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Louie da fly

10th-11th century Byzantine dromon by Louie da fly - 1:50

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4 hours ago, cog said:

Dick,

 

with reference to you statement:

Without these wedges at deck level, the strain on the mast foot would lead to early failure.

 

How do you explain the fact that the wedges were sometimes taken out to increase speed? At least that is something I read about ... (unfortunately age didn't help me remembering where)

 verrry interesting! I have not heard that. Can anyone clarify this? The wedges were solidly hammered in and woolded. It would be no mean feat to take them out and replace them for an extra knot or two even if the mast did not go by the board. Keel-haul the captain, I say!:10_1_10:

Cheers, Dick

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It was done in the 1700's (not sure if earlier) to change the rake.  Usually the captain's decision upon taking command and during the first cruise.  However, the wedges were a lot shorter by then and not roped into place.    I imagine it wasn't the easiest thing to do and I doubt it was done at sea.

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HI Steven

 

you asked for comments on wedging the mast at the deck - wedges at the deck are not required if the mast & other parts are strong enough to not need the extra support, the mast can just flex it's full length & will move at the deck level. It doesn't answer your question about whether or not to do it here, but will hopefully assist.

 

 

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Posted (edited)

Thanks, Dick, Mark  and Mark.

 

I suppose I'll just have to do what seems right. But I think something will need to be done at deck level, because these masts and sails would have imposed pretty strong forces on the vessel.

 

Carl,  I remember removing the wedges being mentioned in Hornblower in the West Indies when Hornblower is an Admiral and his flag captain decides to remove the wedges to speed the ship up in chase of a faster vessel.Hornblower thinks it's unwise, but convention forbids him as Admiral to give a captain advice in the handling of his own ship. Jack Aubrey might have done it, but I think he relied more on cross catharpins.

 

I have no knowledge of it being done in the real world.

 

Steven

Edited by Louie da fly

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A real world example is that medium & large racing yachts have adjustments to increase or reduce the mast bend. In the case of a fore & aft mainsail this would increase or decrease the fullness of the sail & give more pointing or more power etc. I'm not sure how this could translate to square sails though.

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Hey Steven, I really love your dromon build so far! I went back and read it all from the start! Great research too!

 

I do have some info that might be of interest you. Way back on the first page you were wondering on where the oars would go during battle. Well, in alla sensile galleys in the 15th Century they appear to have just hung loose over the side from their oar loops.

 

Here's a fresco by Spinello Aretino of a battle between alla sensile biremes from Venice and the Holy Roman Empire, dating from 1407-1408 CE (Image from Wikipedia):

Spinello-Battle_of_Punta_San_Salvatore-d

There is also a more realistic painting by Carpaccio from 1497-98 CE, The Return of the Ambassadors, which shows an alla sensile trireme galley at port with her oars hanging loose. It's in the background on the left, quite high res if you click through to the image (Again, sourced from Wikipedia):

Accademia_-_Ritorno_degli_ambasciatori_d

and a detailed closeup of the galley (thumbnail from Getty images, but this is a public domain painting so I think it's ok?):

legend-of-st-ursula-the-return-of-the-am

It seems that pinning the oars up may have only been something done in a scaloccio type galleys with their much larger and heavier multi-man oars. I haven't seen any paintings of alla sensile galleys with their oars pinned up that I can recall.  I'm surprised Age of the Galley doesn't discuss this, their section about alla sensile rowing mechanics. My observations may be wrong though!

 

Perhaps letting oars hang by their oar loops was also common for dromons and earlier single-man-per-oar ships as well? I think this makes sense on some level. As the oars were longer than the ships were wide, part of the oar would always remain outboard if the oars were onboarded during battle. This could leave them vulnerable to being easily snapped by enemy ships making a pass, injuring the crew inside and destroying the oars.  And it would impede movement on the decks with rowers, as you pointed out previously. Oars hanging loose would be moved around by an attacking ship, but be less likely to snap. And then the oarsman could just pick the oar up again to continue rowing. Plus, dropping an oar and ducking is much less involved than trying to maneuver an oar inside a cramped ship.

 

Roman Wreck 1 (a later Roman cargo ship, 4th-5th Century CE) from the Black Sea finds might be of some interest to you as well, as it has a "wing" type support for it's rudders. It may just be a convergent design and not a direct ancestor to the later medieval "wings" in your manuscript drawing, but still might be useful for your build:

 

https://twitter.com/sotonarch/status/1075035578096340994

 

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Posted (edited)

That is really fascinating, Alberto. I'm familiar with both these pictures but hadn't previously noticed the configuration of the oars in either of them. Admittedly, I've only ever seen low-res copies of the Aretino one.

 

If Prof Pryor's calculations are correct (and I'm certainly acting on the basis that they are), the oars are almost exactly as long as the midship breadth of the ship. But pulling them inboard and storing them crosswise would make it completely impossible to move around on the upper deck. Just not an option at all. 

 

Your discovery could be the answer to the dromon's oars, rather than having a separate inboard rack for them facing fore and aft between the oarsmen and the gunwale as I'd planned to do. Age of the Galley doesn't mention this problem, and neither does Age of the Dromon (which, given the thoroughness of the book,  means the original sources don't either.) It's certainly a possible solution, and as the only near-contemporary evidence (only 300 years wrong😉!) I'd be more willing to follow that than try a different solution for which there's no evidence at all.

 

While I was researching the dromon build I got heavily into the mechanics of rowing galleys (naturally enough) and found the characteristics of a scaloccio and alla sensile rowing absolutely fascinating. And in fact it appears that the invention of alla sensile oar arrangement was what spelled the end of the dromon's mastery of the Mediterranean. It meant a galley with the same number of oarsmen (and thus motive power) could be much lighter because there was no need for a second, upper deck. It would make for a considerably faster, and probably more manoeuvrable vessel, with which a two-banked dromon just couldn't compete, and they seem to have vanished from the scene within a century of the appearance of the new rowing method.

 

I've been following the Black Sea discoveries with great interest. I'm avidly awaiting the archaeological reports, but it's likely to be some years before they'll be published. In the meantime, I have to be satisfied with the videos. One of them shows very clearly the through-beam on which the rudders are supported but unfortunately there's not enough detail - at least for me - to be sure how it all works .

 

Thanks for this insight, Alberto. Very illuminating.

 

Steven

 

 

Edited by Louie da fly

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Posted (edited)

As Woodrat pointed out, unfortunately there's a bend in the foremast. It needs to be corrected and I really don't have much confidence that if I straighten it out by heat bending or whatever it will stay straight. In my view the problem lies in the inherent grain of the wood I made it from. So I've decided to re-make it, this time taking the grain into account.

 

I got another piece of walnut and split it with the grain.

20190314_155216.thumb.jpg.bde184e4283d7ca9f2e9b90f7240f6cd.jpg

 

 

Then planed it down roughly square in section, with the line of the mast following the grain of the wood.

20190315_190305.thumb.jpg.07c39ac1d588782fdd165d0ce7233df3.jpg

 

Then carved it roughly octagonal and using a medium file brought it to a circular section. 

20190315_210257.thumb.jpg.beb255eb20ba8bf333fc08cacd1dec2b.jpg

Now I need to bring it down to the correct diameter - 6mm at the base and 4mm at the top.

 

As I mentioned in a previous post, I've decided to replace the calcets as part of this procedure. Instead of a single sheave they will have two. The existing after mast is straight so it doesn't need replacing, but I'm going to cut off the existing single-sheave calcet and replace it with a double. One is already made and I'm pretty happy with it. Must be all that practice I've had in making them 😁.

20190315_111426.thumb.jpg.53b391d5508fc8efd69b60cc3392d4ae.jpg

 

Steven

Edited by Louie da fly

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I've made the replacement foremast - this one is nice and straight (and hopefully will stay that way!) The calcet was made as a separate piece, so I can swivel it round till it's pointing exactly fore and aft when the mast is in place. I've also made a double sheaved calcet for the after mast to replace the single sheaved one it used to have.

20190316_172541.thumb.jpg.dbc22a283d1400c3b2c0fe83a81973cf.jpg

And here are the two masts in place, with the spur, forecastle, side castles and awning structure dry fitted. Nice and straight now.

 

20190316_162658.thumb.jpg.5952b8c839cbdc9a06ade117b52acdad.jpg 20190316_162545.thumb.jpg.87d9198a352a932d13c856740b584328.jpg

Thanks Woodrat for pointing out the crooked mast. More work, but worth it in the long run.

 

Steven

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