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Tumblehome design limitations
http://67.205.157.234/forums/viewtopic.php?f=5&t=6034		 Page 1 of 3
Author:  Western_1 [ April 23rd, 2015, 6:16 am ]
Post subject:  Tumblehome design limitations
So lately I have been working on a huge battleship that just so happens to use a Tumblehome design. Right now its just a 3d model I use to help myself scale and position things in a way that looks nice. But at some point I plan to do a proper drawing and a higher quality 3D model.

My question is this: why did Tumblehome designs fall out of favor? The only data I can find on it is that Russia lost a major sea battle to Japan, thus Tumblehome designs lost popularity. What were the specific reasons? I feel like you would want to slope the armor and reduce the flat deck area by as much as possible, both to reduce plunging fire damage, direct fire damage and the penetrative effects of dive bombs and level bombs. I even imagine a proper Tumblehome can feed into a Torpedo bulge seamlessly.

I would like to hear thoughts on why Tumblehome fell out of favor.
Author:  Rodondo [ April 23rd, 2015, 7:22 am ]
Post subject:  Re: Tumblehome design limitations
Well with a torpedo bulge, technically speaking the form of hull for the length of the bulge is tumblehome. One of the main issues with it is the stability, the more a hull rolls, ideally the buoyancy force acting against the force of the roll should increase the more the hull is inclined, with tumblehome, that peaks early due to the shape of the hull. Another issue is they tend to be a bit wet, a flared hull blocks some spray from wave action near the waterline, a tumblehome doesn't as the waterline is visible from the weather deck

[ img ]

There is a solution to this and apparently the folks working on DDG1000 have figured it out as that's one of a few number of warships made after 1900 with such a shape. Half-tumblehome hulls are another, commonly found on sit-on-top kayaks, having a great amount of flare just above the waterline before curving back.

The Russian fleet was defeated at Tsushima due to a large number of factors, a trip more than halfway around the world, less experience than the Japanese, unreliable fuses and shells, poor coal storage, older ships, the fact the Japanese had advanced rangefinders, the Russian rangefinders had woeful limits and were over 20 years old. Admiral Togo by that point and many of his crew had two large battles under their belt and they were experienced in Russian naval tactics, having battled them on both occasions, Tumblehome hulls may have played a factor in damaged stability but not a deciding factor.
Author:  Gollevainen [ April 23rd, 2015, 8:48 am ]
Post subject:  Re: Tumblehome design limitations
Not the mention that the sole proper tumblehome hulled ship Tsetsarevich didn't actually sunk in the 1905 war but performed relatively well. It was it's ill-famous semi-tumblehome sisters of the Borodino class which have tributed to bad reputation of the tumblehome hulls.
Author:  JSB [ April 23rd, 2015, 11:27 am ]
Post subject:  Re: Tumblehome design limitations
As an addition to the above answers (ie stability, that are more important IMO).
Quote:
I feel like you would want to slope the armour and reduce the flat deck area by as much as possible, both to reduce plunging fire damage
You also don't want to angle the belt with the top in and the bottom out but the other way to make it at a greater angle from long range shell coming in at 20 to 30 deg above the horizontal.
(on the other hand it would reduce the deck area so may be better v bombs)
So this makes it a bad idea for dreadnoughts from about 1910-1939 (ish) when long range guns now work but before big bombs do.
Author:  Western_1 [ April 23rd, 2015, 3:14 pm ]
Post subject:  Re: Tumblehome design limitations
Thanks for all the answers, I got the idea that Tumblehomes were bad from the wikipedia article on the subject and I now see that it was very flawed.


Another question I have relates to stability. What if the ship was very large? Would stability be a problem with a ship the size of the Yamato or larger?
Author:  Rodondo [ April 23rd, 2015, 3:28 pm ]
Post subject:  Re: Tumblehome design limitations
krases wrote:
Thanks for all the answers, I got the idea that Tumblehomes were bad from the wikipedia article on the subject and I now see that it was very flawed.


Another question I have relates to stability. What if the ship was very large? Would stability be a problem with a ship the size of the Yamato or larger?
Well it would negate the effect of most weather as you'd need serious weather to effect is but Yamato was even slightly tumblehome in hull shape thanks to her protection scheme, damage stability would be the major concern though, less resistance to capsizing should water start entering the hull. It all relates to your relative beam, displacement and the metacentric height
Author:  acelanceloet [ April 23rd, 2015, 7:20 pm ]
Post subject:  Re: Tumblehome design limitations
tumblehome was also a trait of concentrating the firepower amidships. the disappearance of tumblehome on battleships was about the same time as the appearance of the dreadnoughts IIRC, where we can see very different arnament, engines and armour defining the ships design. in my opinion, a tumblehome hull is always inferior to a flaring hull in seakeeping and stability (for reasons described above). while these problems are indeed solvable by subdivision, careful shaping, heightening the hull etc, it might be easier to separate the 'armoured hull' and the 'seakeeping hull' by putting the armour a bit inwards in the design. IIRC, quite a few battleships do exactly this.
Author:  Western_1 [ April 24th, 2015, 6:31 am ]
Post subject:  Re: Tumblehome design limitations
I wont be on until This weekend, but I figured I would show a super early rough draft of my ship. The Yamato for scale is not my own, I just placed it there for scale. This 3d model is to just help me with placement and scale. My plan is to reign in the design, then make a shipbucket, then make a better 3d model in Rhino 3D (right now its in Sketchup).

I need to make so many changes its not even funny. Preliminary armament is:

15 x 22" primary guns in triple turrets
18 x 10" secondary guns in twin turrets
74 x 5" tertiary dual purpose guns in single gun turrets

[ img ]
Author:  Sumeragi [ April 24th, 2015, 7:52 am ]
Post subject:  Re: Tumblehome design limitations
Wow, if I could I would love to commission you for making a 3D model of a battleship.
Author:  apdsmith [ April 24th, 2015, 1:20 pm ]
Post subject:  Re: Tumblehome design limitations
Hi Krases,

I'd be a little concerned about topweight - the Yamato turret weighs 2,730 tonnes, so your turrets are presumably heavier than this, and you've got A, B and C turrets - on a tumblehome hull. That's a lot of topweight, quite high up, on a hull type not renowned for excessive stability (see earlier in this thread).

Regards,
Adam
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