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Ab Hoving

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  1. I like this thread very much. Only just discovered it. I especially like the way you do your research. In my opinion it does not pay off often to try to build a model of a specific ship, even more so if the data are unsure and controverse. Much better to depict a type, even if you put a name on it later. You found a nice way in between by connecting with archaeological finds and manuscripts. So much better than simply using a plan made by someone who did not know what is right or not either. My compliments Sir. Ab
  2. This is a wonderful tutorial David. Almost a pity that I don’t work in wood any more. 🙂 Ab
  3. The answer is simple. Petr. They are two different plans. The one (on top) was done by Cor Emke with AutoCad, the other one from the book (which is the second one you show here) is hand-drawn by myself. There are some differences, but nothing dramatic. Once you are on your way you will encounter some minor aspects that should be changed anyway. Call it 'developing understanding' over a period of 30 years. If you carefully study the 3D images of the 'witsenscheepsbouw' program, you will see what I mean.
  4. The link to the program about the pinas is: https://witsenscheepsbouw.nl. As to your questions in your first post: The book was published in 1671. The material used for the ship must be compiled in the period 1660-1670. On paintings pinases are often depicted, although not as often as the men-of-war, which are a bit more spectacular than an armed merchant. Here is an example by van Diest: Draughts were not made in those days, as you know. The '134 feet long pinas' by Witsen is only described in words and sketches in his book. In the next version of the witsen
  5. The best I can do is refer to this thread, Im posted this week: I made the plans in 1980-1983 and built the model in 1983-1986. It was purchased by the Noordelijk Scheepvaartmuseum (Norther Shipping Museum) in my place of birth Groningen. The book cane out in 1994 and the English translation in 2012. Here are some pictures of what the model looks like: The last two pictures were taken during construction of the model, when it was temporarily place on
  6. At previous occasions on this and other forums I explained that real trustworthy information about the shape and construction of Dutch 17th century ships is scarce. (http://www.papermodelers.com/forum/ships-watercraft/35441-17th-century-dutch-fluit-14.html, , The Amsterdam diplomat, lawyer, collector and lord-mayor of Amsterdam Nicolaes Witsen (1641-1717) was the first to write a book on the subject of Dutch shipbuilding, Aeloude en Hedendaegse Scheepsbouw en Bestier (Old and Modern Shipbuilding and Managing) 1671. To illustrate his story he described the building of an average ship of h
  7. Dear Jules, Interpreting written sources is always dangerous. I don't have to remind you of the numerous deaths of people who were victim of different interpretations of religious written sources. The nasty reason is that people tend to select the interpretation that suits them best and completely ignore different signals. A nice example is the Witsen drawing you show in #159 (V), where the bottom is planked and the bilge is not (yet). The next drawing in line is the one I showed in #155 (X), where the bilge is planked and an angle does show up. That's pure logic: before a shipbuilder st
  8. Sorry Jules, but I think you have to read better. The method of construction always influences the shape. The borders of the bottom can always be seen, if only by the run of the planking. The transition from a flat to a curve always produces an angle, but the shipbuilder could at wish diminish that angle. But why should he? Nothing remains visible of the underwater part. If you want to give your model a smooth transition, who am I to say that it's not allowed. If you want to read in what I say (or better, in what Witsen writes) that there is no transition, who would fight you over that? I
  9. I think that is the right attitude PietFriet. You will certainly not find me on your way to state that you done wrong 🙂 Ab
  10. Maybe a short explanation about the method of building is useful. When reading contracts for building ships (our main source on the matter) we almost always see the width of the bottom recorded, together with the measurement how much it rose. For instance: the bottom is wide .. feet and rises .. inch. To control that measure the planks of the bottom were laid in a straight line. It is obvious that the more the bottom rises, the harder it will be to locate the transfer from bottom to bilge. Much loading traders had an almost horizontal bottom, while fast sailers had a more rising one. So on tra
  11. Hello Roger, Of course you are right stating that Froude turned tank-tests into scientific rules. But in an empirical way shipbuilders did tests which, according to professor Gerritsma from the Technical University Delft were absolutely valid: for instance in the 1750's Pieter van Zwijndregt built a 186 feet long test track in the Zalmhaven (Salmon Harbor) in Rotterdam, with weights to get an even propulsion and a pendulum to measure the time. Planks were sawn into waterline shapes and of all tests the results were compared and translated into waterline shapes in his des
  12. I agree Roger. Not only the hydrodynamic performance of ships is relatively new, even the matter of stability, seen from a theoretical point of view was left alone for a long time. I spoke to an marine engineer who was (on his own initiative) working on the stability of our post-war Navy ships. Nothing about their stability appeared to be worked out in math. On the other hand, there were shipbuilders in Rotterdam around 1750 who performed tank tests on shaped planks. Chapman came to visit them and published a very identical set-up in 1775. Bouguer, Euler and Bernoulli discovered the physical l
  13. Perhaps with smaller craft the transition is more visible. Here an archaeological find in the Waddenzee, with one single bilge-plank:
  14. Eberhart, I think PietFriet is right here. The fact that Dutch ships showed an angle between bottom and bilge was not the result of a choice the builders had. It was simply the consequence of the method of construction. And of course in some ships it showed more than in other ones. I tested the shell-first building proces, both in model scale and as a witness building the 'Duyfken' in Australia, and the outcome was (apart from that angle) that the bottom planks ran in a straight line in section from keel to the beginning of the bilge. Shipbuilders could choose to lift the outer plank a bit to
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