New port

[happy daze john in oz]

Interesting article in a travel paper at the weekend.
There is a proposal to build a cruise terminal at Greenwhich. It will be for ships of no greater length than 230 metres.
Many cruise ships have a draft in the region of 8 to 9 metres.
The reason for the shorter ships is that they have much smaller draft.

Apparently the river cannot take ships of a great draft, the river being quite shallow.

That being the case how did the ships of our era cope, what level of draft did they have?

[Captain Kong]

Hi HD John.
the depth of water in the Thames varies quite a lot even in the same location, for example around Woolwich one berth can have a max draft of 5 metres and another berth can have a max draft of 7,5 metres.
The Greenwich Pier, four miles downstream of the Tower Bridge, can accommodate ships of from 128 to 208 meters in length with maximum draft of 8 meters. At the moorings around Tower Bridge it is around 5 metres.
Up at Nine Elms, near Battersea Power Station, where I used to take the big Dredgers the berths dry out at low tide, then as soon as the ship starts to bounce on the bottom as the tide comes in, it is full ahead to get through 12 Bridges to get past Tower Bridge outward bound. as then you have the Air Draft to worry about on a rising tide, I was a company Pilot on the Thames for a spell.
Cheers
Btrian

[j.sabourn]

The draft of the average 10,000 ton tramp was about 28/29 feet if remember correctly this was loaded down to her summer marks the FWA (fresh water allowance about 6/7 inches) was the whole idea of the tramp ship which could get into ports other ships couldn't. Was quite common to sit on the bottom at Low water. Was very rare for a ship to come out of the great lakes in Canada fully loaded as maximum draft used to be 25 ft/ 6 inches anything above this and huge fines. The big beamy ships of today with a quarter of a degree list increases the maximum draft by inches, forget the formula for such. As usual too little thought probably has gone into thinking about getting passengers ashore and have relied on cutters to transport them from deeper water. However with the elderly age of most passengers nowadays must be causing some concern. Cheers JS

[happy daze john in oz]

Interesting as I see the draft on the Coronia,'Green Godess' was some 9 meters.

[j.sabourn]

John when they talk about drafts and depth of water they used to refer to Chart Datum which was shown usualy as mean Low Water spring tides. To this you had to add the height of the tide which in different parts of the world varies considerably, in the likes of the Adriatic can be as little as a couple of inches and in some parts of the world like the Mississippi 20 feet plus. My last job before leaving the UK a couple of days later, involved doing a bottom survey a few miles up the Thames, there were really large ships going in and coming out, and I was the one who went aground fortuanetley on a rising tide and a mud bottom so soon refloated on coming astern. The average ship of years gone by it was the usual to have at least 3 feet under the keel and then only go at very slow speed as headway caused further sinkage aft. Larger ships of course had to keep much more clearance under the keel. If you went aground and got neaped you were in real trouble and might as well pack your bags. Probably where the term came from sailing on the tide so as to have as much water under the keel as possible. Cheers JS

[j.sabourn]

Further to previous post, most charter partys in the Tramp Ship Trade were Voyage Charters, a lot of Owners used to insist in charter party when stipulating Lay days, Demurrage, weather working days and all the others regarding money passing hands for stoppages etc etc. to have the clause inserted in regarding loading or unloading to be " afloat at all times." This was mainly for any future claims against insurance when the ship went into drydock and big indents were discovered in the plating adjacent to the keel. On the Pennyworth in 1964 we drydocked in Middlesborough and going in the Dock Bottom inspecting the keel plates there was a huge indent and could stand upright with head and shoulders in. The ship at some time between drydocks had been sitting on the bottom on some boulder. The blame game then starts as when it happened, should it have happened, who was in Command when it happened and a frantic searching of the log books to try and find where and when, then the insurance claims, these claims adjustors most of the paperwork seemed to me as was done by the ships staff. It amazing how many haloes one trips over when trying to find such information. I had just joined the ship so I had the biggest Halo. Cheers JS

[John Arton]

The max length for this new berth could really be down to the swinging room in the river. The Thames as far as I am aware, is not greater than 230 metres wide at Greenwich (or at any point in its buoyed channels, so in order for a vessel to be swung and head bow down, there has to be a cut or inlet/dock entrance somewhere nearby where any ship can be swung in.
All ships experience squat (bodily sinkage or smelling the bottom to give it its non nautical term) when making way, the amount been dependent on underwater hull form and speed through the water (not over the ground).
The small (5500 tons) chemical tankers I was on latterly, with a 14knot speed and 120 metres loa 17 metre beam would squat anything up to 1.4 metres.
You always knew when squat was affecting your ship as she would start shuddering, become difficult to steer and the wake would become much greater, also speed would drop.
rgds
JA

[j.sabourn]

#7... A couple of years ago was back in UK and passed through Great Yarmouth. Driving down towards the River Mouth parallel to the River noticed a lot of offshore vessels parked much closer to the river mouth on both sides. When I worked out of Great Yarmouth used to work off the town quays as far up the river as could get. However getting back out was only the one place with sufficient room to swing and only had a few feet at each end to play with. Maybe the ships working offshore are now longer I don't know or maybe it is now considered insufficient room to swing in Great Yarmouth itself. Anyone on site working out of there or lives in the area like D. Martin know ??? Cheers JS

[happy daze john in oz]

If you can swing an 80,000 ton cruise ship in Napier NZ then I guess you can swing them anywhere.

[j.sabourn]

With all the modern equipment and Bridge control, and probably the company or harbour policy for such ships to employ tugs is not a big deal John. JS