Last update, July 30, 2007
parts for the structure and the planking sheets were ordered from Lone Star
Models in Texas. This company mills modeling wood in sizes that will save time
in building. Click on their catalog
.pdf link above to get a listing of their products. Planks are found in the
deck supports are referred to as ribs as is used in monocoque
construction. These ribs are placed at stations in the hull. Stations
are identified by measurements from the bow of the hull down the centerline of
the boat. EC12 class specifications for the beam of the boat are measured at
5 increments, down the centerline of the hull and at the flange level to the
side, from station 5 to station 55. These specifications are part of the
Rules and should be checked. The length measurement of the
here will put the beam of the boat within the rules. You should check them
nonetheless, before gluing anything in permanently.
The simplest method for measuring stations at the side of the hull is to forget the trigonometry and use a square with the EC12 mast you will use. There is a Deck Jig for the beam widths during the deck structure process. It is only reasonable with those building a number of boats or within a group that would warrant its construction. If you have a 16 right triangle for rigging that will work great. See the marking of the hull if you missed it.
The deck will be supported on a structure of seven stringers and one bulkhead. The bulkhead is for mounting the winch line turning block or the shaft mount option and is at station 3.5. Continuing from the bow, the ribs are located at stations 6, 8.5, 20.75, 24, 27.5, 38.5, 45 and 55. If you would like to draw a picture to your liking, please refer to the photo below. Stations 27.5 and 38.5 are the fore and aft boundary of the hatch. Stations 27.5 and 24 are the support section for the mast, mast rigging and compression strut beneath. Between stations 6 and 8.5 will be the approximant location of the jib rack and station 55 the same for the backstay mount.
These photos do not show the additional ribs, however, all other aspects are the same.
The mock layout shows all the parts at once. Each rib is cut from 1 wide
3/16 inch stock. Which rib is of Basswood or Balsa is identified below.
They also have a curve to the top edge to produce an even camber to the deck
when applied. Here are the parts in detail:
Station 3.5: This is 3/16 Basswood or plywood and formed to fit the hull shape at its location. You may want to place this part at a different location. Some have moved the bulkhead forward toward station 3. If you are moving the bulkhead forward, be sure that you will be able to mount the eye bolt low enough so the sheet lines will not rub on the bottom the ribs. Likewise, it you optioned for the shaft mount for the turning block.
Whereas, this is for locating the bow turning block for the winch line that leads to the sheet lines, consideration is needed that you will have a minimum of 16-1/2 from the end of the block to a point between the jib exit guide (fairlead) and the mast compression strut.
The Eye Bolt Option
Mount the eye bolt in a puddle of fiber filled resin on the hull around station 3 to 3.5. Care should be given in the bonding to the hull. Make sure the hull is clear of resin oils and some light sanding would help. Fashion some holder of the eye bolt to hold the eyelet clear of the hull surface while curing. It is suggested that 48 hours of cure time be enforced before movement of the hull. This is a bond that you cannot afford to have fail.
The Shaft Mount Option
A hole just larger than the shaft is drilled slight off center to starboard so the turning block will be close to the centerline of the hull. Fashion the bulkhead to it will fit as far forward past station 3 as possible but still have room for the shaft to just pass through the bulkhead. If the shaft touches the bow reinforcement resin, it is okay. There will be no pressure against it.
Delta convention: The 3.5 bulkhead serves as additional strength to the bow along with a solid resin nose. The king plank will go to station 6 and stop allowing access to the turning block through the deck if needed.
Here, the jib fairlead is at station 22. These
numbers were determined at the first building in 2000 when the Rig Jig was built
to investigate the resolution wanted when sheeting. It is shown here because it
is an interesting picture. We had no idea how any of this worked and needed a
model. It is kind of funny now. So, the station of this bulkhead is for our
setup in order to provide at least 16" distance between the end of the
turning block and the forward edge of the exit guide. What you are guarding
against is that with the winch at full sheet out, the sheet line collector does
not move aft of the jib exit guide. Think about the considerations to have a concept
of what is going on here. Station 3.5 works and anything forward of that will
If you are using the eye bolt install it now. Trim the bulkhead to fit in the boat, where you want it, and set it aside.
All ribs are notched on their edges to slip
under the gunwale hull flange and to provide a smooth surface transition from
the stringer onto the flange for the deck skin. Holes are drilled to lighten the
weight. Three-eights drills are popular so use that size and just drill more of
them. You are not going to a boat show.
If you do not use the
EC12 Drawing based on Rinehart's
drawings the dimensions are listed below. The camber of the
ribs are important.
Station 6: The width is 2-3/4 basswood and the edge drop for the camber is 3/32 of an inch. Notch the center to receive the Ύ by 3/16 king plank.
The width is 3-7/8 Basswood and the edge
drop for the camber is 3/32 of an inch. Notch the center to receive the Ύ by
3/16 king plank.
Station 20.75: The width is 8-5/16 balsa and the edge
drop for the camber is 3/8 of an inch. Notch the center to receive the Ύ by
3/16 king plank.
Station 24: The width is 9-1/4 basswood and the edge
drop for the camber is 13/32 of an inch. Notch the center to receive the Ύ
by 3/16 king plank.
Station 27.5: The width is 10-1/8 basswood and the edge drop for the camber is 7/16 of an inch. Notch the center to receive the 1 by 1/4 support plank for the mast.
Make an additional one in balsa with no notch for the station 29 area.
The width is 10-7/8 basswood and the
edge drop for the camber is 1/2 of an inch. Notch the center to receive the Ύ
by 3/16 king plank.
The width is 9-5/8 balsa and the edge
drop for the camber is 7/16 of an inch. Notch the center to receive the Ύ by
3/16 king plank.
Station 55: The width is 5-1/4 balsa and the edge
drop for the camber is 1/4 of an inch. Notch the center to receive the Ύ by
3/16 king plank.
This will need to be shaped considerably when installed due to hull shape in
This will need to be shaped considerably when installed due to hull shape in that area.
A small 1 by 1/4 plank will connected to
stations 24 and 27.5 later. Mark and glue in a small support ledge for this
plank on the aft end of station 24.
Once you have cut the
rib to length, the camber
can be trimmed with some sandpaper or whittled with a knife and smoothed with sand
paper. Notch the flange end with a knife and the center king plank slot as you
see fit. Fashion these ribs from the 1 x 3/16 stock. Clean them up and put them away till
they are needed.
Remember, it does not have to be pretty, just fit.