As one of the few people who have sailed on the L7 and who has seen
a bit of the design process up close all the way through the last 9
months I wanted to throw my 2 cents in on Mike's impressive design.
The L7 had an informal design breif of being a safe, dry, fast
foldable trimaran that could retail for under 30K. The idea was
that there is a group of people that would love to own a folding tri
but can't afford 55K for an entry level new boat (I think that is
the full price for a new F24 by the time you are done). I am an
example of someone in this group. I'd love to be able to race with
the impressive sailors that regularly race F boats but I don't have
the money for a new boat or even, most likely, a fast used boat. I
need a boat that can compete but doesn't cost much.
Most of the design decisons on the L7 seem to be completely driven
by this design challenge.
Weight:
A cheap boat can only be light if you use less materials because you
aren't allowed to use expensive materials. Luckily, this builds on
itself. The lighter the boat, the smaller/lighter/cheaper the rig
is, the smaller/ligher/cheaper the sails are, the
samller/ligher/cheaper the winches are etc.
Beam Design:
Even though you want everything to be light you can't skimp here and
the L7 beams have quite a factor of safety on them.
The farrier folding system is a really impressive piece of design.
As an engineer I can only imagine how awesome it must have been to
think of this and than to implement it and to leverage it to build
mulitple classes of boats. That said, the patent is up and the L7
could have used this system. That probably would not have been a
great use of money or weight in a 30K boat... To stay under budget
you probably need to compromise here and go very simple; the offset
sliding beams, the SAS system, is an economocal alternative on a
SMALL boat. Furthermore you can't fit full enough floats for the L7
using the Farrier system. The BIG compromise of not using the
Farrier system is cabin space. The cabin cannot be 8 feet wide and
it has the boxes for the front beams running through it as well.
Float Design:
If the boat is going to be fast is has to have a nice power to
weight ratio but it also has to be forgiving when it gets
overpowered or it violates the safe rule. This really means it has
to have a lot of boyouncy in the leeward float so that it doesn't
stuff and the boat deson't trip over it. There really is no way
around this; the L7 is light enough that it must maintain boyouncy
up front if you unintentionally fly the main hull or things would
get scary fast.
Main Hull Design:
Once you have a lot of boyouncy in the floats you have the
opportunity to take it out of the main hull, especially in the bow.
The other reason this is possible is that there is no way to fit a v-
berth in the L7, the cabin size and beam location make it
impossible. Therefore it was possible to reduce a common complaint
people had about folding tri's pounding to weather by making a finer
entry for the main hull. This design differnece is only possible
because the L7 has to have its boyouncy in the floats for safety
reasons and it is light enough that it doesn't need much help
getting onto a plane.
The cabin is large enough for a port-a-pody (can't take your
wife/girlfreind/kids on a boat without one!) and in the
production design two adults will be able to just barely fit inside
for sleeping.
The cockpit is really as large as a F31R. Because there was no way
to make the narrow cabin into a primary living space it made sense
to take advantage of extra length in the cockpit.
Ride:
The reality is the float designs need to be bouyant or the boat
would not be forgiving enough to be sailed fast. If the boat
pounded or pitched because of this you would probably have to live
with it and take comfort from the fact that you only paid 30K for a
boat that can sail with the big boys. Luckily, the boat turns out
to really have a sweet ride. In PRACTICE the finer entry main hull
seems to more than make up for any ride issues you might expect
from the more NACRA like floats. There was absolutely no
disconcerting pitching even in relatively heavy winds. Furthermore
it was probably the dryest boat in the fleet on the way back from
Catalina in the race a few weeks ago because the floats are so
bouyant. It doesn't at all feel like an overpowered beach cat. The
boat was dry enough that we didn't really need to be wearing
foulies! I even went to deal with a line dragging of the stern
part of the leeward ama and I was completely dry as I sat there and
tied up the line, and we were doing better than 15 knots!
I guess my point is that the differences from the f-boats are mostly
the result of tradeoffs being made for cost, speed and safety in a
much smaller boat. It would not have been appropriate to just
shrink an f-boat. The price constraint of a 30K retail price on a 7
meter boat that needs to be dry, safe, and fast, makes cabin space
impossible, the Farrier folding system not appropriate, and the
float design necessarily fuller.
I would love to have a F31 with plenty of cabin space to
sleep and hang out in, and off-shore capability but given my budget
I would be more than happy to "settle" for an L7 :)
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