Starved dog

[Tony Wilding]

HI, can any knowledgeable person explain why ships of welded construction have that starved dog look, hull sides never look flush, you can see every frame,
? ? ?

[Ivan Cloherty]

WEll Tony

No doubt someone will come up with some thermo dynamics and metallurgical physics to give you the scientific answer; but in short when I used to supervise hull repairs, the plate offered up was always perfect, but during the welding process, which was always started at both ends of the plate at the same time. The heat from the welding machine/torch is transferred to the plate, which when offered up was perfect, but as the heat had nowhere to go it transferred into the plate changing the characteristics, mostly expansion of course, when the plate cooled down it had what appeared to a rippled effect this was further accentuated when the other ribs were welded to the plate internally, and also the effect was more pronounced because the plates were thinner than on riveted ships, advances having been made in steel strengths. Had the older ships been welded rather than riveted then the rippling effect "may not" have occured, but the alternative argument is that because the plates were thicker, more welding would have been required hence more prolonged heat would have been incurred by the plates and may have caused some rippling. Even ships coming off the stocks these days look as if they have been having continuous arguments with the dockside. A weld is very strong, it is very rare for a weld to break, it is invariably the steel in close proximity to the weld that shatters, which is why it is prudent to have half plates along the hull strakes so that you do not get a continuous run of weld running round the hull, which is what used to happen to the war built assembly line Liberty ships which had a tendency to fracture just for'ard of the bridge housing.

Hope this helps but someone will be able to give you a scientific explanation, I can only speak from my dealings with shipyards and foreman shipwrights who were resonsible for the plating activities

Regards Ivan

[Tony Wilding]

Thanks for the info, i know Liberties cracked, as you say just forward of the bridge, also on hatch corners, in Mitchell and Sawers book Liberty Ships it states most cracked in ice conditions , arctic circle trips, it became brittle at low temperatures, they changed the type of steel used and it helped lessen that problem, also many had a rivetted extra band of steel from around fwd of no 2 hatch to aft of no 4 hatch, just below main deck level, but they never looked like starved dogs, maybe the thicker steel, ? passenger ships, ie cruise liners i presume are welded now, but there hulls look flush, ? regards, tony w.

[Doc Vernon]

No doubt someone will come up with some thermo dynamics and metallurgical physics to give you the scientific answer

Well Ivan
None of the above will be of any consequence after the detailed and concise report you have posted!
Very well put!
Thanks
Doc

[Tony Morcom]

Maybe the passenger ships have additional and thicker coatings on the hulls to camouflage the results. At the prices they charge it wouldn't take too many passenger fares to pay for it!

[Ivan Cloherty]

Maybe the passenger ships have additional and thicker coatings on the hulls to camouflage the results. At the prices they charge it wouldn't take too many passenger fares to pay for it!

Passenger ships are built on completely different scantling requirements, tend to have a longer service life than freighters, so more investment is made in them and the material they are built from, don't think you can camouflage steel work with thicker coatings of paint. Even new warships look like starved dogs, warships and freighters although different have the same basic role, need to have a light displacement so that more goods (or armements) can be carried. Passenger ships are fairly constant in their deadweight, ferries normally have the starved dog look (nice descriptive expression that - starved dog) But as I said you will be receiving more scientific explanations along the line, you can bet your bottom dollar on it. I only speak from my own experiences and what I learnt from them along the way.