When Scientists released the discovery of  a series of complex "deadlights" covering the 10 portholes in the Hunley's crew cabin ceiling they were measured to be about one inch-thick made of, cast-iron and served to strengthen the hull to keep them watertight particularly around the glass ports, one of a sub's most vulnerable hull penetrations.

The deadlights also served to mute the glow of light from inside the submarine when she was running just beneath the surface of the
water.

Even though the interior of the cabin was painted white the need for more interior light became obvious yet they had to also maintain their stealthiness by being able to shut the light out to observing enemies.  They thought ahead about light giving away their position and the
more serious problem of the results of leaking.  All of these optional equipment amendments added to the ingenious advancement that
the designers thought out way in advance of any planed attacks.
The Hunley was a stealthy, sleek attack weapon not simply
something fashioned out of a boiler.

In old diagrams of the sub, the word "deadlight" appears in
connection with the ceiling portholes, which acted as skylights
and illuminated the sub during the day. Most people thought
that was merely a reference to the portholes, not any mechanism
beneath them.  

Hunley-full-top By: b_rogoff

The deadlight coverings have been hidden in the concretion
covering the submarine. Scientists are just beginning to chip away
at the mass of silt, sand and shell that has enveloped the sub like a cocoon for more than a century. In some places, the concretion is
harder and thicker than the sub's metal hull. Conservators have
cleared the concretion from one of the two deadlights in the first
hull plate that scientists removed to gain access to the sub in 2001.
The other remains buried under a mass of concretion.

The deadlights kept the Hunley hidden from Housatonic sailors
on the night of Feb. 17, 1864. Although one sailor testified he
saw a faint glow of light, probably from the forward conning tower,
it wasn't enough to give the Union troops much of a target. No
survivors recounted seeing light from multiple portholes.

With the sub cruising just 2 feet below the surface, the portholes
 -- if left uncovered -- would have looked like an airport runway
at night, outlining the sub's exact position.

The thickness of the deadlights suggests they had a more serious purpose, as a thin piece of tin could have blocked the light.
Senior Hunley conservator Paul Mardikian removed the glass from
the  deadlight and remains of a dome-shaped rubber gasket, perfectly preserved.,

GRACE BEAHM/STAFF courtesy of the POST AND COURIER Charleston's Finest Newspaper

Senior conservator Paul Mardikian watches as Philippe de Vivies chisels away concretion Wednesday from one of the Hunley's hull plates.

Mardikian said "the rubber may have buckled or the inside of the deadlight cover could have been shaped to fit into the porthole.
That would have made the sub watertight around the glass,
which was only 1 centimeter thick and vulnerable to gunshot -- or perhaps the repercussion of an exploding torpedo. "

"It was probably meant to plug it," Mardikian said. "It's very funny
with the Hunley, how you think it is so simple and when you get
into the details you are amazed at how well it was constructed."

FROM DICTIONARY.COM
dead·light    ( P )  Pronunciation Key  (ddlt)n.

1. Nautical.
   1. A strong shutter or plate fastened over a ship's porthole or cabin window in stormy weather.
   2. A thick window set in a ship's side or deck.
2. A skylight constructed so that it cannot be opened.

   n : a strong shutter over a ship's porthole that is closed in stormy weather

---

[ Home ] [ Up ] [ NEWSLETTER INDEX AND LINKS ] [ SITE MAP ]

 

Excerpt from Newsletter 61-See Newsletter Index and Links for more