22 PROFESSIONAL BOATBUILDERREFIT: Rybovich Rebuildsmodeling the full hull shape in
Rhino so ware and then applied
Dave Gerr’s best practices to
create what Bandy called “a very
simple pocket” as a prop tunnel
amidships. With the propeller
thus recessed, he found he could
t the engine in with a modest
3.9° sha angle.
Making the plan was one thing, but
the change to the hull was far from
simple. e chine remained the same,
and the deadrise to the keel was con-
sistent with the original. “But the last
third of keel was removed for the tun-
nel,” Bandy said. When he replaced the
frames in that aftersection, he built
in the radius of the tunnel as he’d
designed it, supporting the curved r
sections with plywood gussets. Upside
down, it looked as if the last 7' (2.1m)
of the keel had been scooped o the
boat with a giant melon baller.T
his was the rst point at which the
rebuild was not simply a matter of
re-creating the structures the way they
had been in the 1950s.
“I’ve always been afraid of investing
money in a rebuild,” Bandy said. “In
order to protect that investment,
you’ve got to do a certain amount of
math.” An admitted seat-of-the-pantsequipment, but Bandy and Hall
wanted single diesels. Aside from the
obvious bene ts of durability, safety,
and reliability, the single diesel would
also allow for the engine weight to be
located lower in the hull. e height
constraint imposed by the distance
between the bottom of the hull and the
cockpit sole was 38" (97cm), tight for
the kind of horsepower Bandy wanted
to install. Some online research led
him to conclude that there was just
one powering option for these boats
that satis ed his size and weight-to-
horsepower requirements: the Cum-
mins QSC 8.3. Bandy said the old
small blocks probably weighed 850 lbs
(356 kg) each, while the Cummins
coupled to a ZF 286 transmission
weighs in at about 2,300 lbs (1,043 kg),
delivering up to 600 hp (448 kW).
More important than the weight
di erence was the switch to a single
propeller. is required more than just
bee ng up existing drivetrains to han-
dle a 100-hp (75-kW) jump
in power. Bandy drew on
his previous powerboat
design work and signi cant
on-the-water experience to
redesign the a erquarter of
the classic Rybovich hull
bottom. He started byyears. ere were multiple gaping
holes in her topsides, and green vege-
tation growing on the hull.F
ollowing what he’d seen Bingham
do, Bandy rst stabilized the keel
shape with construction lumber and
then jacked the hull back into shape
where it appeared to have distorted.
After stabilizing the planking by
screwing laths to it from the outside,
he removed the chine, and starting
from a , he pulled one frame at a time,
using them for patterns to cut new
ones. He replaced all but 11 frames in
the boat, using Douglas- r below the
chine and oak from chine to sheer, and
replaced the chine logs and refastened
the topside planking as he went.
With both hulls stabilized, they
turned them over to work on the bot-
toms. Bandy said he needed to replace
the original keel in Timid Tuna, as it
was broken in multiple places, twice
under the original fuel tanks. (Inter-
estingly, her original laminated stem
was perfectly sound.) But he was also
planning to depart from the Rybovich
design in the underwater shape and
con guration.
Originally designed to be powered
by twin gas engines, the hulls carried
their sharp keel and variable deadrise
all the way a . In that con guration,
any protrusion of the engines or
exhaust risers above the cabin sole
could be concealed by built-in furni-
ture in the cabin. Twin 331 Hemis
were original 1950s-vintage operatingThe Cummins QSC 8.3,
nestled in the bilge on the
new stringers and custom
hangers, had to t in a height-
restricted 38" (97cm) space.The 1950s-vintage twin Rybovich
36s Butterball, left, and Timid
Tuna arrived at Bandy Boats
(Mayo, Maryland) in derelict
condition. Butterball had been
tted with a newly cold-molded
bottom.AARON PORTERRybovichRefit170-AdFINAL.indd 22 10/31/17 2:24 PM