Viking tumblehome sterns

The OLYMPIAS trireme reconstruction in the photo uses oars of all the same length, a great advantage in so many ways. Greek oarsmen were paid volunteers and knew how to row, and that an oar can't be much more than 14' for one man. The oarsmen were packed incredibly efficiently. Here are volunteers training on a mockup and later in the ship itself.

 

Yes i can see the setup much better. That rower upper left in your first photo looks in very good shape

 

I guess I could ask a Scandinavian.

 

Ask the Viking Ship Museum. http://vikingeskibsmuseet.dk/index.php?id=1246&L=1

 

Ain't history great?

Might visit NY in 2012.

http://www.triremetrust.org.uk/

The 18th Jenkin Lecture, 1 October 2005: Some Engineering Concepts applied to Ancient Greek Trireme Warships.

http://www.soue.org.uk/souenews/issue5/jenkinlect.html

One comment I did read is that the interior of Olympias had to be cleaned frequently, as the stench of stale sweat became overpowering. The crews had access to toilets. Imagine a lack of those as well.

Early Greeks used sponges and vinegar to wash their vessels and their personal rear ends. So did Romans, which adds a certain piquancy to the passage in the New Testament about the vinegar and sponge offered on a spear to Yeshua Bar Yosef at his crucifiction.

http://30ce.com/

Addendum. The "Cubit" is a unit of measurement with elastic geometry.

"On that very important dimension in any oared craft, we had decided upon the so-called Attic cubit of 0.444 metre. We are now fairly convinced that that was a mistake, particularly since an unfortunately rather belated publication of a metrological stone of the right period from Salamis, which indicated a more likely cubit of 0.490 metre, 10% larger. That could have made a big difference not only in allowing longer strokes to be made, an important factor in achievable power in rowing where water is smooth enough to allow long strokes. More of the crew could have rowed, as they should, with straight arms. It would also have allowed the heads of the oarcrew in the lowest level to pass under the hull beams freeing them to make much longer strokes. That in turn, because all levels had to take the same length of stroke, would have allowed the whole crew to do the same. Such a change in the spacing of oars could well have eliminated the shortfall of 30% in sprint power and gone far to replicate the speeds probably achievable by the best ancient triremes.

We need another reconstruction! We would also, from experience with Olympias, cant the oarcrew so that the butt ends of oar handles would pass beyond the hip of the next man aft, enabling the stroke to be even longer. Oars would be immersed almost entirely forward of athwartships, as indeed they were in the later medieval galleys and are today in sport rowing craft. Our unfortunate choice of the Attic cubit in the reconstruction has a lot to answer for!"

 

Bataan,

Great link. Did you read the article about the Oseberg reconstruction 'Dronningen' and the reasons it capsized and sank on its maiden voyage? Now, the Norwegians are building another one that should correct the shape.

Regards,

P

http://vikingeskibsmuseet.dk/index.php?id=1293&L=1

 

From the link provided by Pericles: http://en.wikipedia.org/wiki/Tumblehome

Now, if it is well documented that moving cannon closer to the centreline, without making any other changes, has a noticeable effect on stability then I really would like to read such documentation. On the face of it the concept makes absolutely no sense, becuase it wouldn't change the height or transverse position of the CoG.

Prove it. Show me the calculations, please.

 

No Idea,

If you are anxious for calculations, contact The National Museum.

http://www.hms-victory.com/

http://en.wikipedia.org/wiki/HMS_Victory

They'll help, just send them an email.

P

 

I think this paper may be useful for the tumblehome debate:

"An Investigation into the Damaged Stability of a Tumblehome Hull Warship Design"
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA338783&Location=U2&doc=GetTRDoc.pdf

Also:
"Dynamic Stability of Flared and Tumblehome Hull Forms in Waves"
http://www.aoe.vt.edu/~mccue/papers_archive/bassler_etal_stab07.pdf

"Pure Loss of Stability of a Tumblehome Hull in Following Seas"
http://www.isope.org/publications/proceedings/ISOPE/ISOPE 2009/data/papers/2009-TPC-584.pdf


Cheers.

 

Guillermo,

Thanks for those instructive links. Bringing a naval architect to a large forum that contains a number of aspiring and hopeful designers of boats, gives us opportunities to learn much, from the interchange of ideas and advice so generously offered.

Tumblehome is descriptive. Roll over and sink home to Davy Jones' Locker.

Warships and sportfishers have something in common.

http://www.marlinmag.com/techniques/outfit-your-boat/the-carolina-flare-53218.html

P

 

Tumblehome-- Tumble( head over heels) Home( a place to come to rest, upon sinking at sea it would indeed be Davy Jone's Locker or as we also commonly refer to it, Fiddlers Green. Well it's another learned tid bit, never related it before.--- Geo

 

Scandinavian view..
Just for a note but to me it seems that an avarage Knarr doesn't have any tumblehome... In some cases a bit of reversed stern (and bow) but that's another thing.

 

Knarrly true.

http://vikingeskibsmuseet.dk/index.php?id=1409&L=1

 

Teddy looking at the model presented at the beginning of the post it seems to be of a different form than the traditional symetric Viking Ship hull. Possibly their heavy freighters were a modified form and it does look to have a tumblehome along a portion of the hull. I think PAR hit the nail on the head on the reason for that design feature.The thread did get off track a little from the origional posted query being related to the stern section. After reading Gillermo's reference site materials I deleted my prev. post as my suggestion was covered quite well in that reference material however i don't know how applicable it would be when referring to the style and armament layout of ships some 200 yrs, ago.--Geo.

 

Now that I have thought about it, my idea is that it is for downwind wave-piercing. Better to have a wave go over you (and be shed w/ the tumblehome, and/or decking) than getting broached or pitch-poled.