Model Ship Builder :: Forums :: Modeling Types :: Computer Assisted Drafting (CAD) 

<< Previous thread  Next thread >> 
74 Gun Ship “HMS Boomstick” From Design to Finished Model 
Go to page 1 2 3 4  
Moderators: Winston, aew

Author  Post  
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  Introduction to the Project Ok guys this will be a complete design/build of an imaginary 3rd rate ship I am calling the HMS Boomstick after one of my favorite sayings from the Evil Dead series of campy movies. I will be doing the drawings in a certain order that should be followed fairly closely. The reason is that there are dimensions that are needed before you begin drawing the ship, thus those items will be required to be drawn first in order to do the proper calculations. I will be using “The Construction and Fitting of the English Man of War 1650  1850 – Goodwin”, “The Elements and Practice of Naval Architecture or a Treatise on Shipbuilding – Steel” and “The Shipwrights VadeMecum – Steel”. These 3 books will give us pretty much all the information and processes we will need to design our ship. I would like to also acknowledge the contributions from what I consider my mentors due to the vast amounts of knowledge and understanding they have taught me and I will be following a lot of their methods so it is only proper I give them the proper recognition they deserve. I would like to thank Don Howe for the PDF of note on the VadeMecum explaining some of the terminology and breaking some of the writings down into understandable explanations. Also for His step by step instructions for drafting out part of the ships sheer plans (it is an unfinished work that he was kind enough to share with me which got me started in my understanding). I also would not be able to start this if it wasn’t for Wayne Kempson and his 2 videos explaining the various lines on the body plan and showing how to loft the body plan using the charts in Steel’s books. And finally, Ed Tosti for the excellent work and support with his plans and books for the Naiad Frigate. I highly recommend Ed’s Books as he explains how to draw up your own plans and provides some very nice plans of the Naiad which I will eventually be building. He is a very helpful guy answering questions I had as I was trying to understand various things he writes about. Though he doesn’t get too deep into the design part he shows enough to get a good start on your own design using cad, not to mention an awesome set of plans and cd’s that come with the books. I will be doing this as a book style with chapters for various sections of the process. As I complete a section it will be made available as a PDF for free download and eventually when finished the complete set of plans in multiple formats. We will also eventually venture into the area of some 3D printing whether it is some cannon that can be printed and used to make molds that you can then make wax cores for casting your own metal cannons or just to print out to use on your model. We will have various parts that we can use for 3D printing or even as parts for CNC Millwork. Downloads: Introduction and Chapter 1: PreDesign Formulas and Calculations http://www.proflooney.net/HMS_Boomstick/74_Gun_Ship_Design_and_Build_Log_Chapter_1_Predrafting_Formulas_and_Calculations.pdf Chapter 2The Body Plan http://www.proflooney.net/HMS_Boomstick/74_Gun_Ship_Design_and_Build_Log_Chapter_2The_Body_Plan.pdf [ Edited Sat Aug 12 2017, 12:25pm ]  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  Chapter 1: Predrafting Formulas In this chapter, we will discuss the various formulae needed to give us certain dimensions we need before we can begin any drafting of the ship. These dimensions we will derive from the formulae are necessary to the overall design of the ship. With these basic dimensions, we can then design any part of the ship we need. 1: The first thing that must be determined is the ships length or the length of the gun deck. The first thing we need to know is the number of guns needed for the lower gun deck. Before we can decide how many guns we want on the gun deck we first need to know how big our cannons are, as that will determine the gunport size and other factors. I will be using 28 32 pounders for this ship. The next thing we need to do is to Look at the charts and see what they call for us to use as our gunport size. (see fig.1) Fig. 1 [ Edited Wed Aug 09 2017, 02:31am ]  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  We can see from the chart in fig.1 that for our 32 pounders our gunports will be 3 ft. – 5 inches wide. We also need to know the working room for each gun which from the chart says we need 7 ft. – 6 inches. The working room is the space needed at each gun so that the gun crew can comfortably operate the gun without tripping over each other. Now that we know the width of the gunports and the working room for them, we now turn our attention to how many gun ports we will need per side. We have 28 cannons, so that means we need 14 ports per side to accommodate them, The formula would be 14 X 41” = 574” (I am using inches here as it is easier than using feet and inches as you have to convert everything to decimal inches for the various formulae anyway). Next we also need to calculate the total working space between the ports and add it to our 574”. We know we have 14 ports so there will be 13 spaces between them. Our formula will now look like this: 13 X 90 = 1,170” then we add our gunport length to that or 1,170” + 574” = 1,744” or 145.33 feet. Now that we know that our next formula is to find the distance from the front of the forward gunport to the Foremost Perpendicular And the distance from the back of the aft gunport to the aft perpendicular. For the fore distance, we need to take the width of 1 gunport + the working room for 1 gun x the multiplication factor D on the table in fig.2. Fig. 2  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  We look at the chart above and see that for a 74 gun ship we have a factor of 1 2/5 or 1.4. Thus, the formula would be 41 (width of gunport) + 90 (width of the working room) X 1.4 (multiplication factor from fig.2 chart D) or 41 + 90 X 1.4 = 183.4” from the front of the fore gunport to the front perpendicular. The distance to the aft perpendicular would be similar formula, with the multiplication factor being from the E table instead of the D. Thus, 41 + 90 x 1 = 131”. Now it is a simple factor of adding all 4 dimensions together: 131 (distance to aft perpendicular from aft side of the last gunport) + 183.4 (distance from the front of the farthest forward gunport to the front perpendicular) + 574 (total widths of the 14 gunports) + 1,744 (total distance of the 3 working room spaces) OR 131 + 183.4 + 574 + 1744 = 2,632.4 or round up 2,633” = 219.5 ft. between perpendiculars or the length of the lower gundeck. However, that length is much larger than what is set in Steels book and from several drawings of different ships. I thought however, for this demonstration to show how one would contrive the length of a ship. The Length will change depending on the size of the cannon used. For this exercise, we will be using the standard set forth by Steel of 176 feet. That way everything else will match up with the tables. The Armament for this ship will be as follows (Using the Black Prince as my reference ship): Armament: 74 guns: Gundeck: 28 × 32pounders Upper gundeck: 28 × 18pounders Quarterdeck: 4 × 12pounders, 10 × 32pounder carronades Forecastle: 2 × 12pounders, 2 × 32pounder carronades Poop deck: 6 × 18pounder carronades  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  The official formula though is the following: L=AxB+C(B1)+D(A+C)+E(A+C) Where L= The length of the lowest gundeck between the rabbet of the stempost and rabbet of the sternpost. A= The fore and aft width of the Gunport. B= The number of guns to be mounted on the lowest gundeck. C= The working room to operate a single gun. D= The multiplication factor to determine the length the fore edge of the foremost gunport and the fore perpendicular. E= The multiplication factor to determine the length between the after edge of the aftermost gunport and the after perpendicular. The values for A and C are in table in fig.1 and the values for D and E are in the table in fig.2 This brings us to the last major dimension we need which is the length of the keel. The actual length of the keel is not the distance between the perpendiculars. The actual length is from the Front edge of the Boxing joint to the aftermost face where the sternpost meets the keel. Ships built after 1700 use several factors to determine the actual keel length. 1: The length of keel for tonnage 2: Length of the gundeck (or lower deck on a singledecked ship) between the fore edge of the rabbet at the stempost and the after edge of the rabbet at the sternpost. The length of the keel is important so that we can calculate the molded beam of our ship. There is 2 ways we can do this: 1: We can multiply the length of keel for tonnage x 9/10 or .900 But that doesn’t give an exact length. Or 2: Actual Length of Keel = AB+C+D Where: A= The length of the gundeck from the fore edge of the rabbet at the Stem to the after edge of the rabbet at the sternpost. B= This is the radius or arc of the stempost which is calculated as: MB/2. C= This is the length abaft the after end of the keel which forms the aftermost boundary for the rake aft of the sternpost and is calculated and is calculated as: (MB/8)x1/2. D= This is for the length of the “Boxing” (which is the type of scarph employed for attaching the stempost to the keel). To calculate this we must know the depth of the keel, which is then multiplied by a given constant which for our 3rd rate ship is 4. MB= Moulded Beam There is the background for calculations we need. For our ship, we need to use the following formula: Actual keel length = [A]176 ft (length of our gundeck) – [b](48/2) (Moulded beam of 48 feet which I got from Steel’s Table) + [C](48/8) x (1/2) + [D] 1.7 ft. (depth of the keel) x 4 Our actual calculation will look like this: AKL = 2,112” – 288” + 36” + 81.6” = 1,941.6” or 161.8 ft  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  This will end Chapter 1: PreDrafting Formulas. In the next chapter, we will start drawing our Body Plan.  
Back to top   
donfarr 
 
Registered Member #2001 Joined: Fri Dec 23 2011, 09:51pmPosts: 1887  Hi Joseph, I for one am following this with the greatest of interests, as an aside when I was much younger and just starting in this hobby before a 15 year absence to take care of my beloved late wife, I had a book by H. Chapell calked boat building, which I learned to loft my own frames and plans if I had one piece like a BODY PLAN I could develope the other 2, remember this was at the beginnig of CAD, and there were no forums available an computers were in its infancy, to old and not much time for that now, at 79 want to do modeling, not much time for the other items BUT STILL VERY INTERESTED......I TRIED TO DOWNLOD THIS CHAPTER BUT GET A MESSAGE .....URL NOT FOUND AM I DOING SOMETHING WRONG.......ALSO NOT TO BE PRESUMPTUOS WHY NOT SHOW THIS ON SOS ALSO MANY PEOPLE OVER THERE HAVE A GREAT INTERESTS IN THIS, i think that is what sister sites should be doing, juyst my opion. DON.......PS TELL ME IF I AM DOING SOMETHING WRONG ON TRYING TH TO DOWNLOAD THIS CHAPTER  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  Yea don ya was doing everything correctly its the forum that screwed up it messed up the link tool it put link in stead of url in the coding. it is all fixed now and works. also I have it both on this and the SOS forum ))  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  Chapter 2: Drawing the Body Plan In chapter 1, we created various formulae in order to determine important dimensions needed to draw up the ship plans. The first thing we want to do is to list them so that we have easy access to them during the design process. We shall also need other key dimensions which we will find in the Tables for forming the bodies from the vademecum and also from the scantlings. We will cover the tables of the bodies further on, but for now let us look at fig. 3 from the scantlings. 1: Length of the lower gundeck (or length between perpendiculars) 176’ or 2,112”. 2: Moulded Breadth (or widest part of the ship less the planking) 48’ or 576”. 3: Total Length of the Keel 161.8’ or 1941.6” 4: Width of Gunport 3’5” or 41” 5: Working Space Between Gunports 7’6” or 90” 6: Main Keel Depth 1’6” or 18” 7: Rabbet 4 ½” 8: Length of Scarfs 4’6” or 54” 9: Number of Keel Pieces 7 10: Number of false keels 2 11: Upper False Keel Thickness 6” 12: Lower false keel thickness 6” 13: Number of false keel pieces 8 14: Room and Space 2’9” or 33” 15: Floor Timber Length Midships 25’6” or 306” [ Edited Wed Aug 09 2017, 02:32am ]  
Back to top   
JosephH 
 
Registered Member #4876 Joined: Fri Dec 23 2016, 03:37amPosts: 1442  Now that we have all the dimensions we need to continue drawing our body plan. There remains one thing we must do which will help on the Fore Stations. We Must draw out our Keel and Stem. The very fore stations ride higher up on the rabbet on the lower stem usually. Thus, we need to know where to place the lower part of our station when we loft it. So Our Next step will be to draw out the keel.  
Back to top   
Go to page 1 2 3 4  
Powered by e107 Forum System