Active Metal Sailboat Designers with Cutting Files

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

  1. Tony the Diesel Mechanic
    Joined: May 2020
    Posts: 7
    Likes: 0, Points: 1
    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

    This forum has been a great pool of information and I have been lurking for years. I'm looking for a 40-44' aluminum round hulled or radius chined pilothouse sailboat design suitable for a couple for year round sailing in the PNW and beyond. My search for a designer has resulted in a few names but even fewer with cutting files. I've found the following:
    Ted Brewer - no cutting files
    John Simpson - Hard chined 40 PH Steel w/cutting files
    Bruce Roberts - not my style
    Dudley Dix - 38 and 43 PH w/cutting files. Worth a look - would be interested in owner reviews
    Van De Stadt - No real pilothouse in the stock plans section
    Dick Zaal - Northern 43 looks nice but not really a layout that works for me.
    The focus is on a roomy boat built for a crew of two and occasional guests. If one of the members here has any other suggestions I would be very grateful to hear them.

    Thanks in advance.
     
  2. Rumars
    Joined: Mar 2013
    Posts: 604
    Likes: 216, Points: 43, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

    A lot of designers don't advertize cutting files on websites even if they have them. Only asking directly will reveal them. Even if they are not available they can be created for any design.
     
  3. Tony the Diesel Mechanic
    Joined: May 2020
    Posts: 7
    Likes: 0, Points: 1
    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

    Thanks for the response. I have spoken to a few of the designers that I have listed. The expense of creating a new cutting file is prohibitive (for my budget). Existing files are much cheaper just hard to find for the boat type that I'm looking for.

    Cheers
     
  4. Phil_B
    Joined: Mar 2019
    Posts: 22
    Likes: 14, Points: 3
    Location: New Zealand

    Phil_B Junior Member

    Kasten Marine are likely to be the guys you are looking for - he does cutting files but does charge a premium over plans which, considering the amount of work involved, is justified:

    Kasten Marine Design - Modern Classic Yacht Design http://kastenmarine.com

    Our CAD Design Process - Kasten Marine Design http://kastenmarine.com/design_stream.htm

    However, the cost of the plans and/or the cutting files are a very small percentage of the overall cost of the vessel. The cost of the CAD files is recouped by the labour saving in cutting the metal and the setup and fairing stages which goes much quicker as you are assembling a kit of parts rather than having to cut, fair and adjust the components. Plus you will get a vessel in a shorter time and more likely to be within the designers weight calculations without the weight creep that occurs with amateur built boats. Bruce Roberts explains this on his website and in several of his books.

    If you are concerned about the costs at this stage, then you need to very carefully review the overall budget. If saving a thousand dollars or so will make or break the project on a 40 foot or larger yacht, then !!!!
     
    bajansailor likes this.
  5. Barry
    Joined: Mar 2002
    Posts: 1,269
    Likes: 129, Points: 63, Legacy Rep: 158

    Barry Senior Member

  6. bajansailor
    Joined: Oct 2007
    Posts: 946
    Likes: 244, Points: 43, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

  7. Tony the Diesel Mechanic
    Joined: May 2020
    Posts: 7
    Likes: 0, Points: 1
    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

    Thanks Phil,
    The last time I checked the cost of custom cutting files they were in the neighborhood of $25k and up for a boat in this size range. The stock - already built - files were cheaper but there seem to be very few to be found. Here's an example: Our Plans List - Kasten Marine Design http://www.kastenmarine.com/plans_list.htm I suspect that not many people want to be the first customer to pay the whole shot of the file development. My budget is ample to build the boat but it would be foolish (for me) to spend 10 - 15% of the boat budget on a file. The savings realized in the hull and deck build process would not cover $25k no matter how I look at it. I make mistakes but not that many. The Dix 43 pre-cut ready-to-assemble kit in steel costs less than one first-time Kasten cutting file.
    The Dix 43PH cutting file was just quoted to me at 4000 euros. That could work.
    The search will go on but as it stands Dix has the advantage.
    Thanks for your feedback, it's all good.
     
  8. Tony the Diesel Mechanic
    Joined: May 2020
    Posts: 7
    Likes: 0, Points: 1
    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

    That's Brian Russel I believe. The phone number listed on the website is out of service but I'm told by someone in-the-know that Brian is out cruising. They say he still monitors the email account so I should hear from him eventually.

    Thanks
     
  9. Tony the Diesel Mechanic
    Joined: May 2020
    Posts: 7
    Likes: 0, Points: 1
    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

  10. gonzo
    Joined: Aug 2002
    Posts: 14,275
    Likes: 584, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    $25K sounds like a lot to convert files to DXF. Most CADD can be saved as DXF. The only problem would be if the design is not based on developable surfaces.
     
  11. Tony the Diesel Mechanic
    Joined: May 2020
    Posts: 7
    Likes: 0, Points: 1
    Location: Vancouver

    Tony the Diesel Mechanic Junior Member

    I'll admit to a bit of ignorance here. I don't know the process but when I talked to two designers just days ago, I was told that many designs were done by hand such as older Dix and Brewer designs. The Kasten website I linked to shows his prices.
    Thanks.
     
  12. Rumars
    Joined: Mar 2013
    Posts: 604
    Likes: 216, Points: 43, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

  13. Phil_B
    Joined: Mar 2019
    Posts: 22
    Likes: 14, Points: 3
    Location: New Zealand

    Phil_B Junior Member

    OK, let me justify the costs of producing a cutting file for metals (or even plywood). First off, as a full disclosure, I worked for a company in the UK that was a water jet cutting company as a CAD technician/production manager, general dogsbody and chief cook and bottle washer ... you get the idea. My job was to turn customers drawings (either paper copies or DXF's) into a cutting file.

    First off, the computer file had to be adjusted for the width of the cut itself and the toolpath had to be offset by half the expected "kerf" of the cut otherwise the part would be undersized by that amount. Not significant on a 44 foot yacht but still needed to be borne in mind.

    Secondly, you cannot start the cut on the line - ALL cutting devices need to be offset from the line on the scrap side of the part as the initial hole that the cutter punches into the plate or material inevitably wanders and forms a ragged hole. Think of an artillery shell crater effect. This needs to be somewhere in the region of 1/2 to 1 inch away, depending on the thickness of the plate - the thicker the bigger the size of the dispersal of the cutting medium. Next you need to command the program to move to the line and then follow the line to cut out your part, bearing in mind that you need to know your machine and cut in one direction (clockwise/anticlockwise) to avoid problems with backlash.

    But wait! If holes (lightening holes, access hatches, port lights etc.) need to be cut too then you need to cut those out before the main outline of the part because the part might move and the holes would then be cut in the wrong place. Work from the inside out.

    No doubt the client will want the most efficient use of the plate being cut so you need to nest the parts manually (SOME, but not all CAD programs have a nesting function) and then work out the cutting sequence - holes first, then the smaller parts cut into the "scrap" from the bigger parts then the bigger parts etc. and all need to be toolpathed properly. To cut down on machine time and costs, the CAD technician will look for ways to share cuts. Imagine you are cutting sheet material to make a picket fence around your house. The top of the panel might be a simple point or a Fleur De Lys which needs to be cut but the planks themselves will be parallel and straight. The CAD technician will have them "touching" and adjust the DXF drawing file to make them wider by the width of the kerf. The price you will pay will be based on the length of the cut and the dwell time (that is, the time it takes to cut the part). So in that simple example, the CAD technicians time and cost is more than saved by not making two cuts to each plank as the cut separating one plank from another will be the cut of the next plank - if you follow my meaning (except the first and last in line). OK, it is unlikely that many parts for a yacht could share cuts (you might want to cut a dozen or so access plates to tanks which could use this idea) but it is a factor that needs to be understood and taken advantage of if possible.

    But wait! There is more! Aluminium has a "grain" caused by rolling at the mill and parts must be orientated to take advantage of the different strength properties. The CAD technician must take this into account when laying out the parts and this may mean that not all the plate is used as efficiently as a steel plate would. In other words, the cutting files for steel and aluminium will be different.

    Since the yacht will be constructed of different thickness materials then the parts need to be sorted according to their thickness. The paper plans will simply state "All frames to be from 1/4 inch plate, keel sides from 1/2 inch, keel base from 3/4 inch" etc. The builder then toddles off and cuts the parts as necessary but our CAD technician must make sure that the separate cutting files specify the parts for that thickness and account for this.

    Now, Tony is looking at a 40 to 44 foot yacht which will have a beam of somewhere in the region of 12 to 12.5 foot so the frames cannot be cut out of a single 8 foot x 4 foot plate but most likely be cut out, as a minimum, in two parts and welded at the keel junction, perhaps in three of four or more parts and that means that the designers CAD drawing of these parts needs to be "cut up" in the CAD program to form these parts, then they are nested, taking account of the grain of the aluminium and the cutting file created, of course.

    Since the finished kit will have a LOT of parts, then it would be handy to mark them. Not a problem, any CNC cutting machine can engrave the part with an identifier such a F4U (Frame 4 upper) and while we are at it, we may as well engrave the waterline, centreline and any other marks that will help the builder set up the frames etc. and ensure that the parts are correctly aligned. This is a separate file from the cutting file (you will not want the text to be cut through the plate) and again, this must be manually done - the paper plans will have all the waterlines drawn as one line superimpsed on all the sections and it would be up to our builder to mark these when lofting from the plans and transfer them to the frame, stem etc.

    Next the work must be checked. Recall that there WILL be various sizes of material (thickness) and you do not want to cut a part from thinner material than required. It COULD be that the designer specifies 3/8 inch plate for the 6 or 7 frames above the fin keel and 1/4 inch plate for all the other frames. Using the wrong sized plate here and/or incorrectly orientated on the aluminium plate could be potentially disastrous so the checking is essential.

    I wish it WAS as easy as simply typing "Toolpath" into the CAD program and it will all be done by magic but unfortunately it involves a lot of manual input, skill and judgement to successfully translate a CAD design into a set of cutting files to produce the kit of parts. You can either pay up front for a CAD technician to do the work and produce superbly accurate cut out parts that will snap together like a plastic model kit. This will save yourself from needing to loft the vessel, spend a lot of time on a dirty, boring and repetitive task cutting the parts yourself, sorting out the material and spending a good while marking up the parts from the lofting board. As usual, you can swap time for money or money for time - if you have lots of time and not much cash, then do the work yourself but if you want a hull that is accurate, to the designers weight calculation and quick to assemble, then pay the cash and specify a set of cutting files.

    So don't begrudge the cost of the designer doing this extra work - it is not straightforward and is something of a black art and an acquired skill to do well.

    And you wonder why I went prematurely bald! >};o)

    While you are looking a the Kasten Marine website, go to this page:

    Articles on Yacht Design and Boat Building http://kastenmarine.com/articles.htm

    At the bottom he has two downloads - Marine Metals Reference and Corrosion, Zincs and Bonding. Both worth studying.
     
    Ad Hoc and bajansailor like this.
  14. Phil_B
    Joined: Mar 2019
    Posts: 22
    Likes: 14, Points: 3
    Location: New Zealand

    Phil_B Junior Member

    One approach Tony could take would be to get a set of estimating plans for his chosen design, search out a few builders and ask for a quote from plans and then ask for a separate quote if CNC cutting files are supplied or he arranges for the parts to be cut himself. There will be difference in cost - the builder does not have to loft and fair the vessel and manually cut the parts which is time consuming and at the builders hourly rates, will not be an inconsiderable amount. Alternatively if the builder is assembling a kit of parts then the time saved will result in a lower final cost, offset against the costs of the CNC files and cutting.

    Then a decision about which method is cheaper and quicker can be made secure in the knowledge that money is being spent as economically as possible.

    Unless of course, you want to build from scratch yourself in which case balancing the time to build against the time you could be sailing is another factor to input against the advantages and disadvantages.

    Bruce Roberts states that building from a kit results in a lighter hull whereas when builders build from plans, the weight inevitably creeps up, alarmingly so in some cases. But that is another can of worms regarding carrying capacity, speed and weatherlyness of two sister ships but with different as constructed weights.

    Hey ho! Nothing is simple, eh? >};o)
     

  15. gonzo
    Joined: Aug 2002
    Posts: 14,275
    Likes: 584, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    A 44 foot boat will not have complicated frames like a ship with lightening holes, etc. He is considering a chine hull. Radius chine is possible in aluminum but probably not realistic for an amateur. The frames are going to be straight with notches for stringers. The only complicated cuts are the hull and deck plating. $25K is way to high for the job.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.