Building the FL12
I wanted to build a small boat, easy to row, easy to
transport and easy to build. I
had never tried the stitch and glue method. In my teens my father and I
built an OK dinghy using traditional methods, and over the years I had
worked on other traditionally built wooden boats, but I had never tried
the stitch and glue method. After
looking at various plans I chose a 12 foot stitch and glue boat called the
FL12 that could be built out
of four sheets of plywood, and a little scrap wood for odds and ends.
I purchased the plans for the FL12 from Bateau.com an
on-line seller of easily built designs, primarily stitch and glue boats.
I bought four sheets of plywood; two 3/8 inch
exterior grade and two ¼ inch marine from a local lumber supply.
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Fig 1. The parts cut out of the four sheets of plywood.
As per the plans I then laid out the patterns on the sheets of ply using a 4
foot straight edge rule and a tape. I used a ½ inch ID PVC pipe as a
batten for curves.The plans
include full size patterns but the designers warned that the patterns may
be off in dimensions due to humidity or shrinkage, so following the
detailed drawings I used the given dimensions to lay out the patterns.
Although they say in the plan notes that a little slop is ok,
I tried to get it as close as possible.
Even so, when I put the boat together there were areas where it did
not line up and adjustments had to be made. |
I then cut out the patterns with a circular saw.
It is relatively easy to follow the curves, and little bit of slop
is ok. However, here’s a
warning. The plans said it
was ok to go ahead and cut out the seat tops along with everything else.
But I found that when it came time to put the seat tops in place
they did not fit properly. Both the rear seat top and the center seat top were too
short, and the forward seat top was too big.
It’s easy to cut something down to size but difficult to make it
bigger.So I would advise
waiting to do the seat tops. Wait
until you get to that point in assembling the boat.
Then measure carefully for each seat top.
Draw them on the plywood and cut them out. They will fit better. This
would not have been a problem if the gap was 1/8 or even ¼ inch but the
gap on the rear seat was at least 3/8 on each end and ½ inch on each end
for the center seat.
I had three or four six foot oak 1 X 6 from an old
bed. I cut three of them into
one inch strips. I then cut the strips into battens for the frames and the
transom. These were glued to
the frames with epoxy resin.
I planned to use a small two hp outboard on this boat
so I thought the 3/8 inch transom would not adequately support it.
I cut out two pieces for the transom; one 3/8 inch and one ¼ inch
to be glued together. I then
cut out two squares five by five of 3/8 inch for backing to mount the
outboard and glued these to the top of the transom at the centerline.
Later on I also glued a piece of vinyl plastic to each side so the
clamp for the outboard would not mar the wood.
However, later use revealed that this did not work well as the
epoxy does not adhere very well to the plastic and they kept coming off.
I will replace this with leather.
Since I had decided to open up the seat compartments,
I used foam flotation rather than air chambers.
I drew the sizes for hatches on each of the seats.
But I decided not to put a hatch in the top of the middle seat.
It would be the main seat for rowing so I wanted to leave it whole. I drew an opening in the rear middle seat frame instead,
which I left open. Structurally
it would still be as strong and would be easier than making a hatch.
One flaw in the plans is they do not provide the
builder with the maximum capacities required by the US Coast Guard.
I calculated the boat’s maximum weight capacity, persons capacity
in pounds, and number of persons, and flotation.
I then calculated from those numbers how much flotation was
required to make the boat float upright if it was swamped. The boat
actually does not need much flotation but I added about 1 ½ cu feet to
provide additional flotation and the ability to float upright. One
common misconception among boat builders is that wood boats don’t need
flotation. This is not
necessarily true. It is much
safer to do the calculations and determine if does or not. How
to calculate Capacities
and flotation.
See also
Go
To Page 2 Calculating Capacities and Labels.
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Fig 2. Foam for the mid seat.
I went to a Home Depot and looked at insulation foam,
most of which is two pound density foam.
That is, one cubic foot weighs two pounds and supports 60.4 pounds
of weight when submerged. They have mostly polystyrene foam, which is fine in this
case, but if you are putting foam in a boat where it will be exposed to
gasoline or other oils, or solvents then you should use polyurethane which
will not be affected by gasoline. Styrofoam will dissolve. They had
sheets of foam, two inches thick, by two feet wide and eight feet long. This is approximately 2 ¾ cubic feet.
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I divided it up into three portions.
I needed some in the stern to float the engine, some in the middle
to provide stability and some in the bow.
I put about ¾ cu foot in the stern, split between the two corners,
¾ cubic foot in the bow, and the rest I glued to the bottom of the middle
seat top. This last portion
would probably never be submerged even if the boat filled with water, but
if it did it would provide very good stability and keep the boat floating
level.
I glassed in the foam in the bow and the stern to
keep the foam in place and so it would not be exposed to gasoline or oil.
But I am getting ahead of myself.
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Fig 3. A frame with battens glued on.
I cut out battens for each frame and glued the
battens to the frames with epoxy. I also glued together the two pieces of
the transom, the transom batten and plates for outboard mount.
I
then assembled the sides together with the butt blocks.
I was confused about how the butt blocks are oriented. It is not clear on the plans.
But after studying the plans and construction notes I think I got
it right. But I should have
left about 5/8 inches of space at the bottom.
Fig 4. Butt blocks for the sides
This allows space for the butt block that glues the
bottom pieces together. Again
this is not clear in the plan notes or on the plans.
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After everything set up I then put in the transom and
stitched it to the sides. I then stitched the bow together.
For stitching I used plastic wire tires.
Mostly I used white or opaque ones but, I used a few black ones.
This wasn’t a good idea as they show through the epoxy when you
cut them off.So use clear,
white or opaque.
Then I tried to insert mid seat frames and the butt
blocks on the sides broke. They were not strong enough to take the bend.
I had made them using ¼ inch ply as specified in the plans. I should have used 3/8 inch. So, I made two new butt blocks
and glued and clamped them directly over the broken ones doubling the
thickness.
Fig 5. Midseat showing broken butt blocks.
This time I inserted the middle seat frames first
before putting the stern and bow together.
Then I stitched on the transom and then stitched the bow together.
I then measured and inserted the rear seat frame and the bow seat
frame.
Each frame was positioned by measuring using the
dimensions from the plans and anchoring them with temporary screws to hold
them in place. But, again I
should have waited to make the seat tops because they were too wide (fore
and aft) and had to be trimmed to the correct width.
I then joined the bottom pieces with the butt
block.
After the bottom butt set up, I turned the boat over
and fitted the bottom to the sides. There
is a lot of overlap. The boat is at least an inch wider at the mid seat
than the bottom piece is. So
I took the mid seat frame out
and removed about 1/8 inch off the ends of the frames. Even after doing
that the distance between the sides was still wider than the bottom piece.
I then stitched the bottom to the transom and sides
at the transom and at the mid seat.I
used duct tape on all seams to hold it all together.
I should have used painter’s masking tape. The duct tape stuck to the epoxy filler after I filled the
gaps and was difficult to get off in places.
Being gray it showed through the epoxy.
Masking tape is at least the same color as the wood filler and if
it didn’t come off would not stand out. Then I turned the boat over to
fill the seams with epoxy wood filler and fiberglassed the seams.
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Fig 6. Taped seams
First
I glued all frames in. I had to trim the bow seat frame a bit on the right
side to get a good fit.
I used some scrap wood and clamps to hold bow seat
frame in place. I put at
least one screw in each frame to hold them in place. Overnight the tape let go and the bottom separated by
at least ½ inch at the bow seat frame.
I used some rope and boards to draw it back into place. And it
seems to have adhered.
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Then I cut all the fiberglass tape for doing the
inner seams.
At his point the weather turned bad.
Since I was doing this outside, as I had no shed or garage, I had
to wait for the weather to improve.
A few days later the weather improved.
The temperature was in the 60’s and sunny
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Fig 7. Improvising clamps
Here is how I pulled the bottom at the bow together
with the side pieces. I didn’t have any of the long extendable clamps so I had to
make do with what I have, which is lumber and rope and smaller clamps.
Actually in the photo the clamps are there just to keep the ropes
from sliding forward.
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I
placed two boards crosswise under the bottom and pulled them upwards to
draw them together with the sides by twisting the rope.
I repeated this at the transom to pull the bottom piece up to the
bottom of the sides and transom. I
started with very large gaps, maybe ½ inch all around.
Now the largest gap was less than ¼ inch.
Following the design instructions I mixed up a putty
of epoxy and wood filler to about the consistency of peanut butter and
filled the seams. Fiberglass
tape was then laid on the inside of the seams. It went very well.
My wife helped and did a great job.
She’s very good at wetting out fiberglass. When doing the filling and fiberglass work, it is good to
have a helper to make the job go easier and quicker.
This way you don’t have to think as much about pot life, and the
epoxy won’t set up before you get the glass on, wetted out and rolled.
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Figs 8, 9, 10 filling the seams.
While waiting for the epoxy to cure I cut out some
wood strips for the rails. After
three or four hours I pulled off all the tape and removed the clamping
boards and rope. There was one small hole that wasn’t filled at rear
seat frame, about a half inch long. I
filled this in later when I did the glass work on the outside of the
seams.
I also cut an opening in bow seat top for a hatch.
I glued strips about two inches wide to the bottom of the seat to
prevent hatch cover from falling through.
Also instead of putting a protruding handle on the hatch cover I
simply cut a one inch hole in the cover.
I cut off the part of the bottom piece that
overlapped the sides at the bow.
As previously mentioned I bought a 2’ X 8’ X 2”
piece of polystyrene foam. I
cut it into separate pieces and installed approximately 0.8 cubic feet
under the rear seat in corners, 1
cubic foot under mid seat and 1 cubic foot under bow seat.
I glassed the rear and bow foam blocks in.
I did this for two reason, to keep water or gasoline (from the
outboard) away from the foam, and to hold the foam in place. For the mid seat, I glued two 2 inch thick layers of the foam
to bottom of the mid seat with epoxy.
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Figs 11, 12, 13. Foam Flotation, stern, bow
and mid seat.
I also cut a small hatch in rear seat.
I then glued rub rails to starboard side.
I glued blocks to the inside of the bow compartment to support the
forward seat. Here I learned
a lesson. For small jobs
requiring epoxy, I had purchased a System Three epoxy kit in two
small bottles to be mixed 50-50. I
used this to glue these blocks. On
bare wood there was no problem, but on areas where there was already epoxy
it did not stick. I had to sand down the epoxy to get rid of the amines that
were preventing a bond between the two type of epoxy, even though I was
using System Three Epoxy Resins throughout.
The rear seat top did not sit level when I put it in
place. I put some putty on rear seat support (on transom) to level it.
The front seat was too wide so I shaved sides of front seat to fit
better.I fastened the mid
seat to frames with four brass screws rather than gluing it so if
necessary it can be removed. I will do the same with the rear seat but I
glassed in the front seat top.
I glued the rub rail to port side. I glued one block to hold front seat that had fallen off.
I glued a small block to bottom of front seat compartment and
another on the bottom of the cover for the cord to hold the cover in
place.
The rear seat had large gaps at both ends.
I glued trim strips to make up the gaps. I then cut out hatch cover
and glued hatch support to bottom of seat cover. I screwed seat to frames
so it could be removed at some point in the future.
I trimmed the front seat top, made a small triangular
piece to go on top, glued top onto frame and blocks.
I cut an opening in rear mid seat frame to use the
seat as storage rather than a hatch.
Fig 14. Hatches and openings.
I then turned boat over.
I ground down all chines, corners, bow, transom and filled any gaps
with epoxy putty. I coated
all edges with resin and put on glass tape.
I coated tape with resin. I ran
out of resin so I put
plastic sheet over the boat.
5/15. Bought
more resin and hardener and coated entire outside of hull. I then covered
the bottom of the hull with plastic as described in the build notes. This
did not work out well
When I took the plastic off the surface was very
uneven. I do not like what
the plastic does. It does not present a smooth surface.
I sanded transom. I
removed most rough spots. Trimmed
off the worst spots of glass sticking out, with a knife. I sanded the
transom with a sanding disk. Carol
sanded one side with an orbital sander (vibrating).
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Fig 15. Coating of QuickFill
I coated the boat with Quickfair.
It looks good but it will need light sanding.
Put some quick fair on bow. Should
have sanded down rough spots first. Does
not look as good as where I sanded first.
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I did not yet make a skeg.
The board I was going to use has a curve in it and it is too short.
The board from the bed is too short and not wide enough.
I will look at what is left of the bed in storage.
I am trying to straighten out the oak board.
We sanded one side and applied QuickFair.
Sanded down the bow area. Quick fair applies much smoother if most
of the rough spots are sanded off first.
We finished sanding and filling exterior. It
looks
pretty good. Carol did
a lot of the sanding and applying the fill. She was very helpful.
I drilled hole in the stem for a bow eye.
I fitted a bow eye but I don’t like how it looks so I took it out
and went with just putting a rope through the hole and knotting the end..
Trimmed the front seat edge to align with frame.
Trimmed the mid seat top to align with box.
Sanded down edges of seats. Planed top of frame battens on mid seat
down to edge of plywood.
Filled all seams around frames and seats with wood
putty. Learned that a foam
pad brush works best for smoothing the putty.
Carol helped with sanding and filling.
It took about 5 days to completely sand the interior
of the boat with 60 grit paper. I
then gave the interior a complete coat of epoxy.
I then lightly sanded the entire interior (not
inside seats) with 150 grit and coated with second layer of epoxy. At this point the interior was essentially done.
I made backing blocks for oarlocks. I made these out
of African mahogany that I had scavenged form a bed made in the 1840’s.
This is truly beautiful deep red wood.
I glued them to gunwales with epoxy.
I put them on the inside of the boat but later after having rowed
the boat I moved these to the outside of the gunwales to separate the oars
by a few more inches.
I bought some 7 foot oars and installed
oarlock sockets and oar locks. The length of the oars
should be about twice the width of the boat which, would have been 8
feet, but the closest I could find ready made were 7 foot. They feel
right when on the boat.
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Fig 16. Skeg
I made the skeg out of white oak and glued it to the
hull. I have been told white
oak does not glue well so I am waiting to see how well this works out.
This oak was also from the bed.
There were three oak cross pieces that the mattress sat on.
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I planed the top (bottom?) of skeg and sanded it
smooth. A nice trick when coating the skeg to
keep the epoxy from running onto the hull, is to put masking tape around the
skeg so I laid tape down to catch epoxy.
I liberally coated the skeg with epoxy. After about three hours
removed tape.
I did some more sanding on the bottom and sides.
I sanded through the epoxy in a couple of spots and had to re
coated with epoxy.
Finally I put on a primer coat. Looks good. Covered
very well. Did not fill much. It used
only one quart. I painted the
outside of the hull with medium blue Interlux Brightside Polyurethane.
It took about half a quart. I
used a foam roller, which left lots of air bubbles so I had to go over the
whole boat with a brush to get rid of the bubbles.
Fig 17.
Paint job
I then made HIN labels and a laminated capacity
label. I put the labels on with epoxy resin.
Total cost was about $600.00. The most
expensive material was the epoxy.
Fig 18. July 5, 2008: The launching. She floats
beautifully. We spent about four hours on American lake. We rowed it and motored with a two horsepower
outboard.
Lessons
learned:
The mid seat is too high. The oars hit my knees on
the back stroke and I am not that tall. I had to move the oar locks
farther outboard and about two inches farther aft. Alternatively, lower
the seat.
The battens holding up the hatches came off when the
hatch was sat on. They had to be made wider and
re-glued.
Plastic does not adhere well to epoxy.
Take your time. Haste results in making parts that
don't fit.
Use a measuring cup or one of the devices sold by the
epoxy makers to measure the two part resins. Measuring by weight is
not accurate. Use volume. Use disposable cups or pots.
It's wasteful but much easier to deal with.
Wear rubber gloves.
Wear clothes you would be willing to throw away at
the end of the project. You WILL get resin on your clothes.
It is inevitable.
The use of a large plastic sheet to get a smooth coat
(what the designer called poor man's pre-preg) did not work well for
me. Maybe I did it wrong.
I think this is a great way to build a boat for an
amateur or for someone wanting to put together a boat quickly and
relatively cheaply. But my feelings about glassing over wood still
leaves questions in my mind. How long will it last? I think I
still prefer traditional methods despite the fact that they take more
skill and take longer. To me they produce a real work of art. However,
this can be done with hand tools and does not require any special jigs or
molds. I built it on a picnic table in an RV park. The only power
tools I used were a circular saw, a power drill, and several orbital
sanders.
Go
To Page 2 Calculating Capacities and Labels.
Revised 01/13/2011 copyright 2008 All rights reserved.
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