Building A 7 ft. 10 In. Sailing Pram
(or Picnic Table Boat Building)
Page 1 of 2.
I was looking for a new project to build. I wanted it to be a sail boat,
but small enough for one person to lift and launch, and easy to build.
I had some designs of my own but while looking through them I found the
plans for a small pram that had been designed for the American Plywood
Association in 1958. I had purchased them back when I was a teen,
but had never gone beyond studying them. The boat was first designed by C.
P. and E. D. Burgess, and later revised by Edwin Monk for the APA, as part
of the APA's program to publicize the ease of building with Douglas Fir
plywood. Probably the best known boat from the APA is the Thunderbird.
However, the plans are for conventional construction and I wanted to do
this one in stitch and glue, slightly modified. Instead of stitching I
would use boat nails to tack the hull together before gluing the seams
with fiberglass tape and epoxy. I do not want to fiberglass the entire
boat. This took some planning on how to proceed. I also
discovered that many details were left out of the plans, and some of the
dimensions did not add up. But, more on this later. So in a way it
is my own design.
The plans called for three sheets of 1/4" Douglas Fir Exterior grade
plywood. I decided to use 6mm Okoume BS1088 marine plywood which is
rather expensive but well worth the cost. But more important, I had
some excellent dark red mahogany wood recycled from a four poster bed made
in the 1840's. I would use this through out the boat. In
addition to trim and small pieces, the transom, rudder, skeg and part of
the centerboard trunk
are all of this wood. I also planned to use System Three Epoxy which I had
great success with on the
FL 12.
I might add that I live in a motorhome, and I am building boats in an RV
park. So my work surface is a picnic table. That's why I call this Picnic
Table Boat Building. This also affects when I can build and how much I can
do. Plus I do not use a lot of large machines. I use hand tools and a few hand
power tools. My only large machine is a portable table saw that I
bought specifically for this project. I needed it to rip out strips
for the miscellaneous parts. They were taken out of the side rails of the bed.
The weather has the largest effect, and here in the Pacific northwest it
rains; a lot! This significantly played into how long this project took.
Fig 1. Plans for the dinghy (click on the image
for a large view.)
Initially I bought 2 sheets of 6mm marine plywood from Edensaw
Woods. Out of one sheet I cut out the two sides and two
pieces for the transom, and out of the other sheet the bottom.
I went back and bought a third sheet to cut out the parts for
the rear seat and forward seat. |
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Fig 2 and
Fig 3
From the head board of the bed I cut out the transom
and the rudder. |
I built a jig, or strong back, to build the hull on. I
used scrap lumber for this. I also built two molds to help the
hull keep it's shape until the Fiberglass tape was applied to
the seams. Fig 4 shows the jig.
Here is where I ran into the first problem. The plans do not
show the angle of the bow and transom. However, from the plans
for the jig it show a measurement for the rise and run
(horizontal distance and vertical distance) of the blocks that
hold the bow and transom. From this you can get the angle. Fig
4 |

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Fig. 5
Also, the plans do not give this actual length of the sides.
It gives the curve of the top and bottom. But you have to fit
the sides on, attach them and then cut off the excess.
Fig 5 shows the sides extending beyond the bow. |
The next step was the bottom. Of course they gave no
dimensions at all for the bottom. So I measured the length and
maximum width and cut a piece slightly larger. This had
to be trimmed down to the right size. Fastening the stern
first to the transom and then then to the bow. Fig. 6 |

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Big problem!. The ply would not bend around that curve (see
fig 5.) in fact the whole thing flew apart and had to be
completely reassembled. The curve on the piece had to be
lowered drastically to fit the bottom. Fig. 7
But I finally got it to fit. |

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Fig. 8
This is what it looked like after the tape was put on.
Initially I used a much heavier fiberglass uni-directional
tape but it looked terrible and so I took it off before the
epoxy could set up. I used 6 oz. 4 inch wide plain weave tape.
After it was ground down and re-epoxied it was almost
invisible. This is before it was sanded. |
Fig 9.
This is my boat building "shed" Of course this is the
first time I had to move (nothing to do with building a boat)
and I had to move 2 weeks later to another RV park. The
weather throughout this has been horrible. We have had about 3
or 4 days of beautiful weather and the rest of the time (about
a 6 weeks now) has been rain rain rain. It's raining as I
write this. |
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The
next step was to flip the boat and seal the inside of the
seams with epoxy putty.
Fig 10. Inner seams
After this I installed the seats. According to the plans the
front and rear seats were the typical platform type seats. I
made them as sealed boxes, air chambers to provide flotation.
The mid seat is a simple athwartship board. it is support by
cleats on each side and eventually the centerboard trunk.
Unfortunately I did not photograph the seat installation.
Continued on Page 2. |
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Revised 04/03/2011 Copyright 2011
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