Scuba Diving - New Jersey & Long Island New York

Scuba Diving - New Jersey & Long Island New York

Welcome to Scuba Diving New Jersey
& Long Island New York  - dive Wreck Valley !

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Propellers, Shafts, & Rudders

propeller

(c) Rich Galiano
A huge modern brass propeller ( from the SS United States ) on display.

(c) Rich Galiano
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.

(c) Perry Arts
The propeller on the Macedonia.

(c) Perry Arts
Propeller shaft bearing and mount on the Macedonia.

(c) Rich Galiano
The propeller on the GA Venturo - a completely modern design.
Note the wide, round blades.

(c) Rich Galiano
The fallen steering quadrant on the Oregon, perhaps 20 ft across.

(c) Ed Knepshield
(c) Ed Knepshield
(c) Ed Knepshield
The steering quadrant on the Tolten


 

Paddlewheels

(c) Denbigh Project

The paddlewheel predates even the steam engine. Horse-driven paddlewheel ferries have been in use for hundreds of years. Compared to screw-type propellers, the design and construction of a paddlewheel is much simpler, and therefore they remained the dominant method of propulsion through the mid 1800s, with some examples remaining in use until after World War II.

Compared with screw propellers, paddlewheels had a number of disadvantages. Greatest among these was efficiency - early-on it was shown that in a tug-of-war, a propeller-ship would pull a paddle wheeler of equal size and power backwards. Paddlewheels were also much more delicate than propellers, especially in the stormy northern oceans, where waves have actually smashed the paddlewheels off a number of vessels, leaving them to drift, or limp home by sail if they were so-equipped. On a warship, a paddlewheel was likely to be the first thing shot away in a fight.

Paddlewheels also had a few of advantages over propellers. They could operate in very shallow waters where a propeller would strike the bottom. Side-wheel paddleboats could operate in extremely tight quarters, literally spinning in place by putting one wheel in forward and the other in reverse. Most paddlewheels also function equally well in forward or reverse, unlike a propeller which is designed to go in one direction only. This made them ideal for use on ferries and tugboats, which often find themselves needing to go backwards.

Mistletoe
The side-wheel excursion steamer Mistletoe. Note the large round box around the
paddlewheel, to contain the spray that would otherwise soak the ship.
If you look carefully, you can also see that she's going backwards.

(c) Atlantic Divers
The "Inshore Paddlewheeler" - the Champion ?

Stern-wheel paddleboats could operate in debris-strewn waters, since the wheel was protected from damage behind the boat. It was also much easier to repair a damaged paddlewheel than a propeller. Therefore, in the later 1800s, paddle wheelers came to dominate river and inland traffic, while the propeller found greater use in ocean traffic. Ultimately, however, the paddlewheel lost out to the propeller entirely, and today it is only found on antique vessels and a few excursion boats.

(c) Denbigh Project

(c) Denbigh Project

CG illustrations courtesy of the Denbigh Project

Above are two truly superb depictions of a Civil War-era side-wheel paddleboat's propulsion plant and wheels. The large brown object at right is a fairly primitive low-pressure boiler. The gray barrel-like objects at the left are the vessel's two independent steam engines, each with a single cylinder. Horizontal direct-acting engines like this were typically found on European vessels, while American designers preferred upright walking-beam-type engines, as is evident in the photo of the Mistletoe above.

Since the two engines here are completely separate, they may be reversed independently of each other, giving the turn-on-a-dime capability described above. This is done not with a reverse gear as in an automobile, but by reversing the engine itself - a trick that is still used in some marine diesels today. Side-wheelers like this were much preferred over sternwheelers for open-ocean service, and I believe that all of the paddlewheel vessels listed in this website are side-wheelers.

(c) AquaExplorers
The remains of a paddlewheel are
evident in this sketch of the "Rickseckers."