tug construction ?

[anhdtht]

i have a drawing about tug construction,but i don't understand some part, such as in the picture.
thanks for helping !
http://s1118.photobucket.com/albums/k618/anhdtht/?action=view&current=6-14-20112-59-58PM.jpg
ps:I can't upload in here

[Ad Hoc]

Those are cut outs for man hole access hatches.

[cthippo]

Something like this:
http://www.sopac.co.nz/Portals/1/images/products/hatches/Freeman%20oval%20hatch.jpg

[anhdtht]

Something like this:
http://www.sopac.co.nz/Portals/1/images/products/hatches/Freeman%20oval%20hatch.jpg

I don't think so.:D

[micspoko]

this cut outs is for manhole like this
http://inventorfiles.com/datasheet.php?id=226001