Moonpools

Offshore
1

Anyone know of large moonpools (say 15’ x 45’) being put into OSVs?

2

I’ve seen a couple of what if scenarios involving pools that big for well completion kits and things. It starts getting fiddly with that big of a hole in the scantlings though. Deck and bottom plate scantlings start getting large or start to require high strength alloys that are very expensive.

3

Some large CSVs have several moon pools to facilitate different activities, but none as large as 15’ x 45’ that I know of off the cuff.

By splitting the moon pools the problem of scantling strength and bending moment is greatly reduced relative to one large opening. (That is not the main reason for such arrangement, however)

As Captain of a small Drill ship with a large moon pool and insufficient strengthening to compensate for loss of longitudinal strength, I learnt that watching bending moments at all times was of utmost importance.

1 Like
4

Interesting. I wonder if it is even possible in say an existing 165 x 58 OSV.

5

I’m nothing like a naval architect, but if we’re dreaming up novel designs…

Could you have a sort of arbitrarily large moonpool if the ship was a catamaran? If you have the hulls say, 8 feet apart at the midship and let the port and starboard sides of the pool take 3.5’ bights out of each hull, then you have your 15’. Then if you made the hulls like 90 feet or more long, you could let each bight be 45’.

     /\           /\
      _____________
    /  \         /  \
      _____________
   /   _\______ /_   \
      |           |
  /   |           |   \ 
      |           |
  |   |___________|   |
      ______________
   \    /        \    /
      ______________
    \  /          \  /
    
     \/            \/

Can it be like this?

6

Aweful wide for only a 165’.

7

I agree, one of my last OSV’s was 200x56’ and it was odd looking.

I’m also not sure why you would even want to put a moonpool that large in that small of a vessel. It would be all moonpool and no deck space. Hell you wouldn’t have much machinery space either.

8

I don’t know ‘why’ either. I was just taking a stab at ‘how’.

9

Correction, length I was thinking of was 265 - not 165.

10

The ship with the largest moonpool was the Glomar Explorer, built in the 60s to recover a sunken Russian submarine.