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

[Louie da fly]

I've been trying to get the keel straight - as it's only 3mm (1/8") square and 490mm (19.3") long there's ample opportunity for it to go all bendy.

 

It's not too bad, but when I tried correcting the sideways bowing by pouring boiling water on it, raising the ends a bit and weighing down the centre, the sideways curve corrected but the keel hogged downwards instead! And when I corrected the hogging (see picture), the sideways curve re-appeared.

 

  

 

So, I think I need to put together some sort of jig to simultaneously correct both faults. I've got some ideas and I'll see if they work.

 

In the meantime, I've worked out the shapes I need for the layers of the plug and I'll be cutting these out and putting them together.

 

 

Steven 

Edited February 13, 2016 by Louie da fly

[Louie da fly]

A very ad hoc jig for straightening the keel in two dimensions at once. A nail at each end and one in the middle to bend the keel around in a horizontal direction, plus a sheet of glass to lift  each end of the keel and a piece of wood to weigh it down in the middle.

 

 

We'll see if it works . . .

 

 

Steven

Edited February 13, 2016 by Louie da fly

[druxey]

Wood will move where it wants to go. Start with a really straight-grained piece from which to cut your keel. It will need to be pinned in some way to your plug. This will keep it straight until your garboard strakes are fitted to it, giving everything a 'T' section assembly that will help maintain straightness.

[mtaylor]

I'm wishing you luck, Steven.  Druxey is spot on about the grain being straight and about the wood doing what it wants.  I've had some that practically went into a pretzel.  What kind of wood are you using?

[Louie da fly]

Thanks, Druxey. As far as I can see the grain is pretty straight, and I tried to choose as straight a grain as I could find, but I agree it will go where it wants to go. I think I'll pin it to my plug the same way you did with yours - it looks like a very good way to go.

 

Mark, it's European plane wood, the same as the keels of several of the Yenikapi galeai were made from. I wanted to keep it as close as possible to the original; the other Yenikapi galeai had oak keels and I could have used that instead, but I've never worked with plane and I wanted to see how it went. Fortunately, Ballarat has street trees of both kinds (as well as ash, elm and other European varieties introduced by the settlers in the 19th century) and I'm able to get a lot of timber from loppings.

 

 

By the way, the jig seems to have worked pretty well. I may have to do a bit of final tweaking, but I'm pretty happy with the result. Next I'll tidy up my scarph joints between keel and the stem and sternposts, and cut out the pieces for the plug. I'm looking forward to it

 

Steven

[Louie da fly]

Just cut the lifts for the plug. As I really don't have much confidence that I'd be able to get both sides the same by eye,   I've screwed together the lifts for one side and I'll smooth this side off, using the sections I've cut out of cardboard to check that I've got the shape right as I go. Once I'm happy with this side, I'll pull it apart again and use it as a template to modify the lifts of the other side. That way I've got the best chance of  getting the shape of the hull symmetrical.

 

Wish me luck!

Edited February 21, 2016 by Louie da fly

[cog]

Steven,

I wish you luck, altough I hardly think you'll need it, the way you go at it ... A very interesting build ... don't mind me looking over your shoulder

 

Cheers

 

P.s. The hull's shape reminded me of something I saw on a site when I was looking for the plans for a gondola ... http://www.veniceboats.com/eng-designs-ships-narrow-ships.htm

Edited February 21, 2016 by cog

[Louie da fly]

That's not surprising, Carl. Any ship that's to be rowed with speed as its objective is likely to have pretty much the same kind of shape - long and narrow.

 

One thing I thought was interesting is the gentle curve of the outline (seen from above). Apparently Renaissance and Ancient galleys had pretty much straight, parallel sides. But the Byzantine galleys found at Yenikapi definitely swelled gently outwards from both ends toward the centre, rather like the Viking ships of the same period.

 

Steven

[cog]

 

But the Byzantine galleys found at Yenikapi definitely swelled gently outwards from both ends toward the centre, rather like the Viking ships of the same period.

 

Not really astonishing, considering the number of Viking warriors entering service at that time and in that region (Eastern Roman Empire/Constantinople, if my history lesson, and reading stuck)

[druxey]

Steven: I've finally had time to look at and absorb your preface to the build. Fascinating reading! Nice to see you actually get started in earnest.

[Louie da fly]

Thanks, Druxey.

 

I've done a bit more but now the weekend is over, it's back to work for another week. I'll try to put up some update photos this evening, then it'll be a gap till next weekend.

 

Carl, I don't think there was any Viking influence on Byzantine ship design -If anything it'd be the other way. But I really think it's just a case of convergent evolution.

 

Steven

[Louie da fly]

Well, here are the photos as of Sunday afternoon. I've roughly shaped one half of the plug - more still to be done; the hard bit, getting it the same shape as the cross-sections say it should be.

 

I learnt something - don't use an electric planer to "just trim a bit off the stern" - it takes great bites out of the wood and I ended up losing a fair bit of the 'tail'. So I've added some builder's filler to make it up to shape again. And from now on I only use the sander. Next weekend I'll sand it properly to shape on one side and then begin on the other half if I have time.

 

 

 

 

I still have to get the scarph joint between the sternpost and the 'tail' shaped properly - it's giving me some problems getting it all to mesh precisely and have the tail go up at the right angle. I think I'll have to make some kind of jig to hold it all while I'm gluing the keel, stempost, sternpost and tail pieces together.

 

Does anyone have any advice for doing this successfully? I have to admit I'm not looking forward to it - too much chance of messing up after all that work. Maybe I should be gluing one joint at a time? I don't know.

 

Steven

Edited February 23, 2016 by Louie da fly

[druxey]

Certainly refining one joint at a time is a good strategy. Also gluing one joint at a time is. Multiple joints and you'll be chasing things around and almost guarantee failure. I personally don't use a jig, but rely on the two pieces I'm joining to line up perfectly on a copy of the assembly underneath. Also, watch out for creep and cumulative error as you build up a multi-part assembly. Adjust as necessary on - pardon the pun - the fly.

 

Also, for model work, I've found power tools a snare and delusion. They always remove just a bit more than you want. But you know that already, right?

[Louie da fly]

Thanks, Druxey. I'm not terribly happy with the joints between the sternpost and the 'tail' - in fact I'm thinking of making them again - the current pieces were cut a little wrongly and so I can't make a joint that will enable them to follow the curve I want in the tail.

 

And if I do that, perhaps I'll have another try at the keel as well - it still bows downward a little in the middle and it's not the same colour all the way along its length. Maybe I can recycle it to make the keelson.

 

I know PVA glue works best when the joint is clamped together. Do you clamp your scarph joints? I was thinking of using an elastic band but I don't trust them much - they tend to mis-align things too easily. Or perhaps I could wrap the joint in thread while it dries?

 

Any advice gratefully received.

 

Best, 

 

Steven

[woodrat]

Steven, is there any indication in the Yenikapi wrecks whether the keels have a convex curve in them or whether they are straight. Some mediaeval shipwrights deliberately built in a curve to make it easier to beach the galley.

Dick

[Louie da fly]

I don't know, Dick. It'd probably be pretty hard to work it out anyway. The  Yenikapi hulls were all incomplete and in pieces - if a keel was curved it might have been by design or because of the twisting and bending effects of being underground for so long. (Oh, and it's an earthquake zone.)

 

I think it's amazing that they were in no worse condition than they were.

 

But to answer your question, I haven't seen anything which mentions whether the keels were straight or curved.

 

Best wishes,

 

Steven

[ggrieco]

Hello Steven,

 

There are fragments of keel from three of the Yenikapi hulls. Combining the evidence, it appears that they were flat for about the first 2/3rds (except for the stem) of the vessel and then swept up at the stern. Perhaps to improve the turning ability?

 

Glenn

Edited February 25, 2016 by ggrieco

[Louie da fly]

That's very interesting, Glenn. Did you get this from the archaeological reports - I don't remember seeing this information in what I've read, but I might have missed it. I'd appreciate being pointed towards where this appears, as I'd like to get the ship as close as possible to what the archaeological evidence shows.

 

Best,

 

Steven

 

PS: I see you live in College Station Texas - do you work at TAMU? If you know Cemal Pulak and you see him, say hullo to him for me and tell him the dromon build is at last under way. He's been very helpful - and generous - with information, and I'm very grateful for his assistance. 

Edited February 25, 2016 by Louie da fly

[ggrieco]

Hello Steven,

 

I built the YK4 model for Cemal a few years ago. The wrecks from Yenikapi were divided up between several institutions. Before publishing, everyone was protective of the data they had and we only had access to the forward end of the keel on YK4. Fortunately, Cemal had some knowledge of the other keels which we discussed while brainstorming what YK4's stern looked like. It has been a while since I looked at the research but if I speak to Cemal tomorrow, I'll ask if there are any published drawings of the other keels. I'll also pass along your thanks to him.

 

Glenn

[Louie da fly]

That would be great, Glenn. By the way, Cemal doesn't know me as Louie da Fly (of course). So tell him Steven Lowe says hullo and convey my thanks to him.

 

And also my thanks to you. That model you made of YK4 was very inspirational and helped a lot in formulating my ideas of how a dromon would be. I consider it a privilege to be in touch with the man who built it. 

 

Steven

[ggrieco]

Thanks Steven,

 

No problem.  I'll let you know if he has any good info on the keel.

 

 

Glenn

[druxey]

Sorry about delay in responding. I'm away right now. Small joints don't really need clamping: gentle finger pressure works for me.

[ggrieco]

Hello Steven,

 

I spoke to Cemal yesterday, he says hello. We talked for a while about the keel and he had some more recent ideas about it.. On each end of the keel on these vessels there is first a timber that slowly curves upward like a forefoot, followed by the stem or sternpost. On another galley that was excavated at Yenikapi, the builder was able to fabricate the entire keel and stern curved piece from one timber. We had a tracing of the timber and originally I thought it was a flat keel that rose in the stern. Cemal has pointed out that it was just a combination of these two timbers. If you have a copy of the IJNA article that shows the site plan for YK4 you can see YK4s sternpost and a piece of this curved timber just above the stern end of the remains. Sorry for confusing the issue and I hope my explanation isn't just more confusing. I wish I had the tracing with me to post but they are in a box in my office. I'll look for it next week and if I can find it I'll post it.

 

Glenn

Edited February 27, 2016 by ggrieco

[Louie da fly]

Thanks for the information, Glenn. Yes that seems pretty clear. I'll have another look at the paper later and see if I can locate those timbers.They really put a lot of thought into these vessels, didn't they? Give my thanks and regards to Cemal.

 

The trouble is that at this stage of the build I'm pretty much committed to the design I have, so I'll be going with a straight keel (though with a very slight downward bow I haven't been able to get rid of). However, what I'm calling the stem and sternposts are curved upward, so maybe I'm closer to the actual design than I thought.

 

Druxey, I'm quite surprised that just squeezing with the fingers is enough. Do you mean you hold it in your fingers till the glue is dry, or do you just push the pieces together and that's enough? I think I might have to hold mine together somehow, as I'm not all that confident in my scarph joints or the straightness of my pieces, especially the troublesome keel. I don't think they'll just lie there together on a flat surface without rolling a little out of position. I don't think it's enough to spoil the model, but after all that work and getting it almost straight I just don't know that trying it again and making another one  would produce any better result.

 

I spent the weekend on the plug and I'm pretty happy with it. I'll put photos up in the next day or two.

 

Steven

[paulsutcliffe]

Hi Steven, if you have a look at daves log on the general hunter and his tutorial on cutting a perfect scarph joint you will see what Druxey means about only needing to hold, once the glue grabs on a perfect joint at the sizes you are working it should hold nicely

Regards

Paul

[Gerhardvienna]

Hi Paul,

Do you have a link to that tutorial? Would be interesting, thank you!

 

Regards

Gerhard

[paulsutcliffe]

Not sure how to post a link?? But if you search for general hunter by daves in scratch built it should come up, its around page 12 I think, he did a little tutorial after a request from me and it helped my joinery skills no end, hope it helps you too

[Gerhardvienna]

Daves report found, very interesting to read! Thank you, Paul!

Regards

Gerhard

[Louie da fly]

I’ve spent quite a bit of time on the weekend on the plug and it’s almost complete. My idea was to screw the lifts of one half-hull together and shape the half-hull, then take it apart again. Then I’d  form up each lift of the second side by putting it back-to-back with its opposite number to make sure the second half mirrored the first.

 

The lifts are 12mm (1/2”) thick pine plank, except for the one at the bottom, which is made of 6mm thick ply. The hull’s cross-section changes shape dramatically about 6mm above the keel, and I decided that this would be the best way to control the change of section.   

 

I used a belt sander to take off the excess wood and all went well until I had the first half-hull shaped. I’d cut out a bunch of concave templates of the cross-sections at 1 centimetre intervals to put against the hull to check the shape at each point. It wasn’t too far off, but I discovered I’d sanded a little too much off in places, so I covered the relevant areas with a bit of builder’s filler, waited for it to dry and carefully sanded it until it was the exact shape at each cross-section. Then I hand-sanded the surface (actually I used a file – it seems to work just as well as sandpaper) until it was nice and smooth.

 

 

Unfortunately, once I’d done that I realised that I’d painted myself into a corner. With the builder’s filler over the joins between the lifts, I couldn’t separate them by simply undoing the screws. So I had to cut through the filler at the joins with a Stanley knife (box cutter), which rather spoiled my nice smooth finish.

 

 

 

Anyhow, I’ve now belt-sanded the lifts of the second half roughly to shape using the lifts of the other side as models.There’s a little more shaping to be done where the lifts meet each other, but it’s looking pretty good.

 

 

 

 However, because the lifts aren’t yet glued together, the bottom lift has started to bend at the ends.  It's only made out of 6mm three ply and is sanded right down to nothing at one edge, so it’s a very long thin triangle. I’m not concerned by this, as gluing and tightly clamping all the lifts together will fix it quite easily.

 

 

I’ve screwed the second side together and it looks ok.

 

 

 

 

 

Today (Monday) I glued the lifts of one side together, and tomorrow when that’s dry (and the clamps are free again) I’ll do the other side.

 

 

 

I’ve also discovered why I couldn’t get the tail to follow the curve I wanted. The sternpost turned out to be not a tight enough curve, so no matter what I did it wouldn’t do what I wanted. It was only a smidgin out – I only had to bring the ends in about half a millimetre (about 1/50 inch) and push the middle of the curve out by about the same amount.

 

I’ve made a new one with a slightly tighter curve and I’ve started refining its shape and working on the first scarph joint, where it joins the keel. Now I’ve fixed that, I’ve found that the ‘tailpiece’ which joins to the sternpost is the right shape to follow the curve, so I don’t need to make a new one.

 

 

Next weekend I’ll be doing more on the plug and the sternpost. I still need to make the part of the second half that corresponds to the tail and smooth it off. Then I’ll have to cut grooves in the plug for the frames. I’ve marked the positions of the lower oarports to make sure the frames don’t cross them, so I’ll be measuring very carefully to get them in the right places.

  

Once that’s all done I’ll be ready to start making the frames – they’re going to be only 1mm (1/25") square in section, so I’ll have my work cut out for me, particularly as I don’t have a bench saw. However, I’m good mates with the bloke across the road who does have one, and he should be willing to cut my planetree wood into 1mm slices for me.

 

Steven  

Edited February 29, 2016 by Louie da fly

[druxey]

Well, you are learning a lot in a short time, Louie! It's good to think out your strategies several steps ahead....