Kurt Hughes updated Trikala 19 trimaran

I'm not against the concept of building hand cut forms but would wonder why you would go down that path for a production boat I'm sure Kurt could supply dxf files so you could have your plywood mold forms cut with CNC or even a complete plug he models everything in CAD so it shouldn't be a problem. It would save a lot of time and give you a more accurate result. I know it's possible to fair everything out but why make extra work for yourself?

 

Which bow does it have? I didn't see anything on the site to tell me, so I am just gonna ask.

wayne

ps - it looks like an anchor whatever it was ...

 

These are just forms for the plug build, the finished boat will have 2 layers of 20oz triaxial glass with 1/2" foam sandwiched core

 

Cost and availability mostly. I have a buddy with a CNC router, but he hasn't learned how to use it yet.

 

I e-mailed Kurt - "Noting that CNC files can be supplied for custom designs, are CNC ,dfx files available for stock designs to support - for example - cutting forms?"

His reply was "can be many formats. native is microstation. can be both flavors of autocad, iges, rhino and a few others".

Frankly I didn't understand the answer fully but such files are available. Since you have already purchased the design package I wouldn't think there would be much of a charge since it is the same information that you already have, merely on a different medium.

 

It's the cost and setup fees of getting it cut that's prohibitive. I will do just fine the old fashioned way. the forms are just for creating the plug, the plug then get's perfected and a mold splashed.

If the forms were for production use, then yess very definitely worth while.

I may get my buddy to CNC cut the foam blanks for the bulkheads for production in the future so they are all the same.

 

Sorry, it's been a while since I checked in. the ply is 3/4" so I can use screws to temporarily secure the strips until the glue dries.

 

We've jumped way ahead, check out the build blog at www.3Hulls.com for more details.
http://3hulls.com/index.php/forum/multi-hull-build-blog-progress/8-chs-x19-trimaran-build-blog.html

 

There are a lot of different CAD formats. Probably that is just a mater of selecting a file format to save it in.

Personally I am getting into CNC, largely to do stuff other than make boats. I did however take a file and reformat it into a cad my machine can use. Then I started organizing it for CNC. This takes a long time. It was designed so that the ply panels could be made up full length, then the parts could be laid out on those panels. So a lot of lay-out, etc... has already been done by the designer. Unfortunately, CNC can only go one sheet at a time, so I have to break up the design, build the joints into it, and format the parts to fit as best they can on single sheets. This took hours just for one panel, and there are dozens in the design and there is a lot more waste of materials. That would only be the begining, then I have to generated all the tool paths, and g code instructions for cutting that. Then I have to figure out how to fixture this stuff. I have to add break outs to all the parts.

It is way faster to do it by hand, just laying out the panels with a batten. Owning a CNC, it would be a little irresistible not to have the machine cut it, even though it takes longer and costs a lot more. Obviously in a factory setting where one is making multiples, this would be recoverable, but not in a one-off. Here in Canada, one of the nice things is that the whole kit for a boat could be cut out during the winter, and stacked in compact pieces in a small space. Then blitz the assembly part when the weather improves.

I have made the whole set of forms for a 40 foot ama in a few hours. I just took the pattern and put it on the wood, and transferred the lines with Pizza wheel and carbon paper. That method is very accurate. Then I bandsawed, or jigsawed the parts out, and faired them with disc sander. This all just rips along. The accuracy is fair lines within a pencil width.

 

Quote:-
I have made the whole set of forms for a 40 foot ama in a few hours. I just took the pattern and put it on the wood, and transferred the lines with Pizza wheel and carbon paper. That method is very accurate. Then I bandsawed, or jigsawed the parts out, and faired them with disc sander. This all just rips along. The accuracy is fair lines within a pencil width. Quote.

We were sent round bilge lines by Lock Crowther to convert chined to round bilge on the B33. We photographed the A4 sheets and produced film slides. We placed white paper on the wall and projected the lines on to it, expanded to actual size. Then we marked the paper with texter pen and cut out the full size patterns to make the hull frames . We did the same for the airfoil sections of the glass/foam wing mast on the Typhoon catamaran.
Quick and easy.

 

Hey you can make a CNC for what one of those projectors costs. Just kidding. Great old technique they used to use for aircraft lofting. There is a fun book on aircraft lofting by Sam Rabl that describes that method. Interestingly you can still buy the projectors that do that from hard copy:

http://www.leevalley.com/en/gifts/page.aspx?p=44193&cat=4,104,53208,44193

Of course, one can print off full sized copies even with a home printer.


One method I really like is the Master Mold method that Newick used for so many of his boats. Unfortunately it probably doesn't suit modern hull shapes all that much. It was a great method, and could be used to automatically print all your lines, or you could even skip the patterns and use it directly to rout the forms. Still relevant for CC hulls or double enders, maybe some proas. Also, you can reverse engineer all the newick study plans, pretty much.

 

If you have Adobe Acrobat Pro you can save a drawing as a .pdf file - most print shops can print it full size.

 

"Hey you can make a CNC for what one of those projectors costs."

Nah! We just used a standard slide projector. In fact I still have it.

 

Might be good enough for your needs, but photographing a section down to a slide and then projecting up to a full size flat sheet will inevitably introduce distortion, with progressively more, the farther from the center the lines are. You may still end up with a reasonably fair shape but it will not be exactly the one the designer drew up. But heck ... it might even be better