other areas when you concentrate on only one factor especially if you
take that factor to an extreme.
As we've seen in the earlier FAQ's above, the basic premise here (that a longer
waterline is faster) is not really applicable to most kayakers. Racers
willing to sacrifice most other beneficial characteristics (including
paddling ease at cruising speed) for a slightly higher all-out top speed being the
There is a price to pay for a
longer waterline, more wetted surface, slower turning, and a greater lever
arm for a strong wind to act on are three of them. The waterline length to
overall length ratio only addresses the later one.
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size kayak is best?
A kayak is an extension of your body much like hiking boots or skis and
ski poles. It should be sized to fit the kayaker who will be wearing it. Not only should
the fit be such that the kayaker is neither pinched by or rattling around in the cockpit,
but the length and width should be proportional to the size and strength of the paddler.
Far too many paddlers are sold kayaks that are too big for them because of a
misinterpretation on their (or the salesmans) part of the "common
knowledge" that "longer is faster" or "more stability is always
better". For a small or less strong paddler just the opposite is most often true.
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kayak is best for me?
To answer that question we are going to need a lot of information: What is your
size? Height, weight, foot size, inseam, athletic ability, disabilities, etc.. How
do you plan to use it? Day trips (70%), overnights (15%), week or longer trips
(10%), fishing (5%) etc.
Where do you plan to use it? The local river, small lakes, big lakes subject to high
winds, the exposed open coast and exploring sea caves?
What other kayaks have you tried and which ones did you like best? Why?
As you can see there is a lot to consider and it would be difficult to try to cover all
the various combinations possible here or in a written description to arrive at the best
choice for you. We suggest you give us a call and tell us as much of the above information
as you can. That way we can ask additional questions and at least shorten your list of
kayaks to test and compare to those that would be most suitable for you. If you can't try them
in person before choosing we will be happy to choose the one we think is most suited for
you and back up our choice with our 30 day return policy. You risk only the freight costs.
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Why don't you
list weights with the other dimensions?
Mariner kayaks are usually made for an individual paddler so the customer
has some choice in the matter. We have made kayaks weighing from 30 pounds to over 70 lbs.
The questions we want to know are what weight would you like your kayak to be and what are
you willing to give up to get it? Strength? Money? Size? Yellow color? A hatch? A rudder?
The point is that lots of choices you make will also affect your kayak's weight. The Sea
Kayaker magazine reviews we have reprinted list the weight for the kayaks they
weighed. We prefer to be asked about weight on the phone so we can explain the range, the
costs, the normal variations that can be expected, which colors weigh the most, etc.
Also, weight is often the most misrepresented dimension in kayak advertising. We try to give our
customers as good an idea about what their new kayak will weight as we can, but at the
same time we don't want our honest answers compared with some of the 10 to 20 pound
misrepresentations we have seen. This includes most magazine reviews and buyers guides
that simply reprint the advertised weights provided by the manufacturer. By contrast the reviews done by Sea
Kayaker magazine all contain what a test kayak actually weighed (but read the
articles carefully because some manufacturers supply graphite or Kevlar kayaks to be
tested). A lightweight Kevlar or graphite test kayak will also make the drag estimates in
the magazine look a little better too. If you are interested in how much, download one of
the spreadsheets Sea Kayaker uses to estimate drag (from our
"Downloads" page) and add more weight, as well as a little more draft, waterline
width and wetted surface and see what differences 10 or 20 pounds can make. We keep a
bathroom scale in our store so any kayak there can be weighed. If weight is important to
you we suggest you take a bathroom scale with you when you go kayak shopping to avoid
relying on outdated or dishonest data to make your decision. We find it is best to stand
on the scale and pick up the kayak and then subtract your weight.
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Why are all your kayaks
The Swede-form shape (greater underwater volume aft of the midpoint) has less
resistance moving at the water's surface than either a fish-form shape (its opposite) or a
symmetrical hull. The finer bow more gently parts the water for less wave-making
resistance. The longer run of positive pressure in the forebody of a hull moving forward
can also result in a longer area of the hull being in laminar flow (laminar flow over a
surface creates about four times less drag than turbulent flow). Note: A fish-form
shape has less resistance underwater or in the air (where there is no wave drag). This has
confused several designers who have consulted hydrodynamic texts, but not gotten the full
picture of what happens at the waters surface. Fast ships, canoes and kayaks are
Swede-form. Fast submarines and fast fish are fish-form. Swede form is also a little
faster at top speed because the wider more buoyant stern doesn't "squat"
into the wave trough as readily as a fine one.
A Swede-form hull has many other advantages over fish-form. They include:
1) Less pounding in head seas because they are narrower in the area where pounding
occurs (but, bottom shape is a bigger factor in pounding so some V-bottomed fish-form
kayaks will be softer riding than some flat bottomed Swedeform ones).
2) Easier and quicker turning (turns are enhanced by the greater curve at the side
of the stern quarter--and leaning makes this effect even more pronounced).
3) Less weatherhelm (more windage and a longer lever arm in front of the paddler
and less behind)
4) Greater gear capacity (more of its volume is in usable storage space behind the paddler
and less of the total volume is in the wasted space around ones legs).
5) A narrower beam where the paddle enters the water means easier more efficient paddling
(less boat to reach over) and less turning moment produced with each (less off-center)
6) Less energy robbing pitching motions in head seas and less wave pressure on the
bow than fish-form mean a faster smoother ride into waves.
Fishform advocates correctly point out that Swedeform is less directionally stable
(other things being equal). One of them used to even say fish-form was self-correcting
(when he really meant self-stabilizing). We think too much tracking stiffness is a
disadvantage. Directionally self-stabilizing just means you work for each degree you must
turn rather than being able to translate your momentum into turning by simply leaning the
kayak as is usually the case with Swedeform. Course keeping can actually be harder with
fishform because correcting ones course after a wave has altered it is more difficult with
a kayak that resists turning. Leaning the hull doesn't increase turning performance of a
fishform kayak nearly as much as with a Swedeform one. The less directionally stable
Swedeform shape will track just fine if some keel is added in the stern sections like we
do. When this stabilized Swedeform shape is leaned it regains its superior
maneuverability. With a Mariner you get the best of both worlds. They track straight when
level yet turn readily with a slight lean. A Swedeform shape is just one of the many
aspects we use to enhance responsiveness in a Mariner kayak's handling.
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Your sliding seat fits me perfectly. Can I buy
one to put in my kayak (or the kit I am building)?
Unfortunately no, we can make very limited numbers of them and therefore
we seem chronically in danger of running out and holding up the delivery of a customer's
new kayak for want of a seat.
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What is initial and secondary
Initial (or primary) stability is how hard the craft resists being tipped from the upright
position. If you are looking at a graph of stability (see the XL review's stability graphs or any recent issue of Sea
Kayaker magazine) the steepness of the angle off of zero is an indication of
the primary stability.
Secondary stability is a lot harder to define. Most experienced kayakers will tell you
they know it when they feel it (sort of a seat-of-the-pants thing).
One designer used to claim there is no such thing as secondary stability and any kayak
that is more stable initially will be more stable at all angles of lean. I'm not sure he
still claims this because I once showed him some stability graphs (Chinook and Puffin in
the Winter 1986 issue of Sea Kayaker magazine) where the less initially stable kayak, the
Puffin, had not only higher relative stability at higher angles of lean than the Chinook
but also a higher maximum stability and a greater total area under the curve). Personally,
I define secondary stability subjectively as how secure you feel when you have leaned the
kayak well to one side.
A kayak whose maximum stability is five times as high as its stability at 5 degrees
of lean will "feel" more secondarily stable than a kayak with a much higher
maximum stability that is only three times as stable at maximum as it was at 5 degrees.
This defines secondary stability as being somewhat in an inverse relationship to initial
stability. I'll make an analogy with rocking back in a rocking chair (low initial
stability/higher secondary stability) and compare that to rocking back in a regular four
legged chair (high initial stability/high total stability/low feeling of security as you
teeter at the balance point). It is hard to lean back on a standard chair (most of my
teachers frowned on my practice of balancing my desks on the back legs when I was bored,
especially when I would draw their attention to what I was doing when I would almost lose
my balance backwards and --in a desperate attempt to recover--crash back down
loudly to the "initially" stable position. I don't remember ever going over
backwards but that was always the risk I flirted with--a capsize to the rear).
Looking at the static stability graphs I would define a kayak with good secondary
stability as one whose stability curves show a relatively shallow angle off of zero (so
you don't have to put a lot of energy into leaning it) but which has the point of maximum
stability (the top of the curve) at a greater angle of lean (and maybe, but not
necessarily, at a higher maximum point) than a kayak with less "secondary"
stability. (See the Mariner XL, Arluk III, and
Solander stability comparisons in the XL review in the Spring 1987 issue of Sea
Even this doesn't totally account for the difference in "feel". A smooth
progressive increase in stability out to near the maximum allows a trustworthy
"feel". Any abrupt changes would be like putting a speed bump or flat spot on
the rocking chair rockers. The above definition is from my own observations and guesses
regarding secondary stability in kayaks. I make no claim to scientific validity or even at
a valid definition of the term (which may exist somewhere in Naval Architecture). I and
most experienced paddlers prefer lower initial and good "secondary" stability.
Easy to lean yet secure while leaned.
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Are there other kinds of stability to consider?
Well, there is what I once called "dynamic stability" until I found out that
Naval Architect's use that term to mean: "the work done to tilt the hull to a certain
angle". Since that is not at all what I meant, I'll try a new name. How about
"Seakindliness"? Seakindliness to me is: "how does the kayak feel in rough
seas?". Does it stay under you or is it always sliding to the side out from under
you. Does it feel neutral and consistent (or even gyroscopic) in waves or are the waves
knocking it around and rocking it. Are the motions smooth or jerky. Do two waves pick the
kayak up by the narrow ends and make you feel like an off balanced turkey on a spit or
does it maintain a comfortable and secure feel in steep waves.
Too much initial stability means the hull stays flat to the wave faces leaving the
paddler to constantly bend the torso to keep a level head. (Note: contrary to what is
usually assumed, this by itself does not destabilize the flat bottomed craft because the
motion of the passing wave moving the hull forward and back creates and "artificial
gravity" that compensates for much of the tilt. However, if the paddler were to stay
rigid in the kayak and swing back and forth like a metronome in waves they would quickly
get seasick if they didn't somehow keep their eyes level with the horizon. The kayak that
is initially less stable can save one a lot of bending at the waist to make this
A kayak with a lower center of gravity (low seat or gear laden) will feel more
comfortable in waves. Imagine a wide flat bottomed canoe with its high seating position in
steep seas. As the initially stable canoe is tilted by the wave the high seat is also
swung to the down wave side. If the paddler attempts to shift their center of gravity
to compensate that
will (by an equal and opposite reaction) also use the seat height as a lever to tilt the
canoe in the opposite way (even further tipped down the wave than it already
was). The canoeist may be able to get down on their knees to lower
the center of gravity to be more comfortable (and maybe to pray that the waves don't swamp the
open canoe) but a high
seat in a kayak is unlikely to be easily lowered to improve stability in
rough conditions. Raising the seat to make a wider kayak easier to lean (as
some suggest--also claiming the higher seat allows for a more powerful
stroke) has several down sides compared with having the kayak narrower
(therefore easier through the water) and gaining back initial and secondary
stability (and seakindliness) by having the seat as low as is practical.
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I need to replace the chart
bungies on one of your kayaks but how do I get the new shock cord through those
tiny holes in the deck?Start with a suitable size
shock cord. We have been using 3/16" natural rubber shock cord from New
Zealand (because it recovers its length better after being stretched and
lasts longer than synthetics). It takes about six feet of shock cord.
For the present hole size you want to use
3/16" (6mm) shock cord. You could use 1/4" (8mm) but you may have
to make the holes a bit larger to do so. Just a bit larger now though! This
needs to be a very tight fit not to leak.
Here is how to replace the shock
cord. Cut the end of the cord with a fresh cut. Next peel the fabric sheath
back until you have exposed about 1/2" of bare rubber strands.
Once you get the sheath peeled back enough to expose a little of the rubber
try to stretch the rubber in order to more easily draw back the sheath
further. Trim off the exposed rubber (try to make the rubber bundle
taper a little like a blunt pencil point when you trim it). Slide the sheath
back into its original position and melt the tip of the tit you formed with
a flame. The melted tip needs to be small enough to easily fit through the
deck hole but big enough to get a good grip on with a pair of pliers. Tie a
figure eight knot in the other end of the cord and trim and seal that end of
the sheath from fraying with a flame. Next push the tit through the hole in
the deck from the inside starting with one of the furthest forward holes.
Grab the end of the cord's narrow tip with the pair of pliers (the blunt end
of slip-joint pliers work well). While holding the pliers pointed at the
deck and tightly griping the melted shock cord tip stretch the shock cord
between your hand inside the hull and the pliers outside the hull until you
have narrowed the cord enough that you can pull the shock cord through the
hole. It may take a little wiggling to get the first wider spot through
(which is why you cut the rubber to a little point to help out). If you have
done all this and you still can't get the shock cord to go through the hole
then the shock cord is likely too big for the holes and either you will need
narrower shock cord or make one of the holes one drill size bigger and try
it again. Repeat as necessary. But remember, if you don't have a very tight
fit when the shock cord is relaxed then you might find some drips coming in
later. Maybe not a big deal, but we should strive for perfection. Before
making any of the other holes larger you might want to test the first fit
for leaks with a garden hose or other source of water. Thread the other five
holes in the same pattern as the old shock cord and tie another figure eight
knot in the tit end, cut the excess off, and melt the sheath to keep it from
fraying. The shock cord should just have the slack removed to fit right but
not be left under tension. If left under tension for some time the rubber
will relax to the point it is not under tension any longer and will lose
some of its resilience in the process. Also, too much tension with heavier
shock cord over a long period could possibly distort your deck some. If the
shock cord stretches out in use (they all do eventually but some do so much
sooner than others--which is why we were using natural rubber shock cord)
you can easily remove the slack with this system by holding the cord from
each side and stretching it to move it to the desired position (that's no
slack and no tension). Now put the inside hand against the deck and
hold that spot so you will know where to tie the figure eight knot. Next
stretch the shock cord again to give yourself some slack to tie the figure
eight knot, trim and melt the end, and then stretch the cord again to easily
move the knot into position just below the deck.
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