Major OT: Ships helm question

[J Miller]

On any big ship you have the helm, basically a big huge steering wheel on the bridge.

How is this steering wheel connected to the rudder hundreds of feet away?

Joe

[Hobie]

Rope...

Seriously, here's ship's helm on the Fram (an arctic exploration vessel). I imagine they connect by wire (computer command) today.
http://www.sethwhite.org/images/fram/helm.jpg

[J Miller]

Hobie,

That's a sailing ship, right? Looks like it. And correct me if I'm wrong the wheel is connected to the rudder with chains. That makes sense.
However the helm on a sailing ship is at the rear over the rudder. On older big ships that are not set up for the wire you mentioned, how did they do that.

Like for instance the Battleship Missouri????


Joe

[mikld]

I believe "Helm" is a position rather than a thing. When "at the helm" you have control of the ship. You may be controlling the ship with a tiller or wheel while at the helm. Hydraulics, cables, and today electrical control (fly by wire) are what are used to "connect" the helm to the rudder. Old ships had either direct control (tiller) or a system of lines and pulleys; block and tackle.

[Griff]

The "helm" is the "ship's wheel". El samo, samo. Helm as you say, also has different connotations depending on how you're using it.

Boats have tillers, basically a pole attached to the rudder, unweildy and too low leverage to effectively steer a ship with that system... ships have wheels... well, so do some boats, but that's another lesson.

[Hobie]

Yep, it depends on the size of the vessel just how they do it.

[BwanaDave]

Joy sticks on new stuff

[Ben_Rumson]

I saw the steering gear on the Queen Mary many moons ago... Where the rudder shaft ( at least 3 ft in diameter) comes through the hull, two massive opposing steam cylinder shafts are connected to a bell crank that fits around the rudder shaft...I’m not positive if the QM had live steam at the wheel that feeds back to the cylinders but I do know that other ships employed the system.. Wish I could find my pics of it... hth

[Hagler]

Like for instance the Battleship Missouri????


Joe

Joe,

I imagine that those IOWA-class ships, and other, similar vessels, used elctro-hydraulic/ electro-mechanical contols (like servos & rams), along with propper gearing to control their direction.

My friend, Raymond Williams, served aboard the Iowa, BB-61. In 1989 & 1990, the main 16" guns were still guided by gyroscopes & mechanical computers from the 1940s. The serial numbers on the Iowa's equipment were below "10" (the Mk 6 Stable Element, pictured, below, was #004, I believe).To whit:

http://en.wikipedia.org/wiki/Armament_o ... battleship

The function of the Mk 6 Stable Element (pictured) in this fire control system is the same as the function of the Mk 41 Stable Vertical in the main battery system above. It is a vertical seeking gyroscope that supplies the system with a stable up direction on a rolling and pitching ship. In surface mode, it replaces the director’s elevation signal.[11] It also has the surface mode firing keys.

The Mark 1A Fire Control Computer (pictured) was an electro-mechanical analog ballistic computer. Its function was to automatically aim the guns so that a fired projectile would collide with the target.[11] This is the same function as the main battery’s Mk 8 Rangekeeper above except that some of the targets the Mark 1A had to deal with also moved in elevation — and much faster. For a surface target, the Secondary Battery’s Fire Control problem is the same as the Main Battery’s with the same type inputs and outputs. The major difference between the two computers is their ballistics calculations. The amount of gun elevation needed to project a 5in shell nine nautical miles (17 km) is very different than the elevation needed to project a 16in shell the same distance. The ballistics calculations in these mechanical analog computers were performed by things like differential gears, levers, and small rods riding on the surface of a three dimensional cams. These mechanical adders, multipliers, and table lookup devices were hand made at the factory, and were buried deep in the workings of the computer. It was not possible to change a computer’s ballistics at sea until the advent of fast digital computers. The anti-aircraft fire control problem was more complicated because it had the additional requirement of tracking the target in elevation and making target predictions in three dimensions. The outputs of the Mk 1A were the same (gun bearing and elevation), except fuze time was added. The fuze time was needed because the ideal of directly hitting the fast moving aircraft with the projectile was impractical. With fuze time set into the shell, it was hoped that it would explode near enough to the target to destroy it with the shock wave and shrapnel. Towards the end of World War II, the invention of the VT proximity fuze eliminated the need to use the fuze time calculation and its possible error. This greatly increased the odds of destroying an air target.

By the way, how much black powder do you think this is (U.S.S. Iowa)(very large pictures)?:

http://upload.wikimedia.org/wikipedia/c ... r_bags.jpg

http://upload.wikimedia.org/wikipedia/c ... r_bags.jpg

http://upload.wikimedia.org/wikipedia/c ... g_tray.jpg

...and what beautiful, black powder breechloaders!:

http://upload.wikimedia.org/wikipedia/c ... -61%29.jpg

Shawn

[Cliff]

From what I have seen on the various military ships there is two helm controls. Depending on the age most have some sort of wheel as mentioned, newer one use a joy stick or roller ball. They all are linked to the internal system of electric-mechanical systems to control the rudder. If the bridge is hit the auxillary rudder control takes over and located near to the rudder machinary. The one I saw was a little wheel about 6 inches in diameter, which actually controls the rudder itself. The big ships, aircraft carriers, battleships and such have super big heavy rudders and need a lot of power to be moved. As mentioned hydraulic and electric system provides the power. Of course in a really bad situation I suppose they could probably grab a hundered or so enlisted men and have them move the rudder by hand

[Old Time Hunter]

Same way your newer cars operate with their foot feeds (Oops, gas peddle for the minions), you have foot throttle sensor or wheel position sensor that transmits the position to a receiver that tells the actuator which movement and by how much to move the rudder. Then it is instantly reported back to the operator position through the J1939 CANbus system. Berger Yachts uses the same electric over hydraulic wireless interaction system as Boeing uses on their 787. No wires! No cables! No chains! Hope that makes you feel comfortable.

[mescalero1]

Absolutly not,
what do really think happened to that Air France flight from Rio to Paris.

[Bullard4075]

GOSH I love this forum

[milton]

Quote " Absolutly not,
what do really think happened to that Air France flight from Rio to Paris."

What did happen ???????

[Hagler]

Joe,

I talked to Raymond. He said that the Iowa used electro-hydraulics for rudder control. The helm, or ship's wheel, moves a synchro (http://en.wikipedia.org/wiki/Synchro), which, in turn, moves another synchro that is closer to the rudder. This second synchro acctuates very large hydraulics that act on the steering mechanism that is connected to the rudder. Turning the Iowa's wheel, from full-right to full-left, as fast as you can, causes the rudder to complete the movement in about 4 seconds. The Iowa is capable of a full-right, or full-left turn at 33 knots. That's changing the direction of a 58,000 ton ship at 37.9757218 mph!

Another electrical control device, used on some other ships, is the Amplidyne:

http://en.wikipedia.org/wiki/Amplidyne

Raymond also worked for Bier Radio. He installed positioning systems on modern oilfield boats. These systems often used two GPS navigation systems, coupled with electro-mechanical gyroscopes. The gryos are suspened by a conducting/ insulating liquid, inside of a sphere, and use mercury as an electrical conductor. Some of the helms on these boats are nothing more than a small potentiometer (like a volume control) that the wheel rotates. This signal is tied into all sorts of computerized rudder & motor controls. Propeller & waterjet motors are used to change direction, to dock, and for station-keeping.

I hope this rounds out my earlier answer.

Shawn

[J Miller]

Shawn,

Thanks that does make it clearer.
I didn't think the wheel was connected directly but I couldn't image how they did it.

Joe

[Ben_Rumson]

In the same class as the Iowa battleship is the BB-63 Missouri .. Here is a couple of photos of her electro-hydraulic steering gear to get a better idea of things..
http://navsource.org/archives/01/015910a.jpg
http://navsource.org/archives/01/015910b.jpg
More details here: http://www.navsource.org/archives/01/57z.htm

OT on the OT.. Reading about the aftermath at Pearl Harbor and the immediate operations on righting the battleships and battle damage is fun..
Here's a couple of pix of the Oklahoma getting rolled back over http://www.history.navy.mil/photos/imag ... h63915.jpg
http://www.history.navy.mil/photos/imag ... 410534.jpg
Link to the page: http://www.history.navy.mil/photos/imag ... 410534.jpg

[Griff]

BTW, I believe those are 30# bags of BP. So, that's be a 90# charge.

[Blaine]

Maybe Grizz will chime in....he's a ship's captain.

[Griff]

Well... I was wrong. If that is a 16" Mk7 gun breech.

Per NY Times from April 23, 1989: "...The propellant consists of small cylindrical grains of smokeless powder with an extremely high burning rate. A maximum charge consists of six silk bags, each filled with 110 pounds of propellant..."