Propellers, Shafts & Rudders

propeller & rudder
modern brass propeller
A huge modern brass propeller ( from the SS United States ) on display.
shipwreck Delaware propeller
Looking down the prop shaft at the iron propeller on the Delaware. The narrow squarish blades indicate that this is a rather primitive 1880's model, unlike the more modern rounded prop on the Macedonia below.
shipwreck Macedonia propeller
The propeller on the Macedonia.
shipwreck Macedonia shaft mount
Propeller shaft bearing and mount on the Macedonia.
reef Venturo propeller
The propeller on the GA Venturo - a completely modern design. Note the wide, round blades.

Breaking a propeller shaft at sea can be a disaster. The propeller stops turning and becomes a drag, while the vessel's momentum carries it forward. The propeller slams backward, extracting the broken shaft and often mangling the rudder. This leaves a large hole open in the bottom of the vessel, directly into the bilges and machinery spaces. On a large vessel with a deep draft and a large shaft, the water comes in like a fire hose - uncontrollable.

The engine is soon disabled, and along with that the pumps, which in any case are probably not big enough to keep up with this magnitude of flooding. The outcome may take several hours, but it is inevitable unless maybe the Coast Guard can fly out a special de-watering pump on one of their big helos. Unlike a collision, storm, or rogue wave, there is usually plenty of time for an orderly abandon-ship, and there are seldom casualties if rescue is available.

Shipwreck Emerald
The "Emerald" fell victim to a broken prop shaft in 1873, and the Lady Gertrude sank the same way in 2016.
shipwreck Oregon steering quadrant
The fallen steering quadrant on the Oregon, perhaps 20 ft across.
shipwreck Tolten steering quadrant
Tolten steering quadrant
Tolten steering quadrant
The steering quadrant on the Tolten

By Bret Gilliam - 3/16/01
Technical Diving Editor and CEO
Technical Diving International

Are we hypocrites, or just following established guidelines established by reasonable people to protect our clients??

The April 2001 issue of Rodale's Scuba Diving has numerous articles acknowledging the practice and practicality of Solo Diving. I'm going to enter the articles and acknowledge the authors of each (rather than plagiarize these good peoples work)

Let's welcome the new millennium by finally ending the absurd controversy over solo diving and grant certification status to experienced divers through formalized process.

Codifying solo-diving with practical standards makes sense for two reasons: First, divers are who currently diving independently without formal training will be encouraged to receive the instruction they need. Second, the buddy system is deeply flawed. It fosters dependent behavior in many divers and is a proven not to enhance safety. In fact, it may do just the opposite for many divers forced into the role of buddy.

Printed from njscuba.net