Tribal Menace
A 22.5' Performance Coastal Cruiser
By Chris Ostlind (aka ChrisO)
When the first Lake Michigan Challenge was announced, I picked up a pencil and
began drawing a series of Class 4 boats that might be interesting entries for a
race of that type. The first boat off the drawing board was the previously
published A18. After I got that boat underway in the shop, I was looking to
design a really light boat for a crew of two that could carry a decent sail
size when the wind came up. The new double would also need to be human powered
for the inevitable sections of the course where there would be no wind at all.
The boat had to be able to be reasonably sized to handle the sometimes-large
conditions that can be present on such a big lake. It would also not be so
designed for those conditions that it would then become over weight or too
susceptible to weather cocking when being paddled. I felt that the limited
duration of the event allowed for a more exposed craft in which the crew could
decently achieve some modest measure of adventure style comfort while still
banging their way around the course.
To be sure, these types of boats are going to expose the crew to the elements.
It should be possible to snatch a few minutes (or hours) of less exposed
comfort within the hull to provide for a reasonably recharged crewmember when
it is their turn to take the watch, but it's no Marriott with a shower by any
means. Geez, it's not even a lo-dough motel with questionable plumbing.
After distilling these design types for the last couple of years, I have arrived
at a boat that I feel would be not only a winning, crewed entry as a Class 4
boat, but would also make for a wonderful platform for minimalist, long
distance coastal adventure cruising.
The result of all this fiddling is the 22.5' Tribal Menace.
The Boat
Originally, the TM was designed to be constructed in foam core sandwich with
S-glass outer skins and Kevlar inner laminates in epoxy for durability, low
weight, and maintenance ease. The maintenance issue was one of my main concerns
as boats of this type are going to be subjected to regular hard use and the
ding fixing process could be a decent part of the regular preparation for each
and every journey.
Tribal Menace Specifications
Length Overall |
22'6" |
Length Waterline |
22'1" |
Vaka Beam Overall |
38" |
Vaka Beam Waterline |
23" |
Beam Overall |
17'4" |
Draft Board Up |
10" |
Draft Board Down |
42" |
Sail Area |
170 sqft |
Displacement |
1100 lbs. |
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Subsequent designs have been developed to allow the boat to be built from marine
ply in a multi chine design form for stitch and glue construction. This allows
the eventual builder to have a choice as to how they wanted the boat of their
adventure dreams, within the budget limitations of their choosing.
The specification data for the design is carried in a separate box within this
article so feel free to examine the data to get an overall idea as to how the
boat measures-up.
I estimate that this boat can be built at just over 400 lbs. dry weight if done
in foam sandwich. The plywood version should show-up at something over 500 if
the builder is serious about use of epoxy and saving weight. At these weights,
there is little in the way of interior finish work, save for very lightly
sanded epoxy joints. One might call it race boat interior quality where no
extra coats of epoxy are applied to smooth the weave.
Exterior finish is taken to a smoothly floated finish in which the boat is
painted if foam built and if done in plywood, either left bright and varnished
or also painted. Premium Okuome is necessary to get the really lightweight in
the ply boat, but it could also be built, with a slight weight penalty, in less
expensive Hydrotek or Aquatek ply to keep the budget more under control.
The Rigs
The twin, wishbone sprit boomed rigs are built on 18' carbon windsurfer masts
with epoxied, 2' mast base extensions to take them out to a full 20'. The masts
are self-supporting through the deck with a 28" bury for enormous strength. The
sprit-rigged sails are hoisted in sail tracks that are glued to the carbon
sticks with Sikaflex. This allows the sails to be easily reefed while retaining
the lightweight philosophy of this boat. The wishbone sprit booms can be either
a single or dual configuration depending on whether the owner wants the
projected weight savings of the single boom or the tough durability of the dual
bone setup.
I chose this rig setup for a number of reasons. The mast and sail combinations
are very light in weight for the power they can deliver. The aspect ratio of
the sail is low and decently powerful in a wide variety of conditions. The
sails are easily reefed, either singly or in concert. The center of effort for
the entire rig is kept low, reducing righting forces. This keeps the volume
needs of the amas low as well, further reducing overall boat weight. If the
boat is caught way out in an exposed situation in a bad squall, the forward
mast can be dropped and secured, a drogue or parachute anchor thrown off a bow
bridle and, with a seriously reefed aft sail, the boat can ride- out the squall
in safety.
Rig Enhancements
The illustrations show the boat with a carbon bowsprit while flying an
asymmetrical chute. I'm not entirely sold on this idea as a spinnaker of this
type can actually drive the bows down while sailing unless the crew is well aft
and outboard on the tramp/ama. I've spent a lot of time sailing spinnaker
equipped beach cats and while the chute can deliver eye-popping speeds off the
wind, it is also a huge handful that requires a lot of attention. If the
spinnaker option is chosen, the forward mast will need to be stayed in a
conventional fashion to safely handle the extra loads.
Perhaps a more elegant solution would be to fly a traction kite from the forward
beam and get more power from the same sail area with none of the downward
tendencies. In fact, a kite will create lifting tendencies, which will reduce
the wetted areas of the hulls and lead to a faster boat.
Foils
There is a single, deep rudder on the vaka to keep weight down, along with
providing solid steering even when the main hull starts to lift a bit. The
rudder is a bungee-loaded rig that can ride-up over any obstacles and allows
for beaching without damage to the boat. The foil section is designed to
provide control through a wide latitude of angles of attack without stalling. A
surface dam on the rudder will be suggested to keep the blade from sucking air
down its length during fast sailing, causing a stalled foil.
The rudder can be controlled from outside the hull via standard, beach cat
style, tiller extension, or it can be controlled from inside the hull at the
aft cockpit location with typical, foot pedal fixtures. This means that the
boat can be sailed from inside the hull in light-to-moderate winds, which will
reduce exposure to the conditions and extend the comfort range of the crew.
I don't anticipate that this boat will be sailed hard in conditions, which would
lift the main hull, unless the crew is very experienced multihull sailors and
can read the wind and the performance of the boat critically. More likely, it
will be a fast cruising mode that can be kept-up for long periods of time,
especially in ideal conditions.
The keel functions are handled by a rotating leeboard that tucks up under the
hull deck flare when not in the water. The leeboard is of a moderate aspect
ratio to provide lift, resistance and keep the draft to a minimum for the
shallow waters of the Florida Coast. It's from a foil section that optimizes
efficiency while resisting stall at low speeds.
Like any foil, the trade-offs of design are managed by taking a long look at the
principal areas of performance and forming a foil decision that keeps the boat
running well throughout its intended use curve. The TM is capable of some
pretty decent speeds on the water and could utilize a foil section that is
optimized for that potential. The drawback is that for the boat to demonstrate
good qualities while in light air, especially upwind, it needs to have a
different foil in order to work acceptably in all conditions.
I would rather pay a small performance penalty at the high end than have a boat
that is just dreadfully aggravating when the wind is light and you need to make
headway.
Design Utility
The main hull is designed to provide a fast, controlled sailing experience while
presenting the slimmest forward section for efficiency. The slim sections are
balanced with the need to give the crew some measure of comfort while on the
water. Specifically, the off-watch crew gets to lie down in the hull with a
degree of comfort and not have to feel as if they've been squeezed into a human
sized gelatin capsule for their needed sleep.
It's a fine line trying to develop a hull that is at once fast under sail and
paddle and also provides enough room for the human body without severe
claustrophobia. The TM addresses that issue nicely.
There are two, cockpit style openings in the deck; one for each crewmember. A
structural bulkhead separates the two areas internally. There are also fixed
bulkheads at each end of the hull for flotation compartments. These flotation
bulkheads have watertight hatches for access and stowage of light gear.
Each cockpit can be equipped with a folding dodger at the leading edge and
extending about midway back on the cockpit rim to keep out wave action and
spray. Seating is key for a boat of this type as there could be long periods
where the Mirage systems are employed and crappy seats can quickly push the
experience into the "Never Again" category. The TM is equipped with plastic
tractor-style seating with folding backs. It is intended that the crew will
equip the seats with the Crazy Creek folding pad setups that have the mounting
straps under the hard shell seat for secure seating.
The seats are hung from light gauge, stainless, Ronstan sail tracks under the
gunnels and can be adjusted up, down, forward and aft as well as full control
of the pitch. This allows for infinite comfort adjustments underway and gives
the crew total control of their seating positions to break long spells in one
position. If the boat is taken to shore during a casual coastal cruise, the
foam seats are removed to serve as camp chairs and/or sleeping pads. Another
piece of equipment that serves two and three duties; saving weight, adding
utility and giving increased pleasure to the whole expedition.
Amas
The amas are super slim to allow for the least resistance, to be as light as
possible and to still provide for a minimum of righting moment. If you were to
look at the hulls of a beach cat that carries the same sail area, you would
find that they are nearly twice the width of these hulls.
The ama flotation is heavily biased towards the bow to further resist pitch
poling while reaching and running. Their unique form presents only as much
wetted surface to the water as is needed while under sail. The decks are canted
6 degrees to the inside to present the smallest wetted profile to the water as
the ama is pressed. This reduces drag and makes for a faster boat.
Design Philosophy
The TM is meant to be an actively sailed boat; one in which the crew is
designed as part of the righting moment package from the beginning. This means
that if the wind comes up while under sail, that both crew members could be
potentially obligated to get out on the tramps to resist the power being
generated, or sheet out and reduce sail area so that the boat can keep blasting
down the course.
Like all designs, this boat has to decide for which master it will dance. Some
boats dance for stable, predictable movement through their environment. They
provide consistent pace and allow for reasonably predictable rest and drive
cycles.
Others take the tempo up a notch and find their groove at a faster pace. These
boats, because of their enhanced speed potential when the conditions are
favorable, sometimes have to toss previous plans for resting cycles. This is
where the designs for a two-man crew have their biggest advantage. They can
power right through rest stops by providing the crew a reasonably comfortable
place to rest while the boat continues. The caveat is that to have the best
part of this advantage, the conditions need to be favorable. Without these
conditions, the boat is in among the rest of the fleet and will have to rely on
human power and slick sailing skills in light air.
There have been a wide variety of boat types and configurations in each of the
previous EC's. With this design, I have chosen to give the boat a superior
sailing performance function that pretty much obligates the crew to be slightly
better than average sailors. The payback for that skill, in the right
conditions, will be a boat that can cover huge amounts of water in a short
amount of time.
This is not a boat where you can button-up and the boat will sail itself in
stronger conditions. It is possible to reef and tune each sail to provide for
optimal control and the schooner rig is ideal for that application. Still, the
driver on watch will need to be the master of his domain and the boat will
require that he pay attention to avoid being dumped.
The reward will be watching the competition recede over the horizon as you
press-on down the EC course.
The narrow bridge filter of the EC is addressed in the same manner as my other
boat, the A18. Each aka is sectioned into three pieces. This allows the center
element to be removed so that the amas can be re-attached closer to the main
hull to allow the boat to navigate the smaller bridge opening. The
self-supported masts are lifted and stowed on the shortened beams and the boat
goes under the bridge. Once on the other side, the order is reversed and the
boat is quickly back to its original form, ready to move on.
Human Power
Human powered propulsion is handled by one of two approaches. Principal drive is
via two, Mirage pedal units, and one in each cockpit section. There is a main
deck in the boat that is slightly above the water line. This means that each of
the Mirage units, when installed, sits neatly in the designed trunk and only
the pedal levers are seen above the deck opening. The crewmember sits on a
folding, Crazy Creek style, foam chair and comfortably strokes the Mirage down
the course. When the Mirage is not being used, a watertight plug fits into the
trunk, keeping the interior dry.
Either crew can provide propulsion in this manner or they can switch off to get
some rest while the other continues.
The Mirage drive, to be really effective, needs about 14" of water under the
hull. For truly thin water, that also requires a good degree of steering
control, the crew simply pushes the Mirage blades up against the hull and they
switch to stowed paddles for continued mobility.
Really thin water applications are not this boat's forte. The TM really belongs
out in deeper water where its attributes can shine. There was a brief
discussion on the Tribe Forum (see here:
http://www.watertribe.com/Default.aspx?ucPtr=Discussion/DiscReadMsg.ascx&strThread=1429&strNumReplies=18
) regarding the potential for carrying a folding or inflatable kayak for thin
water exploring while still using a Faster Class 4 boat for the bigger sections
of open water. I completely support this approach for non-racing expeditions as
it has a small weight penalty compared to the increased versatility that such a
setup provides.
(To be clear, I'm not suggesting that the established rules for the future UC be
dickered-with regarding this issue. This, agreement with concept, only applies
to my philosophy regarding other types of coastal adventure cruising.)
So, there it is, The Tribal Menace. A multihull, Class 4 boat for winning the EC
with enhanced coastal adventure cruising capabilities that make it the perfect
crewed boat for locations such as The Keys or Belize. It can be a minimalist
Mother Ship for paddled waterway adventures or a stand-alone boat. It's easily
trailered with its lightweight and reasonably familiar crew can assemble it in
less than 30 minutes.
I will entertain any and all comments and constructive criticisms via the
Discussion Forum. That includes anyone who wants to call me a destructive
weenie that is ruining the sport. I've also been called a couple of names that
were waaay too flattering. Neither position is true.
I'm just a guy who is trying to advance the sport and its potential through
design development.
A Special Opportunity
Because I am in the middle of building a couple of prototypes of my own design
right now and I still have a photo career to manage in my spare time, I am
going to put this offer out to the Tribe members to see what might come of it.
I'm looking for someone, with a good crewmember, who is serious about winning
the next EC, or even the first UC and is willing to build a fast and versatile
boat in which to do it. I would like to have you send me a written proposal as
to why you would be the best candidate to build the first Tribal Menace
example.
The WaterTribe member I select will get a full set of plans and instructions for
the construction of the TM at no charge. They have to commit to a full, written
and photographed report during the build, as well as a review of the boat after
its first trial sailing/pedaling use. There is no demand that it be done in
foam sandwich construction in order to qualify for the plan set, though, I'd
really like to see it built that way and preference will be given to anyone who
will take the boat in that direction.
Send your pitch to me at: Chris at Wedgesail dot com
© Chris Ostlind 2005
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