
SUPERYACHT #517 May 2005
Article selected from our quarterly magazine dedicated to the largest
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Article by Lino Pastorelli

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DIANO SHIPYARD The kingdom of wood
A visit to the Diano Shipyard in Riva Trigoso creates a strange
mixture of sensations. If on the one hand there emerges the spirit
of tradition and amid the smell of wood the almost obsolete jargon
of the old shipyards rediscovers life and meaning, on the other
hand we encounter designs, lines and power that have little to do
with imaginary memories of a distant and smaller nautical world:
or perhaps this functional antique-modernity too, so imbued with
the Ligurian nature of Diano and his personnel, is already
classic, just as the things that the sea has selected over the
years are classic.
Mario Diano set up his Shipyard in 1979,
deciding to build in wood precisely at a time when fibreglass had
entered predominantly into the superyacht market: ".... years of
easy money, they were selling boats at the price of wooden ones
though they only cost a third to build. but I insisted because I
came from another culture, first commanding big wooden yachts,
then my work with Sangermani and with Spertini Alalunga; in a
word, wood as a raison d'ˆtre. Now I congratulate myself on the
choice. My boats are highly sought after, they maintain their
price, they sail well, they last long. And then a detail that is
not negligible for someone who already has a lot and comes to
purchase a yacht of this kind: they're one-off pieces!"
Mario Diano explains the specifications he needs from an owner: speed,
power, layout, this in order to position the hull within the
desired size range. "... if for example on a 23 metre we're
building at the moment the owner had asked for only 2 x 1300 HP
engines, the boat could have been 21 metres as per the original
request. The decision to install 2 x 1500 HP meant lengthening the
engine room and hence the boat by a metre and a half to maintain
the right spaces and proportions. And then the request for the
galley on the lower mid deck to keep the saloon unencumbered:
where will you find this on a mass produced boat? In brief, a boat
of mine is like a bespoke suit, it certainly "hangs" better than
something off the peg!".
Given that the group's boats - the Diano
models built, to be precise, in Riva Trigoso and the Santa models
in the yard at S. Margherita - are all fast planing hulls with
flying bridge and lengths between 20 and 33 metres, let's take a
look at how they are built. The boat's spine, the keel, at least
for lengths up to 30 metres, is of the mixed type: the rectilinear
part aft is in solid mahogany measuring around 230 x 200 mm. and
is joined to the curve and the bow upright, constructed in
laminate: the ten 20 mm sheets of which it is composed mean that
the necessary curvature can be followed without inappropriate
cutting of the wood fibre and without excessive waste. The yard's
biggest vessels however - the 33 metres of the Santa 33 - require
lamellate for the entire keel: the stresses of the 2 x 2500 HP
engines are considerable and it is better to section and
reassemble a plank in order to be sure of its perfect intactness.
Mahogany is also used for the girders, the six reinforcements
which run longitudinally from bow to stern, average size 150 x 100
mm, and which, suitably capped in steel, support the engines.
Mahogany is again used for the shelf-pieces, the frame-floors, the
coamings (the "joints") of the deckhouse and stringer and the edge
of the planking between bottom and side frames. Forward, given the
necessary curvature, it is in lamellate.
We find lamellate again
in the false keel, the wedge-shaped "fin" up to half a metre long
which lends directionality and toughness. Certainly not of
secondary importance is the advantage this appendage gives in
limiting leeway during manoeuvres. The frames, the transversal
skeleton of the boat, are in ash: the positive factor lies in the
high flexibility of this wood which can absorb lateral shocks
without too much stress on the overall structure. Their spacing is
proportional, reaching centres of 150-200 mm. at the points of
greatest stress, i.e. the bottom and the forward part of the
vessel. The planking is differentiated: for the bottom, a base of
RINA homologated 18 mm. ply, known as "armoured" because it has
double the average number of layers, is nailed to the framing and
faced with a 16-18 mm. layer of solid mahogany glued with deck
rubber. Heavy duty bolts with stainless steel pins, made directly
in the yard, fix the whole of the planking to the girders, and the
false keel too is bolted with the same system, using staggered
holes to avoid weakening.
The side frames are in RINA ply with the
thickness increased to 20 mm., as is the transom. It should be
specified that the elegant inverse transom of the Diano is in fact
a panel constructed in laminate, three 6 mm. layers, whose
envisaged function is shock absorption. The actual structural
transom is vertical and laid on a tough mahogany frame. So double
planking for the bottom and single for the sides. Here, to obviate
possible scoring of screws and pins, 3 mm. ply is glued to the
sides with the vacuum technique (certain parts of the furnishings
are also created in this way): "... two extra weeks of work for
each boat, but it's worthwhile because the finish is excellent!"
Aft of the engine room a further reinforcement is glued and bolted
to the bottom: 50 mm. of wood that gives the propeller supports
and the boring of the prop shafts a tried and tested toughness.
The teak deck and the superstructures in solid wood, ply or
laminate depending on aesthetic and functional requirements, are
laid on mahogany beams.
The finish of the hull is obviously
commensurate with the rest: three coats of West System for total
impregnation of the wood, then a primer, two coats of putty with
intermediate sanding down, an enamel undercoat and then a final
coat of Awl Grip enamel. Given the fundamental nature of the thing
we asked Diano about his relationship with the suppliers of his
raw material, wood: "... I buy from Magnino Legnami of Alessandria
and our relationship is very simple: I ask for prime quality wood
and he gives me prime quality wood. When it's necessary I go, or
send someone, to see the mahogany trunks. We select, we buy, we
have it sawn and then we leave it to season up there, to suffer
the cold and the bad weather, in a word to age. At the right
moment, meaning when a job starts, we cut and plane and reduce the
wood to measured planks, since we already have a clear idea of
what they're to be used for, be it keel, lamellate, girder or
whatever. The core of the trunk is not used, nor is the internal
and external layer of bark. There's considerable waste: for a 24
metre boat you need about 70 cubic metres of trunk, but at least
there's no problem of waste disposal; the chips go for horse
litter, the sawdust for making fertilisers and the logs for the
country people's stoves!".
We also asked Giovanni Magnino, one of
the biggest timber dealers, something about the wood in question.
"... From me Mario Diano buys prime quality European ash (Fraxinus
excelsior) and African mahogany (Khaya ivorensis). Mahogany was
first used in shipbuilding in the 19th century for ship furniture
and then planking before it was realised, on the diminution of
traditional national woods, that it could be used for all parts of
the vessel except the framing. With present day epoxy treatments,
anti-woodworm and antifouling, there isn't the minimal risk of
parasite attack, even in tropical waters. These wooden boats are
so anhydrous that it is actually easy to find cobwebs in the bilges."
We then spoke again with Mario Diano, asking about his
immediate projects. "I've got orders for a 33, a 27 and a 20
metre, as well as the idea for an open, backed up by several
customers: 30 metres, in lamellate, 45 knots. I'll try to go ahead
with it even if there are some objective difficulties with
municipal administrations that consequently influence planning."
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