Examples of traditional frame-first boat construction in
Asian cultures are rare. Throughout the Far East, Middle East and east Africa,
shell-first construction of planked boats is the norm, where it is used for everything from
sampans and junks to dhows. One of the few exceptions is the vattai, an open, sail-powered,
flush-planked (carvel) fishing boat common in the state of Tamil Nadu, in India’s
southeast.
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| A vattai in Tamil Nadu. Source: Blue (click any image to enlarge) |
The vattai is described by Lucy Blue in “The Historical
Context of the Construction of the Vattai Fishing Boat and Related Frame-First
Vessels of Tamil Nadu and Beyond,” published in Ships and the Development of Maritime Technology in the Indian Ocean
(David Parkin and Ruth Barnes, editors; Routledge, 2016). The information and images
in this post are from that article.
To quote Dr. Blue:
"Vattai, are flat-bottomed, have a box-like transverse section and are near wall-sided over much of their length. They range in size from around 13.72m long, with a beam of 2.13m and a depth of 1.37m, to the smallest vessels of c. 5.18m x 1.07m x 0.76m. However, irrespective of their size, they are all similar in shape with very high bows, and two or three masts each with a settee-lateen sail, a balance board, and, uniquely on this coast, leeboards."
The design process is of much interest. A single mould form
or template is used to lay out most of the frames on a scrieve board, the form
being flipped to draw the port and starboard half-breadths. (Forms for
different boats differ from one another, apparently, only in the radius of the
curve that joins their two straight, right-angled legs.) Since the boat’s
cross-section (half-breadth shape) is constant across its entire midbody, a
single shape drawn on the scrieve board suffices to define most of the frames, and
this follows the exact shape of the form laid square to the edges of the scrieve
board.
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| Use of the mould form and scrieve board (A) to create the shapes of the "equal" frames for the midbody (B,C,D), and the progressively narrower frames toward the ends (E, F, G). |
Fore and aft of the “equal” frames that constitute the midbody,
each of the next three progressively narrower frames at the bow has an
identical counterpart in the stern. These frames that define the ends are
derived from the same mould form according to a formula that defines how far in
from the scrieve board’s upper edge and how far up along the diagonal the form
is placed. By rotating and raising the form, different frame shapes may be
drawn to create the narrowing and flare of the hull’s ends. The final three
frames in the very bow and stern, however, are not drawn or gotten out at this
time.
In the boat recorded by Blue, there were 15 “equal” frames
for the midbody plus 12 “unequal” ones, evenly divided between the bow and
stern. The midsection always consists of an odd number of frames – the central master
frame, and equal numbers of identical frames fore and aft of it. The design can
be readily made longer by the addition of more equal frames in the midbody with
no changes to the ends, and made wider starting with a wider scrieve board but using
the same mould form. Rules of thumb establish ratios between length, breadth, depth,
and frame spacing, so the builder’s discretion to make changes is limited mainly
to his choice of the mould form and number of frames.
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| Vattai construction drawing |
Frames are built up from floor timbers and futtocks, which
are assembled with “a complex dovetail joint” that “extends right through the
turn of the bilge.” The vattai has no backbone, so apparently the frames are set
up on the straight, flat bottom planking, which must be laid down first. Stem
and sternpost are butted with a lap joint against the ends of the central
bottom plank. The article states variously that the shapes of the very ends are
determined by battens (ribbands) or by laid planking between the
midbody frames and the end posts. Whichever is truly the case, these define the
shapes of the three final pairs of half-frames at each end. Only in these final
three sets of frames do the shapes of the vattai’s bow and stern differ. They are
installed without floors, their lower ends overlapping fore-and-aft where they land on top
of, or are notched onto, the stem and sternpost. (This detail can’t be
determined from the drawing.)
I have been unable to find any other photos, descriptions or even references to the vattai through Google searches and would welcome additional
input. There is much else I’d like to know, including:
- whether the planks have a caulking bevel, and the materials (if any) used for caulking
- the design process for the end profiles (i.e., whether the stem and sternpost shapes are determined by template or drawn by eye.)
- details of the rig and leeboards
- details of usage: crew size, responsibilities, sailing procedures and performance
I would also much like to see additional photos. Google
image searches for terms like “fishing boat Tamil Nadu” yield a number of stock
photos of open fishing boats that do not appear much like the vattai (the distinctive bow shape is an easily-noticed identifying characteristic), and nothing
else even close. Please communicate in the comments if you can add to the
discussion.