Active Metal Sailboat Designers with Cutting Files

Discussion in 'Boat Design' started by Tony the Diesel Mechanic, May 5, 2020.

  1. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    With all my respects but it seems, I repeat that it seems, that you do not know what you are talking about. There are very complicated areas, which are not the hull or the decks, which are not easy to define. The only difficulty of the shell is when you have to develop the plates or prepare the templates to bend them. Apart from that, there are countless little details, especially in the small pieces, or in the stiffeners, that not everyone is prepared to define correctly. On the other hand, I agree, $ 25,000 for that job seems like a little high. But as always, stating that it is high, without knowing the boat, is unacceptable and can damage the reputation of honest professionals who do not have to try to take advantage of anything or anyone.
     
  2. Phil_B
    Joined: Mar 2019
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    Location: New Zealand

    Phil_B Junior Member

    Not my reading of the initial post when he specifically states "a round hull or radius chine". On looking at the Kasten Marine website, Tony MAY have seen a design that caught his eye and is now considering.

    However, if he selects a chine hull that has developable plating, then the frames will not be made out of straight bar or L section material. The plates will develop curves as they are bent around the framing leaving half moon shaped gaps between the plating and frame. So unless the flat material is formed to the correct curve to account for this, then you will need to bodge the gap somehow or put up with unfair plating.

    Is $25,000 too high a price to produce the cutting files for a yacht of that size? I have never had to do that for a yacht but assuming that the CAD technicians time is charged out at a nominal $100 per hour, that is about a months work or a little more (call it 6 weeks) which would not be an unreasonable amount.

    Yacht designers and their staff have to eat and pay taxes, just like the rest of us and the overheads of running a design office/company are something that needs to be borne in mind too. So I am reluctant to say that the designer is ripping his customers off until I know more about the time spent on the process and the hourly rate of all the staff charged to the project.
     
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Are you saying developable surfaces can't be designed with straight frames? Further, the CAD files are already made for the frames, keel and bowstem. They would only really have to add the plating. If the frames, etc. are not in a CAD file already, there are no plans to sell.
     
  4. Phil_B
    Joined: Mar 2019
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    Location: New Zealand

    Phil_B Junior Member

    I bow to your superior knowledge and experience.
     
  5. TANSL
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    TANSL Senior Member

  6. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Take a normal power boat with the bottom of the hull curving up and the side curving into the bow. But a design that has developable surfaces.

    When the chine, gunnel and keel are parallel, the frames can be straight line with the frames being perpendicular to the keel and obviously vertical

    But when the sides and bottom begin the curve to the bow, the developable surface creates a curve perpendicular to the keel and flat frames will not work. AND KEEP THE AT 90 DEGREES AND VERTICAL

    A simple proof of this is to take a regular 8 1/2 by 11 inch piece of paper, lined is best.

    Call the left hand edge, the 11 inch edge the keel and the lines then are perpendicular to the keel, lift up the right hand side lower corner 3 inches. Then just follow a line, you will see that obviously the paper forms a curve along the line.

    And straight vertical frame will not fit the curve
     
  7. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    What he said!!

    Also, not forgetting... the structure drawing that has been done, requires every single mouse hole - for plate seams - and cutouts for longitudinals etc to be in the correct location too.
    So you lift off the shape from the dwg...er... well...no...it also need to be a continuous polyline, otherwise the router will stop and not know the lines are connected. So each frame needs to be "remodelled" to be a single continuous line, this is not a 5min job. In addition, what about bkts?...well, it takes a few seconds to get an off cut of plate and cut in the guillotine. But if you want the whole plans for CNC and not cutting.. then every single bkt in all the locations need to be drawn so you must draw the whole structure of the whole boat finished often in 3D so there is no manual cutting later.....and again, all these bkts too need to be made into polylines and then - as noted - nested in the correct thickness of plate to maximise the usage and minimise the wastage. Also not a 5min job!

    And... that is still only half of the job...

    What used to be done several decades ago by many people, from mould loftsman to carpenters making the wooden templates to cutters and platers etc... is now done on the PC. The process is still the same, it is now just digital. But still takes time and skill to do and do correctly. Pressing a single button it is not!
     
  8. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    For developable surface to have sections perpendicular to the centerline to be exactly straight the deadrise/flare needs to be constant. Otherwise for the frames will need to be curved to exactly conform to the plating. (An individual frame may be straight without constant deadrise/flare but not adjacent frames). Whether the deviation from straight justifies building curved frames depends on the shape and surface quality requirements. I visited a tug boat builder a few years ago and noticed the frames were all straight, made from L or T sections. The firm's designer said the advantages of straight frames were worth the disadvantages of non-developable surfaces for their application. The plating was obviously sufficiently fair for their customers but would not be considered acceptable for most yachts.
     
  9. gonzo
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    gonzo Senior Member

    It'a a 40 foot boat. That is about 20 frames at most, with maybe two stringers on each flat section.
     
  10. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Why do you simplify things that are not simple? Saying that everything is very easy does not increase your wisdom. Deciding the separation of frames requires some preliminary calculations and to take into account certain considerations, unless you do not care about the weight saving nor the construction facilities.
     
  11. M&M Ovenden
    Joined: Jan 2006
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    M&M Ovenden Senior Member

    Hi Tony,
    The real advantage of having the boat done in CAD is that it allows direct cut to build without lofting on a floor. If you have the model it also helps during the construction as you can take all sorts of diagonal measurements to make sure things are aligned. We had our boat NC cut and it was amazing. We are lucky that my wife designed and built the boat so all the details were at our finger tips.
    Some info her on her website: Concept and Design http://mimijane.ca/concept-and-design Building the frame http://mimijane.ca/the-frame-structure
    Cheers,
    Mark
     

  12. Tony the Diesel Mechanic
    Joined: May 2020
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    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

    Thanks Mark (and everyone else),
    I understand the basics of CAD and can see the advantages of CAD design over lofting from drawings. I have spent quite a bit of time lately learning about the lofting process. It must be a very rewarding experience but I would rather spend the extra time sailing (not to mention all the advantages mentioned by Phil and others about CAD design).
    I started this thread with the hope of finding more designers out there that offered cutting files (or there affiliates like Dix and Alumar). So far it has further demonstrated that affordable files are relatively rare and files for a pilothouse suitable for the PNW are even more so. This could be a great business idea for someone, especially if potential customers in Vancouver or Seattle could actually tour a new build of a contemporary design. As it stands, I will likely fly to some distant port to tour a Dix, Ovni, or others before deciding whether to build, rebuild or abandon ship.
    Typo? - We are lucky that my wife designed and built the boat. Treat her well, she is in high demand!

    Tony
     
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