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Everything posted by Dr PR
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Making sheaves for blocks and bitt pins
Dr PR replied to Kevin Kenny's topic in Masting, rigging and sails
I do not have a lathe (on my wish list, but first I need a shop to put it in) so I have come up with a very simple way to make sheaves down to 0.078 inch (2 mm) diameter using ordinary brass washers. In this link I made sheaves for a 1:48 scale model: https://modelshipworld.com/topic/19611-albatros-by-dr-pr-mantua-scale-148-revenue-cutter-kitbash-about-1815/?do=findComment&comment=616985 For a list of brass washer sizes see this link: https://www.mcmaster.com/standard-washers/material~brass/ -
Tim, I'm not sure about using the bolt ropes to produce "skeleton" sails. I haven't seen a model rigged that way but it does seem a bit odd (unusual) to me. However, I have seen models where some of the sail rigging is included without the sails. For example the fore sails have halliards and inhauls/downhauls that can be hooked together when the sail isn't rigged (usually at the inhaul block on the bowsprit/stay). Likewise square sails have clew lines and sheets that can be hooked together at the end of the spar. Gaff sail outhauls and brails can be rigged this way at the end of the boom. Buntlines could be hooked to the spar. I'm not sure what you would do with bow lines that normally attach directly to the sails. I think you can include most of the sail rigging in this way.
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I have been following this discussion because I went through a similar search a year or two back. Wolfram zu Mondfeld's Historic Ship Models (Sterling Publishing, New York, 1989) shows the construction of gun ports (page 96) and gun port lids (page 176) in pretty good detail. I realize many modelers play down Mondfeld's book because it isn't specific to any particular ship or nationality, and he doesn't list his references. This is true. But the book's greatest virtue is the descriptions of parts of ships as they evolved over the centuries and in different parts of the world. For example, he describes gun port lids for British, French and other Continental navies from before 1550 through 1890. Much of what this thread is about is discussed in his book. The book isn't perfect, but it does explain many of the differences you see in contemporary models from different nations and time periods.
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Kieth, Your work, and the photos you post, are a modeler's eye candy! Beautiful research, design and implementation! One of these years I hope to achieve a similar level of perfection.
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We had a board similar to the second one on the quarter deck (in port) of the USS Oklahoma City CLG-5 in the 1970s. It carried the names of all the officers assigned to the ship (about 200). Each name was engraved into a plastic strip. The name strips slid back and forth in metal guide rails. The "quarter deck" was the area where the officer's brow (gangway) attached to the ship - where officers left or boarded the ship. As officers came and went from the ship the name strips were moved left or right to signify whether the person was on board or ashore. This allowed the Officer of the Deck to keep track of which officers were aboard. I have no idea if the "officers name board" had an official name. Phil
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William, Good to hear from you. I don't know where I will go with the project either. My intent was to create a complete set of 2D drawings that modelers could use. This turned out to be a massive undertaking - a side profile drawing takes 5-6 days to generate from the 3D model (on a 4.7GHz i7 machine with 32 Gbytes of the fastest RAM I could buy, running 24/7)! Then it will take a week or two to clean up the drawings and scale them for plotting. I wanted to build a 1:96 scale model, and the hull is partially completed. 3D printing has come a long way since I started the project in 2004, and I am considering converting many of the files to printing files. But there will be a pretty good learning curve and I don't know when I will start that. First I must build a workshop to house the tools and the model. Who knows when/if that will happen! Converting the 1 Gbyte of files to a new format for Flight Simulator is not something i am interested in doing.
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George, This is a little late, but I will post it for your information. Here are photos of a sliding hatch on the Lady Washington. This type hatchway was/is very common. The part under where the hatch slides back isn't wasted space - it is headroom as you descend the ladder. The top is not always sloping. On some vessels it is parallel to the deck.
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Laggard, Patience and perseverance are the most important qualities of a wooden ship model builder, and if you have made it this far through this thread you have both! Don't be too critical of your first model or two. They are learning experiences. None of us builds a museum piece on our first try. There are a lot of new techniques and materials to learn about, and even some historical trivia to enlighten the experience.
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Macro photos with an iPhone
Dr PR replied to Tomculb's topic in Photographing your work. How to do this.
Tom makes an important point! Phone cameras have fixed lenses that do not zoom. When you magnify the image on the screen you are not actually changing the focal length as in actual zoom lenses. Instead it takes single pixels and expands them to 4, 9, 16, ... pixels. This would produce a really "chunky" image with huge jaggies but the software blurs adjacent pixels to reduce the undesirable jaggies. But the result is a blurrier image with less sharp detail. Some cameras claim to have "macro" lenses, but they always have far fewer pixels than the regular or wide angle lenses. I am suspicious that all they are doing is just taking the small center part of the image of the wider angle lens for the "macro" photo and discarding the rest. So the actual 12 megapixel image is just cropped to 4-6 megapixels. Likewise, some cameras claim to have enormous number of pixels for wide angle photos, more than high level "professional" camera bodies costing $5000-$6000. I am skeptical about this - it may be marketing BS. They may be repeating a digital scanner scam where an image is actually scanned at X pixels resolution and then expanded in software to something like 4X pixels. An actual 12 megapixel image is blown up to 48 megapixels. Again, the results are blurrier than the actual optical resolution of the photo element. You can't get something for nothing! But at least one phone I know of has a sliding lens carrier that moves different focal length lenses in front of the same photo element. It has real wide angle, portrait and macro lenses. In this case every image has the same number of pixels. Having said all of this the only really important things is whether or not you are satisfied with the photo you get. If it is too blurry, zoom out and try again. I have seen some very nice close-up photos made with phones! -
Tim, I have been studying schooner rigging for the last year or two, and have posted what I have learned here: https://modelshipworld.com/topic/25679-topsail-schooner-sail-plans-and-rigging/?do=findComment&comment=750865 The thread also includes discussions of the most common reference books for ship and schooner rigging. Although I am working on a topsail schooner model, it seems to me that the rigging is the same for the gaff sails on a fore-and-aft only schooner as on the topsail schooner. The only difference seems to be the addition of the square sails and their rigging to the normal fore-and-aft sail rig. I have posted a spreadsheet to calculate masting and rigging diameters for schooners. It includes the dimension calculations from some standard reference works for square riggers and schooners. The big difference between schooners and square riggers is the mast diameters. Because the schooner rig is much lighter the masts are thinner and different calculations are used for mast dimensions. Schooner masts carrying some square sails may be a bit larger diameter than the ordinary fore-and-af sail masts. Once you have the mast dimensions - the diameter at the partners (deck) the calculations for rope sizes are the same as for square riggers. One thing I have learned in my research is that there is no single "normal" or "standard" way to rig a schooner. If it can be done you can be sure it has been tried at some time. There is a tremendous range of variations in schooner sail configurations and rigging - at least a dozen ways to rig a gaff topsail! American built schooners often carried more extreme sail plans and rigging than the European counterparts, and pilot boats were no exception. There was serious competition between indiviual harbor pilots - they were paid by the job - and they raced out of port to meet incoming vessels. Pilot boats were built for speed.
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Ladder steps
Dr PR replied to allanyed's topic in Discussion for a Ship's Deck Furniture, Guns, boats and other Fittings
In modern US ships the number of treads in a ladder (vertical or angled) depends upon the vertical length. This is divided to give a number of equal spaces between the treads (top of treads) somewhere around a foot (12 inches). This can vary between about 10" to 13" between treads, with the bottom tread on vertical ladders as much as 18" above the deck. Angled ladders tend to have the same spacing from the deck to the top of the lowest tread as the rest of the treads. Blueprints usually don't actually give the spacing, but just give the height of the bottom step from the deck and the distance from the top step to the deck above, and show some number of treads and say "Equal Spacing." The rest is left up to the shipyard. I suspect ladders have always been made this way. You have a space to fill with steps and you want them spaced in a reasonably familiar way. The fact that the spacing differs from ladder to ladder doesn't matter. Take my word for it - I climbed all over ships at sea with varying tread spacing and never had a problem missing steps. But it is important for the spacing to be equal on a given ladder. Also, the lowest tread should not be too close to the deck - that can cause tripping. And the top tread should be about the same spacing below the upper deck as the tread spacing in the ladder, but often is shorter if necessary to get appropriate spacing between the other treads. You don't have trouble finding the deck above the ladder when climbing - it is wherever your foot lands. - again, I speak from experience! Well, if you are climbing a ladder in the bow while the ship is pitching in high seas you may find yourself catapulted into the air just as you reach the top step with the ship dropping out from under you and then have momentary difficulty finding the deck, but gravity quickly remedies that! -
I have been looking for more information about the historical use of the jib stay traveller. Every book I have looked at mentions the traveller, but most stop there. Darcy Lever's 1808 "The Young Sea Officer's Sheet Anchor" is an excellent period source about rigging and sailing. In the ship handling part of the book in Section 84 "Taking in the Jib, &c." lever describes lowering the jib to the bowsprit to reduce wind effect on the bow that is making it difficult to keep the ship on course. "... when it is close down on the Boom, if the wind be likely to encrease, the Stay or Out-hauler ... is let go: it [the sail on the traveller] is hauled in close to the Bowsprit Cap and stowed away ..." So the traveller was used to bring the jib tack back to the bowsprit cap when the sail was to be stowed. However, there are also references implying that the traveller may not always have been positioned all the way forward, perhaps as Ian Grant said, to change the effect of the wind force on the sail. Lever discusses the effects of wind force on sails forward and aft of the center of gravity that cause the ship to change course into the wind (griping), and methods to reduce these forces to allow the ship to be steered without using the rudder (which increases drag when it is turned off midships). However, he does not mention reducing the fore sails for this purpose, but does describe raising and lowering them when turning the ship to allow the fore sails or mizzen sails to bring the ship about. In Section 60 "JIB, &c." Lever discusses the inner martingale stay that is attached to the traveller to generate a downward force to counter the lifting force of the jib stay. "Many vessels have only the outer Maringale-Stay; but the inner one is very serviceable when the Jib is a third, or half in, as it acts immediately under the Stay." [my emphasis] George Biddlecombe's 1925 "The Art of Rigging" (page 99) also describes hauling the traveller back to the bowsprit cap to raise the sail. "The Jib being ready to bend, haul the jib stay and traveller close in to the bowsprit cap; ... reeve the stay through the hanks (which are already seized to the head of the sail) ... haul it out to the traveller; hook the stay [to the traveller] ... then haul the traveller out to the jib-boom end (if required), and set the stay up." [my emphasis] So both authors imply that the traveller may be positioned at places other than full forward or full aft. But neither actually describes doing this to moderate the forces acting on the ship. So historically the traveller was used when setting or reefing the jib. But I still don't know how common the use of a traveller was, and especially on topsail schooners.
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Thanks for the replies. Hauling the traveller back to the bowsprit cap to make it easier to handle the sail makes sense. But ... I have seen photos of vessels that have a traveller but do not use it when lowering the sails. Here are some photos of the modern La Recouvrance topsail schooner. First a clear shot of the outer jib and traveller. It appears that the outer jib stay also serves as the outhaul. The vessel also has a jib and a fore staysail. Here is a shot of the fore sails lowered: The dolphin striker (martingale) is visible, and the traveller clearly hasn't been hauled back to the bowsprit cap. Finally a photo of the furled sails. The traveller is still near the forward end of the jib boom. Why have a traveller if you don't use it? Many modern schooners do not have a traveller for the jib(s). So I was wondering how common it was in the past.
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I am curious as to how common it was for vessels to have a traveller on the jib boom for the jib/jibstay? Lever, Biddlecombe and Lees describe how travellers were constructed and how sails were rigged to them. But many models do not show a traveller, and photos of modern vessels often do not show a traveller. The typical traveller was a ring that fit loosely around the jib boom (or perhaps the flying jib boom) and was free to slide fore and aft along the boom. The jib stay led to the traveller and the jib sail tack attached to the traveller. Inhauls and outhauls moved the traveller along the boom to position the foot of the sail. Note: This is a simplified description. The jib stay could also serve as the outhaul. Also, there were other types of travellers used elsewhere on ships. What was the traveller used for? Obviously it changed the position of the tack of the sail along the boom. But why? Searching this forum for "traveller" revealed opinions that it could be used to reposition the sail to gain best advantage of the wind. But some people say it was just a convenience feature to allow the jib to be hauled back to the bowsprit cap to make it easier to reef the sail without climbing out to the end of the jib boom. Since many vessels do not have a traveller, just how common were they? I am especially interested in topsail schooners, but apparently travellers were used on all types and sizes of vessels.
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Kev, I see a problem with your sketch in post #6. If the fall of the boom sheet was secured to a cleat on the boom, and the boom was swung overboard, you wouldn't be able to reach the boom to untie the sheet. I think in a small rig like a long boat you probably would need only two single blocks , and the fall would be secured to a cleat on the rail or bulwark. It was common to secure the gaff sail sheet to a cleat on the boom near the boom jaws where it was always accessible. On larger rigs the sheet attached to a two block tackle that was attached to the jaws of the boom and the fall to a cleat on the boom.
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Terry, Thanks for the drawings - you saved me the trouble! They illustrate the ideas perfectly. And they show quite clearly that with a constant camber deck the resulting "rail sheer line" where the deck and hull surfaces join is a smooth fair curve. There is a potential problem with the "saddle shaped" deck as shown in your drawing. Of course the curvatures are quite exaggerated, but even with milder curvatures there would be a problem laying constant width wooden deck planks on this surface. If they were placed side by side at the center of the surface (longitudinal and transverse center) they would splay apart at the ends. But this would be a problem only if the individual deck planks ran the full length of the deck. In practice the planks were much shorter, and each run would be created with multiple planks. This would make it easy to bend the planks to the curvature of the deck surface. I have walked the decks of several ships built this way and the plank curvatures are so small they aren't noticeable. In steel hulled vessels the deck plates were cut to fit the curvature.
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Caarles, I do not follow your description in post #29. In my perspective drawing in post #24, there is no incidence of the center of any of the red deck beams coincident with the black curve. There are no cases where the red camber lines, the red vertical lines and the black curve intersect. The drawing shows the case where the center of the deck camber curves intersect the straight green longitudinal "sheer line" at the point where the vertical red lines intersect the green line. The black line is just the coincidental intersection of the deck surface with the hull sides (not shown) projected upon the vertical centerline plane (not shown). It would be possible to create a different deck surface using the same constant camber deck beam curves just by lowering each camber curve to where the center point of the camber curves is on the black curve where the vertical red lines intersect the black curve. In this case the black curve would be the centerline sheer line of the deck (modern usage of the term sheer line). This deck would be "saddle shaped."
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Tom, Excellent presentation! And I certainly agree that modern construction methods are different from those used in the past, and cannot be used for accurate reconstruction of ancient ships. After all, shipbuilding has progressed by learning from mistakes of the past. I wasn't trying to say older ships were constructed with constant deck camber. I just disagree with those who say they couldn't have been built with constant camber. The difference between the "constant camber" method and the "variable camber" method described in your post is interesting. It all depends upon which "sheer" line is the controlling factor. In the constant camber method the "sheer line" is the longitudinal (fore-aft) curvature of the deck at the centerline (crown sheer line). All transverse (side to side) deck beams are positioned with their top center on this centerline sheer line. The location of the line at the intersection of the deck surface and the hull surface is not predetermined, and is just the result of the shape of the two surfaces. Likewise, the vertical distance between the centerline sheer line and the hull-deck intersection line is coincidental. In the variable camber method an arbitrary "sheer line" (rail sheer line) where the deck surface and hull surface intersect is drawn on the profile plan. Another line is drawn for the curvature of the deck at the centerline (crown). The vertical distance between these two lines determines the curvature of the camber for each deck beam. The curvature for each deck beam would have to be calculated. I have to wonder why anyone would have used the variable camber method? It is a lot more trouble to produce and the resulting deck would be less "fair" (could be wavy) and not better structurally than the simpler constant camber method. My guess is that ship designers had not yet developed the drafting methods necessary to determine the intersection of the deck and hull side for the sheer plan.
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Jaeger, No apology necessary. I have seen the term "camber" used for both the longitudinal )fore-aft) curvature of the deck and the transverse (side to side) curvature. I have also seen the term "sheer" used for the longitudinal curvature of the deck at the centerline (the modern use of the word) and for the curvature of elements on the sides of hulls (sheer strake) and the line where the deck intersects the hull sides. Unfortunately, many people are familiar with only one use of a word and assume it has the same meaning for everyone, everywhere and at all times. I have also seen plans showing the fore part of the deck near the hawse openings angled down (but not the other decks). I assume (but do not know for sure) this is to cause water coming in the hawse openings to be confined to the bow area. But this downward dip can be created with constant camber deck beams. The centers of the beams just have to follow a downward curve of the centerline sheer line toward the bow.
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I have read through this thread several times and most of it makes no sense at all. There are too many undefined terms, ambiguous wording and simply irrational statements. It seems several people have said you cannot build a "fair" deck if all the deck beams have the same camber. I assume "fair" means smooth and not wavy, as in a smooth curve or surface. However, virtually all modern ships are built this way. This image shows the curvature (camber) of the transverse (side to side) deck beams (red). They all have the same curvature or camber. The green line from bow to stern is the centerline along the deck surface. The center point of each red transverse deck frame is positioned on the green centerline. The black line is the curve of the deck edge from bow to stern, as shown on profile views. This drawing shows quite well that anyone saying you cannot build a "fair" deck using the same camber at all stations (or deck beams) doesn't know what he is talking about. Actually, the deck surface is just a section of a cylinder, like a pipe, where the diameter (curvature) is the same all along the length of the cylinder. This is an image of the actual boat. It is a 40 foot personnel boat used by the US Navy for the last half of the 20th century. Note that the curvature of the hull where it joins the deck surface is "fair" - not wavy. The entire deck surface and hull surfaces are "fair." The deck does not curve down into "swales" at the bow and stern. Another example of a model of a 19th century wooden ship constructed with the same deck curvature (camber) at every frame can be found in this post: https://modelshipworld.com/topic/19611-albatros-by-dr-pr-mantua-scale-148-revenue-cutter-kitbash-about-1815/?do=findComment&comment=603771 In this case the deck has sheer (curvature along the longitudinal direction). The deck surface approximates a hyperbolic section, although in this instance it isn't an actual mathematical hyperbolic surface. It resembles a saddle surface, or the surface of a doughnut hole, where the deck curves downward from the centerline in the transverse (side to side) direction (camber), and curves upward from midships in the longitudinal (lengthwise) direction (sheer). The line where the curved deck surface intersects the molded surface of the hull is not wavy, but is "fair," and the deck surface does not dive down to a lower level at bow or stern. I am extremely familiar with the construction of the Cleveland class cruisers of World War II, having studied thousands of blueprints for 14 years to build a detailed CAD model of one of these ships, and I can assure you that these ships were constructed with the same deck camber at every frame on the main deck and most higher weather decks: https://modelshipworld.com/topic/19321-uss-oklahoma-city-clg-5-1971-3d-cad-model/?do=findComment&comment=590447 I have given examples of ships that were built with the same transverse curvature (camber) at each deck beam/frame, in cases where the vessel had no sheer and where it did have sheer. In each case the lines of the deck and hull were "fair." And in no case does the deck curve down (longitudinally) at bow or stern. Now can anyone explain why a ship built in ANY period could not have fair lines if all deck beams (in the same deck) had the same camber? NOTE: If you do, please define every term you use so we have a chance of understanding what you say. Otherwise it will just be more incomprehensible gibberish.
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Allan, Thank you very much! I thought about doing what you did, but I don't have enough information about individual English ship hull and mast dimensions to get any meaningful results. I was pretty sure Lees was using what some authors call "measured length" from the foot to the top. But quite a few authors (and rules) use the hounded length, so I wasn't certain. I am using Lees' rules for rigging to determine rope sizes. I figure that regardless of the type of ship and ship size the relationship of mast diameter to rope diameter/circumference was probably about the same for all ships. Schooners typically had smaller mast diameters than did full square rigged ships, but the mast diameter should still serve to determine rope sizes. Small boat rigging is another thing!
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