The San Marco mosaic ship c. 1150 by Louie da fly - 1:75

[liteflight]

Lovely work Steven, and fascinating research and evidence from the massed ranks of MSW stalwarts.

 

My belated tuppence worth:

All that has been said about curved keels is true and very valid.  I can attest to the fact that even the slightest rocker in a keel improves turning ability enormously ( I used to race R/C yachts for amusement)

Better turning  = less rudder movement to get the required turn

Less rudder movement = greater boat speed

 

I remember reading the detail of the keel of one of the big, excavated Viking burial ships (almost certainly Oseberg) and learning that the main keel member was a single riven oak log.  
What boggled my tiny mind was that the overall length was iirc over 80 feet ( 24M) with over a foot ( 300mm) of rocker.  ( as well as the complex cross section to accept the garboard strake)

 

Good jig for the mast steps!

andrew

[knightyo]

On 6/13/2023 at 9:40 PM, Louie da fly said:

The first three frames. Of course I'm labelling each one so I don't get them mixed up.

 

The build would be more exciting and memorable for you if you skipped the labeling process.

 

It's really looking great so far!

 

Alan

[Louie da fly]

17 hours ago, knightyo said:

The build would be more exciting and memorable for you if you skipped the labeling process.

I'm sure you're right, but I think I'll give that a miss. I get confused enough already without adding to it.

 

And here are all the frames that rest on the keel - all numbered, knightyo! This is how they'd be without numbering - 25 of them.

And here they are in size sequence. Top row, from left master frame and two of every size steadily going towards bow and stern, continued in the second row.

The frames at bow and stern still need to be made, but first they have to be designed. I've worked up some tentative shapes using my trusty t-square and setsquare and roughing the frames out in what I hope is a correct sequence of shapes (bottom left of the sheet, and cut-outs sitting on the T-square). I'll make up bulkheads in scrap to these shapes and see if they work. The last time I tried it (with the Great Harry, as the first iteration was completely wrong, so I'm not brimming with confidence at the moment.

I've now retired my framing jig, but just putting it into storage, for I have a cunning plan for the future (which cannot possibly fail).

 

Steven

Edited June 20, 2023 by Louie da fly

[Louie da fly]

I've been working on jigs of various types to enable me to do the framing and keep it straight and square. There's been a bit of experimentation involved, some of which I cancelled because I'd found a better way, others because I hadn't thought far enough ahead and had to undo things because they got in the way of other things.

 

First, emulating Woodrat's 14th century round ship build, I made a cut-out template of the hull shape with slots for the ends of the frames, superimposed over a base to take the keel and the bottoms of the frames. Aren't photocopiers wonderful! Those scrawled figures are the overall widths of the frames, worked out by the mezza luna method (thanks, Woodrat!)

And here's how I intended to support the keel - version 1. The thin masonite strips ('packers' as used in the building trade) have nice vertical sides and are thin enough to let the keel stick out above them a little. The truncated triangles at the ends are right-angled, to keep the stem and sternposts exactly vertical.

And a piece to slide along the keel (it has cut-outs at the bottom to fit over the keel and the masonite packers) to ensure the frames are vertical and at right angles to the keel.

A jig to keep the frames vertical while I drill holes for pins to hold them to the keel (they'll be both pinned and glued). This is different from Woodrat's method, as I'll (hopefully - see below) be using a drill press to make sure the drill bit is vertical. I used bits of scrap wood but they have nice vertical edges.

The upper template held above the lower with long bolts. The sliding jig had to be cut down shorter to pass between the upper and lower templates.

A lot of mucking around in this procedure - on the first bolts I bought the thread didn't go all the way along the shank - something I hadn't noticed when I bought them. So I had to go and get new ones that did. But there weren't enough nuts with the bolts - I'll have to go and get some more to screw the tops of the bolts down on top of the upper template. I also found the triangles I'd made to keep the stem and sternposts vertical GOT IN THE WAY, so I removed them and discovered that the bolts were doing the job very nicely, so they weren't needed after all.

 

Now I have to wait for the rain to go away. My shed has a drill press but no power (can't fit it in the budget at the moment) so I have to string a power cord from the house to the shed if I want to use power tools. And electricity and water aren't a very good combination.

 

In between times, I've pencil-marked the locations of the wales and the deck beams on each frame, as well as the location of the proposed holes for the pins to hold them to the keel. I've also pencil-marked the locations of the frames on the keel itself, so I can do the corresponding holes for the pins.

 

There's quite a bit of drilling to be done before I can move on to the next step, but it's nice feeling I'm making progress, however slow.

 

Steven

[Glen McGuire]

Masterful work on the jig, Steven!  Fascinating build.

[druxey]

I had just read an article (elsewhere) in praise of jigs when I saw your preparatory work here. I'm sure the time you took to make this is well invested.

[Louie da fly]

18 hours ago, Glen McGuire said:

Masterful work on the jig, Steven! 

Thanks, but I won't celebrate till I've made sure they actually work - otherwise I'mm being a bit previous.

 

17 hours ago, druxey said:

I had just read an article (elsewhere) in praise of jigs when I saw your preparatory work here. I'm sure the time you took to make this is well invested.

I certainly hope so 

 

Steven

[liteflight]

Nice idea of the jig ensemble - it works in principle even if it may need modifying in detail.

 

AND

 

At least the frame squarifying jig will work on any future ship that has frames and a reasonably parallel keel.

[Louie da fly]

Well, the jigs worked  - sort of. It then comes down to "how accurately can I centre this tiny drill in this almost as tiny floor timber?" So, we'll see how it all goes. Unfortunately, the handle of the drill press (you know, the three-armed thing with knobs on that you rotate to get the drill to descend) knocked the stempost off the keel as it came down. DAMN! Fortunately, no actual breakage, just have to glue it back together again 

 

But it means I've got those pinholes drilled to pin together the frames and keel, except for the ones on the stempost (obviously!) and the sternpost, where I couldn't drill vertically into a curving timber without the drill bit bending to follow the curve. After a couple of attempts I gave up.

 

No photos unfortunately. Didn't think of it.

 

Steven

[woodrat]

per ardua ad adversitatem.

Never trust a power tool!

😎

Dick

[Louie da fly]

While I was waiting for the rain to go away so I could get power to the shed to drill holes for pins to join the frames to the keel, I thought "Can't sit around forever, waitin - I'll carve one of the merchants who pinched St Mark's body and brought it to Venice, as shown in the mosaic."

 

Here he is (the one on the left) his name is Buono. The other one is called Rustico. Perhaps those names are made up - "Good" and "Farmer" - it is, after all, an apocryphal legend.

  

   

I'm very happy with the shading of the face. It looks more natural than any I've previously done.

 

Frames dry fitted, to check that they go into the slots in the jig (quite a few of them didn't, so I had to widen the slots).

And in the process of gluing them in place

And all glued in. The pins are temporary - much too long - the keelson has to go directly over them. I intend to replace them with slivers of bamboo (I have a LOT of bamboo!) cut to length. I may have to drill the holes a bit deeper to make sure of the joint.

I'm still working on getting the shape of the end frames correct. I don't want to make a bunch of them and then find I've wasted my time and effort. So the plan is to make a 3D "filler" of bits of plywood (the same thickness as the distance between the frames) laminated together, with paper between layers so I can pull it apart when I've got the shape right and use them as templates. Fortunately the bow and stern frames will be identical. 

 

Steven

[Glen McGuire]

Your carving of Buono and Rustico is incredible.  Wow.

[botra288]

Your carving of Buono and Rustico beautiful 👌😀

[Louie da fly]

Well, only Buono so far. But thanks, people.

I'm still thinking about my options for the framing at bow and stern . I might just pinch Woodrat's idea of using a temporary batten at gunwale level. Though his bow and stern  are a lot blunter than mine so maybe I won't need to. Still thinking about it.

 

Steven

[Louie da fly]

Progress has been a bit slow. I've glued the bamboo 'pins"' into place to join the frames securely to the keel, and it has admittedly made quite a difference.

 

Here's an example, to give you some idea of their size (it's the little thing just under the end of the steel rule).

I decided to bite the bullet and make the bow and stern frames based upon the templates I'd cut out. I'll put one set in at the bow or stern and see if they work, if they are the right shape to continue the line of the frames. Only one set, in case it's a total disaster. Here's the first of them being glued together.

And in place (far right-hand end). Just held with a dab of glue till I figure out whether I've got it right, so I can remove them if needed.

 

I've also glued the keelson in, using push pins to make it conform to the curve of the keel. It's held centrally by the side pieces of the mast steps - they are only dry fitted at the moment;  I had to trim the knees supporting the sides of the mast steps so the openings lined up and the side pieces would fit in place. I think I still need to tweak them a bit more.

More to come fairly soon, if all goes well.

 

Steven

Edited July 13, 2023 by Louie da fly

[Louie da fly]

A bit of an update. Still at the fiddly stage - I need to secure the frames so I can take the model out of the jig - at the moment they're held only at the keel. So I've been cutting and bending the clamps to take the deck beams. With clamps in place, the frames will be securely attached to the hull and connected to each other so they don't move.

But first, the frames at bow and stern. These were mostly shaped by guesswork, and I was prepared to take them out again and re-think the shapes if needed. And I did on the last two at each end.

This is a bamboo batten to see if the gunwale will work with the end frames.

Clamps bent and the larboard one temporarily in place.

 

Clamps bent to take the shape at bow and stern.

The piece of wood wasn't quite long enough for the clamp to reach the whole length of the vessel.

However, I'd forgotten I had to make breast hooks as well. And they will take the place of the clamps at both ends, so the clamps will be long enough after all.

 

I also faired the inside of the end frames - it was easier than I'd expected, just using fairly fine sandpaper. But I forgot to take photos of them. (The frames for the rest of the hull really didn't need fairing on the inside because the curve was very gentle.)

 

The breast hooks were made from a forked branch from a tree that died in the garden (an apricot, it was), so the grain followed the arms of the breast hook. There was quite a bit of trial and error getting them exactly the right shape to fit against the frames. But I must have done something wrong, because two of my first three attempts broke in half while I was working on them. I think I cut the fork at the wrong place. However, I finally made a couple that seem to be working ok. Here's the bow breast hook complete, and the stern one in progress.

And I had to duplicate Woodrat's strategy in putting triangular section pieces between the floor timbers and the stem and stern posts to follow their curve, so I can drill through and fix them securely. Not sure if the photos really show it very well. They're pretty tiny.

 

 

And finally, I've put in the filler blocks that create the slots for the mast steps.

That's all for now.

 

Steven

 

Edited July 22, 2023 by Louie da fly

[BANYAN]

You're making some great progress there Steven.  The 'skeletal' framework looks very delicate, so I hope the fitting of the clamps, breast kooks etc stiffen this up sufficiently for you when working the planking etc.

 

cheers

 

Pat

[Louie da fly]

Thanks, Pat. And thanks everyone for the likes, which I'm a bit behindhand in acknowledging.

 

Now onto theory/research. I'm looking at the masts, in particular the interface between the tops and the calcet (halyard sheave assembly). All five mosaic panels show tops like this:

which I have interpreted as being (in 3 dimensions) of this cylindrical shape (from the leaning tower of Pisa, begun in 1173, shortly after the mosaics).

  

The question is - how does this top, right at the very extreme top of the mast, interact with the calcet (assuming there is one, which I think there must be).

 

The from about 1300 shows the calcets (black in the picture) as joined to the top of the masts with what is effectively a scarph joint, to minimise the turning moment/shear force that would weaken the joint.

 

Woodrat's Venetian Round Ship build shows it in practice.

But of course, this configuration means that the top has to be one side of the mast, when the mosaic (and the Pisa bas-relief) show it around the mast.

 

It seems to me that there would have been more than one way to have the halyard sheaves fitted to the mast, and that a removable calcet may be only one of them. Perhaps it is an integral part of the mast itself, as it seems to be in this picture (12th century, from the church of San Pietro in Ciel d'Oro, Pavia, Italy):

and that the top may be built around it. This looks feasible to me - you'd just have to watch yourself not to trip over the halyard while you were standing in the top. And this one (1339, from the tomb of St Peter Martyr, church of  Sant'Eustorgio Milan) appears to show the halyard going up through the floor of the top (granted that the top in this case is somewhat off-centre, it still appears to be around the mast).

Also, the earliest clear representation of these offset calcets I've been able to find is in the Spanish Cantigas de Santa Maria from around 1250, up to 100 years after the mosaic (yes, I know absence of evidence isn't evidence of absence).

 

At the moment I'm inclining to having the sheaves cut into the mast itself, probably just above the floor level of the top (that way the sheaves don't weaken the mast just below a point of load, and in the mosaics the mast seems to extend somewhat above the upper surface of the top), but I'd appreciate input and suggestions from other members.

 

Steven

 

 

Edited July 23, 2023 by Louie da fly

[Mark Pearse]

Hi Steven

 

The model is showing a boat with a very pleasing shape.

[woodrat]

21 hours ago, Louie da fly said:

But of course, this configuration means that the top has to be one side of the mast, when the mosaic (and the Pisa bas-relief) show it around the mast.

Whatever you choose to do, the top must NOT project forward of the mast since the yard has to be able swing past the front of the top when tacking or gybing. This is what was done in latin rig of the time, as you know.

This is John Pryor's concept:

Dick

[Louie da fly]

That's a good point, Dick. Definitely food for thought - and considerable pondering. I've just scanned through all my mediaeval pics of lateeners, and only the San Marco and Leaning Tower representations show the top extending forward of the mast - in all the rest (the ones that do have tops), it's behind, except in two which I'm not terribly willing to take as Gospel.

 

Could it be that the mosaic artists and the Pisa sculptors got it wrong? Perish the thought! 

 

In the meantime, I've shaped two of the masts and roughed out the other. I was thinking of recycling an unused mast I'd made for the nef but it wasn't quite long enough.

I've drilled and pinned the bow and stern frames,

glued the clamps in place and added the breasthooks. 

 

 

Steven

Edited July 24, 2023 by Louie da fly

[Louie da fly]

A-a-a-and - the hull is off the jig. I ended up having to pull the jig apart to get the ship out, but worth it. Then I had to do some correction. The pegs are gluing into the correct position some frames that were angled incorrectly (not perpendicular to the keel).

Then onto making stringers to make the structure more rigid, and deck beams. Here's my poor man's plank bender (a cheap soldering iron) to get them the right shape.

And here are the first bits of deck beam - or are they stringers? I've sort of lost track. (one of them is to be cut up to provide pieces of stringer for the bow or stern, which explains the complex curve).

Gluing complete - here she is without the pegs.

Adding stringers at the turn of the bilge. There'll be corresponding wales on the outside of the hull, and there'll be strengthening stringers and wales where the second and third futtocks join, and a wale in line with the clamp.

The mosaics seem to show a reasonable number of wales, as do the near-contemporary picture from the History of Genoa and the carvings on the Leaning Tower of Pisa.

 

 

  

 

View from the bow.

I'd miscalculated the length of the clamps, so they didn't quite reach the breast hooks. Because they didn't meet the rigidity of the hull was lessened, so I glued bits of wood into the gaps to make each assembly effectively a single strong unit.

   

Smoothing off the pieces that fill the gaps.

 

Still some tidying up and smoothing off to do. They won't be visible under the deck, but I'll know if I don't do it right.

 

And the stringers lined up with the join in the futtocks. They will be curved to follow the line of the join.

Like this . . .

And that's it for today . . .

 

Steven

 

Edited July 27, 2023 by Louie da fly

[Cathead]

That looks amazing.

[Glen McGuire]

Such an intricate hull.  Fascinating to watch you piece it together! 

[BANYAN]

Very nice work on such a delicate skeletal frame Steven.  Not surprising you had to make a few corrections, but it all looks symmetrical and starting to look a little more robust.

 

cheers

 

Pat

[Louie da fly]

I decided it was time to add the gunwales. They add to the strength of the hull, tie down the upper edges of the frames, and also define the shape of the vessel itself. The biits of wood I'd cut them from weren't long enough to stretch the full length of the hull, but that turned out to be a good thing, as the gunwale kicks up quite a bit at the bow, and it's easier to make that piece as a separate item.

I discovered that one of the frames at the bow had come away from the breast hook, so it had to be glued back into position. This seems to be happening a lot.

 

Here are the two gunwales seen end-on at the stern.

And here are the end pieces of the gunwale to go at the bow.

And the larboard one glued and clamped in place.

To overcome the problem with frames coming away from the clamps, I started drilling holes and inserting treenails at intervals. I'm hoping I don't have to do this with all the frames, but if it's needed I will. Here's a hole drilled joining frame with gunwale.

 

I began with bamboo toothpicks when I was pinning the frames to the keel, but once I got to the gunwales I changed to walnut to match the rest of the ship - I don't want my treenails to be obvious - I don't believe they were visible in the real world (though it's not all that important - the ship's going to be painted black anyway, to make it look like it's tarred.)

If you look carefully you can see the treenails (not yet trimmed flush with the gunwale)

Once I'd faired the frames I discovered I'd been a bit too enthusiastic with the disc sander in places, so I had to add some filler to bring the frames back up to the right shape - fortunately not many times,

Bow ready to receive the extension to the gunwale.

Extensions in place. They line up nicely. I'm quite happy with their consistency - I think I'm getting better at bending.

Joins between the gunwales and the extensions - I'm getting better at scarph joints, too.

  

More to come in due course.

 

Steven

 

Edited July 31, 2023 by Louie da fly

[Louie da fly]

I have a bit of a quandary. Most of the mosaics show uprights extending up above the gunwales. They appear to be frames that haven't been cut off flush with the gunwale, and there are what appear to be rope loops (unless they're string of pearls - anything's possible in a religious mosaic!) hanging from most of them. I'm assuming they're belaying points.

  

 

Do the members agree with my interpretation, or are there any other possibilities that come to mind?

 

Steven

 

PS: I've just noticed that the last picture shows three (three - count them!) anchors at the bow of the ship - and that's just on the starboard side! This makes sense. As I discovered researching my dromon build, anchors made by hand by a blacksmith on a forge were pretty limited in size and therefore in weight. You'd need quite a few - the 11th century Serçe Limani Shipwreck had 8 of them, of which 3 were reportedly bower anchors.

[Glen McGuire]

5 hours ago, Louie da fly said:

Do the members agree with my interpretation, or are there any other possibilities that come to mind?

I agree that the uprights look like frame extensions.  But the small loops hanging outside the gunwale don't look like rope loops to me, since the other rigging ropes are all dark.  The small loops being so bright, it seems to me like they were made to stand out, perhaps an illustration of some of the relics that were transported with St Mark's body?  Or maybe trade beads?  Certainly an interesting question to ponder!

[BANYAN]

Hi Steven, these could be the upper ends of the rising timbers but might also be the tops of cavels or the like - see attached which is from 'The Neophyte Ship Modeller's Jackstay'.  Also, I agree these appear to be 'something' formed in loops as they appear to be draped over the timber tops rather than as a ring attached/fitted to the hull proper.  Whether they are rope though I am not sure, as this is an unusual way to depict rope.

cheers

 

Pat

[Knocklouder]

religious mosaic might have put in a few roeserys  would be my guess, but I would be guessing  lol.