Building
the SC-1

The perfect flatwater kayak for
beginners.
The perfect ocean kayak for
surf enthusiasts.
The original Coaster was designed
by Cam Broze of Mariner Kayaks in 1985. This 23" wide 13'5" kayak
quickly gained cult status as a superior kayak in the surf.
Surprisingly it went on to prove itself as a remarkably versatile sea
kayak for smaller paddlers as well. Whereas the Coaster won’t win a
sprint against a longer narrower kayak it is very fast for its length,
it draws no penalty at cruising speeds and is actually more efficient
than much longer kayaks at speeds up to 4mph because of its reduced
wetted surface. Every sea kayak is a compromise but the Coaster seems
to get away with a bit more than it's fair share. Some sprint speed in
exchange for better cruising efficiency, maneuverability, portability,
and large usable cargo space, a pretty good trade. This kayak is very
stable, swift, turns especially quickly yet tracks well even in
difficult cross-wind and following sea conditions. And it screams in
the surf zone without pearling. A great boat for kamikaze surfing AND
peaceful flat water exploring.
After the success of my own Mariner Elan inspired Ginnyak, I wanted to
sink my teeth into a Coaster. I didn't want to reinvent the Coaster
though; I wanted a skin kayak built as close as possible to the
Coaster. So I obtained permission from Matt Broze of Mariner Kayaks to
try to replicate the Coaster in skin-on-frame construction. My next
challenge was to find one to copy. Coasters have been unavailable for
two years and owners guard them zealously. A used Coaster will still
sell for the price it was when new. Thanks to Dave Graham for loaning
me the Coaster I tested and copied. I tested the original kayak in
every possible sea condition until my arms wanted to fall off. The
primary stability was a bit much for my tastes, and I can't stand the
slapping noises of any fiberglass kayak, but I knew that building it in
skin-on-frame should automatically solve these minor problems.

Skin-on-Frame

A brief word on names, Coaster is a registered trademark
of Mariner kayaks. While I can build a similar kayak I can't
appropriate the name. However, names can't just be arbitrarily
assigned, they have to be earned and I want to make sure that this
kayak gets the right name so it make take some time. For the
remainder
of this article and on the website I'll refer to the Coaster copy as
the SC-1 (skin coaster one). Also, Mariner does not endorse,
approve, or associate with my kayak in any way. It is not my
intention capitalize on their reputation. If and when Mariner
liscences production of their fiberglass designs again, I'll
reccomend them to paddlers who would be better served by a glass
boat. There are compelling reasons to paddle glass, just as there
are compelling reasons to paddle plastic, skin, or buy a motor
boat.
I've heard that Mariner is taking limited orders from Oregon,
Washington, and Northern California. I'd buy one personally but
it seems like I'm always losing boats off the top of the car and glass
boats don't bounce down the freeway nearly as good as skin-on-frame.




note: the real Coaster looks way cooler, but the SC-1 is a bare hull,
ready for perimeter lines and hatches. What do you get from a
glass boat? Storage space, longevity, (a skin boat will not last 30
years!) puncture resistance. A skin-on-frame kayak is ultra
light, has better impact resistance, less slapping noises. It's
not a contest.
Documentary
of building the SC-1
I decided to take a unique approach to prototyping the SC-1; I invited
a student to build the first prototypes with me as a class. My risky
reasoning was that with a deadline and the responsibility for the
students' kayak I would be a lot more motivated to 'get it right'. This
was new territory for me. After building a dozen kayaks from historical
drawings I immediately realized the difference of the challenge of
rebuilding an existing kayak. I knew how this kayak was supposed to
paddle, and I would know if I got it wrong. Also I wouldn't be able to
replicate the Coaster exactly so I had to distill the key elements of
the design and apply them to skin technology. The Coaster is not an
easy shape to copy; it includes a variety of cross sectional shapes
over its length (where most hulls are simply smooth variations of their
midship section shape tapered out to each end). There are deep and
shallow V'd sections and a host of other nuances that are critical to
the design that would be so easy to 'fair out', ruining the kayak. The
process was exhausting and stressful but when the week was done I
launched the SC-1, still sticky, into a thick Pacific swell. In short,
the design worked. It's a little different but still very much like the
Coaster. When you press the chine it still turns in any
wind. It doesn't rise quite as high in a foam pile and the
net result of that was that I got a thin sheet of water over the bow
when punching some very large waves, this is easily fixable and
is due to a deliberate deviation from the lines of the
original. It still has the net effect of climbing over huge
foam and not spearing into it.
Technical changes to the boat from the original are. A 3/4" lower
bow, 3/8" lower depth, a 3/4" upsweep in the extreme stern, less
of a boxy section at the gunwale, a bit less of a shovel nose at
the bow, 4 inches more length, different stem and stern
shapes. I may made these changes based on hunches and I'll be
varying the recipe a little bit with each new model.
A slightly lower
volume. I dropped the depth of the kayak 3/8" to suit
my personal needs. The original Coaster can carry a 400 lb payload. The
skin on frame version won't hold the same cargo load so it doesn't need
the same reserve buoyancy concentrated at the gunwale.
A ridged front deck. Again it drops the volume and the reserve buoyancy
a bit. I like the aesthetic.
My own deck line setup. Years of fishing, kiting, and touring in rough
water have made me very particular about what I like for deck lines. I
use latigo leather because it is simultaneously elastic but still
strong enough to tow or carry by. Toggles allow tightening.
My version of this boat is hardly better, but different. I'd guess I
get some turbulent losses from the harder chines and concave surfaces,
probably something like three percent. I might get that three percent
back in displacement with less wetted surface from less weight.
Then again I might loose it due to flex, I don't know, I'm not a naval
architect.
My boat will carry maybe 2/3 the load of the original but considering
the original held everything but the kitchen sink I still feel flush
with all the room. An interesting effect I discovered was that the surf
beatings were noticeably less shocking in the skin version, with the
flex of the kayak absorbing some of the wave energy. And like all my
skin boats, it's half to two thirds of the weight of a glass
boat, and quieter on the water. In the final analysis what
makes a sea kayak a success is how easy it is to use and how much fun
it is. I tend to design for specificity so it's surprising for me to
like a versatile kayak so much. The only 'camping kayak' I've ever
enjoyed as a day-tripper.
This kayak will replace my Ginnyak design this year, not because I
still don't love the Ginnyak, my low volume hybrid, but because I only
can work on one new design at a time. Ginnyak is slated for redesign
anyways.

The SC-1 will climb through a huge foam pile but there is still such
a thing as being in the wrong place at the wrong time.
More surf photos to come.....

The very first SC-1 class finishes on a cold wet January
day. These are some seriously committed students. And then
there's Douglas who just had to build a Baidarka. Honestly, the
Baidarka is a great boat and it looks so much cooler than than the
SC-1. But for me, this year, it still all about the SC-1!

Getting the shape right. Reworking a cult classic kayak is a huge
risk to my reputation and my business. If the boats don't paddle
right "real" Coaster owners will rake me over the coals and this design
will perish.

Christine bending in ribs.

Me giving Douglas's baidarka a test run.
NEW: unedited email
correspondance with students.
This is the link to how the boats are REALLY performing.
The good, the bad, and the ugly. No Hype. SC-1
design evolution page
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