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| USF Essex POF CAD Plans | ||
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Moderators: Winston, aew, Donnie, bikepunk
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| Gary M |
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 Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Hi Mario, Welcome to the dark side!!! I recognize this picture and, it came out much better than mine did! G | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Step 3: Establishing the Lines Used for Lofting: Now that the dimensions have been well established in the preceding two steps, it is time to mark the Water Lines, Load Water Line, Gun Ports, Upper Height of Breadth, Lower Height of Breadth, Gun Deck, Forecastle Deck, Birthing Deck, Top Timber Lines, etc. These lines will be essential as we move towards lofting the ship. I chose not to loft the Buttock Lines for the Essex, since I had already done so by hand and they were not faired and as a result were not of use. They were off by a full 1/8”+ when comparing water and buttock lines when lofted. In other plans, the two sets of lines may be of more use. The below illustration shows the sheer of the ship as well as the essential lines for lofting. It’s important to note that I did not spend a lot of time on the ancillary details such as channels and rails. I will go back at a later date to work these in. The immediate goal is to get to the lofting of frames. During the build, I can go back and add details that are not otherwise available in the book. I will however do a fully detailed Keel, Stem and Stern for pattern making.  essex_sheer_and_essential_lines.pdf.pdf [ Edited Tue Nov 18 2014, 11:09pm ] | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Step 4: Establishing the Midship Station Lines: Goal: To determine and mark the correct location for midship station line and to understand it’s relevance and to mark the other station lines. Before blindly tracing station lines from the paper plans to your CAD drawings, It is essential that the midship bend be located as described in the book. In reading Steel’s Vade Mecum the correct placement of the midship bend was essential to a ships sailing qualities. While I am no expert in this area, here is what I understand: The midship bend will represent the widest portion of the ship in terms of breadth. Moving forward from this bend, the frames will have a more pronounced bevel on their forward face as they taper when approaching the bow. The opposite is true moving aft, away from the midship bend. The location of the bend helps to determine the placement of the Fore Mast as well as other essential structures. If the bend is placed too far back, the ship will have a tendency to dive in heavy winds and seas, place to far forward will affect the sailing qualities as well, resulting in too much drag from the aft end of the ship. This all being said, the center of the ship is not the location of the midship bend. The book tells you the exact location for the bend. It’s a simple matter of measuring from the FP and then plotting. Sure, you could use the plans and just trace it, but what’s the fun in that. And yes, the plans are correct.  essex_ms_to_fp_measurement.pdf | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Step 5: Calculating Station lines through Room and Space: Goal - Understand room and space calculation and the function of Station Lines. Now that the midship station line is established, we will turn our attention to calculating the “room and space’ for the square frames and mark the stations This was rather a simple step since the math is already done for you on page 10, “Final Room and Space Calculations”. Using the center line of the midship bend as a starting point, I measured 11” on either side and drew parallel lines up to the sheer. These lines represent the space for the square frames which is 22”. I then marked off 3.8” for the “room”. Almost immediately, you will note that the original station lines are a “tad” off. I kept going and am fine with the new station lines as I have drawn them. You will see in the image below that I went ahead and added the square frames. I made a 6” port sill for each and shortened the frames by the same amount. These measurements will all come into play when we loft the actual frames. I adjusted the port openings just slightly fore and aft so that they were sided by a frame or to add more "meat" to what would have been a sliver of a frame from the port up to the sheer. In addition, these minor adjustments (which will not be noticed by the human eye) will reduce the number of filler frames. CAD allows for this kind of "what if" adjustment. I am sure such hands on "as built” adjustments were done on the ship so as to take advantage of the frames to frame the ports and to keep the upper works as light as possible. On later installments, I will ensure the deck beams are centered at the gun ports so they can carry the weight of the guns more efficiently. Keen eyes will note the use of filler blocks to be made when assembling the frames. I’m not adhering to strict construction practices here since the upper works will be planked. Now, I will turn my attention to the Keel and the associated assemblies. essex_square_frames_and_stations.pdf [ Edited Tue Nov 18 2014, 11:10pm ] | ||
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| teleman |
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 Registered Member #1925 Joined: Tue Nov 29 2011, 05:32amPosts: 1296 | Gary, I understand everything you are saying, because I have read the same thing. such as lining up the port holes and frames. On your last post. Are you missing a bit of detail between frame 4 n 5? | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Step 6: Stern Detail, Rising Wood, Stem Details: Goal: Utilizing the AOTS book, copy, scan, scale, and trace details for the Stern, Rising wood and Stem. We are getting closer to the lofting of frames. Since the book shows the proper height of the stern deadwood and the rising wood, we should take advantage of this information and incorporate it into our Sheer Plan. If this information was not given, then we would go directly to the lofting of frames and allow the frame bends to show us where the stern deadwood and rising wood should lay. See pdf's for clearer view. example_of_sizing_stern.pdf example_of_keel_and_stem_detail.pdf1. Make a reduced scale copy of pages 36 and 37. Splice them together. The size reduction is not all that essential at this point, but should just fit an 8 ½ x 11 sheet of paper so that it can then be scanned into the computer with minimal distortion. 2. Once scanned into the computer, make a jpeg of the file as we had done with the Sheer Plan. Enhance the jpeg as desired. 3. Import the jpeg image into CAD. Go to =>file, import image (from file). Paste image next to your Sheer Plan. Our goal here is to scale the new image to that of your Sheer Plan. Note: Moving forward, all images must scale to your Sheer Drawing. I cannot underscore this point enough. Despite the high quality of the drawings in the book, the reality is that these have been copied many times before they got to you and then you copied, scaled, printed, scanned, etc (tortured them). There will be distortion. It’s how you deal with the distortion that matters the most. 4. Through trial and error, adjust the size of your image. You may need to click off the aspect ratio so that you can shrink or pull the image in one way or the other. I found that no matter how much I stretched or shrunk my image, that I couldn't get it to line up perfectly. The compromise that I made was to fit the aft portion of the image to my “master” Sheer Plan and traced the stern deadwood. I then adjusted the image to capture the stem details. You may note some “hogging” amidships, just marry the fore and aft drawings somewhere towards the midship bend and you should be fine. 5. To assure that your new image is the size of your Master drawing, copy the Master Drawing and move it over the new image. You will then see how much you need to shrink or pull the new image so that it is at the proper scale. Below is the overlay of the sheer onto the new image.  The above is an example of the Sheer Plan image being pulled over the new image. The new image still needs to be scaled here. See how its too small. It needs to be enlarged for both height and length. Below is the finished product. The stern details have been incorporated into the Master Sheer Plan. Next steps are to add the stem details.  | ||
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| Mike 41 |
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 Registered Member #702 Joined: Fri Feb 05 2010, 10:37pmPosts: 1238 | Hi Gary, You are doing an excellent job on the Essex. Mike | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Hi Mike, I really appreciate the comment. I am addicted to ship design and lofting. When I finish the Essex and Peacock plans, I will search for my next drafting project. Most likely the Granado, although, that's already been done... Best, G | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Step 7: Bearding Line: Goal: To scale the Bearding Line, incorporate into our “Master” Sheer Plan and to understand its purpose. The bearding line represents the bottom of the stern canted frame feet. It should have a smooth sweep as it moves from frame 23 (last square frame) to the rabbet on the outer keel post. When thinking about how the frames will look in this area, they will have a systematic “rise over run” measurement as you move aft. It’s important to note that when you make the actual frames, they will have some thickness at the bottom of the foot and are actually inset into the keel slightly. The image for the Bearding Line is found on the plan on page 38. Scan, import, and size the bearding line to your “master” sheer plan. For proper scaling, I copy, and then move the aft portion of the sheer plan over to the imported drawing. I then delete most of what I copied over, except for a reference line. I trace the bearding line using the “spline” option and then copy and move the bearding line and my saved reference line back onto the master sheer plan. Once pasted, delete the copied reference line. Make adjustments to the bitter ends of the bearding line as necessary. This line will run from the rabbet of the stern post to the edge of the last square frame. Of note is the lower edge of the rabbet, which disappears at frame 24. The keel is inset at this point, moving aft, so there is no need for a rabbet line on the plan. The Garboard Strake will wedge into this area and up against the keel. Its a small detail, but worth mentioning - the rabbet along the stern is on the outer post, dont mistake it for where the outer and inner post meet.  essex_stern_example.pdf [ Edited Tue Nov 18 2014, 11:11pm ] | ||
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| Gary M |
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| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 909 | Step 8: Stem Details: Goal: To scale the stem and incorporate into our “Master” Sheer Plan. Just as we have done with every other image, copy, scan and scale the stem image found on page 46. Trace it away from the master sheer plan and then move it into position as done with the bearding line and other tracings. This is not rocket science, but it does take a methodical approach. Develop a system and stick with it. essex_stem_example.pdf [ Edited Tue Nov 18 2014, 10:25pm ] | ||
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