Professional BoatBuilder - February-March 2018

FEBRUARY/MARCH 2018 23

Rather than a grid, the 60 has

four full-length stringers cored

with Diviny cell H100 and

H130, plus two shorter string-

ers because of the break at the

forward end of the engine bed.

Hull No. 1 of the 60 has Kevlar

down the center and over each

of the strakes, which are  lled

with putty and glassed over.

 e lamination schedule for

the hull forward: gelcoat, 2-oz

chopped mat, (1x) 1708 E-glass

double bias w/mat, (1x) 3610

E-glass biaxial w/mat, 1" Core-

cell M130 foam core, (1x) 1708

E-glass double bias w/mat, (1x)

3610 E-glass biaxial w/mat.

Core thickness is increased a.

The topsides layup includes

Spraycore 1800LS as well as

Corecell M80.

While Blackwell, Cody Kozlowski,

the customer service manager brought

over from Cigarette Racing, and I

observed, the crew pulled vacuum on

hull No. 9 of the 35.  ey held it for at

least six hours to get air out of the

materials and con rm vacuum integ-

rity. “Everything gets real tight then,”

said Blackwell. “Burnout tests show

70%  ber and 30% resin.  ose are

phenomenal numbers, better than I

thought we could get.”

Corecell foam core is employed in

the deck, topsides (^3 ⁄ 4 " M80), and tran-

som of the 35. Here is the lamination

schedule for the 35 hull bottom for-

ward: gelcoat, 2-oz chopped mat, (1x)

1708 E-glass double bias w/mat, (3x)

3610 E-glass biaxial w/mat, (1x) 3408

E-glass we triaxial w/mat. A , there

is an extra ply (4) of 3610 E-glass biax-

ial w/mat.

“All kinds of heavy-duty materials

go into this boat,” said Blackwell. “But

we don’t put exotics in just to put exot-

ics in.”  e only carbon  ber in the

boat is H84 in the window pillars to

support the  ybridge.

and roll. We decided on a robust o -

shore hull for the 35 and didn’t think

we needed to go as extreme as the

1960s design, allowing for better per-

formance, propeller pockets [10° sha

angle], and a drier ride.  e new 60'

Bertram is 17° at the transom with a

deep entry with plenty of recovery for-

ward, with a hull design well suited for

upper 40-knot speeds and superior

ride.”

Considerations for the 35 ran

deeper than the lines and look. How

the boat would be put together utiliz-

ing current materials and processes

also in uenced the design.  e 31

consisted of about  ve molds; there are

nearly 60 in the 35. On the old 31 the

 ybridge was bolted on and seams

covered with aluminum J molds—

unacceptable in today’s market. And

reinforcements were basically mat and

woven rovings, though the judicious

use of Kevlar was later added.

“ e 35 is completely 3D-modeled,”

Peters said. “All plugs are cut with a

router.  e hull and most parts are

infused.”

Peters said he personally recruited

Earl Blackwell to help set up the Ber-

tram shop. “We can’t design with no

one on the other end,” he emphasized.

“We have to draw what somebody

understands how to build. Earl was

over at Chris-Cra and we’d done a lot

of work with them. I got a note one

day that said Earl had le CC. I called

him up and dragged him over to Ber-

tram. Designers can’t work alone. You

can’t design in a vacuum. You have to

work with the builder. You have to say,

‘Can you guys do this?’  ey might

say, ‘Here’s an easier way to do it.’ A lot

of designers don’t do that, just give the

builder the drawings and say, ‘Make it.’

 ere is a big di erence between pro-

duction and a one-o. We go through

every  ange and connection. It’s much

harder.” —Dan Spurr

Bertram 60

Instead of a molded structural

grid, the 60 (18.3m) has four

foam- lled longitudinals glassed

and bagged to the hull.

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