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40' Cruising Sailboat by BenF89 - 1:12 Scale

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Well, I hope I am off to a good start with naming the log appropriately. It's a scratch build even in the sense that this boat doesn't exist at all in 'real life', so it doesn't really have a name. Yet.



Before diving into the details, I'll share the backstory of this project. I am a Naval Architect, and while I was at school, another student was getting rid of an old fiberglass hull shell model that he acquired during one of his internships. He wasn't going to use it, and, at the time, I aspired to be a cruising sailboat designer. So, he let me have it.


I immediately had visions of a fully detailed interior arrangement (complete with books on the shelf, that sort of thing), as well as a detailed exterior. Very similar to a doll-house miniature type display.


So, I now had this hull, and lot's of visions for the future of it. And, also was a full time student at a rigorous college taking what's effectively a double major's worth of work in Naval Architecture and Marine Engineering. And I had a long-distance girlfriend. So anytime not spent studying and doing school work was spent on the phone or traveling back home. Once can see where on the priority list a complete designed-and-built from scratch model of a sailboat fell - completely off the list!


Fast forward 5-6 years. Now married (to the same girl), with a nearly two year old little girl, and another baby on the way. Also, just under halfway through the third year of my career (at a builder of high-speed aluminum government and military boats...not exactly the cruising sailing yachts I was hoping for as a college sophomore!), coming off a major push to get a first-of-class patrol boat in the hands of the Navy. This hull was still sitting in our spare room, albeit with some dust on it. [To be fair, in the time between graduation and the beginning of this new saga, I did have time to finish two plastic kit builds (1:350 Tamaiya Bismarck and 1:350 Minicraft Titanic, both of which I had started in high school), and do another complete kit build of a Netherlands Coast Guard rescue vessel that I semi-customized into a research vessel.]


After a major house clean-up and organization push, my wife decided we have to do something with the boat. She has been wanting to get some dolls for our daughter, and while thinking about that, she came up with the idea of making the empty hull into a 'doll-boat' - like a doll-house, but, you know, a boat. I immediately latched on to the idea - usually, a little girl gets a doll-house, but her Daddy's a NavArch, so she gets a  doll-boat!


So, I agreed to the doll-boat. My only condition was that once we are past the age of playing with dolls, I can take it back and finish it to completion beyond what I would be comfortable doing while it was still being played with.


And that is the story of how this project was conceived. My next post will start detailing the design progress I've made, some of the major challenges I am facing that I am looking forward to getting input on, and an outline of the general path I am wanting to take to achieve the goal of actually completing it.


And, since everyone likes pictures, attached are several of the shell I have to work with. It's a pretty contemporary looking hull form, about 40 inches long, and 10-1/2 inches wide. The daughter loves it already!




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So, I agreed to the doll-boat. My only condition was that once we are past the age of playing with dolls, I can take it back and finish it to completion beyond what I would be comfortable doing while it was still being played with.

Hi Ben,

The original and nice idea!

Till that time you can construct the model of this model yacht for an interior of the doll boat and it will be really SMALL ))).


Best Regards!


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(This is a long post; I'm kind of long winded.)



With this post, I am going to start detailing the design and planning development.


Hull Form

 I knew since I acquired the hull that I would need to find a way to determine the form! I had no drawings, so even though what would arguably be one of the more difficult parts of completely building the boat from scratch (namely, framing and planking and fairing the hull) was complete, I didn't really have a way forward. And that was one of the primary challenges that kept me from doing any sort of work on the boat until very recently.


With the motivation to work on the boat again reignited, I was again faced with this challenge. Enter you guys! About two weeks ago, I posed this question in another area of the forum. I immediately got a bunch of great suggestions for how to overcome this challenge - the post is here for anyone interested: http://modelshipworld.com/index.php/topic/9528-determining-hull-form/#entry281249


Based on all the suggestions, I think my approach will be to mark the hull at even station intervals, and then use a contour gauge to capture the section shape at each station.I can also use it to capture other tricky areas of curvature, such as the slight rounding of the deck at the transom, or the proper shape of the reverse rake at the aft end. I'll transfer the curves to paper, and using a tape measure to ensure the height of the keel above ground at each station, I can generate a lines plan. That's my theory at least. If it doesn't work, I can fall back on the method of using a screen/grid and taking offset measurements at each station/waterline intersection. 



The first issue I had to decide, before even attempting to make a GA, was the scale. My wife pointed me towards the dolls she wants to get. They are 5" for an adult. Given an adult male is roughly somewhere between 5'-6" and 6'-6" on average, this leads to somewhere between a 1:12 to 1:15 scale. I initially chose a 1:15 scale (and that is what the drawings and images below represent), but upon doing some research on standard sizes for doll-house miniatures, I found that 1:12 seems to be the most common, but that 1:16 and 1:18 are also not unheard of. 1:18 would lead to a 7'6" adult, so that one is out. And 1:12 left me with a boat that was just a LITTLE too small to fit all I wanted in (isn't that always the case, though?). So, in the final analysis I am going forward with 1:16. This will lead to a 6'9" adult, but should be in the realm of TLAR scale (TLAR = That Looks About Right - this is apparently a common term! I discovered it doing my doll-house research!)



While I wait for the opportunity to either borrow or buy the contour gauge, I have 'eyeballed' the hull form to a degree suitable of rough concept sketching and even some 3d modeling for use in determining the General Arrangement.


I did get myself a little out of order, though, and started on a couple alternative GA's before I had fully developed the Statement of Requirements. As such, I designed myself into a couple different boxes trying to satisfy requirements that were not totally necessary. So, I've paused in the GA process while I finish fleshing out my own Statement of Requirements for the boat. I'm on page 5 now.... 


But, nevertheless, I do have some rough ideas of what the GA will be, and I've developed one for an Aft Cockpit concept, standard to many cruising sailboats, and also a Center Cockpit concept, which is less common but not UNcommon on larger boats. Plus, I like the aesthetic of a center cockpit better (when it's on a larger boat).



Below is my intial concept sketch for the aft cockpit layout:




And here is the same sketch, but with some spaces labeled for clarity:




I also have access to some 3D modeling software, so I've started developing this concept in 3D (using my best eye-gauge for the station shapes). The blue figures are Ergonomic representations of a 95th percentile male (a big, like 6'4" guy -similar in height to me, which is why I'm using him!)


First, the exterior:




And the interior (so far):




The interior model labeled:





Like I mentioned, I am also working on a center cockpit concept. The initial sketch for this one is below:




Here's the initial sketch with labels for clarity:




And, of course, I threw together an exterior model for this one, too:




My biggest challenge with the Center Cockpit is headroom under the cockpit-area. As can be seen in the section below, the lower deck has to be quite low in the hull to get any semblance of comfortable headroom, and even then, it restricts the utility of the space, since the head of the person would essentially be right up against the bulwark of the cockpit. The red arrow is supposed to be indicating how low the lower deck would have to be, but it didn't quite work right. I suppose one shouldn't have lofty expectations of perfection out of MS Paint....




I am hoping the jump form a 1:15 scale to a 1:16 scale will give me the boost in beam and depth I need to pull this off, but I have my doubts. Basic ergonomics and geometry may nix the center cockpit layout for me. I've seen a bunch that appear to work really well in the 52-53 ft range, but they all have about a foot more beam than my hul, and I don't know how much more freeboard they have.




So that brings you all up to date with where I am now. I do have a first coat of black paint on the underwater portion of the hull, but it definitely needs a second. (I'm using off the shelf rattle can Flat Black from the department store down the road.)


My intended route from here is:

1. Complete Statement of Requirements (SOR), as a way to organize my thoughts and not get hung up on a non-requirement at the expense of a good design (e.g. a center cockpit boat with a non-functional galley....)

2. Finish painting the hull - black underside, raspberry-pink above water

3. Measure the hull

4. Finalize arrangement

5. Develop build plan/sequence

    5a. Determine what infrastructure improvements I need to make - tools, space, etc. I currently have no dedicated workspace, and minimal tools. So that will be an important step.

6. Determine materials list

7. Make Sawdust!


I will certainly be posting progress, and seeking input, on most of these steps. (Though, I'll only post my final SOR document if it is desired). 


And, I am of course accepting of any input on the design thus far. I'm not an experienced cruiser (I just wish I was!); I'm definitely an armchair sailor. I have several reference books I'm using to help me develop the design [most are my own from high school and college, when I wanted to make a career out of sailing yacht design...interests changed (sort of), but the books stayed with me.] The books I'm using are:


Designed to Cruise by Roger Marshall - using for overall arrangement development

Choosing a Cruising Sailboat by Roger Marshall - using for overall arrangement development

The Modern Cruising Sailboat by Charles J. Doane - using for overall arrangement development

The Principles of Yacht Design, 2nd Ed by Lars Larsson and Rolf E Eliasson - using for overall arrangement development

Yacht Design Details by Roger Marshall - will use for interior details/ideas

Boat Interior Construction by  Michael Naujok - will use for interior details/ideas


I'm also using arrangement drawings for a bunch of different cruising sailboats as inspiration.


I'm really excited to actually be moving towards reality on this build after so many years, and I hope the accountability of posting progress on here will keep me moving forward. It will definitely be difficult at times, since we are also trying to get some major outdoor work done before the new baby shows up in June. But, I think I have given myself a generous deadline. The doll-boat should be ready to be played with by Christmas 2016 at the latest, and by my daughter's third birthday in May 2016 if possible. Hoping I can pull it off!




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Hi Ben


Seeing your sketches makes me wish I was a naval architect as well! Not for want of trying though, but my maths scores weren't high enough at school, hence I missed out. The reason I'm saying this is because it's a marvellous opportunity that you have to combine your professional skills with your modelling skills. I envy you!!


I'm also, without a doubt, going to love following your build log.


All the best!



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What an excellent project.  And I hate to say it, but you may never get that hull back. :)  :) :)  


If I'm reading all this right... you want to build hull (eventually) out of wood?     If so, figure out how to make a mold out of the outside.  Then you can slice the mold up transversely and have cross-sections to copy and modify for your framing.

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Patrick - thanks for the encouragement! I've really enjoyed perusing through your builds as well; I just started following the Rainbow J-Class. I am quite sure it would fit well with my boat as a model boat on my model boat!! And, the sketches mostly come from lot of practice over the years (I've been drawing boats since I was 4!). The arrangements in the sketches just came from mixing and matching different cruiser arrangements, and trying to apply the rules of thumb and principles in the reference books.


The unfortunate side of Naval Architecture is that it's broad, so we spent a lot of time with bulk carriers and containerships and such, and I never really took any specialized classes or training in sailboat design. So, with some practice in technical drawing, you could make a concept arrangement just as much as me! In fact, seeing the kinds of projects you do, I think that designing your own boat for building a miniature model would be a great thing! You could even do what I'm doing (sort of) and take an existing hull form, but customize the insides to be your dream boat. (You know, if you were the size of an electron or something  :D )


Mark - No, I'm not intending to make the hull again out of wood. I was just commenting that I have a complete hull - which is one of the hardest parts - but without knowing the form, doing anything with it (on the inside) is tough. And, I have considered the possibility of not getting it back! I have been thinking I may have to take it 'out of service for upgrades' periodically - its 'age appropriateness' can mature as she does. That way I don't have to wait until she's done to proceed with detailing again.

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Hi Ben.

In modeling this the interior bulkheads and panels will be much thicker than the scale size.

Will dolls and fingers be able to get into the small areas without dananaging the construction ??

Adding the clothing thickness and the dolls not true to scale ..Will they fit ?

I ask the questions as I have designed a few dolls houses based on real houses that the child is living in.

And a child and the scale bannisters lasted about 1 hour. With damage over the next few weeks almost made me cry..

I put it down to fine scale modeling not being sutable for children or adults to interact with.


Please don't take the above thoughts as critisum. Just my expearance.

I will be following this build as I like your idea's.


Regards Antony.

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Hi Ben


Many thanks and yep, like you, I've drawn lots of boats and drafted plans in the past...but there's nothing like having your qualifications and training.  At school, Tech Drawing was one of my best subjects and i regularly got 10/10 for my drawings.  Enough of me, though.  The focus is on you and your wonderful dolls boat for your daughter.  


One question, though.  How are you going to build all the interior items so that they're removable for your daughter to play with?  If so, how easily will it all fit back in?





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Hi Ben, I’m enjoying your thinking things through in designing this boat.  You said that you mainly learned about designing large ships, so here are some pointers concerning smaller sailboats.  You know what you want in the boat and the problem is figuring out how to fit it in.  Besides just placing things as you would in a cargo ship, try to imagine how it would be for the person sailing in this small boat.  The heeling of the boat the bouncing around (At 56’ it is not that stable.) has a lot to do with the room required around things.  I remember one designer I read said he always put the head under the fore deck where a person had to sit to use it.  He said’ “Any man that thinks he can stand in a sailboat while urinating will only make a mess”.  Also so many designers try to stuff in as many beds as they can and advertised this as an advantage.  The truth is a boat can only sleep as many as the galley can feed. 


On a different thought as you know, having looked into doll houses, they are built at 1:12 scale.  The advantage to using this scale is that when it comes to furnishing the boat those tiny things that make the house or boat livable can be bought in the correct size instead of you having to make the pots and pans.



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I again appreciate all the input! It helps to have multiple perspectives to think things through.


Antony - I appreciate the insight from your own experiences. That further motivates my decision to try to do this in steps - step one being a not-fully-detailed model meant to be played with. No intricate things like light fixtures or hinged cupboards (or, if there are intricate things, I make them easy to replace, and make a bunch up front with replacement in mind.) It's all about expectations, I guess. 


And the points about scale and doll size are good ones. I am actually thinking about getting one of the larger dolls to measure it, and make sure that the ergonomics work with the doll scaled up (rather than a person scaled down!). I am also considering Cap'n Bob's comments regarding scale - that is something I found too, that many objects are in 1:12 scale. The upside of a boat is that not many things commercially available 'work' for boats - boats have odd shapes and sizes for beds, all the furnishings are built in, and the furnishings themselves are more....creative. Lots of odd shapes and sizes. But the point about things like pots and pans and other 'loose' items is a good one. I have to decide up front how many loose items I want to provide. (More loose items = more things to lose. Or to be left out and stepped on in the middle of the night. Oh - just got the worst idea. Scale legos for the children on board!) 


But, I have spent a little time rethinking the arrangement in a 1:12 scale - meaning a roughly 40' LOA. Still a good size boat for any family, but I think it would require cutting out one of the features that I've really been hoping to work in - a workbench or workshop room. To incorporate that into a 40 footer would, I think, reduce the number of berths too much, and would eliminate a quarter berth or aft stateroom (which is a preferable sleeping location underway...from what I've read). I do dislike that part of designing that requires compromises. But I suppose it's more of a challenge.


That, or I could just conform to the layouts I've seen in basically every other 40 footer with a similar hull style. I suspect they are the way they are because they work. Reinventing the wheel takes a lot of effort... but at least it involves learning why and how it got invented in the first place.  :)


Patrick - My intent wasn't to have the interior removable, but then again, I don't have much experience with normal doll-houses. I know the furniture is removable (but it is in a real house, too.) A sailboat's furniture is fixed in place, though. Many times it's part of the vessel structure. So, my intent was that the boat, as a doll-house substitute, would be open topped and the dolls played with inside. That said, If the joiner bulkheads and furniture above the sole are fixed to the sole, I could have the entire thing lift out. (I even thought of building two interior options - a 1:12 scale one for the doll house, and then a 1:16 scale one that could replace it later. Then I realized that I had been thinking about this too long and had descended into delusion...)


More to come as I work this out. I really do appreciate the input. Designing in a vacuum = a poor design.

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As a P.S. - in my research, I've been finding that many boats in the 38 - 55 foot range do not have similar proportions to mine. They all (to scale) have at least another foot of beam, many times even more in the 40' range. It makes it difficult to find layouts that work with a narrow beam. If a I use a 1:12 scale, this hull would have a deck beam of 10-1/2 ft. Many 38-42 ft boats I looked at had a common beam of 12.17 ft (I bet there was some racing rule or class design or something that set that...), and many others had beams in the 12-13 ft range (or more!). You can do a lot with 3 extra feet of beam!  I only found 4-6 layouts (out of the several hundred I perused through in the 38-42 ft range) that had beams even comparable - and those were generally a foot or so beamier. Only a couple had beams less than 11 ft. So, that's my other challenge, having a narrow beam in proportion to other boats that would be similar length to scale.


Incidentally, the proportions seem to work more the larger the boat gets (i.e. the smaller the scale). The few 52 ft boats I looked at only had another foot of beam to scale, compared with 2-3 ft at the 38-42 ft length range.

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Update on the search for scale: After a little more digging, and recalling that the person I got the model from mentioned something that led me to believe it was a model of a Gulfstar yacht, I think that I've found the parent hull. I believe that the model may be of a Gulfstar 60 hull - see pics below. I added a rough outline to the pics of the model, since it's hard to see.




The shapes look right, and a quick check of dims, assuming published Loa of 60.50 ft and published beam of 16 ft and model Loa of 40", leads to a model beam of 10.56" - I measured 10.5" using my eye gauge for locating max beam, and looking at the tape, and saying 'eh, 10.5 looks close enough'. So, 10.56" is well within the measurement error of my process. 


In summary - shape and dimensions lead me to the conclusion that the hull model is of a Gulfstar 60. So now I know it was intended to be a roughly 1:18 scale model of that hull, which would explain why the proportions don't work as well the larger the scale gets, to the point where the beam is 2-3 ft narrower than most boats at 1:12.


I am leaning back toward thinking the 1:16 scale is the best compromise. But I'm going to wait to actually get one of the figures here before making the final call. In the meantime, I'll finish writing the spec and generate another concept or two.


It was an interesting little detour to do a detailed review of so many boats of different sizes (beyond just finding some representative examples of layouts), which I likely would not have done were it not for the thoughts offered regarding scale and the practical side of being a 'doll boat.' 

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While I have been doing arrangement design, I have been able to go ahead and paint the hull. 


I marked the waterline with a sharpie attached to a gizmo I made. I got the idea somewhere, but I can't recall exactly where. But it's basically a couple pieces of scrap wood i had laying around from one of our garden projects. A larger piece for the base, and a narrow tall piece as a marker holder. I measured up from the bottom to where I wanted the waterline (taking into account the thickness of the base I have the boat on), and then taped the marker in place. A picture is below:




It mostly worked. The marker was kind of dry, and where the bilge rounding is extreme near the stern, it got weird. But, it was good enough to lay tape against, which I then tweaked and eyeballed until I was happy that it was a line mostly parallel to baseline.


I started with the bottom paint. I chose black for the bottom anti-foulant. Maybe it's just my experience having done only black and gray boats in my career to date, but I like the look of black on small boats.


It took several coats, and learning how to actually use spray paint effectively. The nice thing about the black is that it makes it easy to see where the paint is too thin. This is also the annoying thing about black. A picture of the hull after the first coat of black spray paint is below:




After a bunch more coats, the bottom was finished. Below is a picture of the finished bottom, with the masking removed. I've also put the spray paints I'm using in the picture:




Then I masked the lower hull. For masking both the upper and lower hulls, I used standard blue painter's tape, double layered. Part of the tape was used to attach a series of plastic bags to cover the rest of the area not being painted. Since I was using spray paint, I was concerned about overspray, hence why I completely masked the unpainted areas. Masking is shown below:




With the bottom masked, I applied the top paint, which is a glossy Raspberry Pink. (Incidentally, this is the first time I've ever spray painted something pink. I believe I may now apply for official membership to the Dads of Daughters club....) 


The glossy paint worked a lot differently than the flat paint. It ended up applying a lot thicker than the black, and it even had some drips and runs after the first painting. So, once it was dry I used a fine to medium sandpaper and wet sanded it to get rid of the blotches and runs. I was much less trigger happy with the second painting, doing a series of quick, light sprays. The final result came out much better, and with the masking removed it looks like a proper boat now!





I've also gone ahead and purchased a 6-inch contour gauge, which I was hoping to use to take stations from the hull. Two problems arose during my attempt, though. The first was that the depth of the boat is greater than 6 inches, so I couldn't get a complete station in one go. The second was the the curvature is too broad. Essentially, since the hull has a lot of curvature, and the scale is so much larger than the normal uses of contour gauges, the pins bunched up and seized at the turn of the bilge. So, it isn't really effective for taking station shapes. I'm sure I will find some use for it that will supplement taking offsets, but taking offsets is indeed what I need to do. I'm hoping to get to the hardware store next weekend to get egg-crate light panels to take offsets in a manner similar to one of the NRG's articles on the subject. (I would have gone over the holiday weekend we just had, but apparently we have a thing called a 'budget' and I 'spent mine' already for the month...)


That's all the current progress with the physical hull; I have made some progress in design development that I will post a little later this week. I'm also waiting for Pa Pioneer, the first doll in the collection, so I can take some measurements and make a cardboard mock-up of a couple spaces in different scales to lock in the one which works best.


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  • 3 weeks later...

It's been a little bit since posting last, but I have been busy. Lot's of pictures/renders for this post.




First off, I have finally locked in the scale I intend to use. The first doll, 'Pa', arrived a couple weeks ago. Here he is next to the boat:




And here is my little girl playing with him in the boat (she can say 'Boat' now. One of her favorite words. I approve.  ;))




I used a pair of calipers to measure the doll, so I could make a 3D model approximation.


But, while I was waiting for the doll to arrive, I put together a couple more concept sketches for a 1:12 scale. The first attempt at a 1:12 scale wasn't so hot. See below:




There were some areas that I think mostly worked ok, as indicated by the region with the thumbs up. There was a little bit that I wasn't to thrilled with, but seemed functional. I called this area 'Meh...' And then, there were areas that were just odd shaped and non-functional, hence the thumbs down.


So, I took the areas that were good, and revised the rest, to develop the second 1:12 scale concept, below:




This one I liked much better, so I went ahead and 3D modeled it. A series of shots of the modeled layout are below (again, the blue figures represent a male in the 95th percentile for size)


Overall Top Isometric:



Overall Interior Isometric:



Isometric Detail of the Dining area:



Centerline looking port:



Centerline looking starboard:



Back to Pa. Like I said, I modeled him up. Then I scaled him up by 12 to see the fit with the full size arrangement I had just finished modeling. The fit was pretty good, but I must say the disproportionateness really comes out when he's scale up by 12.


Overall Interior Isometric:



Centerline looking Port:



Centerline looking Starboard:



So, as can be seen, the size fits about right. To take this to 1:16, like I had intended, he gets freakishly large and wouldn't even pass for a 'that looks about right' scale (let alone have enough room to be played with).


To conclude this post, I want to again express my appreciation for the input. I likely would have gone far down my original path and then found the boat to be non-functional. With this adjustment to scale, I think that I will be able to make a functional boat - and to Bob's point, I can outsource many items I would have had to make! (Not that I won't make some of my own custom things anyway.) If you have noticed, I've also revised the thread title, since the boat's not 53 ft anymore...


In my next update, I'll go into the details of measuring the hull form (finally!), which is what I am currently in the process of doing. And if I figure out a way to post downloadable files, I'll share the Excel sheet I put together to do all the work of taking my measurements and turning them into useable offsets.

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Hi Ben


I'm really enjoying seeing you work through the various design issues and challenges you're faced with. It makes me wish I had your skills and expertise because this is going to turn out to be a beauty of a design.


I hope your daughter has many magical years of enjoyment with it. The effort and commitment you're showing is amazing.


Well done.



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  • 3 weeks later...



Finally got the boat measured!! The picture below is the initial (i.e. not cleaned up/'faired') output from the measurements I took:




I will do a longer post about the setup/method, etc sometime in the near future, perhaps tonight if I get the opportunity.


But I was so excited that I finally finished this major milestone, I had to do a quick post.

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Patrick - thank you for the kind comments you offered recently! And thank you also to those who have been following along and like what I have to offer, especially since it's mostly design and planning, and not even actual building yet. I really appreciate you all taking the time to follow my thought process and, at times, offer input!


Now, for the hull measuring explanation I promised in my last post.




So, as I mentioned in my previous post, I finally measured the hull! It took quite a bit of preparation, and then a couple hours of actual measuring. 


The Jig

I'll start by describing the jig. It follows the concept laid out in one of the NRG shop notes - essentially it's an egg-crate style ceiling light panel, cut in half, and bolted together with some spacers. Then it's attached to a large base. I did deviate in some respects from the design laid out in the NRG article. For one, I used more bolts. (Must be an engineer thing...) Also, I didn't add end brackets - I found the assembly was sturdy enough without them. In the original design, these end brackets also seem to be what secures the egg crate assembly down. I overcame that problem using some nails drive in at an angle into my base spacer, so that the egg crate assembly can't lift off. 


 I did make one other change from the design presented in the NRG article - since my model is small enough, and portable, I attached it right to the base of the jig using painters tape (since it was what I had). I did this because I expected that I would not be able to do all the set up, spreadsheet development and troubleshooting (to make sure it did everything I wanted the way I expected), and measuring in one sitting with a wife, toddler, and outdoor projects to attend to. I was correct in my expectation. It took one slice of time to set up the boat on the jig, another to set up the spreadsheet, another to start measuring only to be interrupted after a couple measurements, and then finally an extended period this morning to measure the whole boat.


Pictures speak better than words (and by my word count so far in this build log, I owe a LOT of pictures), so I've attached some showing the whole assembly.








The Measuring Stick


I also made my own measuring stick using 1/2" square balsa. It reminded me of a project we had to do in 8th grade where we were given a length of balsa wood, and had to make a meter stick. I didn't quite make a meter stick, but I made something like a half meter stick, with a tiny aluminum rod sticking out to be the measurement probe, so I was hitting points on the hull.






I chose to take my data in metric (millimeters) for two reasons - the increment is smaller than 1/16th inch, allowing for finer precision, and because the metric system is based on tens, it makes figuring out what the increment is a lot easier - 154 millimeters vs 6.0625 inches. But, I chose to convert back to imperial once I took the data, also for two reasons - it's more intuitive for me to think in inches in general, and most supplies I get will be categorized in inches (wood thicknesses and such) so it will be best to do detail design in inches for that reason.


The Spreadsheet

As I alluded to, I made a spreadsheet to do all the hard work for me. The first sheet does all the work; the second sheet is just a replica of the egg-crate screen where I can input the measurements.



Sheet 1, way zoomed out to see it all. More explanation of this one below.



Sheet 2, way zoomed out to see it all. Essentially just a replica of the egg-crate grid


On the first sheet, I input some basic parameters - block size of the screen, distance from boat centerline to where I took the measurement, height of the base the boat is on, height of the first row of the screen, etc.



Inputs section of Sheet 1


Then I made three tables - the first takes the measurement directly from the second sheet, but consolidates the date so there aren't 'empty' columns (as there are in the second sheet - I took a measurement on every other column). The second table then converts the data from table 1 into imperial units from metric (if the input measurement is metric), or just repeats the data if it was already taken in imperial units.



Tables 1 and 2 on Sheet 1


Finally, table 3 scales the data to full size, based on an assigned scale factor (1:12 in my case).


I was going to upload the spreadsheet I made, so it was available to anyone who would find it useful, but apparently excel sheets are not a supported uploadable file type (I checked with the moderators.) If anyone would like it, I can either (1) e-mail it, or (2) upload it to some type of file sharing site (google drive, or similar). Just either mention your interest in a reply to the post, or you can direct message me.


Taking the Data

With the jig, measuring stick, and spreadsheet set up, I was finally able to take data. This process went fairly smooth - it took maybe 2 hours to take all 215 data points.



Taking a measurement



Close up of measuring stick reading


As I took the each point, I plugged the result into the spreadsheet on my laptop. I set the sheet up to plot the points as I took them, to see if there was anything super wacko going on. This ended up helping me twice when I accidentally skipped a station on the measuring grid. When I saw that the curve plotted by the points seemed to be further outboard than the trend of the last few stations made me expect, I recounted the column in the spreadsheet vs the column in the jig, and sure enough I had gone one column too far on the actual jig. I wouldn't have caught that until the very end when nothing seemed to make any sense.



Laptop next to me to record data



Close up of data input sheet, demonstrating the in-process tracking of the shapes of the stations



I posted the graphical output of the initial results of the measurements in my previous post. There is a bit of fairing and follow up work to do. I still need to somehow capture the sheer line, the stem, and the stern. But these seem like much more manageable problems, and really, once I fair the data I have, I could use only that to start final production design for the interior (since there isn't really anything going in the extreme bow or stern.)

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Many times I’ve used Excel to convert offsets in feet – inches – 1/8 to 1:48 inches, but I never thought of having it draw the sections for me.  Thanks.




Yeah, it's a neat trick. Y-Axis is waterline height above baseline (or whatever your reference plane is) - this data set should be the same for each station; X-Axis is the offset. Each station is a different series on the chart. I manipulated the data using an if/then formula so that IF the station was aft of the maximum section, THEN the offset was made to be negative. That creates the fore/aft split around centerline seen in the chart. 


Drawing the sections in Excel was something we did a couple times for projects in college. It adds a visual element to the data, and also allows for identifying anomalies without having to manually plot the points and hand draft just to find something's out of wack.


I really like it for that second reason. I'm much more visual in my thinking than numerical, and while I may have a suspicion the numerical progression of points doesn't seem right (for instance, a point seems like it 'jumps' too much in value given the previous points), plotting the section confirms it (or shows that there is a bilge turn or something not obvious by just looking at the model - with a black underbody, it's hard to judge the curvature. It just all looks black.)


My next step will be to actually plot the data in AutoCAD and try to fair it out. The mid sections don't seem too bad, but the forward sections are pretty wonky. Don't know who was taking this data, but they did a crappy job! ;)

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  • 3 weeks later...



It's been a few weeks since my last post, but I haven't been sitting around. I've been trying to fair the lines of the boat in between other work and home projects. At home we have been preparing our garden for spring/summer, and at work we are preparing to launch another boat - third of this class. So, it's been quite taxing on time, especially once down time with family is factored in. But, I have made enough progress to remind me why entire, high point value, multi-step, multi-week projects focused just on lines drawings and fairing in school. Because it is incredibly tedious and takes forever (to do it right at least.)


Our first major project, that we started just a few weeks into the first semester of our Freshman year in college, and spent most of the rest of the semester working on, in stages, was a hand-drawn lines drawing based on a given set of offsets for something like a 12 ft sailing dinghy. And, honestly, based on how things are going with this model, I'd much rather go back to duck weights and splines rather than multi-control point mathematically defined curves in a software program. Getting a fair curve with duck weights and splines was easy compared to endless tweaking and nudging of control points. 


The second major project where we had to generate a set of lines from minimal data was during Senior year, and was part of our whole-senior-year design project for a containership. We used AutoCad to do the drawing and fairing of the lines, once we had generated a rough hull form that got the length, beam, draft, displacement, etc that we needed to meet design requirements. I happened to locate that particular project, so I took some screen shots and posted them.



Container Ship Body Plan



Container Ship Lines


For that project I used a very similar method to what I am doing now -

1 - take the offsets (see previous major update...)

2 - plot the body plan to the offsets,



Initial body plan from measurements


3 - transfer to the half-breadth and profile grid,



Initial lines transferred from body plan


4 - then fair the waterlines (since they are generally have the least curvature and should in theory be the easiest to fair initially),



First pass at waterline fairing


5 - transfer the results of fairing back to the body plan,

6 - take the first whack at fairing the new data,



In-process steps 5 and 6


7 - transfer the first attempt at faired curves back to the other two views,

8 - fair the waterlines a second time,

9 - and repeat the rest of the process until the body and half-breadth plans are fair.


Once I have the body plan and half-breadth plans fair, then I'll look at the profile plan, fair the buttock lines, and then fiddle with the other two views to make them all match. Like I said, tedious.


Although, I think what makes this exercise more difficult than I remember the container ship being is the fact that with the containership, it was to some extent my creation, and I could take some license with the original, rough hull form and change it to make fair lines. With this boat, I have to make fair lines that MATCH a real thing. Meaning I have to be very judicial about balancing the fairness with the adherence to the measured data, and make a fair lines plan with as little deviation from the measurements as possible. I tell you all what, this project is stretching my professional skills more that I expected it would, not just my modeling skills (especially since I haven't actually MADE anything yet!)


I have to remind myself that fair and accurate lines are worth the effort, because once I get to production detail design, it should save a lot of headache and minimize exclamations of l 'why doesn't this fit!' I'm sure it will happen, but likely less than if I didn't spend the time making the lines right.


My hope is to have the lines complete, and a new 3D model of the hull generated, in a couple more weeks. Then, I can adjust the arrangement I decided on a couple posts back, ensure it's still functional, and proceed into detail design (which I'm already thinking about, of course....)

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Hi Ben


Certainly looks like painstaking work! Just thinking about your comments on the use of the Software - Kinda counter-intuitive though, because you'd think that the software should make your life easier...not harder. I do, however, understand and appreciate your reasons for being true to the actual shape of the real hull, though.


I'm looking forward to your next update. Perhaps, your next ship may be the container ship that you've drawn?





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Hi Ben


Certainly looks like painstaking work! Just thinking about your comments on the use of the Software - Kinda counter-intuitive though, because you'd think that the software should make your life easier...not harder. I do, however, understand and appreciate your reasons for being true to the actual shape of the real hull, though.


I'm looking forward to your next update. Perhaps, your next ship may be the container ship that you've drawn?






The software makes things easier in some ways, definitely. For example, the lines can be tweaked with control points, vs. erased and redrawn. I suspect the real issue is that I am currently distanced enough (over 7 years....GAH!) from that first hand-drawn lines that I remember all the charm and none of the fact that the 'charm' was overshadowed by drawing and erasing lines at 3 am to get the project done before the deadline!


As for my next project, alas, I already have a kit of the Edmund Fitzgerald sitting on my bookshelf. My wife has already informed me in no ambiguous terms that I can't start any more projects until I finish this boat and the Fitz! (I get told this all the time as ideas pop up)


I see a kindred spirit in Popeye (Dennis) as I've been following his Andrea Gail build and how he mentions his other incomplete projects and new crazy ideas. Although, I can say I've already finished my Titanic model  :D . 


My eventual goal is to make an RC Scratch Built model work boat or merchant ship of some sort. What exactly it will be when I ever get to that point remains to be seen. I may even make an RC scale model of the real boat I've been working on professionally. It would be an easy hull form - planing monohull with mostly geometric faces rather than sweeping curves. The propulsion would be the interesting challenge - it's waterjet driven. There are certainly working model waterjets out there, but they don't LOOK like the ones on the boat, and since they are a prominent feature of the transom, that's a problem to overcome....


But I've digressed far off the current path at this point. Anything to avoid fairing lines, I suppose  :rolleyes:

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  • 3 weeks later...


(A.K.A Just Keep Fairing, Just Keep Fairing, Just Keep Fairing Fairing Fairing, What Do We Do - We FAIR!)* 

           *Parody of Dory's 'Just Keep Swimming' song from Finding Nemo for those unfamiliar with the reference...


Well, I made more progress with the lines, but I've run into some hiccups. The lines are getting fairer, but the hull I have in CAD is not the hull I have sitting in my spare room. The 'form' is close, but I've botched something up with (I think) the grid. It's either too short in length or too tall in height, and so when I lay my profile plan over a profile picture of the boat, it just doesn't match. I initially thought it was height, but laying in a plan view, it may actually be a length issue. See screen shot below.



I just ....don't know. ¯\(°_o)/¯


So, I've been frustrated, and decided to take a break from lines and do something else, for fear of getting so bogged down with this issue that I just throw in the towel (my knee-jerk tendency). 


My remedy was to select, and then start researching a build process for, the auxiliary diesel for the sailboat.




I had already done preliminary engine selection when I first started laying out concepts. However, I never went back through the spiral when I changed scale to 1:12. To do that, I basically opened up one of the books I have, made an Excel spreadsheet (which is essentially an engineer's first reflex when solving any problem  :rolleyes:), and listed out all the boats in the 38-42 ft range, along with their installed power. I 'weeded' racing boats and cruiser-racers, to focus on cruising boats only. Then averaged the lengths and installed power. Based on that, I selected for this boat's auxiliary diesel a 38 HP Yanmar 3JH5E w/SD-60 saildrive. I selected this specific model for two reasons: 1 - it fit in the boat (very important consideration....) and 2 - Yanmar's website had a downloadable 3D model of the engine. (unfortunately, they didn't have a model of the saildrive unit, so I had to generate that myself using their ok-ish drawings.



3D Model of Engine (from Yanmar's site) and Saildrive Gear/Strut (developed by me from drawings)


I've broken the models up into system-based chunks (e.g. - main engine block; fuel system; raw water supply; etc.). An example of just one of the systems isolated is below:



Example System grouping - Fuel System


Each system grouping is further broken down into smaller chunks - for the fuel system, the injectors are a chunk, the injection lines are a chunk, the injection pump is a chunk (with even smaller components itself, since it's pretty complex), etc.


In this way, I can plan the build of the engine in chunks, starting with the block, and working to the insanity that is the fuel injection system. 


This leads me to...




With all the problems I was running into with the lines, as I mentioned I was getting discouraged - mostly because I just wanted to build something! So I started with the engine block.



Iso View of Block and Mounts


I scaled the part, and printed it 1:1 so I could glue it directly to my piece of balsa wood.



1:1 Printout of Engine Block


Prior to scaling and printing, I bought a grab-bag of balsa wood from a craft store for something like $10, which was awesome since it had a big range of sizes and types - square stock, planks, slabs. It just so happened that I had one slab 3/4" thick, which was PERFECT, since that was the width of the block.  



Printout with Balsa Slab


I glued the printout on, and cut the first part! Hooray!!



First Part Cut!


The first owner's inspection went satisfactorily as well :)


post-17514-0-14251000-1430412908_thumb.jpg post-17514-0-88201300-1430412911_thumb.jpg

First Owner's Inspection  :P 


From that first piece of wood, I then carved out the shape of the block, adding in some additional details using other pieces of wood as appropriate.


post-17514-0-02319400-1430431179_thumb.jpg post-17514-0-06439400-1430431181_thumb.jpg

Engine Block - shaped


Once I completed the block proper, I still had some time left last evening, so I decided to make the mounts and mount bracket. Given that I've never really done any scratch building, I was fully prepared to have to make a second (or third) attempt. The first issue was even what to make them from (at scale, the wood was just too thick). Enter my hoarder tendencies! I had some old plastic model kit sprue lying around, and an initial inspection identified that the label plate for the sprue was the right width, and appeared to be appropriate thickness.



Sprue used for Engine Mounts


A bit of cutting and fiddling later, with a fair amount of - clean - negative exclamation, I had engine mounts!! I used the sprue label for the bracket, some small polystyrene tube for the boss plate on the bottom of the brackets, some 0.035" diameter rod for the stud, and some 0.100"x0.100" polystyrene square stock filed to shape for the mounting feet. Then I glued it all together...then dropped the parts, then they fell apart, then my tweezers got stuck to them, then (and on, and on). But - I eventually got a set of two engine mounts! Woohoo!



First Mounting Bracket



Both Mounting Brackets and Engine Block



Boss Plates and Studs Added to Brackets; Mounting Feet Made



Mounts Completed



Completed Mounts Next to Block


So now my next problem is figuring out how to bond the plastic to the wood. I tried a couple super glues, but my suspicion is that the balsa is too porous, and so the adhesive just soaks into it. I was thinking that some method of sealing the wood first (a coat of wood glue, or a thicker super glue, like Gorilla glue or other gap filling super glue, may do the trick.) Anyone have experience trying to do this? Any recommendations?


Tonight I am going to start on the cylinder and cylinder head block, since it's another fairly blocky, easy to form piece, and it's the logical next step since it mounts to the top of the block.

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Balsa really is a very soft and porous wood.  You might try several coats of a 50/50 mix of white glue and water on it.  Then lightly sand and coat again. It will seal the wood the strengthen it.   An alternative low-budget would be basswood.  A bit harder but will probably still need the diluted glue treatment.  Then, if Ca doesn't work (use the thick or gel kind), use epoxy.

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