The 1st helm (in the navigating bridge among all the telegraphs) was for shore navigating. When the ship had to dodge islands, charted reefs/rocks, other ships close to port, and the like near shore, it made sense to have the helmsman where the officers could give orders to him faster while maintaining a clear view of the surroundings.
The 2nd helm (inside the enclosed wheelhouse) was the main, open-ocean station for the quartermaster. His job was to watch a compass on the binnacle, not what the ship's surroundings looked like. That's why you'll see the QM's head tilted forward and down like he's asleep at the wheel in just about any Titanic movie. By removing his vantage point, distractions were kept to a minimum, and the QM could focus on his compass. But the main reason was because of night and bad weather sailing. The navigating bridge was a 'lights-out zone' at night to aid the watch officer's ability to see at night. The navigating bridge was also open at the sides to whatever weather the sea gods threw the ship's way. The enclosed wheelhouse gave the quartermaster at the helm a warm, dry, and lighted place to do his job.
The 3rd helm (on the docking bridge astern) was for docking. Docking orders were largely called for on the docking bridge and having a wheel there made it easier and faster to communicate any desired rudder movements.
The wheelhouse helm was used 99% of the time. However the other two also served as backups in case the gadgetry that made the wheelhouse helm easier to use crapped out or some other problem incapacitated the main helm.
It should also be pointed out that the steering gear in the stern was controlled by Brown telemotors (hydraulic lines) from the navigation bridge and wheel house, while the aft docking bridge was connected by mechanical means.
There was also a spare tiller arm that was placed above the working tiller that could be used in case the quadrant and working tiller became disabled. This tiller could be worked by warping capstans in an extreme emergency in case everything else breaks.
I do not doubt that you are right Sean, but you must admit that it sound stragne to build 2 weelhouses right behind eachother, when all the 'equipment' easily could be tucked into one single wheelhouse, that could be kept warm and windtight by using a completly normal door.
It seems like this inner bridge's main purpose is to keep the helmsman from taking his eyes from the compass for 2 seconds to look at a seagull that happend to fly by. I mean all the work with building a extra helm with it's connections and all that must be very expensive.
But englishmen are known to love strange solutions...
Actually the open bridge wheel was designed to be used during pilotage, suez canal transit (if required) fair weather and tropical night use.
The enclosed one is as already described - for winter, cold climate ocean passage work.
I suspect the aft one was an emergency steering position should the long connection between bridge and steering engine be damaged or break down in any way. As Sam says there was an additional jury steering facility which afforded a direct mechanical connection with the rudder quadrant or tiller. Almost all ships had this facility.
Some still do. At the very least, they have the capability to steer manually or locally in case the bridge is blown away, swept away, wrecked, or in some fashion, rendered inoperable. As backups go, it's essential. If you lose helm control from the bridge, you could find yourself in some heap BIG trouble. Those rocks you're heading for aren't going to move so you had better be able to.
If any of you ever get to Wilmington North Carolina, you can go down to the steering machinary room on the battleship USS North Carolina and see some of this for yourself. I may be confabulating here, but I seem to recall that they could rig up some tackle to move things manually if you really had to.
Mike -- you may be remembering the tiller and block-and-tackle displayed on the S.S. Willis Boyer in Toledo. That ship is contemporary with Titanic. It had the conventional steering system, a "trick wheel" at the steering engine, and a cast steel tiller that could be rigged to steer by using a docking windlass and a block-and-tackle arrangement. The Boyer also has a second "emergency" wheel connected directly to the steering engine should something happen to the pilot house.
>>Mike -- you may be remembering the tiller and block-and-tackle displayed on the S.S. Willis Boyer in Toledo.<<
You may be right. I'll have to double check the North Carolina the next time I go for a look. Since that ship had a twin rudder system, I suspect that it may have been a lot trickier to set up something like this.
Oh my!!! Michael, I didn't think that you were that old that you would forget seeing the block-and-tackle rigged to the Boyer's tiller? Let's see, it was just about two years ago in Toledo, OH, wasn't it?
>>Let's see, it was just about two years ago in Toledo, OH, wasn't it?<<
Yeah. Lotta water under the bridge in even that small amount of time. We really need to have a meet there sometime, hopefully in the near future. Since the Boyer is supposed to be under new management, it would be nice to see how they're doing. They missed the scrapyard by the razor's edge.
Given that the physical layout of the equipment is different, the drawing posted by Jim is exactly the jury steering system on the Boyer in Toledo. Having studied it a time or two, I'm convinced that while the concept is fine, it would be extremely difficult to accomplish in anything but pleasant weather. Still, you have to have a "go to H..." plan.