Frequently Asked Questions:  

Do you rent kayaks?

What is hull speed?

How is hull speed calculated? (or is it measured?)

Since longer kayaks are potentially faster should I buy a longer kayak so I can paddle faster?

What size kayak is best?

Which kayak is best for me?

Why don't you list weights with the other dimensions?

Why are all your kayaks Swedeform?

Your sliding seat fits me perfectly. Can I buy one to put in my kayak (or the kit I am building)?

What is initial and secondary stability?

Are there other kinds of stability to consider?

I 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 sea kayak models 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 pocketbook).
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What 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 you.
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 (LOA) as 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 (and 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 (EWL) number 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. The point I want to make is that too high a ratio is likely to result in some big negative characteristics.]

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 exception. 

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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What 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 salesman’s) 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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Which 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 Swedeform?
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 water’s 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) stroke.

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 stability?
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 Kayaker magazine).
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 compensation.
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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1999-2008
Matt Broze
Mariner Kayaks