36
SVN Solovelanet Global
On top,
the bulb of a
T-shaped keel
touches the
water during
launch. On the
left, a lead bulb
has hit a rock.
As you can
see, it has been
warped, and
in this way it
has absorbed a
substantial part
of the impact.
Below on the
left, a trapezoi-
dal lead bulb, a
shape that is no
longer in use
Nowadays the world of appendages is continuing to
evolve, and the frontier is again the America's Cup,
where foiling technology has been embraced, as well
as offshore regattas, where most open ocean boats
are now using canting keels. So let us take a look at
the world of keels, starting from the materials used.
Lead and cast iron keels
The two main materials used for manufacturing
keels are lead and cast iron. The main difference
between the two is the specific weight, cast iron
being significantly lighter than lead (7 kg/dm3 ver
-
sus 11.34). This means that, given the same weight,
cast iron will have greater volume and therefore resi-
stance to water. For this reason, many racing boats
are equipped with a lead keel. Lead is also superior
in case of collision, since it tends to deform, cushio-
ning the blow and also making the damage easily
detectable. A cast iron keel, instead, because of its
hardness, will transfer the impact to the boat while
hiding the damage done. At this point you probably
will be wondering why aren't all keels made of lead.
The answer is easy: lead is much more expensive.
