confusion about the holes in the outer hull
 

Hi,

call me picky but what's really up with these holes at the side of a submarine ? I mean their number and arrangement.
On many pictures you see a gato class sub having these kinds of holes:
http://military.discovery.com/techno...to-625x450.jpg

while on some others you see this:
http://upload.wikimedia.org/wikipedi...%3B0821201.jpg
Both are supposed to be gato boats. The latter one is the USS Gato, specifically. But a detailed model of the USS Gato also shows her like this:
http://www.falconbbs.com/m42-069.jpg

So, which one tells the truth ? Did the outer hull and therefore maybe the holes change during the war ? Are some of the pictures incorrect ?

Thanks for any hints, i.

I don't know why specifically they added more holes, but look at the conning tower in the b/w picture compared to the one on the model. IF they are both USS Gato it would be after a major refit. I would not be surprised though. Some Gato boats were still in service as radar pickets off Vietnam in the mid 60's and Gato herself wasn't struck from the Naval Register until 1960. That is why you see so much variation in undated pictures of the class.

Well, you can tell by the conning tower that the one with more vent holes was a later war boat. I imagine that the extra holes made submerging quicker to avoid those air attacks that people keep denying happened so much around here.

The faster you can move air out of the outer hull area, the quicker you will submerge. It makes sense that they would add more.

But that's only a logical approach and logic doesn't work with history. So it's time to call for Davey!!!!!!!

More holes means more drainage! The superstructure is nothing but pipes, tanks, escape trucks and sail struture welded to the hull. It is a maze of steel, valves, wire. Water gets into the super structure and needs to exit the superstructure. More holes and you get this done quickly both ways.

Nisgeis asked me to take some pictures of the superstructure on the Torsk. I did so this weekend. I will post these pictures as soon as I can. I got pictures of the torpedo tube flasks for compressed air, the hydraulic motor/gear for the dive planes and the trunk of the escape hatch. You will see the reason for the drainage holes because the superstructure is really a large void that takes on water as the sub submerges.

Actually, RR was spot on.

In these pictures, the rounded outer hull can be seen right at the waterline. The vertical, slab sided structure above this is called the superstructure. The superstructure serves several purposes.

It needs to be remembered that from a purely technical standpoint, the fleet boats were really not true submarines, they were actually submersible surface ships (I hate to admit that, but it is true! :cry:) These boats spent most of their at sea time on the surface and thus their design was optimized for surface operations. The superstructure's primary purpose was to provide a ship-like hull that would efficiently cut through the water while on the surface. It also provided a fairly smooth hydrodynamic fairing around the main ballast tank vents, the access hatches, engine air induction and exhaust piping, and the bow plane operating mechanisms, all of which had to be external to the pressure hull. The superstructure existed entirely outside of the pressure hull and was free flooding. It was always completely full of water when the boat was submerged.

The fleet boats were very large boats in order to provide the necessary fuel bunkerage for long Pacific patrols. Thus, the superstructure was correspondingly large as well. When the boat submerged, it took a while for the superstructure to fill up with water. To expedite this process, holes were made in the sides of this structure so that it would fill up faster. These holes are called limber holes. The pattern, size, and number of these holes were unique to the design to which the boat was built. Some of the earlier fleet boats of the Salmon/Sargo classes were even built without limber holes at all! The superstructure was still free flooding, but it took a little longer.

There were two very similar, but unique designs for the fleet boats. The boats in the photos above are indicative of the design drawn up by the Electric Boat Company of Groton, CT. The large, semi-circular limber holes that are placed right at the bottom edge of the superstructure aft of the bow planes are a feature of the EB design. Boats built at Manitowoc Shipbuilding in Wisconsin used the EB plans and thus they have the same limber hole pattern.

The other design was drawn up by the Portsmouth Naval Shipyard in Kittery, Maine and was also used by Mare Island Naval Shipyard in Vallejo, CA. and Cramp Shipbuilding in Philadelphia. The limber hole pattern consisted of smaller, rectangular holes that ran in two parallel rows. See this photo of Halibut:

http://www.navsource.org/archives/08/0823203.jpg

The roughly 50 second dive times for the as-built design for the fleet boats was more than adequate for peacetime operations. But once the war started, the necessity of making very fast dives became quickly obvious. Getting the superstructure to fill with water faster was one way to quicken dives. Almost immediately refit crews began adding more holes. This was done between patrols and there was no set pattern to it. The original holes remained, but by the end of the war there was an amazing variety to the limber hole patterns as new ones were added.

So, actually all of the photos you posted are correct. They just show Gato class submarines at different points in time.

As the war progressed, there were also several distinct modifications that were done to the Gato class conning tower fairwaters. I have written an article on this subject for my website Pigboats.com. My website partner, Ric Hedman, is busy converting it over to html for posting and when he is finished I will let you know. I think it will answer a lot of questions.

Woohoo ! :know: :up:

EDIT: Please, write a book :D

I always thought it was about diving time. The outer casing by nature would trap air during a dive and thus slow the dive. The more wholes allowed more water in, displacing more air and making for a qhicker dive. The difference may only be 10-20 seconds, but that is an eternity when a destroyer is bearing down on you.

The Limber holes on a submarine gets its name from the Limbers of old wooden sailing ships. Although the function and design of submarine limbers is different from the design of wooden ship limbers, the basic concept is similar and so is the name. To understand the etymology of the word Limber, it is necessary to describe early uses of the word.

Limbers (which has, as one of its components Limber Holes) were certain square holes cut through the lower parts of a ship's floor-timbers, very near the keel. Being disposed in a line, parallel to the keel, they form a channel, which communicates with the pumps throughout the whole length of the floor, so that the water which enters by a leak, and would otherwise be intercepted by the timbers, is easily conveyed to the well-room, where the pumps are fixed. [southseas.nla.gov.au]

The Limbers on a submarine no longer consist of the channel and are located on the top of the submarine. Their function is, however, similar. Limbers on a submarine allow water (when surfacing) and gas (when submerging) to easily escape from the spaces between the pressure hull and the outer structures of the submarine. In essence the submarine Limbers are conveying water/gas out of the submarine and, in this function comes the etymology of Limber.

Here is where it gets wacky. According to the Concise Oxford Dictionary of English Etymology the origin of the term Limber, in the context of holes in timbers for the passage of water. XVII. perh. — (O)F. lumière light, hole (used in the same techn. sense) :- Rom. *liminiria, fem. sg. use of pl. of L. liminire light, lamp, f. limen, l?min-

This seems quite a stretch to me. The term Limber Hole was in use starting in the 1500’s. I suppose that some designs of limber holes “could” allow the passage of light but it just does not make sense. Far be it for me to disagree with the ODEE, but perhaps another source would shine more light on the origins of Limber.

Like many of our words, the etymology can be unclear. There are other sources that link Limber to the Middle English lymour from the Latin limonarius, meaning shaft of a cart (this is incidentally where we get the word limousine.) [www.yourdictionary.com]

This makes a little more sense as in the original usage of Limber, it was a system of channels (shafts?) between parts of the ship to convey water either overboard or to a sump for pumping.

Probably more than you wanted to know about Limber holes

Any holes acquired during a patrol are unauthorized and will be seen as mistreatment of government property.

That is all.

We'll let the Japanese know that they are breaking regulations. =p

To give you an idea as to way these drain holes. The following pictures are from the bow of the USS Torsk. This is just below the deck and is the superstructure. Water fills this space and needs to fill quickly on a dive and drain quickly on surfacing.

Steps down to the hull.

http://i133.photobucket.com/albums/q...k/DSC03442.jpg

At the bottom of the steps is the escape hatch to the escape trunk. Note the struck is welded to the top of the hull. Same as the con. The sail is welded to the superstructer.



http://i133.photobucket.com/albums/q...k/DSC03438.jpg

Ok, you know the torpedoes were expelled from the tubes by compressed air. Ever wonder were the air was stored? Below are the air flasks for each tube in the bow. Here the air was stored under pressure to blow the torpedo out of the tube.

http://i133.photobucket.com/albums/q...k/DSC03439.jpg

Another picture of what it looks like under the deck and above the hull. Note, the owl was not original;)...it keeps the pigeions out...well sort of.

http://i133.photobucket.com/albums/q...k/DSC03440.jpg

The structure to the left is the life line to the surface if the escape hatch was used. This houses rope and flotation device to carry the rope to the surface. http://i133.photobucket.com/albums/q...k/DSC03436.jpg


What you are looking at here is part of the dive plane hydraulic system. All of this is found under the deck and part of the superstructure.

http://i133.photobucket.com/albums/q...k/DSC03441.jpg


This is just the bow. The entire submarine is like this from bow to stern. An awful lot of space that fills with water when submerging. These pictures should give you an idea of the reason for drain holes.

I love finding out details like this. Thanks all.

Thanks for the pic's. Great stuff.:yeah:

Yes, thanks ALL above ......... I don't say it enough.

- I come to SS looking for something specific - like this morning for example - and always get pleasantly sidetracked by topics like this one.

Happy Hunting!

Art

Those are really cool pics AVG. :salute: