Found this Link : https://www.sculpteo.com/blog/2015/09/07/the-ultimate-finish-from-3d-printed-to-final-product-look/
Claudio
I’m very keen to go have a look 
Abs would be an amazing plastic and you could do an acetone brush on the interior skin of the hull to weld it up but it’s such a pig to use without getting warping.
One of the reasons my build of Claudio’s Narrow has ground to a halt was the purchase of a Prusa type acrylic printer. I used it to create the mould for my bulb and got that extremely close to the desired weight.
I also just printed my first test mould to create a rudder. The test finish was excellent at a print height of 0.1mm with a 0.4mm nozzle.
And this is the test layup.
So for myself, I’m sitting somewhere between yourself and Claudio. I’m using the printer to create moulds that I can use more traditional methods on. This gives me better resolution than my handcrafting skills allow but I can reference proven cloth weights etc. Having said that, one of my main reasons for not attempting a completed hull is my printer is not up to the task imho. I’m having z-axis issues at larger heights so hopefully I can give it a bash down the line.
Nice work, Naptalene.
A good printer is a significant investment, but the good news is that a professional printer is not required for good results. Of course, the best that can be afforded is the way to go, then time spent testing and working to eliminate things like reduced accuracy at the upper limits of a build. Printing is Selwyn’s domain, not mine, but I can say that a printer like the Wombot Exilis can do the job. Perhaps with some more refinement to your setup, your printer can do hulls, too.
Because of the printer cost, Selwyn and I have always shared a vision of the printer being a club resource. Most clubs probably have a couple of geeks like Selwyn and I…one who likes to design and one who likes to engineer. Maybe that’s the same person, or maybe the designer is someone whose files are published like Claudio or myself. If everyone in the club chips in to fund the printer, it suddenly becomes much more affordable. All club members can then benefit by having hulls and parts printed at very low cost.
Selwyn and I have had some chuckles during our project, because we are, in fact, prototyping our own vision. The club in our case is a small group that has collaborated, each contributing a particular expertise. And we’ve even demonstrated that the “club” doesn’t have to be local…ours literally spans the globe, and the only frustrating part of that is having to wait a week or more for printings to ship from Australia to the USA!
Have you seen the resin printers … OMG I need one lol.
Are you guys available anywhere in particular to answer some questions? I’d love to know things like wat brand of filament, material, height resolutions etc. have been chosen for different reasons.
And silly things like how you choose where to cut the hull, what kind of joints are you using, which glues etc.
Are the files of hulls available blah blah blah lol. I’d love to be able to try print out an existng design where the stl’s have been made so I can have a benchmark of things.
Cheers
Andrew
Andrew, Selwyn has offered to answer questions here https://3dprintedradioyachts.com/question-contact-selwyn/
I suggest you read all of the site material, then be as specific as possible.
Bill
I went there last night 
I was worried that I would be bugging him in his personal capacity as opposed to on a forum
I’ll get my questions coherent and then send him a mail, thanks.
Selwyn sent me some pics of the maiden voyage of our latest RG65.
Interesting pictures that are the laborious results of a new technology. Congratulations !
What are the mini/micro waves composing the Bow Wave ? Roughness, Vibrations ?
How much the total weight ?
Why not painted ?
ClaudioD
Thanks, Claudio.
Total weight is 1020g. Ballast ratio 60%.
I don’t think Selwyn wanted to paint it. This way people can better see the printing…not just the hull, but the internal parts, too. People have been very curious about this when he sails.
I’m not knowledgeable enough to know what forms the waves. I sent a couple pictures to Graham Bantock for his thoughts. He suggested that they are capillary waves that are more prominent the shorter the hull length, and nothing can be done about them. He did feel, however that the boat was trimmed a bit nose down, and that the bow wave might shorten if the trim is changed a bit. I forwarded that to Selwyn, so maybe he will try an adjustment.
Graham also said that, although there is plenty of research on hull finish at high speeds, no one has been able to any true testing of different hull finishes at model speed…so we don’t know what is optimal.
Hi Bill,
probably the immersed and wide bow combined with short oscillating pitching or vertical vibrations are the cause of this peculiar phenomenon.
I went to the other picture and enlarged the bow area and there it is possible to see where probably all that begin.
I wonder about the source of vertical vibrations like something is oscillating inside the hull or outside deck like the Jib boom where the attachment is rather recessed.
It is also my understanding, nevertheless, that any form of wave production made by the boat subtract energy from sail power and by consequence from the propulsion movement and speed.
Attached some RG65 pics where these micro waves are absents.
Longitudinal trimming may cancel the phenomenon.
Data about friction coefficients are available in books (Reynolds formula), for sure physics are rather explicit about the surface finish where smooth surfaces are far better then rough one if we exclude fish skins and associated polymers generation…
ClaudioD
Thanks, Claudio.
I’ll narrow the bow a bit for the next version, just in case that is contributing. Will also tell Selwyn to make sure the bow bumper is tightly glued. He has moved the battery aft and will test again.
Roughness should not be an issue…he sanded this one. He’s tired of people telling him they don’t think the finish is smooth enough, even though there is no evidence to that effect. I know you are convinced that a glassy hull is best, but no one has shown any evidence of the effect of roughness at model speeds. You refer to studies, like Bethwaite perhaps, that make the case for glassy finish…but his work was done on much bigger boats at much higher speeds than ours. There is no evidence that his research scales down to model sizes and speeds.
At any rate, if finish seems an obstacle when Selwyn goes beyond the club level again with these boats, sanding and painting is a simple option which produces an excellent finish. Selwyn’s outstanding print quality allows the hull to be sanded without uncovering any pinholes or gaps. Those who’ve done some 3D printing will understand how impressive that is.
Just got some pictures of Selwyn’s latest hull. He has refined his printer settings so that it produces a finish that I think is just amazing. Tight and smooth (but not glassy) to the point where no epoxy coat is needed. IMHO, no sanding is needed either. If you prefer sanding to a glassy finish, clearly it would be easy to do given how smooth this is to start with. This is just getting better and better. It’s too bad the forum reduces picture sizes…the full res shots give you a better idea how tight the printing really is.
In a few weeks, I’ll give you a report on his new IOM. He’ll be printing this week to get it ready for a couple of big races in AUS, so we’ll be able to see how the technology hold up in serious competition.
More and more interesting as such that, in spite of my residual reticence about surface finish and fragility, I do also consider this technique in my last design model the “ESTEREL” where I search how to improve speed performances among models in the 39" - 50" range.
Claudio, I don’t know if you have worked with any printed PLA stuff, but I can assure you that it is a very tough material. I gave up trying to cut hatch openings, etc. with an Xacto knife. Instead, I do all my cutting with a Dremel. It is also very resistant to a drill, so I make holes with the dremel and a grinding bit.
Where it does have some fragility is at the corners of hatch openings and the like, where the hull can split along the lines that it was laid by the printer. The tighter the printing quality is, the less this is a problem, but I don’t know that it will ever go away. After cutting a hatch opening the other day, I was thinking it might be better to to “drill” holes at all corners first, so that the corners would be a bit rounded. Haven’t tried it yet. At any rate, hatch openings do need to be reinforced.
VERY nice to see progress on 3D printed hulls! Talks are now about construction details and not anymore about feasibility or toughness. Cool!
Hi Bill,
close to my house there is Technology Hub and find out that in May a new Tech-Lab will be opened fully dedicated to 3D techniques including printing and formation to CAD.
Tomorrow I will meet a Company dealing with 3D printers, but the 3D learning course with them is over 2000$. Hope to see some 3D samples
Bill,
just back from 3D-Synergy producing 3D printing objects to customers.
I took with me two hulls of 1000mm, one in FBG and the other in Carbon/Kevlar for 150g and 120g respectively. FBG Hull too heavy !
They could evaluate the rigidity and strength and confirmed that with 3D printing they cannot achieve the same results within the measured Hull weight.
Materials they often uses :
PLA is suffering UV, is fragile if not above 0.8mm or dual coaxial printing, is biodegradable, that’s means that will suffer if in contact with water, is a porous material therefore cautions shall be taken for Sailing Hull applications. Density 1.25g/cm3.
I have seen several samples, one was very flexible like a normal Bristol paper of 7.5oz. The measured thickness was 0.26mm.
ABS is lighter and stronger but suffers UV exposure with time, like PLA. Density 1.1g/cm3
PET is the plastic used to produce water bottles. Good mechanical resistance, no UV problems. Density 1.38g/cm3, a bit too heavy.
CFR-PETG is a mix with Carbon powder and Teflon, very strong and light, resist to UV, Stainless steel Nozzles needed, conductive, suffer humidity. Density 1g/cm3
They claims that there is a large number of filaments combination of different materials including metals.
Conclusion :
External finish required all the times to remove roughness and care shall be taken to avoid loss of thickness or opening leakage points.
Good option for internal hull structures with resolution/precision better then 100µ. PET a good compromise.
Prices average 27$/kg.
Not recommended 3D printers below 300/400$. most of the times vibrations are the major drawback. Good quality printers, with almost no maintenance, starting from 3000/4500$. This is what they use 24h/24h.
I think, with these additional information coming from a professional company, my initial doubts are confirmed, nothing better then a good carbon fiber/epoxy lamination in spite of sanding and preparation time required, they says !
All I can suggest in response, Claudio, is that, although professionals, they have not spent the many, many hours and hundreds of tests that Selwyn has done specifically toward the goal of printing hulls. The people you talked with have never printed a hull.
Very capable printers are available in the $700-1000 range that can print an RG65 in 2 sections, and an IOM in three.
We have float tested printed hulls with no epoxy coating for 20 straight hours without a drop of water leaking in.
Though not needed for water proofing, a thinned epoxy coat makes cutting, drilling, and handling easier without contributing much to the weight. It also improves impact resistance.
The technology may not be right for you, but it is for others. I just finished building a Footy: printed hull with epoxy coat 44g, printed fin and rudder 26g, 3 AAA battery pack 32g, servo/receiver assembly 30g, lead bulb 340g. With rig, that’s a 500g Footy with a 68% ballast ratio. I think anyone who has built a Footy would be impressed with that result…it certainly compares favorably to the one you built.
We hope that using 3D technology will be attractive to younger modelers than you and I, and be a contributing factor to our sport remaining viable for the future. IRSA has enough confidence in technology to establish a new provisional class called the Nano, a 500mm monohull which must be 3D printed. More info about that will be available very soon.
Our new IOM is printing now, and should be sailing in a few weeks. After that, we are working on a bigger surprise…stay tuned.
Bill,
they never made a hull since not part of their business, but they have made a lot samples with various materials that I have seen and touched. They acquired a lot of experience in almost 5 years work. They have seen also my AC100 hulls of 2007 and got the idea about thickness and strength. The weight is 118g (1x 80g/m² + 1 x 162g/m² - skin thickness 0.45mm). Certainly could have been made much lighter with 2 layers of carbon/kevlar of 73gM² and reaching 77g hull weight for 26.5dm² of surface.
The Esterel Footy could be used to play rugby with 2 x 105g/m² - probably also there 2x 80g/m² would been better !
This is why they told me at 3D Synergy that similar hull strength and weight could not be achieved with 3D printing.
Just close to my house there is a “FabLab” Association that is going to open in May. Various activities will take place, one is dedicated to 3D design software learning and 3D printing. I will enroll as Member. http://open.artilect.fr/
What is important is the consistency of the object for the purpose is made for.
I appreciate, nevertheless, what your friend Selwyn is making and I whish him to proceed in his effort.
Claudio
Claudio, I have never, ever claimed that PLA is a better material or stronger per gram than carbon fiber. That is not the point at all.
I have said that strong PLA hulls can be printed at comparable weights to other construction methods in the Footy, Rg65, and IOM classes. We just started experimenting with larger hulls, and initial results are promising, but the jury is still out.
This is a Footy hull with a brushed coat of thinned epoxy weighing 40 grams. It is supporting 4085 grams (nine pounds) of lead…100 times its own weight. I guess it could support more, since it doesn’t show signs of stress, but that’s all the lead I had handy that would stack on the hull. The hull is 1/3mm thick, and the end pieces (which would make it even more rigid) are not yet in place.
The point is, that with a thickness and weight comparable to other construction methods, this hull is plenty strong for its intended purpose.
Which is not rugby, but maybe if Selwyn printed one as heavy as your hull you could play rugby with his, too.