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Dr PR

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  1. Roger, That is a clever idea! Officers' gigs and barges in the 1970s had mahogany decks with white grout (see image below). It is also common on civilian yachts. I have often wondered how to model that.
  2. Chapelle (The Baltimore Clipper, Edward W. Sweetman Company, New York, 1968, page 4), in speculation on the origin of the Baltimore clipper, describes an earlier 1770s French lugger Le Coureur. "The lines show a powerful and fast craft with ... great deadrise and rather sharp waterlines." The faster ships being built at the end of the 1700s had very sharp lines below the waterline with hollow "cheeks" and a great deal of deadrise amidships. By "sharp lines" I mean small angles between the lines at the bow and stern relative to the ship centerline, and waterlines that were concave (curving inward) forward and aft, and convex (curving outward) midships. This is in contrast to the "bluff bow" that was common on larger merchant and warships of the 1600s and 1700s where the waterlines were convex from the bow. The bluff bow designs had waterlines that began at the stem almost perpendicular to the centerline. This created a lot of drag, but it was a necessary feature to keep the bow afloat. Buoyancy (the forces that keep the ship afloat) is proportional the amount of water displaced. These forces are greatest amidships where the beam is widest and the greatest amount of water is displaced. But at the bow and stern the forces are less because less water is displaced. This is the major factor causing "hogging" of a ship, where the bow and stern sag lower than amidships because the forces lifting them are weaker. With the weaker structural designs in early ships the bluff bow and square sterns were necessary to support these parts of the ships. By the late 1700s ship designers were learning how to build very strong hulls. Think of the diagonal members in the Constitution's hull, and the diagonal metal straps used in the later clipper ships. This allowed the "sharp entry" into the water, both bow and stern. Another factor was the deadrise. This is the angle of the cross section lines to the horizontal. Most large ships of the 1600s and 1700 had nearly flat bottoms amidships to maximize cargo space. But this created a large cross section area, and that meant high drag. The French lugger Chapelle mentions was unusual because it had fairly high deadrise - the bottom formed a "V" rather than a "U". This had two effects. It reduced drag, but it also reduced buoyancy amidships. The combination of sharp lines fore and aft and high deadrise amidships evened out the differences in buoyancy along the length of the ship, creating less strain and hogging. This made for lightweight and very fast ships with smaller cargo capacity - sort of the FeDex of the day. It is these features that come to mind when I see references to a "sharp" ship. I would add one more thing here. These effects of deadrise and sharp lines were not unique to older ships. Modern steel hulled ships suffer from the same hogging effects, and some designs were especially at fault. American cruisers of the late 1930s and 1940s were prone to structural failures because of extremely sharp and long hulls with relatively broad midships cross sections and very little deadrise. This had the effect of magnifying the hogging stresses. Several of them lost their bows in heavy seas, and many were scrapped after the war because of structural failures instead of being mothballed for future use.
  3. I have a friend who has been making HO scale kits for decades. He taught me how to cast the low temperature metals. He uses some home made centrifugal rigs to spin the mold while he is pouring to be sure the metal flows to the ends of the cavities and to expel air from small cavities. A centrifuge isn't essential, but if you will be doing a lot of castings it might be worthwhile. I have an ancient laboratory centrifuge that was used in school chemistry and medical blood test labs. It has a nice shield around it in case the hot metal leaks from the mold. You can pick these things up pretty cheap and replace the centrifuge head with a plate to hold the mold. It has a variable speed motor control and a lid. The molds are flat, with the poring funnel in the center and the mold cavities arranged around it. Here is an example, with the brass originals below on the left and the cast pieces on the right. Note that some of the pieces are cast with an angled tab on one end. Notice that there are no vents for simple pieces like these. The mold halves are not clamped very tightly so the air escapes easily. A bit of flash might exist on some pieces but it is easily removed. A trick he uses is to dissolve hand soap (he used Ivory soap) in water and paint this on the mold surfaces. It reduces surface tension and sticking to the RTV, and it washes off with water.
  4. I'd guess the normal blocks on the Eagle would be about 8 inch to 12 inch, or 0.032 inch or 0.048 inch at 1:250 scale. You could try cutting short lengths of small diameter hypodermic tubing and flattening them with pliers (with a length of wire in the opening to keep a hole for the line to pass through. This should give a fairly uniform size. You could then lead the running line through the hole and tie the standing part around the block. You would need to experiment with tube diameter to get the "right" size after it is flattened. Aluminum tubing should flatten easily around a steel wire and still leave a hole the diameter of the wire. You might look through jewelry supplies - they sometimes have bags of 50 to 100 pieces of short small diameter tube spacers. They don't call them spacers but have a jewelry name for the, but they are spacers anyway. I have never tried this so you are on your own. **** If you do come up with a clever way to make tiny uniform sized blacks be sure to post a thread telling us how you did it!
  5. I have glued black paper strips to the edges of deck planks. The paper strips were a bit wider than the planks, and were trimmed on the bottom side before gluing the planks down. After the planks were glued in place the deck was scraped to remove the high edges of the paper, and then sanded with coarse grit sandpaper because the planks that came with the kit were not all the same thickness. Then the deck was sealed with clear lacquer and sanded again with a fine grit to remove scratches from the coarser grit. The final finish was with 0000 steel wool. There was no fuzzing. I used an organic solvent based wood glue (Duco) and that soaked into the paper and wood. After it dried the paper was pretty hard. You can choose a paper thickness equal to the scale thickness of the grout on the ship you are modeling. I used a full scale 3/8 inch grout width. At 1:48 this was about 0.008 inch, and I found a black paper about that thick. Nothing fancy, just ordinary craft paper. For a 1:96 scale project I will need a 0.004 inch thick paper, and that is about the thickness of ordinary 24 pound printer paper. 20 pound paper is about 0.003 inch thick.
  6. I have a large 100+ Watt solder gun, and small Weller 25 Watt soldering "pencil" and a 250 Watt American Beauty resistance soldering unit. I have the pen and cable set and the tongs for the resistance unit. For most things I use the soldering pencil. But the resistance unit is really good for quick spot soldering on large pieces. It works by flowing current through one of the pieces to be soldered, through the flux/solder and then through the second piece to be soldered. You place the probes on opposite sides of the joint so the resistance is lowest at the point to be soldered. Because the resistance is greater through any other path, even if the two pieces have been soldered together at other points, the current flows through the least resistance path and generates heat in the solder at the joint. As long as you allow the parts to cool between joints you don't need heat sinks. The power can be adjusted from 0% to 100% of the output to meet the needs of the job. If you want a really fast operation crank it up to 250 Watts and the joint is formed almost instantly - however, you can generate too much heat and actually melt very thin metals. However, I find it very frustrating to use because the tips are brittle carbon that breaks extremely easily. I go trough them almost as fast as the solder. It takes a while to learn how to use the resistance unit effectively. If anyone knows of any other more durable tips I would appreciate learning about them. I bought the thing after I learned that they are used on those very nice HO and O scale brass locomotives that sell for an arm and a leg. By using the right flux, a small amount of solder and the proper technique you can create complex brass assemblies with absolutely no solder showing. **** I used to do a lot of micro electronics soldering while designing and assembling prototype electronics assemblies. For that I used the pencil iron with a very tiny tip for solder joints on ICs with 0.01 inch (0.25 mm) wide pins with 0.01 inch spacing. We soon learned that the best flux is the aquatic citrus based flux. It smells like orange juice! It is a liquid and you can paint it on with a small brush. It flows readily between the two pieces to be soldered and draws the solder in for an excellent joint. It flows into extremely tiny holes and cracks. Then, being water based, it is easy to wash off the residue. It works for any type soldering. It is my go-to flux for everything except very high heat soldering with a torch.
  7. I think maybe you enjoy building the tools more than the models? That's a clever idea building the caliper into the tool. That is a lot cheaper than some of the digital readouts that are for sale.
  8. Here is an example of a binnacle on a modern (1895) schooner C. A. Thayer. The companionway is offset to one side and the binnacle (the thing with the curved top) is tied down to the roof of the cabin on the ship's centerline, forward and below the boom rest.
  9. Just a guess, but ... Modern ships fly the flag from high on a mast when at sea, so it can be seen from a distance. When in port the flagstaff is raised on the stern, and jack staff on the bow, and the flags are flown from them. When the ship gets under way the flag is changed to the mast and the flag/jack staffs are stowed again. I do not know how long this practice has been used, but from some of the pictures posted above it may be that it was the practice several centuries ago.
  10. Every creature is food for some other creature - including us. There are too many people and pandemics are nature's way of correcting that. The influenza pandemic a century ago killed millions. That should have been a wake up call. But we have become complacent because medicines and medical practice have improved a lot since then. But we now have four times as many people, mostly crowded into less area. And we move around (spread diseases) a lot more than people did then. COVID-19 is just taking advantage of the opportunity we have given it. We are it's lunch, and we have prepared a banquet!
  11. I live in a college town with lots of Asian students. Super market shelves stocking rice were empty before the toilet paper ran out. Other than that I didn't see much else out of stock at the store. And toilet paper was back in stock yesterday (but there was still no rice). Luckily the Asian food stores still have some. I have a PhD in Microbiology, and I have studied virology, immunology, pathogenic microbiology and I used to run a medical microbiology laboratory. I wouldn't call myself a virologist, but I do understand what is happening. I recommend ignoring just about everything except the Center for Communicable Disease (CDC) web site. They know as much about this as anyone. https://www.cdc.gov/coronavirus/2019-ncov/index.html About 1.2% of reported COVID cases in the US have resulted in fatalities (44,183 reported cases, 544 deaths as of 23 March 4PM EDT). That is much higher than normal influenza (about 0.1% fatalities). So this is something to take seriously. However, only about 15% of people who are infected are expected to have symptoms serious enough to cause problems - like going to a clinic or hospital - and therefore being reported. So the fatalities are in the 15% who have serious symptoms. That should come out to actual fatality rates for everyone who is infected to about 0.2% - 2 per 1000. Two things make this illness more serious. First, noticeable symptoms do not occur for a week or two after infection, so people go around spreading the virus for quite a while before they know they are infected. Second, the virus remains viable (capable of infecting) outside the body for a day or two on steel and plastic surfaces (hand rails, door knobs and latches, grocery cart handles, etc.). So it is a good idea to wash your hands frequently to prevent spreading the virus in case you are infected, and it is a good idea to wash your hands frequently in case you have picked up the virus from something you have touched. The virus cannot infect your outer skin (the epidermis) because it is made up of dead cells. But it can infect any moist tissues (lips, nasal passages, eyes, ureter and anus) you touch with your hands. Finally, the shutdown restrictions will not cause the virus to go away, or prevent the spread of the disease. They may not even reduce the total number of cases in the long run. But they may prevent a sudden influx of serious cases that would overwhelm medical facilities, denying treatment to those who need it. That should reduce the overall mortality rate. That may allow the medical people to keep up with the case load and allow the supply system to keep up with demand for medical supplies.
  12. Along the straight part of the rabbet in the keel the garboard plank (strake) does not need trimming, so both sides of the plank are parallel. Where the rabbet starts curving up the stem you should start trimming the garboard plank on the rabbet side. Keep the edge of the plank opposite the rabbet straight (don't trim it). Just let it bend up naturally along the forward curved surface of the hull. Take off a little bit at a time on the rabbet side and test the fit after each cut until the garboard plank tapers to a point and fits tightly into the rabbet. You will need to taper each plank near the bow, again starting where the hull surface transitions from relatively flat to the bow curve (about the same place along the hull length you started trimming the garboard plank). Phil
  13. wefalck, I have seen some sheet metal design programs that will unfold curved surfaces, but I can't recall the program names. One of the DesignCAD users wrote a BasiCAD macro that unfolds complex 3D surfaces into flat 2D patterns. It even works with things like spheres and toruses. However, the results can be pretty unpredictable with really complex curved surfaces and you may have to repeat the process, starting with different orientations, to get something really useful. I have used it to unfold fairly simple things like truncated cones, curved funnel caps and skirts around the base of funnels (see attached picture) and it works nicely. I haven't used it for hull strakes yet, but when I get around to plating my 1:96 USS Oklahoma City CLG-5 model I will give it a try. Phil
  14. Dan, I will miss your work and experience. It will be a loss for us all. I lost my wife to cancer after a seven year battle, so I know what you and yours are going through. Take comfort knowing you have left a great legacy on this Forum.

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