Open hold container vessels

[holedrille]

I have seen the occasional reference to container ships designed with no hatch covers. An example is the pair of Wagonborg ships Reggeborg and Reestborg now converted to livestock carriers, but these are forward bridge designs that have a certain amount of protection for the open aft holds.
What stops the waves filling the open holds in rough weather? I can see the great advantage in loading, but it does not sound very safe. How common is it, and do larger vessels have the same feature?
Holedriller

[ozzy76]

@ holdriller.

Here's some pictures of some larger open hatch box boats.

http://www.shipspotting.com/gallery/photo.php?lid=121333

http://www.shipspotting.com/gallery/photo.php?lid=150333

Taken from shipspotting.Thanks to the original posters.

[ozzy76]

 Also in most modern cellular box boats..(The bigger ones..not the feeder type)  The Hatches are not hydraulic.
The lids just cover the hold and for discharging the hold..The lids are removed by the spreader and placed on the quay side wall. So I guess, very little time would be saved by a hatchless design.

[Dеnis]

Open hold containerships usually have high freeboard to sail safely in rough seas.

http://www.shipspotting.com/gallery/photo.php?lid=1468237

[holedrille]

And large bilge pumps!
Thank you all for your replies, I still find it a rather suspect principle for an ocean going vessel.
Holedriller

[rgr004]

Good day all,

The main reason behind hatch cover less container vessels was to avoid having containers lost overboard as a consequence of excessive lashing forces.

The project was partly "killed" because the tonnage rules made this ships too expensive to operate.

The lashing bridges that are now common on all modern container ships are an excellent alternative, especially because of stack weight issues on hatch cover less units.

Rgdfs / Roland 

[holedrille]

I can see how a hatch cover, with say 6 containers on it, and 6 underneath it in the hold, helps stack weight. The bottom one can only have 5 resting on it, rather than a max of 11. Significant advantage!
But I cannot get my mind around how a coverless design helps reduce lashing forces. The undivided stack is twice as high, so to achieve stability the vertical lashing force must be much greater to stop them toppling over. The opposite to what you are suggesting.
How do tonnage rules penalise a hatchless design?
Holedriller

[rgr004]

Hi Holedrille,

On hatch cover less vessels containers are retained by the cell guides, you only find lashing bars on the very top tiers in some cases only.

Cell guides are welded to the structure and are strong enough to keep containers in position despite heavy rolling and pitching.

Trust this clarify.

Roland

[Captain Ted]

@rgr004
cell guides are virtually on all container ships nowadays, otherwise it would be a time consuming task to place one on to top of another. I was in the mid eighties on reg coasters and we had to stack containers without cell guides,, what a mess.  They do not much to avoid movement. They limit it however. The main reason why it functioned is the high hold coamings, virtually high holds, but that as mentioned is what killed them. The GRT got high and that is was most probably the killer for them.
@holedrillrer
to move them is rather quick, but it cost substantial dock space, have to place them somewhere on the dock, the other point,, no maintenance if you don,t have hatch covers !!
How the bilge pumps worked, no idea,  I mean now from the point of dirt into the pumps and how often to be cleaned and such matters and yes,, they must have been pretty big, however don,t overestimate water by spray, seldom that a wave would really go that high to go straight into the holds and spray can be pumped out "rather" easy I would say.  One other thing which I really don,t know,,how the holds holding up to the elements, inside rusting away like no tomorrow,, was special steel/paints used ?   For sure no time for maintenance,,that,s for sure 

[sandygates]

Open top container ships naturally allow a certain amount of water to enter the holds.  This may be rainwater in a tropical rainstorm, spray or seas washing over deck on the ocean.
In order to avoid flooding of the containers on the tank top, the open-top ships are equipped with 200 to 300 mm high pedestals on the tank top, on which the bottom containers are stowed.
The ships are equipped with at least three independent bilge pumps each capable of pumping the maximum hourly rate of sea water in seagoing conditions as established in the model tests.
The bilge system for cargo holds is independent of the machinery space bilge system and located outside of the machinery space.
IMO regulations require that the maximum hourly rate of ingress of sea water in any one open hold determined from model testing should not exceed the hatch opening area multiplied by 400 mm/hour.
All open cargo holds must further be equipped with bilge high level alarms.
All these features should prevent cargo at the bottom from being sacrificed in the case of water ingress.  However, they cannot prevent cargo in holed containers from becoming water damaged.  Even the newest containers can be damaged during loading or discharge operations.
Some open-top container operations have fitted their vessels with

[miraflores]

Another reason might be the different hight of certain container.
When you can store them in an open hatch you loose no space below the hatch covers.

http://www.sh-touri.de/fotos/vera_rambow02.jpg
http://www.sh-touri.de/fotos/alana02.jpg
http://www.sh-touri.de/fotos/akacia02.jpg
http://www.sh-touri.de/fotos/ida_rambow04.jpg

and many, many more samples.

Rgds.
Juergen