Amidships

[happy daze john in oz]

Over time shipping has transformed from the ships we knew to the container ones of today.
Tankers are no different.

But there was a time when they were built in a very different manner.

The bridge and officers accommodation were situated in the midships housing.

Obviously there was a reason for this at the time, but the question is why?

[Ivan Cloherty]

Obviously there was a reason for this at the time, but the question is why?

Evolution rather that revolution, you have to go back to sailing ship days when steam engines were first introduced into sailing ships which had very high coefficients of fineness of the hull form and for stability purposes the engine had to be placed as near midships as possible, as this space was lost to cargo availability it followed that the deck space above the engineroom was used for other purposes and thus accommodation blocks evolved. Previously accommodation had been aft and all cargo spaces for'd of the poop deck, this space had now to be used for cargo spaces and thus started the evolve of the 'three island' vessel to house crew, heavy machinery, windlasses, capstans, steering gear etc, heavier anchors and chains, so accommodation evolved above and adjacent to chain lockers (some of us will remember that, no alarm clock needed), then the introduction of the steering flat for rudder head and endless screw machinery, again accommodation was introduced above that, accommodation was already above the engineroom. Evolution and great advance in stability calculations and more importantly stability rules meant that designs evolved into all kinds of possibilities in designs today that at some time previous were only seen in Dan Dare comics. Of course volumes have been written about this subject which are still available if you suffer from sleep deprivation

[Louis the fly]

The reason why midship accommodation was built this way on early tankers is the accommodation was air conditioned, not for the comfort of the crew, but if a gas leak occurred all doors and port holes were closed.

[John Arton]

The traditional 3 island cargo ship was built using transverse framing with engine room situated around two thirds length, this required a shaft tunnel in the hold after of the accommodation space that results in a loss of cargo space in those holds. Nowadays ships are built with longitudinal framing , introduced by Joseph Isherwood years ago. This method of framing allows for ships to be built of much greater length and placing accommodation and engineroom aft means a shorter propellor shaft.
Lewis's container ship is built with longitudinal framing and transverse stiffeners in the form of hold bulkheads etc. The engine room is positioned at the optimum length from the stern that the propellor shaft will allow, too long a shaft length would result in high torsional stress on the shaft. The bridge is situated where it is atop of deep transverse frames but also due to the requirements of the vertical and horizontal separation of the fore and main steaming lights being such that they can still be seen one above the other at a certain distance ahead, there is a diagram/calculation in the collregs
As to older tankers being built with midships accommodation, again putting the engine room and engineers accommodation aft makes sense regarding shaft length and as ships length became longer it made sense to put the bridge midships to give strength to the hull form with the hull below the accommodation being used as a bunker or pump Room space.
Rgds
J.A.

[Tony Taylor]

The reason why midship accommodation was built this way on early tankers is the accommodation was air conditioned, not for the comfort of the crew, but if a gas leak occurred all doors and port holes were closed.

I think it was the British Crown? blew up at Umm Said due to a cabin fan and open port? no aircon

[happy daze john in oz]

Was the concept of the engine room aft first on such as the Canberra and Southern Cross, Northern Star.
Or were there ant prior to that?

[happy daze john in oz]

Thanks Lewis, I always thought the SC was first but not sure.
Did a lot of Ten Pound Pom runs in her day.

[Robert Barrett]

Steamships had huge boilers and engines. The best space for them was midships. That together with funnel, ventilators and access to the engine room via skylights made the area ideal for the housing and bridge.

[James Domleo]

Was the concept of the engine room aft first on such as the Canberra and Southern Cross, Northern Star.
Or were there ant prior to that?

On retirement,went on Carribbean cruise on th Canberra.lovely comfortable ship.

[James Domleo]

On retirement,went on Carribbean cruise on th Canberra.lovely comfortable ship.

Unless there was a strong following wind,smoke carried aft and away from ship.