50' performance cruising sailcat

Discussion in 'Projects & Proposals' started by vanquishcc, Aug 13, 2019.

  1. vanquishcc
    Joined: Aug 2019
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    Location: Maryland

    vanquishcc New Member

    Greetings,

    I am in the process of designing a 50 foot performance cruising sail cat. I have been looking at many designs and cannot find the perfect one. This boat will be for me and my family to eventually cruise the world and I have some requirements. The designs I have been looking at are from Schionning, Grainger, Dix, etc. The cost of said designs is quite great. Especially when I want to make some changes to the design. The cost goes way up. Plus I am locked into using Duflex pre-cut kits from their suppliers. With exception for The Dix, in ply, which is the best bang for the buck. With changes even the Dix cost goes way up or he will not work it. Now I am not nocking any of that. Those designs are great. Many have been built and are successful designs. However, I am not a pro boat yard. This will be a side project with help from some of my employees when the time allows. I need to keep costs reasonable and I fully expect this project to take years to complete. One of those Duflex kits with plans puts me well over 100k just for materials. At the moment I am not willing to do that. Also, I do have large CNC routers and I have always wanted to design and build my OWN boat. I do have experience building yachts up to 57’, so I am not concerned about ability. I use Rhino3D for everything I design and build in my business as well. I can handle that part of it.

    My main problems I need help with are hull shape, scantlings, and some structural items. I would be interested in receiving some help on the hull shapes, then I can design the bridge deck, coach roof, and interior appointments. Then revisit with a designer to go over the final scantlings, structure, etc.. It would be a collaborative effort. None of the big designers I have spoken with so far were willing to meet my demands. If they could the cost would be extreme. I understand their reasons, but this is my project and I want to be able to get in there and design everything in CAD prior to starting the build. I am looking for a designer/naval architect that is willing to work with me on this. Here are some of the requirements I am looking for.

    CAD: I need CAD files so I can do the next step in the design

    This boat will likely be foam core sandwich construction. Much like a Duflex or KSS system. Flat panels for much of it. Round bilges though. I can build a mold for that and infuse some glass. I am willing to use Carbon where I need to for rigidity, but only where needed.

    Rotating carbon mast most likely. I would like to build the mast as well.

    Composite one piece longeron/forebeam

    Hydraulic swim platform(I can infuse some carbon to keep it light)

    Dual exterior helms, raised much like many cats have these days. I want to be able to see over the coach roof. I love the Alibi 54 helms. Clean and simple. I will also have an interior helm up forward. I may nix the wheel for just a nav station with autopilot control, but either way there will be room up forward for one or the other.

    The coach roof will have bench seating across the aft rim. I will probably use the helm seats as steps to access it. Maybe a sunpad as well. The coach roof will have solar panels also.

    The forward cabins shall have berths athwartship on both the port and starboard side and will extend slightly over the bridgedeck. If I can move the aft cabins forward slightly I would like the bed to be split down the middle much like in the MC50. With a filler when a larger bed is needed. This would put the engine room access on deck, but I am ok with that.

    The starboard hull will have a large head with separate shower up forward and smaller head in the aft portion or amidships. The port hull will have bunk beds up forward with a head amidships.

    I prefer strait shafts if we can manage it for the engines. I have considered electrics, but I think the cost is too great and the performance to be lacking a bit. We can revisit that when the time comes though. I may change my mind.

    Fairly large windows in the hulls for the berths.

    Daggerboards are a must. I like the hydraulic centerboards on the MC50, but not as easy to sort out a problem if one should arise. Especially in remote areas.

    50’ to 55’ LOA
    26’ to 27’ BOA

    I have other design requirements, but those are the main big ones. Please let me know if anybody is interested in helping out. This could be a paying job for the right person.
     
  2. Alik
    Joined: Jul 2003
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    Alik Senior Member

    I would not use any Duflex too. The cost of the kit is 5 times from alu kit, for boat of the same size/type.
    The main reason why some designers use Duflex is simple: those designers are not able to design the structures themselves, so they get kit suppliers to do that ;)
    There are other better ways to build boats, without secondary bonding which is always a risk.

    Regarding 50-55' custom design and engineering for sailing cat, it can't be cheap. Only stability calculations book for sailing cat is 100+ pages, takes 2 weeks for experienced naval architect to produce, to ISO12217-2 standard. From now, structural engineering involves FEA for global strength analysis and some details (this is a catamaran!). I don't think such design can be done by one person, as it involves too many skills in different areas of engineering. Here is the list of documentation for our 44' stock design, and this does not include detailed interior styling, and minimum number of calculations only... can imagine the design fees!

    Alos there will be difference in design fees between 'yacht designer' without formal degree, and a naval architect. I think this is understandable why.
     

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  3. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    Your requirements are mostly met with a C50 or C60 harryproa, down to the athwartships bunks and steering with all round vision, but without having to climb on the roof
    .
    By far the lowest cost materials is infused foam and glass, if you can accept predominantly flat panels. The C60 materials, including beams, booms, rudders, hulls and tender are about $30,000.

    Unless your employees are boat builders they will not be much help with a conventional design. However, with Intelligent Infusion, they will be able to do almost all of it, including the rotating carbon masts. The C60 will take about half the time to build as a conventional boat, and you will not get sticky or dusty. It will be lighter and lower cost, so will performa as well or better.

    Cat hull shapes are all similar. And the differences don't seem to matter much as most of them are compromised to make tacking easy. The C60 shunts, so the hulls can be optimised for performance. However, bigger than the gains from hull shape is the weight, work and windage saving from flat floors.

    Dagger boards and props fixed under the boat are prone to being ripped off by logs, whales, containers or the bottom and limit your shallow water and drying out possibilities. Harryproa rudders are oversize so boards aren't needed. They are liftable, kick up in a collision and have no holes below the waterline.

    Harrys use the tender (8m/27' long on the C60) as an outboard sled. No expensive, smelly, noisy engines taking up space in the hulls, the prop can be lifted and cleared in an emergency and hitting something is a non event.

    Stock plans are silly. Everyone wants something different. We can usually supply it, although the hull layout is so simple most don't need extra plans to get their preferred layout. Several of our clients design their own boats with help from us.

    Any questions, let me know. Either here or on harryproa@gmail.com
    C60 CRUISER 60 – HARRYPROA http://harryproa.com/?p=1747
    C50 CRUISER 50 – HARRYPROA http://harryproa.com/?p=1749
    Intelligent Infusion Intelligent Infusion – HARRYPROA http://harryproa.com/?p=1845
    Shunting SHUNTING – HARRYPROA http://harryproa.com/?p=1910

    rob

     
  4. Alik
    Joined: Jul 2003
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    Alik Senior Member

    No-no. Any boat should have re-sale value. Who would buy a second-hand proa?? :)
    Sorry to say that, but true...
     
  5. rob denney
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    rob denney Senior Member

    Either the same people who would buy a home built one off cat designed by someone with no experience and some unusual requirements, or someone who wanted a fast, safe, easily sailed and maintained cruiser and did not mind if it looked different.

    The difference is, that the proa will cost about half as much to build and be a vastly better boat for the purpose. Consequently, you will be less inclined to sell it. If you sell a cat which cost 500k to build for 300k, you only need to get 50 for the 250k proa to be even.

    Plus you have had 250 earning interest while you have been sailing. 5 years at 5% compounding is 70 grand in your pocket, so giving the proa away, you are still better off than with the cat, plus you have had a much more enjoyable boat building and owning experience, partly because you have had 4 years sailing the proa and only 2-3 sailing the cat.

    The proa will have required much less maintenance in that time as it has no rigging, no extras, less deck gear, one motor instead of 3 and nothing solid in the water to hit stuff and need repairing. It will also be faster, easier to sail and more weatherly, so you would have done more miles and visited more places.

    Ballotta catamarans https://www.cata-ballotta.com/contacto is a professional builder of harryproas. They are averaging an enquiry per week. I'm not sure how this relates to second hand harryproa demand, but it is pretty positive for new ones. I only know of 2 harryproas that have been for sale (owners died) in the last 5 years. Both were sold within a couple of weeks of going on the market.
     
  6. Alik
    Joined: Jul 2003
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    Alik Senior Member

    That's a good question: is any of Your proas certified, say, CE-certification? This means are they designed to ISO Small Craft standards?
    Average catamaran would be, thus it might be heavier and will have more equipment. On a very light multihull boat, it is impossible to comply to ISO category A requirements (used to be 'offshore').
     
  7. Deering
    Joined: Feb 2005
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    Deering Senior Member

    Having recently completed a somewhat smaller project similar to yours (mine is an aluminum powercat) I would pass on a few thoughts from my experiences:

    1. It will take three times as long and cost twice as much as you anticipate. Or you can reverse those figures - twice as long and three times...

    2. Be clear about your top priority here. Is it to cruise the world or build a boat? Either one is fine, but just be honest with yourself.

    3. Don’t let the perfect be the enemy of the good. Whatever you build won’t be perfect, not by a long shot. Resign yourself to that. As you go through the process you’ll see the mistakes you made and how you could avoid them the next time. I used to joke to my wife that after learning so much building this one, my next boat will be a lot easier. Her response was, “tell it to your next wife.” I’m not sure that she was joking.

    My project turned out successfully and has largely met my original design objectives. But I’m not sure I’d do it again. I spent 4 years of my life on the project. That was 4 years that I could have been on the water if I had just bought a boat that met 80% of my ‘perfect boat’ standards. But hey, it’s done now, and it’s faster, more fuel efficient, and more functional than any boat I could have bought (within my budget). It also gets lots of positive comments from knowledgeable people in the harbor, which feels good. And I learned a ton doing it - with a shoutout to many generous folks on this site that helped advise me. But I’m not sure if it was the right decision...
     
  8. rob denney
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    rob denney Senior Member

    The comparisons above relate to non CE boats, the type that have been built in Australia and New Zealand for 60 years, without the need for lowest common denominator scantling rules. No harryproa owner so far has seen the sense in so doing, preferring to rely on first principals engineering tempered by 40 years of designer experience. Consequently none have been designed, including the half dozen built in Europe.
     
  9. Alik
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    Alik Senior Member

    So as I understand, those proas are 'substandard' in terms of modern regulations/design practices, and there is not much engineering behind (stability, structure, etc.). This is exactly the difference between professional design/built and amateur design/built. If the boat can't be certified and complies only to 'designer's experience' then nobody can be sure about safety and the re-sale value is almost zero. The same would be for any amateur designed and built catamaran though. What I am trying to say is: once topic starter asked for assistance, better to involve professional naval architect/boat designer (TANSL offered his help) who can approach the design from engineering side, rather than involve another amateur designer who might not be useful designing something beyond his experience.
     
  10. rob denney
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    rob denney Senior Member

    You understand wrong about 'these proas'. The structural calcs are by a highly qualified and experienced composite engineer. Using first principals, not "rules" based on old technology.
    Stability calculations on a medium size multihull are a classic example of rules for the sake of making rules.
    Certifying a boat to "rules" when the rules are not relevant is buck passing. Designing a boat to rules that are biased towards heavy boats results in heavy boats, which is expensive, takes longer to build and are poor performers. I/my engineer take full responsibility for the structure of the boats I design.
    I was not offering to to help the topic starter get a heavy, poorly performing boat that passes a lowest common denominator rule. I was suggesting a boat that matches his requirements rather than all the ones he mentioned which didn't.
     
  11. Alik
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    Alik Senior Member

    I think You have poor understanding of the rules. And once You don't understand them, You prefer to ignore them. Well, this approach will 'work' unless You have some serious accident with one of Your boats in commercial service.
    The old technology rules were 'one inch of pine per every 5 foot of length - no serious designer is using this anymore.

    Modern structural rules for composite boats define a) design loads, which are based on full scale measurements on boats and models and b) safety factors. They are de-facto first principles rules. I am involved in making some of these rules especially for multihull composite craft, and we and colleagues do a lot of testing assessing real life loads before we write something. You can open any rules available, say LR SSC, ISO12215-5 and look how the loads and safety factors are defined. Modern composite design rules use either laminate stack analysis procedure, or CLT, or FEA. Is this what You mean 'old technology'?

    Stability of small craft and multihulls in ISO standards is based on statistics and testing performed on models, say, capsizing on breaking waves, also in wind tunnels. Those research allowed to define capsizing conditions and stability criteria to follow.

    But of course, amateur boat designers without engineering degree think they know more than all those researchers ;)
     
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  12. vanquishcc
    Joined: Aug 2019
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    vanquishcc New Member

    I appreciate the sentiments. I was figuring 5 times as long so we are already ahead of schedule! Just kidding. I do appreciate the positive and realistic advise. This is a bucket list item for me. If I were to buy a boat it would not fit my needs perfectly. Maybe 60%. Plus I cannot afford to buy an HH55! I want it to meet my needs and wants, but I also enjoy the build and the design process. Something I have always wanted to do. My kids are very excited to help! No doubt that will be a disaster, but it will be fun memories. This is not my first boat build, but it is my first cat build and I intend to make it awesome! I will likely spend most of the fall/winter designing the new boat. Maybe I'll go out to the shop and CNC a nice model for the kids to mess around with. We do plan to do some world cruising. I very much would like to do so before the kids are grown up. That is the only factor that pulls me towards the "buy a boat" button. I expect this build could take us 5 years to complete. All depends on time and money of course.
     
  13. Deering
    Joined: Feb 2005
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    Deering Senior Member

    Truth be told, it was a helluva lot of fun designing and building. But stressful once I realized it was all on me. It’ll suck up a lot of time in your life. That’s time you could be spending with your kids. And it’ll be stressful as you get into it because success won’t be at all certain with such a big investment in time and $$.

    I’m not saying don’t do it, but think carefully about the risks and opportunity costs. Once you’re in the middle of it it’ll be too late to change your mind.

    But it sounds like this isn’t your first rodeo so you probably have a good idea of what you’re getting into. Keep in mind that when you’re building a cat you’re in reality building two boats at once. Good luck and please keep us posted.
     
  14. Rumars
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    Rumars Senior Member

    Since your design seems to be driven by the interior and you have 3D modeling capabilities why don't you model what you want and then go to the designers. It's much simpler for them if the client brings the 3D model and says: "This is my desired interior arrangement, make hulls to fit and sail to xyz performance. You are only allowed to add space around it, no cutting into it or other changes". They either say "no can do / not interested / needs a bigger boat than you want" or "yes chief, costs xyz thousand". If someone takes the comission it will cost you a healthy sum, there is no way around it. If some NA would accept to work with you as you imagine, the costs would be even greater because they would bill you by the hour.
    Designing the whole boat yourself and hiring a specialized company to determine scantlings is not cheaper, and the boats sailing ability would be entirely your responsability.
     

  15. Alik
    Joined: Jul 2003
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    Alik Senior Member

    In fact, 'designing boat yourself' and then hiring naval architect to do some works is more expensive, than just hiring naval architect to do proper work from scratch.
    We charge triple if we have to work with third party models/plans, and we charge for every update. And finally, no one is taking full responsibility for the result of such design.
     
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