| Model Ship Builder :: Forums :: Modeling Types :: Computer Assisted Drafting (CAD) |
|
<< Previous thread | Next thread >> |
| Marble Head Schooner AKA "Sir Edward Hawke" CAD Drawings | ||
| Go to page 1 2 3 ... 10 11 12 | |
|
Moderators: Winston, aew, Donnie, bikepunk
|
| Author | Post | ||
| Gary M |
| ||
 Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 908 | Hi Dave, Yes, lets make this a collaborative effort. I love the idea! When you get a chance, read the thesis, it is very exact for measurements. We will need to figure out the drawing sharing thing. http://nautarch.tamu.edu/pdf-files/Gordon-MA2009.pdf G | ||
| Back to top | | ||
| Gary M |
| ||
| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 908 | Mid Ship Frame: Shown below is the Mid Ship frame for the SEH. This is the most important frame of your plans. Get this one wrong and your entire set of drawings will be off. There is a lot of information on this drawing, so I will walk through each piece: 1. Note the keel dimensions – originally, I had the keel at 11” sided, but wanting to stick with dimensional lumber, changed it to 12” and thus at 1:48 scale, is an even ¼”. 2. In order to properly calculate the inside frame line, we will first need to establish the height of the rising wood. I made the wood 4”, but three might have been better for reasons discussed above. I will most likely go back and change it to 3”. The floor that crosses the keel is a solid 9”. Once we have these measurements in place, we now know the end points for the inside frame lines. 3. Top timber thickness is set at 4”, again, three might be a bit more realistic. Even though these dimensions are negligible at this scale, I plan to go back and change it. Ships such as the Peacock, were ocean going and much larger and had Top Timbers of 5”. I am thinking that in a Schooner, the top timbers would be thinner; both due to scale of the vessel and a desire to keep the upper works as light as possible. 4. Using the spline tool, I then shaped the inside frame line to be thickest at the bottom and to taper as it approaches the top timber. This is more art than anything else at this point. 5. Also on this drawing are the markings for the upper and lower wales and the bottom of the gun deck. I will place these marking son all the station frames. I find it a bit overkill to place on all frames.  Fairing the drawings: In this drawing, the dots that are circled belong to the next frame in the series. When drafting, I overlay them on the previous frame so that I can observe the bevels as I go along. You will note that the dot in blue circle is actualyl off the line. This area of the plan will need to be faired. I am making a Table of Offsets for the SEH as part of this build as described in Chapelle’s book on wooden boats. I have decided not to use the Buttock lines in the remainder of the drawings since they were so off the mark. I may go back and fair the plans so that they are of use to future builders who want to layout their own frames. Not essential to lofting, the buttock lines reveal detail about the lower aspects of the frames.  Top Timber Line: Inside the circle is the Top Timber line as it transitions from Frame 5 to 6. There is an increase in the sheer height at this point as well. There is also an increase in the tumblehome at this point as can be seen when viewing the half-breadth and body plans.  Below in green is the half-breadth view of the top timber line and its change from frames 5 to 6.  Maximum Breadth: The maximum breadth comes into play as WL3 curves inward as it approaches the ends. I calculated that the maximum breadth is at about 3.5 on the grid at MS and rises slightly as you move fore and aft. I will make this measurement on each frame, anticipating a reduction in breadth as shown on the half-breadth. You will note that frame 4 is too wide and will need to be tightened up a bit.   [ Edited Tue Jan 27 2015, 09:23pm ] | ||
| Back to top | | ||
| Winston |
| ||
winston  Registered Member #1 Joined: Sat Jun 13 2009, 02:08pmPosts: 2305 | Don't know what time I'll have to work on "another" project, but hey what the hell.  I'll start a new project thread and we'll get to work putting together some information. | ||
| Back to top | | ||
| Gary M |
| ||
| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 908 | Inside Frame narrowing: As discussed earlier, the more you move fore and aft, the more pronounced the angle is where the frame futtocks meet the rabbet. The frames should have the same thickness at any given point as you move from one to the next. It is now that we need to allow the rising wood to rise. In the below photos, please note the circle with the frame number, this is not just for identifying frames. The circle is 10” diameter. I line it up with the edge of the frame at the keel and make sure the futtocks approach the keel at exactly that dimension on each and every frame. It is necessary to move the rising wood up to ensure the right dimensions. Later, I will transfer the rising wood dimensions to the Sheer Plan so all correspond nicely. You should also use the circle to layout the inside frame line, which will be higher at the floor on the side closest to the midship frame.  Here is the correct height of the inside frame line. Note the floor dimensions have stayed the same, but the rising wood is taller in this photo as compared to the photo above. Also, the keelson has moved, but its dimensions are stable.  With Frame 11, below, you can see how the aft side of the frame (dashed red lines) begins to rise. This will be more pronounced as you move along.  More on the Top Timber: I have found that one of the hardest things about lofting is figuring out is what is the top timber line and what is something else. In the half-breadth below, you will note that the green lines are the top timber lines and that there is a transition (circled) between frames 5 and 6 where the top timber is closer to the CL of the ship. If you look at the Sheer plan, you will note that frame 6 is taller than frame 5 and that they run along the same plan, just that frame 6 terminates higher up and as a result, closer to the CL of the ship. When drawing the frame, its essential to create this smooth flow along the naturally occurring arc of the frame.  See the difference in height between frame 5 and 6 as represented in the Sheer Plan below.  Below is an example of how one frame is higher than the previous one, yet the smooth arc is not compromised.  Rising Wood Aft Section: At this point, all the square frames have been lofted. Before moving into the cant frames, I wanted to first sketch in the rising wood dimensions. In the below photo, note the thick black lines. These measurements were pulled directly from the lofted frames and represent the measurement from the rabbet to the underside of each floor at the aft side of the frame. Later on, I will draw in the slope of the stern deadwood, but will first let the cant frame feet tell me the true dimensions. As we loft the stern cant frames, we will be establishing our bearding line as well as the length of our frame feet. Here is what we have thus far.  [ Edited Mon Feb 09 2015, 06:38pm ] | ||
| Back to top | | ||
| Gary M |
| ||
| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 908 | Stern Cant Frames: The below drawing shows the start of the cant frames at Frame 15. There will be 7 cant frames in the aft section. Note the heavy black lines; these represent the fore and aft side of the frame feet. The top of the foot for frame 15 is at 25” above the rabbet line and lines up nicely with the keelson for the square frames. Once all the feet are established for each of the cant frames, I will go back and lay out the stern deadwood. As with everything, there will be some minor tweaking along the way.  When laying out the cant frames, the most important things to get right are the base of the frames and the location of the top timbers. We need these measurements to ensure we get the sheer height measurement as well as the foot height for lofting. In the below photo, you can see how these lines are pulled up from the half-breadth plan and over the sheer plan (dashed black lines).  seh_2_aft.pdf I find that drawing the cant frames to be a bit tricky. When designing the turn of the bilge, I am trying to visualize the shape of the frame and use the buttocks lines to help define the curvature.  Bow Cant Frames: The bow frames are layed out exactly in the same manner as the stern. Its important to note that a schooner has a rather sharp and fine entrance, so will want to visualize that as we draw the sheer plan lines. There will be less curvature in the lines as compared to a bluff bowed ship. There are 9 bow cant frames.  Below is the Sheer Plan with all the frames layed out. We are now ready to continue lofting. We will still need to define the stern and stem deadwood and will do so as we loft the frames. We will use the HMS Haddock (Bermuda built ocean schooner), HMS Tecumseth (Lake Schooner) as well as Hahn’s original drawings for the SEH to help guide in the design of these sections. Additional resources will be consulted as we progress. UPDATE: I revised the plans to show frames 15 and 16 as square frames. The first cant frame is 17.  [ Edited Mon Feb 09 2015, 06:40pm ] | ||
| Back to top | | ||
| daves |
| ||
| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2624 | why did you put 9 cant frames in the bow? the Newash has 4 Hahn also use 4 in his SEH the Nancy also had 4 seems 4 is the standard number of cant frames in the bow. Looking at the Tecumseth the builders carried the whole frames as forward as all possible by cutting deep notches in the keel and keelson. I think cant frames are the weak link in the structure of a hull because they are only nailed to the side of the deadwood. I would have made frames O,P,Q,R the cant frames [ Edited Sat Jan 31 2015, 02:58pm ] | ||
| Back to top | | ||
| Gary M |
| ||
| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 908 | Hi Dave, just seeing this post. I will rework the area. In hind sight, 9 is way to many, even for a bigger ship. The only down side is I already lofted all the frames, but hey, it's just time and it's fun. Thanks for the input. G | ||
| Back to top | | ||
| daves |
| ||
| Registered Member #105 Joined: Wed Jul 15 2009, 12:01pmPosts: 2624 | I hope I am not being to obnoxious by posting things like hum I don't think so! or hey that ain't right. My social skills are not what they should be so I am told. this is your topic and really who am I to say anything [ Edited Thu Feb 05 2015, 04:57pm ] | ||
| Back to top | | ||
| Gary M |
| ||
| Registered Member #4198 Joined: Tue May 07 2013, 10:50pmPosts: 908 | Hi Dave, NO, you are not being obnoxious. If anything, not critical enough... I really want to perfect my drafting (and modeling) skills and need this constructive feedback. What is the value of a set of plans if they are not reasonably correct? I spend 100's of hours making them and I want them to be used and the best way to get them used is for them to be accurate and for them to be accurate, I need the feedback. How's that for a long winded sentence... Stay tuned for updates. Thanks again. G | ||
| Back to top | | ||
| twintrow |
| ||
| Registered Member #121 Joined: Tue Jul 21 2009, 04:41amPosts: 436 | Careful Gary telling Daves to critique, it takes him two paragraphs to say Good Morning!! He can write a two page dissertation when all he needed to say was "move it two mm to the right" ;o) The good news is, what he says is usually accurate....and well researched. | ||
| Back to top | | ||
| Go to page 1 2 3 ... 10 11 12 | |
Powered by e107 Forum System