Richard Braithwaite
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Everything posted by Richard Braithwaite
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I like your method of taking the shape of the floors. I built my trireme model is a similar way (planks over a jig and then shaping frames to fit...) It took ages, as every frame was different... And after -
I suppose its a good thing that his head is made of wood... Its taking me long enough to build this one so I don't think Ill be making another one soon. I have been developing a computer simulation, however, which I'm hoping might be useful in supporting some design work to assess the extent to which performance could be improved by optimizing the layout.
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A little animated gif of my the manikin at this thalmian position. His rowing technique leaves something to be desired (!) but he does illustrate one of the difficulties of the design. The limited space between the deck beams meant that these rowers tended to his their heads at each end of the stroke. It was a particular problem at the finish and could be dangerous if anyone caught a crab… They mitigated it on trials by putting the smallest rowers in these positions (I based my Manikin on a 50% 600BC Athenian build…) and fitting a restraining rope to the oar so that it wouldn’t break their necks if they caught a crab. Not ideal, and the power delivered from this level suffered accordingly. One of the issues to address in any Mk II design… Just noticed that his foot rest had dropped and disengaged from the locating dowel. Should have lashed it tighter... oops!... I think my manikin achieves about 720mm of the full 800mm design stroke. I have modified his joint already to make him a little more flexible but he still had problems pulling the oar right into his torso at the finish of the stroke (as you can see from the GIF above). However, I don't think they often achieved the full 800 mm stroke on trials for the reasons given above...
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First Thalmian (lowest level of three) Rowing position in place (minus the leather foot and heel straps. The small dowel in the stretcher is used to locate the footrest and allow some adjustment for the rowers leg length. These foot rests are pretty much hidden underneath the seats once they are all installed. (Drawing shown is an extract from John Coats Plan No 9 titled "Trieres Foot Stretcher" © Estate of John F. Coates, reproduced with permission)
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Removed the canopy sections so I can start to install the oar seats etc for the lower level (Thalmian). Probably should have done this earlier in the build, but the ability to dismantle my model helps me get away with it! First photo shows the longitudinal stringer that supports the inner end of the Thalmian beams installation using a jig to ensue the correct vertical location. The next photo shows a couple of Thalmian beams in place with a plywood jig to fix the 3 degree rake. The deck beams, walkway, inner stringer etc. all comes away as a boltable assembly, which means I can only fix the inner ends of these beams. The outer end is left resting on the Thalmian stringer. I'm hoping that once I have installed the seats and stringers (which connect the beams longitudinally) this cantilevered arrangement should be stable enough...(Extract of John Coates Midship Section Drawing ‘© Estate of John F. Coates, reproduced with permission.)
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Looks a little "robotic" though. Hopefully can use them for illustrating how the three tiers work together through the rowing stroke. I don't think I will be making 170 of them though...
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An Athenian Marine... I've been looking for a scale wooden artists manikin to demonstrate ergonomics of rowing equipment geometry etc. but they are all on much too large a scale for my model. So I decided to have a go myself at a 1:24 version. For the dimensions I found a good source of ergonomic data for US Marines (https://apps.dtic.mil/sti/pdfs/ADA581918.pdf). I took the data for the 50th percentile marine and scaled it according to the mean height of a classical Greek male (approx. 5 ' 7" as identified from Archaeological studies of skeletal remains ref S. C. Bisel, J. L. Angel, "Health and Nutrition in Mycenean Greece: A Study in Human Skeletal Remains," in N. Wilkie, W.D.E. Coulson (eds.) Contributions to Aegean Archaeology: Studies in honor of William A. MacDonald (Minneapolis 1985)). Given both US Marines and Athenian oarsmen are likely to be of a similar muscular build, I thought this approach would give a reasonable approximation. I know that trials on the full size of Olympias had some difficulties fitting 20th century oarsmen in some of the rowing positions... Anyway the resulting model is shown below: I've used two sort of joints to give the required mobility: 1. ball ended pins to simulate the ball and socket joints of the shoulder and hip (and the rotational joints of the neck and heels) 2. simple one degree of freedom pin joints for the knees and elbows. This works for an oarsman at around midstroke as shown below: And finally standing on the helmsman's platform of the model to give an indication of scale: I'm planning to make 3 of these manikins so I can check the arrangement of the rowing equipment (seats, stretchers etc,) on the model for each triad of oarsmen.
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Insallation of the ladders on the model. The left hand image shows the aft end of the gangway and part of the helmsman's platform with the aft canopy sections removed. the brass lined holes in the deck are to locate the pins on the base of the ladders. The brass lined hole for locating the aftermost stanchion of the aftermost canopy sections can also be seen in the deck beams just outboard of the gangway as can the bolted lodging knees that are part of the system that enables the unbolting and removal of the entire deck assembly. The right hand image shows the ladders (and the aft canopy sections) installed. Finally a view of the ladders, quarterdeck (with Trierarch's chair!) and helmsman's platform looking aft from canopy level. The slots in the quarterdeck (with the turned rollers) are form the steering oars to pass through which are fitted with athwartships tillers controlled by the helmsman standing on the platform in front of the Trierarch.
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Three ladders completed. The brass rod sticking out of the base of the ladders is to enable location on the model. At the moment I'm leaving the top unsecured... Not very seamanlike, I know, but hopefully my model shouldn't be experiencing any violent seas!
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An overall view of my lovely Unimat configured as a milling machine. I bought it in 1985 and its been well used since. The motor packed in some time ago and has been replaced with a rather less elegant modern version unfortunately...
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I've got 4 ladders to build and have constructed this jig for cutting mortices for the rungs. Essentially one cuts the first mortice and then uses the jig to hold the side of the ladder in place while the next one is cut ... .
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Will get round to the rigging in the end... Don't think I will make sails though. My main interest is in the oar system...
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A view of the seat frame located on the quarterdeck compared with a picture of the full size Olympias. I have built my model as closely as possible to Coates design drawings (the drawings sheets contradict one another in some cases - as you would expect from what was essentially a prototype for a reconstruction of a warship which hasn't been built in living memory...). These include: 1.Differences in framing of the stern. 2. Removal of the footrest from the Trierarch's chair. 3. Differences in the leather upholstering of the Trierarch's chair. 4. Removal of the handhold post at the head of the ladders from the quarterdeck to the gangway. 5. Additional bracketry alongside the steering oar slots. I am sure some of these changes were incorporated at build and others were introduced as sea trials progressed. Not unlike my own experience of designing and building modern ships!
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Seating for the seat (?) installed on the quarterdeck. I've taken a piece out the planking between the morticed longitudinals to allow the seat to be lashed down the to the deck as shown in the trireme seat drawing. This differs from the drawing of the quarterdeck (extract shown below with the photo of my model) which would not have allowed for the seat to be lashed down in this way.
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Completed chair frame. Not perfect by any means, but the smallest pinned mortice and tenon joints I've ever tried! At 1:24 the chair is about 1 inch wide. I do like the grain on holly...really fine... almost like 1:24 oak!
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Really interested to see how this turns out. My rowing machine is fairly primative in that it describes a constant speed elliptical orbit and will not follow how an actual oarstroke would work when operated by a real human being (particularly during the acceleration phase from a stationary start...) I have been doing some research into this and writing some simulation code (in C++ for speed of execution). the purpose of this exercise is not to support any rowing machine but to gain an greater understanding of oared warships and how they could have been optimized in design. Some time ago I found a paper online describing a rowing machine model that used a weighted pully system so that the pressure applied during the power stroke (when the oar blade is in the water) is constant from catch to finish (cant find the reference now...) which I thought might be quite interesting..
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I have a load of Meccano that I inherited from a cousin years ago. Made various things with the kids over the years but hadn't thought of using it for rope making machines etc.
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Probably an excessive investment in time given what a minor component this chair is of the overall model....But I've found it an interesting challenge to see what I can achieve with a hard, fine grained wood and a Unimat lathe/milling machine.. This project has been going on for so long now that I tend to see it as a series of sub projects and get my satisfaction from each of them rather than targeting overall completion... Hopefully, Ill get there one day, but then Ill have to find a rather large area of the house to keep the model!!
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Armrest construction for the Trierarch's chair. Ability to dial in the positions for this complex joint really helps at this scale
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Continuing with the Trierach's seat back. Photos in order from top left: 1. Seat back reoriented in jig. Shown after the rear face has been machined. 2. Jig altered to take out the 20 degree angle so that the front face can be machined parallel to the rear face. In order to hold the piece down I designed the jig with two clamping positions. This photograph shows the first clamping position which allowed the top half of the front face to be machined. 3. Clamp moved tot he second position so that the bottom part of the front face could be machined. 4. Front face completely machined 5. Completed seat back. As the maximum dimension of this part is only 23mm I think I would have struggled to make it without the help of my Unimat🙂
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Continuing to machine the seat back... Built a simple jig to bolt to my Unimat milling table to incline the seat back at 20 degrees so that the slot for the tenon connecting the two halves could be milled...
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Richard, I've also spent many years developing hullforms as a Naval Architect in England. Rhino is a great product, which I find really intuitive and easy to use. My main application was developing early stage concept design of warships and then rendered them using the addin renderer flamingo. My workflow generally involved developing the hullform in Paramarine and then importing the iges surface into Rhino to develop the superstructure and detailed 3D model for visualization. Main reason for doing it that way was because we needed the Paramarine model for sizing and analyzing the design before we reached the stage that we wanted a more detailed 3D model. Paramarine is slightly painful for use for generating hulls (although you can get proficient in just about anything if you really have to!!!). Rhino is also a lot less expensive to buy. Looking forward to seeing how you go about hull modelling in Rhino BTW Have you ever tried the Rhino addin ORCA?
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