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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 4, 2017, 2:56 pm 

Joined: March 13, 2010, 10:51 am
Posts: 1058
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When hull sections of two ships are joined to make a new ship, are the ends butt welded together without additional structural members overlapping the two sections ?

No. The edges of the insert and the existing hull are butt-joined (often new material must be inserted at the cutting points) but continuous strapping is welded to the main deck longitudinally across the insert and the two original pieces of the hull as well as outside the hull and often on the bottom of the hull (the latter increases resistance, although this is generally overcome by the the longer hull being more efficient). Brackets are also often used between the old and new structures in the holds to help connect and maintain rigidity between the new and original sections. Back in the day of rivets it was much easier to separate a vessel for lengthening by removing rivets and then matching the original holes with holes in the insert for fresh rivets, but I believe strapping was still done.


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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 4, 2017, 10:34 am 
When hull sections of two ships are joined to make a new ship, are the ends butt welded together without additional structural members overlapping the two sections ? TIA


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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 3, 2017, 7:06 pm 
Whence the reason the Cliffs Victory had hatches aft of the engine room. It was from a different class of saltwater boat, but the profile was retained for an expedient conversion.


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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 3, 2017, 3:51 pm 
Great information. Thanks to all.


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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 3, 2017, 3:19 pm 

Joined: March 13, 2010, 10:51 am
Posts: 1058
In 1950 Congress passed legislation to allow Great Lakes operators to purchase surplus government vessels for conversion, citing the exigencies of the Korean conflict. At the time, Great Lakes shipyards had full order books, with around six large newbuilds, which forced the construction of the Johnstown, Sparrows Point, and Elton Hoyt 2nd to the coast. Consider the three Republic C4s that cost the government $24.5 million to build that were sold to Troy Browning as agent for Nicholson-Universal for a mere $308,000, so the economic incentive was huge to convert surplus vessels. Hanna and Sand Products acquired a seven year old state-of-the-art turbine propulsion system and about a quarter of a ship and Maryland Dry Dock Company and Ingalls turned that into a virtually new ship for less than $5 million, the cost of the much smaller carferry Spartan then building at Sturgeon Bay. The government sale also included a generous tax provision allowing Hansand to write-off 60% of the construction cost as depreciation in five years. As an aside, the Marine Robin when launched was touted as having been constructed solely by African-America labor at Sun Shipbuilding's segregated No. 4 yard at Chester, Pennsylvania.


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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 3, 2017, 2:59 pm 

Joined: July 28, 2009, 10:30 pm
Posts: 484
Still cheaper and faster than building a new engine room.


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 Post subject: Re: Conversion to laker of Joseph H Thompson
Unread postPosted: December 3, 2017, 2:28 pm 
Guest wrote:
I found this fascinating article on the conversion process which leads me to a question. What was the advantage over a completely new ship if only the stern section of the original salt water vessel was used and it was modified at that ? The entire process seemed very labour intensive, involving a lot of towing, etc.. Why not just build an entirely new ship ? Just curious..

http://duluthshippingnews.com/building- . -thompson/


Several layers here. For one the stern, with the engines, is the most expensive area of the ship. At this time great lakes shipyards were booked solid building ships. Faster than building from scratch.


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 Post subject: Conversion to laker of Joseph H Thompson
Unread postPosted: December 3, 2017, 12:00 pm 
I found this fascinating article on the conversion process which leads me to a question. What was the advantage over a completely new ship if only the stern section of the original salt water vessel was used and it was modified at that ? The entire process seemed very labour intensive, involving a lot of towing, etc.. Why not just build an entirely new ship ? Just curious..

http://duluthshippingnews.com/building- . -thompson/


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