Once again the heat continues inside and outside of Naval Yachts this week. As per the title most of the work was focused on giving Möbius her curvaceous shapes as the 3D curved hull plates you may recall seeing us receive in last Friday’s post were hoisted up onto the framework and tacked into place. These thicker and heavier curved plates take much more time to get into position and tacked in place than the flatter and lighter plates previously installed but as you’ll see below most of the plates on what will be the Port/left side are now in position. Show me don’t tell me right, so on with the show we go………..
First step with these thicker 12mm/1/2” and 15mm / 5/8” hull plates is to bevel all their edges to create the V grove where they butt up against each other and enable the welds to fully penetrate from each side. These curly chips are from cutting all those bevels.
One of the great things about aluminium is how easily it can be worked with woodworking power tools so as you see Enver doing here, a router fitted with a 45 degree carbide cutter with a bearing follower is used to put an even chamfer around all the edges of each plate. Other than the horrendous noise it works quickly and well.
As each plate is beveled the whole crew helps to flip it over and work on the next one down in the pile. Those stripes let you see where the wheel rolling and hydraulic presses the bender uses to create these very complex curves.
They work through each plate in the pile and put the bevels on all their edges.
Once all the plates have been prepped it was time to put in a call to the preying mantis crane truck to lift each plate up onto the hull.
Just before we jump into this week’s work on putting these 3D curved hull plates in place here again is view of the 3D model showing the different plate thicknesses. The curved plates which are going into place this week are the green 12mm / 1/2” thick and the Cyan 15mm/ 5/8” bow plates. Note also the “shark fin” Keel which protects and supports the propeller and shaft which also had more work done this week.
This is the 15mm “ice plating” that forms the first 5 meters of the hull back from the bow.
The super long reach of the crane makes short work of positioning this plate where they want it.
And then the crane comes back for the next one.
This is the 2nd plate back from the bow on the Port side and you can see just how complex the combination of the CNC cutting and the rolling/bending of the 3D curves has to be.
Moving forward on the Port side you can see the 3rd plate back from the bow being set temporarily in place. If you refer back to the coloured 3D model above you can see there is a long tab where the framing for a future stabiliser sits and you can see Umit and Uğur fitting that tab into place on the bottom edge of this plate.
You can also see that some lengths of 15mm plate have been tack welded along the entire lower plate’s edge to ensure it stays in just the right place and tight up against the stringers and frames while they tack the new plate’s edge.
Moving right along, here is the 2nd plate back from the bow being manoeuvred in place with some short vertical bars tacked onto the horizontal stiffeners to keep it from slipping off the edge as they move the plate into position.
The bends in the plates seem to be matching up just right against the underlying curved framework. You gotta love the accuracy that comes from 3D models and CNC cutting!
If you click to enlarge this and look very carefully where the plate edges touch the stringers you will see the little step in the stringers which allow for the transition from this 12mm thick plate to the 15mm thick ice bow plate that butts up against it. This ensures that the outer hull surfaces are all flush and smooth and the welded transition is on the inside.
Time to move that 15mm bow plate into position.
Here you can see the scrap bit of plate with a hole in it is tacked to the plate to provide a place for the hook on the chain hoist to attach and let the plate slide all the way forward. You will see this in action in the video below.
And here is that eXtremely thick ice plate in position and ready to be pulled tight against that massive 25mm thick Stem Bar and welded in place.
Looking straight up the Stem Bar where that ice plate meets up with the Stem Bar and the 10mm upper hull plate will give you a sense of how strong Möbius’ bow will be.
And now the fitting and tacking begins to pull all these thick curvy plates tightly up against the framework and tack them in place.
Moving over to the yet to be plated Starboard side you can see these new curved plates being tacked to the frames and stringers.
Looking aft along the Port side wtih all its 3rd row of plates in position now you can start to see Möbius’ sleek slippery curves starting to come into view now.
Still lots of curved plates waiting for their turn next week as the process is repeated and the Starboard plates are lifted in place as the plating of the hull continues.
Taking the plate to even greater eXtremes here is the 50mm / 2” thick grounding plate which will soon be welded onto the bottom of the 25mm thick “shark fin” shaped Keel where the prop shaft extends out.
Work continued on that shark fin shaped Keel and you can see Uğur welding in the 25mm vertical frames which, when covered with 12mm plate will create the geometric curved foil shape to maximise the smooth flow of water feeding the eXtremely big 1m OD four bladed CPP propeller.
And lest you think that we never see the light of day outside of the shipyard building, here is what else has been going on this week in the Antalya Free Zone.
This little fella went sliding by our front doors on Wednesday making its way to the launching ramp after a complete refit after it was flooded when originally launched after being built at a yard in Italy.
And remember this rendering of the new home of Naval Yachts that is being built 2 blocks over from where we are now?
Well this week all the steel columns were stood up onto their deep concrete footings.
The thick huge concrete shop floor will be poured over all this dirt in the next few weeks
Work on the concrete part of the building for the offices and workshops has also been moving along quickly.
If work stays on schedule we will be moving into this new building around November and this will be where the right side up hull of Möbius will be moved to be fitted out with all her systems, equipment and interiors.
So that’s the week that was July 16-20, 2018 and below is the summary video of the week as usual.
Our continued thanks to you for taking the time to join us and please add your questions and suggestions in the Comments field below.
I take it the principle being followed is, “If the piece fits, it’s right. If the piece doesn’t fit, either the piece is wrong or there’s an error in the contruction up to this point because the piece is supposed to fit.
“NO FORCING THE FIT or FILLING IN GAPS TO BRIDGE THE PIECE INTO ITS PLACE”.
Hard to believe that garentees the hull being constructed follows the design lines making a symetrical hull true to design.
It does, it’s just hard to believe.
You’ve got it just right on both counts John; both the “if it fits it’s right….” and “NO FORCING THE FIT”. It does take most crews and yards awhile to build up the trust in what the CAD/CNC combination gives them. However, to borrow the phrase from a completely different context I’d say the best practice is “trust and verify”. So there are LOTS of checks throughout the process to verify that what is being built conforms to the model. And let’s be clear that a CAD model is NOT infalable, there can be mistakes in the model which get passed on to the CNC which very accurately follows the incorrect instructions it is given by the model’s cut files. For example with all the hundreds, perhaps thousands of slotted joints used in Möbius it is possible that one of the intersecting pieces does not have a deep enough slot in it, or maybe any slot in it. The two pieces intersecting perpendicular to each other appear at first glance to be fine but on closer inspection you see that solid metal on one is passing “magically” through solid metal on the other. Or other times a part changes and the cut out slot does not get adjusted along with the change.
Technically these kinds of errors are avoidable, especially with 3D solid modeling software which either won’t allow you to create such fits or will generate an error when two parts interfere with each other but solid modeling is used more for manufacturing and doesn’t suit boat building as well where surface modelers are more the norm. As usual software is advancing and CAD such as Fusion 360, which I am now personally using more and more, are able to do both solid and surface modeling within the same program so these kinds of errors will become less and less common.
I should also be clear that there is still some degree of “hand fitting” going on. For example we purposely had the upper edges of the upper hull plates extend about 30mm further up past the deck level because there can be some “lost in translation” dimensions when converting the 3D hull plates into flat plate shapes for the CNC cut files. This edge extra margin will be cut off quite easily following the deck plates to get it just right. And we also had some areas where we decided to make changes to the design after the cut files had been generated and sent off to the cutter which has required cutting some new parts and fitting them into the hull. When Naval Yachts move to their new shipyard at the end of this year they will have all the CNC for both metal and wood/plastic in house and that will improve things dramatically when such new parts can be CNC cut more “on demand” so the process is constantly being improved.
And I smile and nod with your last observation about the fact that this process works in reality and as you put it “It does, it’s just hard to believe” and also shake my head right along with you that it is hard to believe what we are able to do today. Reminds me of a favorite Sir Arthur Conan Doyle quote “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.”
And I quite like the fact that I’m still able to be impressed by technology, and humans, and hope to never loose such fascination and awe.
I am amazed at how well this boat appears to be “clicking together”! I have not seen an aluminium build in this much detail, but I would have imagined considerable trimming, remaking and forcing to go on. For example, I am surprised that you can leave the 25mm keel bar so late – my amateur guess would be that this would be located first as it could never be bent in after!
For the rolled plates, the calculation of plate dimensions and shape to CNC cut pre-bending must be very difficult – is there really no trimming involved? You can tell your friends!
Maybe I should ask Dennis this, but I guess you will know the answer, what software is used to design the boat and output the cutting files? Does that same software program provide 3D visual renderings, weight, centre of flotation, cut away drawings, strength, stability and other hydrodynamic calcs, etc? Or is the model exported (or rebuilt) in other packages too?
Interested to know if Dennis has had to examine and tweak every part and check how it impacts with its neighbours and consider how the boat is make-able (access to weld etc) – or whether the software copes with a lot of this????
Again thanks for your feedback, Wayne, and for making such an interesting and inspiring blog.
The software I use for the modelling and to generate the cutfiles is Rhino 3D, a surface modeler. There is a fair few number of hours in sorting out the fit between the pieces, basically the boat is built on the computer, all manually checking each piece and intersection. The computer does not do any of the work, so figuring out welding access for example has to be taken into consideration at all times. I hope that I have not missed any potential interference, these little mistakes that sometimes creep are annoying, since the builder must decide whether it is a mistake or not. Perfection s the goal, but elusive =] I learned from my own boat project that every hour of modelling saves at least ten in the workshop. As soon as you have to stop to take measurements, mark out the shape on a piece a piece of aluminium, cut it and fit it, the hours start stacking up at an alarming rate, especially if the piece is not a simple flat bit, but has curvature.
I know there is software that automates some of the part generation, but I have not tried any yet.
I have to admit I left figuring out the shell expansion of the round hull panels for the yard. Judging from the pictures they have done a sterling job of it.
The hydrostatics etc. are done in Rhino, using a plug-in called Orca 3D. Orca is also used in the weight estimate of the modeled structure and fluids.
I hired a structural engineer to do the scantlings.
Ahhhh, now we have someone who really knows what he’s talking about to answer some of these questions! Thanks much Dennis, you are not only the expert here but also able to articulate your expertise succinctly with an order of magnitude less words than I use with my bumbling and amateurish answers. It continues to be an absolute delight to work with you on the design and now building of Mobius. You have exceeded all our hopes of finding the “just right” designer for our new home and as she now takes shape before our very eyes we could not be happier. Hope you will be able to come visit for or before her launch??!!
Thanks for the kind words Wayne! I would very much like to come and witness the launch, maybe take part in some of the sea trials. Also I would like to meet the crew at the yard.
We’d LOVE to have you come see your designs being transformed into real aluminium and to get some time with this great crew here. We’ve got a room all ready for you at our apartment anytime so just let us know when it would work out for you to come visit, maybe even several times!
I’m chasing a rabbit here that I have chased for longer than I care to mention. However I never miss a chance to chase it again. Hull Performance. I’ve not used it myself but from what I read the HydroComp series of SW, which is in part based on some work done by Norm Riise some time ago that was useful for design considerations in the “long, light, round bilge canoe bodies” used in the FPBs, maybe useful in current design efforts.
How did you come up with the Mobius hull shape?
I have no experience with CFD, apart from having attended a seminar and watching online videos. The technology is still a bit complex for non-experts like myself, but I remain hopeful that in a few years it will be part of my toolbox. There is a Rhino compatible software/plug-is by Simerics out that looks interesting, so things are looking good on that front.
in the mean time, If a project comes along that would require a CFD analysis I would contract the work out.
Mobius’ hull shape was designed the old fashioned way, in Rhino and Orca.
I meant how did you come up with the hull shape? What are its characteristics?
I wasn’t refering to the tool you used to record your work.
I see, not so much about the tools but the hull itself!
We went through a few rounds of the design spiral to get to the final shape. The hull started off a bit shorter, and with twin engines, and a developable shape, and ended up rather a bit longer and rounder in the end.
After the final decision on the engine and propulsion system was finalised we were able to start locking down some parametres, First of course the displacement, which is the key to everything. A preliminary model of the structure is done to get a good handle on the weight, and a spreadsheet to monitor all other weights. Getting to a good estimation of the vertical centre of gravity is vital for the stability and rolling characteristics, not too quick, not too soft. I tend to lean on the hard side, since this is inherently safer and easily made softer if required by raising the CG. Lowering the CG is a fair bit harder!
From there it is a question of choosing a suitable waterline beam, prismatic coefficient for the target cruising speed, trying to keep the Longitudinal centre of flotation close to the longitudinal centre of boyancy, keeping the hull balanced fore and aft, minimising the wetted surface as much as possible, maintaining a sharp entry… So a lot of variables need to be kept in mind. All the while going back to check that nothing funny is taking place, and checking that the interior arrangement that we settled on in the preliminary design stages fits within the hull shape and structure.
I would describe the shape as conservative, well balanced, and suitable for the power available, nothing unusual or experimental happening here. Well, perhaps the propeller tunnel is a bit out of the ordinary, but well justified as it helps keep the draft under control and the propeller shaft angle closer to horizontal.
Hope that answers it well enough. =]
Thanks much for your expert overview of the hull design process Dennis. We certainly didn’t make it easy for you but as always you came through with flying colours. While we won’t really know how the hull performs until we get her in the water and can collect some real world data, we are extremely pleased with how great the hull shape looks as it steadily comes into view more and more as the construction continues. She is slender, slippery, safe and sexy! Who could ask for more??
Great questions as always from you Nigel and John. You now have the official and expert answers from Dennis at Artnautica Yachts based out of Auckland NZ who has been working with us from the very beginning when Project Goldilocks first emerged as a vision of the future Christine and I were forming. We spent a long time searching the world quite literally for the “just right” designer to work with and as you can see we found exactly what we were looking for when we first met Dennis and have been working with him for almost three years now.
As per Dennis’ response here, Rhino is the primary CAD software supplemented with extensions such as Orca3D and additional specialized software for specific tasks. Rhino has captured a tremendous amount of the yacht design world and our equally “just right” builders here at Naval Yachts also use Rhino extensively so the transition from Dennis’ design work to their build work has been very seamless. As Dennis noted Naval used some specialized software for example to “flatten” the curved hull plates needed to generate the cut files and to some of Dennis’ points of labour saving features, you’ve seen in recent posts all the marks and lines etched onto the 3D curved hull plates to assist the benders with aligning the 2D templates used to check those complex curves along the surface and allow them to do that still very manual and human task of bending those plates.
This example of the plate bending and Dennis’ comments about all the manual checking and designing he still needs to do are great illustrations of what I think is most often the ideal combination as we strive for the elusive goal of “perfection” is this mix of technology, automation, machines and human skills that is needed to get it all “just right”. I found it most interesting in following what is going on with the Tesla Model 3 production that Elon came to this same realisation and found that they had gone too far with automating and computerizing everything and it was reducing their productivity and production rates and he needed to change many parts to add in the human and manual elements at appropriate spots to get it all “just right”.
And to your question yes there still is some trimming involved in different places along the edges of these curved hull plates. There is still some degree of “lost in translation” as these plates are transformed from curved in the design model, to flattended for the CNC cutting and then curved in reality so the smart strategy is to leave a bit of margin along these edges so their final fit where they butt together with each other can be trimmed just right. In almost all cases these are straight line edges and butt joints so after you set two adjoining hull plates together and get them tacked in just the right position, it doesn’t take much time for a cutting disk in an angle grinder to cut off the overlap of each plate and get a very tight but joint that welds up very nicely.
Leaving the 25mm keel bar so late in the process is mostly a result of choosing to build the hull upside down which was itself a long set of discussions. As with most things there is no “right way” to build a hull from this perspective though there are some very strong feelings of the different camps who like one over the other. Both have their pros and cons and in our case we largely went with what the builders are the most familiar with. As you have been seeing on the blog posts with the building of Möbius this meant that the jig was where the work started and where the initial layouts and checks were made as the deck plates went on which in turn set out the exact placements of the frames as they were stood up and then the tank assemblies lowered in place. Only then was it possible to put in the 6m/20ft long keel bar lengths of 25mm plate. One feature of this method which you allude to is that this late fitting of the very rigid and straight keel bar serves as good check against the placement of all those frames because as you said “… it could never be bent in after”. Delighted to report and as you literally saw in the videos, those keel bars dropped right into the 25mm wide slots in all those frames and down the bow as it turns to become the Stem Bar which made all of us here smile and raise our confidence in this whole design/build process.
So we too are “awemazed” at how well everything is quite literally “clicking together” here and how close this very first iteration of this line of boats comes to executing the “jigsaw puzzle” style of design we are striving for.
Are you keeping track of the “adjustments” to create an “as built” series of documents?
Yes, absolutely keeping track of all the changes throughout the construction process John. We pull out specific parts and areas to work on them, make modifications and the update the overall model with these revised parts. So in the end we will have an “as built” model that should reflect the real world boat and we will use that throughout the life of the boat for maintenance and updates we do along the way.
A real base line from which you can vary and still return to base line config if the experiment didn’t lead in the direction you expected.
Dennis, thanks for the walk through on the design spiral. I’m getting the feeling that this “type” of passagemaker has the bow of a wave piercer, the center sections of a canoe and a bit of not quite yet settled stern shape(s) somewhay driven by the number of engines. Some other common features are shallow draft and well over built strength everywhere. The variability in living arrangements is driven by life style. The boat is designed to be maintained while afloat as much as possible by the owner live aboard(s).
I’ve never seen a site like this where the people; owner, designer and constructor, are so transparent in showing their thinking and work. You could build a very good series of courses around this! Espically if you saved the design spiral data.
By the by, I read that one designer of planning high speed boats uses a program in which he has fifty parameters.
My question to Wayne about keeping documents up to date is driven by “as designed” – “as built” – “as is” knowledge requirements.
Glad you are continuing to enjoy these posts John and that they are of value. I describe Project Goldilocks as “a collaborative work of art and engineering” and it only seems right to share everything as we strive to be true to this being a true collaboration. We see contributions such as the questions and ideas people joining us here like yourself as being part of this collaborative effort and “we” are always smarter than “me” right?
As I outlined in the post about “Standing on the Shoulders of Giants” we have all learned so much from others who share their work, ideas, techniques and processes so we also feel a strong sense of wanting to contribute our fair share in kind and keep this constructive spiral of learning going ever upwards.
I’ve always been a DIY, hands on, “maker” kind of guy and so I’ve been really enjoying how there has been a slow but exponential change in the spread of a more “maker” mentality with more and more people of all ages, and perhaps one of the most important aspects of this change is the sharing mentality that has become more and more pervasive. Thanks for your comments and confirmation that we are continuing and adding to these trends of sharing and collaboration. IMHO the world is a much better place as this spreads further and faster.