WesWorld

I'm rather enjoying Gran Colombia in Navalism these days...

I seem to recall that, who's your main advasary at the moment?

Playing both France and Russia is a lot...

I think Rocky is still searching for one.

Atlantis, Carthage, Israel, Persia... The Middle East and Mediterean is getting pretty crowded.

My other options would be: Mexican Empire (inc. Southwest US, Central America, parts of Carribean)
Or a bigger, stronger Siam (with parts of Indochina, Burma, Malasia, Indonesia & Singapore)

Rohan is still not yet friend or foe to Gran Columbia. The Columbians seem to be focused on internal matters, Franch Brazil's interal problems, and Spanish Cuba's external problems (communism).

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How cool would it be to have Tarantry as part of the Wesworld in the next go round?!

*starts drooling over Sans Souci*.

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*starts drooling over Sans Souci*.

I think you'll like the Oyama hybrids once they get fully realized.

You know, I think I'd rather go with a real Brazilian Empire, one with a Pacific Coast. It'd be nice to have a real power in South America, instead of the regional quasi-powers that we presently have.

Patagonia, the Brazilian and Mexican empires and Gran Colombia would make things interesting in South America.

Well with a Cental Empire of Brazil, and either a one or both of the other two (Gran Columbia and Hispanic Federation) the power of the region would increase a little as long as there were no other little nations on the continent, and parts of Central American, and Spain were added (Hispanic Federation includes Spain as a late member/figurehead if I remember altnaval's fiction correctly).

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Originally posted by Red Admiral

[...]

Transom sterns give a fuller hull-form aft increasing waterplane area there. Essentially the skegs do the same thing, but in a different way. They generally smooth the flow out - making it more efficient through less drag.

[...]

Regarding efficiency you wrote skegs helped to smooth the flow out. Keeping the other effects in mind oyu mentioned like protection of the screws and shafts one wonders why this configuration wasn´t used more often? AFAIK it was only used on BB57 and planned for a french CV-design while the Germans tried a different solution with their "Tunnelheck".

So if there are only benefits why wasn´t and isn´t this type of stern used more often?

What are the negative effects it generates?

Thanks,

HoOmAn

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*starts drooling over Sans Souci*.

Make way for famed Terrentrian Admiral Swampy Delacriox....

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What are the negative effects it generates?

HoO,

My own opinion is the tunnel stern wound up on the South Dakotas because of their very short length. I think had they been as long as the North Carolinas, they too would have had inboard skegs, as the subsequent Iowas and Montanas did.

G & D have some pretty good descirptions and info on the hull forms of the North Carola's and South Dakotas. One of the negatives of the twin skeg format seems to be vibration at certain speeds. This was present in the North Carolinas with their inboard skegs, and also encountered in the South Dakotas with their outboard skegs.

Quite a bit of testing was done with North Carolina. (On a side note: She steamed in and out of New York so often testing prop combinations at one point the Washington's band assembled and played a song from "Showboat", the Broadway musical of the same name that was then running. The nickname for the NC stuck, and even at the memorial she's called "The Showboat" to this day.)

In any case, a solution was varied props inboard and outboard. When commissioned, the South Dakotas had four four-bladed propellers. By the end of the war, all had five-bladded props on the outboard skegs and three bladed props inboard. The North Carolinas had four four-bladed props fitted to correct their vibrations, with the inboard and outboard propellers having slightly different pitch and diameter. In neither case were the vibration problems completely eliminated, but they were not experienced in the Iowas.

One of the big advantages for a skeg hull form is reducing resistance. In the North Carolinas, a 5% reduction was noticed at 15 knots, (cruising speed) and 28 knots (max speed). At 21 knots, the reduction was only 1%.

So the only problems came from vibrations?

What about steering? Is the turning radius of such a ship larger compared to a standard hull form?

What effects can be expected from combat damage? What if the skeg is hit by a TT? It may protect the screws but won´t it generate an "additional" rudder due to plates bend into a direction? What about water entering the skeg and flooding it? What does this mean regarding the ships balance, trim, counterflooding etc.?

From your post I still get the impression everything was fine with this stern configuration - well, short of the vibrations which aren´t much of a problem. So why don´t we see this stern layout more often?

Thanks,

HoOmAn

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So why don´t we see this stern layout more often?

Its easier to use a normal transom stern on more modern ships to reduce the drag. There isn't a great deal of point in fitting skegs and a transom. There would also be no efficiency gain with 1 shaft. Absolute speed isn't so much of an issue today but a higher range of speeds is more needed.

Steering more depends on the rudders. With twin rudders you bleed off more speed in the turns but can turn tighter. The twin rudder layout on the US fast bbs worked ok.

Damage- there isn't much volume in the skeg to actually flood with water. A hit would create an additional turning moment, but this can be overcome with the rudders and props because they can still direct the flow - unlike Bismarck.

Assuming that the damage to the skeg does not either damage or impinge on the rudders or props on it's side, anyway.

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What about steering? Is the turning radius of such a ship larger compared to a standard hull form?

The skegs didn't seem to interfere with the maneuvering capabilities of the US BBs. They were very handy with their twin rudders, Iowa being able to turn in her own length. Note that Iowa's twin rudders were in the race of the inboard props, while Alaska, with a single skeg and single rudder amidships, was much less maneuverable than Iowa, even though she's considerably smaller. Also the Fletcher class DDs, with their single rudder, were notorious for turning OUTSIDE the Iowas. (Probably their worst characteristic. Most that stayed in service were fitted with a larger rudder to aid maneuverability.)

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What effects can be expected from combat damage? What if the skeg is hit by a TT? It may protect the screws but won´t it generate an "additional" rudder due to plates bend into a direction? What about water entering the skeg and flooding it? What does this mean regarding the ships balance, trim, counterflooding etc.?

Any hit that can distort a prop can cause considerable damage, as the historic hits on Pennsylvania and Prince of Wales showed. I would say the skeg would minimize this, with more structure around the shaft to support it. Such a hit would still have a serious impact on the shaft alley, and leaking would still occur well into the ship. In my opinion, it would be less serious than those on Pennsylvania and Prince of Wales, and even though the skeg could ostensibly fill with water, it would have minimal effect compared to water ingressing into an engine room.

As for maneuver in a damaged state, I think you have a point, but I don't think they wouldn't have much impact. IF the rudders are intact, I think any 'rudder effect could be overcome. If the rudders are damaged as well, it could be difficult to try to overcome with 'engine only' steering.

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So why don´t we see this stern layout more often?

I think there are a couple of reasons.

First, enclosing the shafts increases displacement. Historically, with nearly every ship treaty limited, (and even Yamato bumping into limits on her displacement) taking the skeg step is going to have to be paid for elsewhere. I think it is really only practical with capital ships. And the US built some very efficient capital ships and could afford to pay that displacement.

Second, the USN had requirements like no other fleet. With the expanses of the Pacific, always operating far from base, it was willing to pay that displacement for the protection and structural strength skegs impart. ( A good example of the strength is here:

http://www.navsource.org/archives/01/64b.htm

In the fourth photo up from the bottom, Wisconsin is docked at Guam. With skegs, drydocking a ship can do without special blocking to support the stern.)

The RN, MN, RM, KM and IJN never had that same mindset, where they would be crossing great expanses of ocean, far from base, fight a strong enemy fleet, take damage and have to return home.

My thoughts,

Big Rich

Which brings us back to one of the original questions...Why does Italy need this hull form if they are operating in the Mediterranean and Red Seas? There doesn't seem to be a logical point to it when a more traditional hull form would do.

Why does Italy feel the need to be cutting edge in a area they don't need?

Italy's treaty obligations to Iberia, the Netherlands, and Denmark (and others?) might require her to deploy naval forces rather beyond what might be expected otherwise.

Extremely likely to be hit by torpedoes in the Med. environment.