Return to Great Lakes & Seaway Shipping Great Lakes & Seaway Shipping Online
Discussion Boards
Please click to visit our sponsor
It is currently February 22, 2018, 12:00 am

FAQ | Instructions | Help
Search for:



Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: Re: Telescoping hatch covers
Unread postPosted: December 6, 2017, 3:27 pm 

Joined: March 13, 2010, 10:51 am
Posts: 1059
Quote:
What changes were made to the John G. Munson to allow the fitting of one-piece hatch covers?

It received a new deck, hatches, and coamings when lengthened, as I recall, and a low-profile hatch crane.


Report this post
Top
 Profile  
Reply with quote  
 Post subject: Re: Telescoping hatch covers
Unread postPosted: December 6, 2017, 12:31 pm 
Guest wrote:
It was because they were self unloaders and cable swung booms at that. Deck room was at a premium already, so room for the hatch crane and boom clearance were issues.



What changes were made to the John G. Munson to allow the fitting of one-piece hatch covers?


Report this post
Top
  
Reply with quote  
 Post subject: Re: Telescoping hatch covers
Unread postPosted: November 29, 2017, 1:48 pm 
It was because they were self unloaders and cable swung booms at that. Deck room was at a premium already, so room for the hatch crane and boom clearance were issues.


Report this post
Top
  
Reply with quote  
 Post subject: Re: Telescoping hatch covers
Unread postPosted: November 29, 2017, 11:49 am 

Joined: March 13, 2010, 10:51 am
Posts: 1059
Here's what hayhugh2 (first paragraph) and I (second) wrote about this subject in 2010 on this board:

Telescopic hatches with 12 foot centers were utilized on the self-unloaders so as to fill up each hatch for more tonnage. one piece hatches needed space between hatches for stowage. Not an issue on ore boats, but boats in the stone and coal trade used all available space and would still not put her down to her marks.

The commonality here is that newbuild self-unloaders after 1938 had telescoping hatches, probably since the unloading booms and hatch cranes as then utilized were thought to be incompatible for clearance reasons. The first new self-unloader I can think of with a hatch crane was the Cape Breton Miner. Early conversions of vessels with single-piece hatch covers, beginning with the E. B. Barber, John T. Hutchinson, and Hochelaga the year the Cape Breton Miner was built, 1964, retain the hatch cranes and, probably, original hatch covers. I do find it odd that a vessel like the Adam E. Cornelius did not have one-piece covers and a crane. I wonder if the switch from flat to tubular trusswork for the unloading boom resulted in more clearance for the crane.


Report this post
Top
 Profile  
Reply with quote  
 Post subject: Re: Telescoping hatch covers
Unread postPosted: November 29, 2017, 9:35 am 
It seems strange that the John G. Munson, Detroit Edison, John J. Boland, and Adam E. Cornelius were all built by Manitowoc Shipbuilding with telescoping hatch covers while that yard's last ship, the Edward L. Ryerson, had one-piece hatch covers. The only difference I can see between these ships is that the former vessels were built primarily for the stone and coal trades and the Ryerson for the movement of ore. Perhaps the telescoping hatch covers were fitted to allow coal to be loaded over the edges of the hatches? Single piece hatch covers require a different spacing or pattern to allow hatches to be laid alongside the openings or stacked. Was there an advantage to having a large number of closely arranged hatches afforded by telescoping hatch covers in operating in the coal and stone trades at the time of these ship's construction? The John G. Munson did receive one-piece covers at some point in its early career, most likely during its lengthening in 1976. As it seems that the telescoping hatch covers are more labor intensive to operate, there must be a logical explanation.


Report this post
Top
  
Reply with quote  
 Post subject: Telescoping hatch covers
Unread postPosted: November 29, 2017, 9:13 am 
Were there any advantages to these over the single piece style that are now used ? I'm wondering why the Saginaw, built in 1953, had telescoping hatch covers these were long out of favour. TIA


Report this post
Top
  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 5 hours




Return to Great Lakes & Seaway Shipping  
Copyright Boatnerd.com All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Use of this site is based on the Terms of Use
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group