wrkempson

I have no knowledge of Spanish practice regarding the rabbet and the keel. I say this to excuse myself from comment only because I would like to be helpful but my knowledge base is restricted to English ships. I do observe, however, that on RN drawings the keel is more of a convention than an actuality. The men in the yard would not use a drawing to cut in the rabbet. So, to answer your question one would have to know the practice of the Spanish yards. All of this is to say: I don't know. Wayne

Am I following a good approach, or are there features of Fusion 360 that I have overlooked that would make this easier? I believe your approach is sound and you are not missing some "secret." Programs dedicated to ship hull design handle things pretty well it seems (I have not used one to date), but hulls are fairly challenging for programs like Fusion 360. On the TurboCAD forum a ship's hull is something like the Holy Grail of lofting. How do incorporate the station lines that couldn't be used in the loft + rails? It helps when all the stations have the same number of nodes. I sometimes add a node to account for a missing water line. The key is not so much that the added node is on the same plane as the water line as it is that the computer can loft "node to node" (I just made that phrase up). How do I close up the shape at the bow? Think of the rabbet on the stem as a kind of station line, draw it and loft to it. This will get you in the ball park but is not the total answer. Come to think of it, I'm not sure anyone really knows the total answer. At the gripe a lofting will do some funny things. Of course, added stations at the bow will facilitate things quite a bit. How do I force curved edges of a body like the one below into straight lines that can bend at sharp angles? Your picture illustrates the basic problem of lofting a hull. You can think of the lofting process as akin to the computer connecting your stations with splines (with the fit points falling on the stations). Now, in your illustration the lowest spline (so to speak) takes a downward drift in order to set up for the hard upward turn. Doesn't it look like a driver who swings wide left to then turn right? The closer the stations are to one another the less the swing which is why adding stations can help. The same thing happens at the bow in the area of the gripe. At the rail the problem is evident again, but is more easily fixed by using the rail line to create a loft which is then subtracted from the hull. Now for the necessary disclaimer. I am not trained in CAD nor do I work in the field. The above is the result of my own experience. I remain open to a more perfect way and bow to the expertise of others. Wayne

Mark, I found this and it may solve your problem. My copy of F360 refuses to load for some reason so I can't check it out, but it sounds to me like the answer you need. https://forums.autodesk.com/t5/fusion-360-design-validate/rotating-3d-wood-material-in-render-mode/m-p/7905382#M155048 Wayne

A work around for TC Deluxe is to put your monogram on the barrel, then create a tube around that section of the barrel that has an inside hole that matches the barrel as to angle but is (say) an inch larger in diameter. Then subtract the tube from the monogram and you will be left with an upper surface of the monogram that is curved with a radius parallel to the barrel. Takes but a minute.

Breathtaking. The level of detail is amazing. Congratulations on your work. It seem to me you must have a very large file for this project. Can you give us an insight into how large? What are your render times for the complete model? And, just because of curiosity, what is your computer set up? I would guess you have a pretty good bit of horsepower. Thanks so much for sharing. Wayne

See above post #22. Does Solidworks have something called a Style Spline and is that the same thing as a Bezier? I can spell Solidworks and that exhausts my knowledge of the program. I may be confusing you by using the names given to spline tools in TurboCAD. At this point, it seems to me that splines and their control points all use the same equations, but differ in how one manipulates the control points. To be sure, I am not the person to opine here in that my acquaintance with mathematics falls in the interested hobbyist category. There are videos on YouTube that explain Beziers and the history thereof using basic algebra. That and a series of Google searches constitute the foundation of my awareness of the math involved. Wayne

I am with Druxey on this. Take a look at this part of EdT's log on the Naiad (a vessel of similar size and construction). This is page two of his log, Find post #57 and begin reading. You will find many helpful photographs of how the internal planking might be done. As a further caveat, Steel says that the limber strake is drawn on the inboard profile plan as a line parallel to the cutting down line (which amounts to the bottom of the keelson). On Steel's plates this line for the limber strake runs the length of the keelson, although as Druxey ponts out it is fairly impossible to place a single plank this entire length and so the channel ends much sooner The original plan from RMG shows the limber strake line the full length of the keelson. I did not build Euryalus. Perhaps Allan can give us some better insight here. Wayne

You ready for this bit of wisdom? It depends. I used something that TurboCAD calls Beziers which is fit points plus control handles for every point. I have more trouble with the other versions of the spline (by control or by fit points). I find "fit points" easier to use than "control points" and Bezier easiest among the three. So I would say use what makes the most sense to you. I would expect there to be a learning curve on using splines. rtwpsom2 says he prefers the control point splines to Beziers, I have the opposite preference, mostly on the basis of what I am most accustomed to using. I like Beziers but have seen some lines drawn with fit points and control points that were just as good. Use what falls most easily under your mouse. There are folks on this forum who do CAD for a living, and I would greatly appreciate reading their insights on this. My CAD work and knowledge is purely that of the interested amateur. Lately, however, I have been trying to use arcs rather than splines. Sometimes that works out, sometimes it may be more trouble than it's worth. I hope this helps. Wayne

I am not a mathematician nor do I play one on TV, but I find the visual explanation of Bezier curves to be quite interesting. The math behind it is barely in my range of comprehension. This link gives a picture of how linear, quadratic, cubic and quartic curves are generated. This is a very amateur understanding, but it takes something of the mystery out of how the spline is drawn and what is happening as it is adjusted. https://www.jasondavies.com/animated-bezier/ Also, the Wikipedia article on Beziers has some interesting animations about two thirds of the way down in the article. https://en.wikipedia.org/wiki/Bézier_curve#Constructing_B.C3.A9zier_curves There are some other basic articles explaining Beziers curves and thus indicating how splines are generated. As far as I can tell, a spline by control points and a Bezier are generated with the same equations. None of this changes how we do things, but I thought it useful to visualize how the computer is doing things. Wayne

Both the drawing and your procedures are works of art. Thanks for sharing. I did not understand how the offset of the splines was used to center the traced working line. This may be because I do not have access to Solidworks. Still, I couldn't get my head around the theory of it, but it sounds like a useful thing to know in general (unless this is Solidworks specific). It seems you have a very good original plan. Even at that, I take it you did a bit of work to straighten some lines out prior to use in CAD. I find all this very interesting. The tools available to you for curvature analysis are fascinating. In TurboCAD I rotate the drawing and eyeball down the line, a method similar to the actual method on the lofting floor. I like the more accurate tools in Solidworks. I believe similar tools are available in Fusion 360 and Onshape. This looks to be a very interesting project. Wayne

Good observation, Rick. When you speak of splines are you including Bezier curves in that category? Frankly, while I use Beziers quite often, I cannot think of a time when I have used a traditional spline. The control handles on Beziers make them a very powerful way to create a curve. With that said, and with my completely amateur status noted: The "arc or spline" question might have the age old answer: it depends. For earlier plans arcs reflect the original practice; so if you want to mimic the old ways then an arc is your friend. On the other hand, later plans I suspect made more use of ship's curves for which Beziers are a good substitute (vis-a-vis a collection of tangent arcs). Using arcs is not as well adapted to 3D modeling since they complicate the need for uniform node counts, etc. Beziers, as pointed out, can produce all kinds of accurate curves. There is something satisfying to me in drawing out lines with just arcs and a straight edge. But for actually getting the work done splines (Beziers for me) are great. So, as one who started out using Beziers (splines, if you will), and then learned to use acrs, I suggest we have both in the tool box. Wayne

If your program has this tool, construct a circle from three points along the curve of the stem. I would use a portion of the curve that does not intersect the base line since if there is more than the one arc, the second arc will be found at the base line. The center of the circle will of course be the center of the arc. The same end is accomplished geometrically by placing three points on the stem arc. Join the bottom and middle points with a line. Draw a perpendicular line to this line that bisects the line. Repeat the process for the middle and upper points. The intersection of the two bisecting perpendiculars will give you the center of the stem arc. If your heart is pure you will find the artist's pin prick nearby. It may not be useful, however. I have yet to find a table of scantlings helpful in drawing the stem curve. I have always had to find the center myself. By and by, I am thinking we are talking about the arc of the rabbet which often is the after face of the stem. Be careful when then drawing the forward face of the stem since that arc does not necessarily share the same center. The forward face arc center may have to be found separately. Also, the stem arc can be two (as per Druxey) or as many as three arcs. This is known by observation. I don't know if this helps, or even if I am on topic. In my defense I will say I enjoy drawing out the stem arc(s). Of course, the curvature of the cutwater is even more a thing of beauty. Wayne

It seems to me that a measurement taken from the plans should trump one taken from elsewhere. A contract measurement might trump the plan but only if the contract is for the specific vessel at hand (ie, not from a sister ship). My observation indicates that the lines on the plans are about 1/4" wide or so, so a variance of 1/2" is understandable in this case. I love the zebra analysis. The curvature of the rabbet in the area of the fore foot seems to be off, but that is due to the program, not your work. Wayne

So I took the Fusion 360 challenge. Having used Turbocad for years, I found F360 to be fairly straight forward. The hardest part is finding the tool you want and learning the peculiarities of the program. I have done some work in Onshape and found it comparable. It seems to me that anyone willing to put in a bit of time, willing to look at training videos and willing to persevere can learn both F360 and Onshape in a reasonably short time frame. The work flow details differ, but not so much as to make difficult the adapting previous of methods to each program. Both Onshape and F360 are free cloud based programs. Onshape's free version is fully functional but limits the number of files one can store to 10. Fusion 360 offers the fully functional version for free to hobbyists. You do have to sign up and indicate that you are either a hobbyist or a start up business. The guidelines for signing up are very clear. I choose to model a 29' Launch in TC and F360 just to compare the two. I was learning F360 from scratch and have done a fair amount or work in TC. The results are appended. Do not get too excited about comparing the renderings since my skills in rendering are quite crude. The point is that each program produces an interesting model. Perhaps I will test out converting the models to 2D drawings at some future date. I should mention that launches were still whole moulded, so there was very little employment of Beziers in these models. This the the Launch from Fusion 360: And the same plan in Turbocad v. 19: Wayne

In theory this arrangement keeps the planks for sliding alongside one another resulting in a stiffer longitudinal structure. In the hold of USS Constellation the ceiling planking has square cutouts across the seams into which a square block is inserted in order to stiffen the hull as well. The attached photo shows these openings, some of which have had the blocks fall out. Indicated in red are examples of an empty and a filled opening. Other instances are apparent as well. Wayne