Converting a list of desires into a physical boat-How to start?

Discussion in 'Boat Design' started by WolframM, Jul 4, 2022.

  1. WolframM
    Joined: Jul 2022
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    Location: Kentucky, US

    WolframM Junior Member

    I intend to build myself a boat in the next 4-5 years. I have a mechanical engineering and fabrication background, and I own a machine shop where I've done aluminum repair and fabrication for over 10 years. I currently teach high school machine shop and engineering.

    I think I know what I want to build, but there is a LOT about boat building that I don't know yet. I have had two fibreglass boats in the past, and currently have a 14ft aluminum jon boat.
    Below are the items I know I'll need answers to, and I would appreciate it if some of the experienced builders here can help me fill out the list of all the questions I need to answer.

    "Shall Be" Items:
    Approximately 18ft long, with around a 7.5ft beam. Maximum beam may not exceed 8 feet.
    Welded aluminum hull
    Console controls
    Single outboard engine
    Waterjet cut panels from the local aluminum shop-they can cut up to 5ft x 25ft sheets

    "Should Be" Items:
    High stability hull design-It doesn't have to be the fastest boat, but I surely don't want to worry about turning it over while sitting still.
    The forward part of the hull should be higher than the rear-I see boats that have a knee-high rail all around them and I'd like the front part of the boat to be about hip-high, and a little more than halfway to the stern the gunnels should drop down to about mid-thigh around the rear of the boat. I don't know what this is called, but of all the boats I've been on this has been the most comfortable for me to stand and fish from.
    "Walk-around" design-I think this is what it's called-where you can walk around the perimeter of the boat while the console and any main compartments are in the middle. Being only 7.5ft wide, I may need to just put the console to one side and live with it.

    "Might Be" items:
    Fold-down seats from middle console/compartment area?
    Somewhere to put a livewell

    Primary use will be freshwater fishing on medium to large lakes-Not the Great Lakes, but Lake Cumberland, Dale Hollow, and Kentucky Lake are the largest bodies of water it will spend significant time on. I will likely never be lucky enough to fish with it on the coast, but even if I did get the chance an 18ft boat would be too small to get too far out from shore.

    I have some sketches of what I think it should be, and lots of photos collected from the internet. I really like the MetalBoatKits.com "6 Meter Euro Sportfish" design, and would like to build something similar. Until the price jumped from 650$ for the plans, to the current 1170$ for the same plans, I probably would have bought that set of plans and built to them. Now, I'm interested in designing a similar boat for myself, so here I be.

    Any information is helpful at this point!
     
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  2. BlueBell
    Joined: May 2017
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    BlueBell . . . . .

    SOR is Statement Of Requirements which is half the design right there,
    so you are well on your way.
    If you are concerned about boat plan prices then you should not be building your own boat.
    The cost in the long run of building your own boat is exorbitant.
    You'll be miles ahead buying a prebuilt boat.
    And inches ahead building a boat from a proven plan.
    And tens of thousands of miles behind designing and building your own.
     
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  3. Milehog
    Joined: Aug 2006
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    Milehog Clever Quip

    Inflation is real and it is ugly. That the plans price has jumped that much is hard to swallow.
    But.
    There is a 99.87% chance a boat of that scale you design yourself will be a bitter disappointment.

    Building a boat is hard to pencil out. You will pay retail. Pros buy everything at wholesale/jobber prices.

    I cheaped out on plans for my first build and it was a disaster. Buying plans from a living, up to date, experienced professional designer is mandatory.
    You sound earnest and capable; I have no doubt you could build a good boat to plans.
     
    Last edited: Jul 4, 2022
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  4. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Bluebell and Milehog have given you wise words of very good advice above.

    Please do not try to design the boat yourself in order to save a few $$'s - this is very much false economy, and it will cost you dearly in the long run.
    It might seem to be daylight robbery re how your plans have almost doubled in price, but this is still only a small fraction of what it will cost you to build this boat, even if you supply all the labour.

    Here is another source of aluminium boat plans - they have quite a wide range -
    Mono-Hull Boats | Aluminum Boat Plans & Designs by Specmar http://www.specmar.com/aluminum-boat-plans/monohull-boats
     
  5. WolframM
    Joined: Jul 2022
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    WolframM Junior Member

    You all seem to think that I'm new to large fabrications...I have been the engineer, fabricator, and machinist for many large fabrications over the years. I *currently run a fabrication shop*. This means I do not pay retail costs for metal material, I have suppliers that I buy from at jobber and lower pricing. It means I already have the tools for cutting, bending, and welding aluminum and steel sheet. Yes, I only run the shop part of the year now that I've taken a teaching position, but that doesn't change the supply costs much-the serious reduction in the world supply of magnesium has hammered the cost of some aluminum alloys, though.

    I was fully willing to pay the 650$ for the plans-until they suddenly doubled in cost. At 650$, it was not worth my time to develop a set of plans, but at 1200$, that's about what I would charge to develop prints for a project this size-granted, I've never done a boat.

    Now that we're past that, I have looked at Specmar's plans. One of theirs that I like is the 16ft Orca, but I'd like it a bit bigger-the 18ft does not have the raised bow design like the 16ft does, and neither has a centered console-this is something I want, but can compromise on and get a right-side or left-side console.

    What I came here looking for was resources on how a boat hull is designed-I'm looking for the math and rules-of-thumb to start laying out a design. I've found a few things, but don't have the background to correlate them together, nor can I find a local NA that will return a phone call.

    For example, hull deadrise. I understand this to be the angle from 0 degrees to the chine, and in the boat designs I'm looking at, measured at the transom, it ranges from 13 to 18 degrees. As the hull sweeps forward, at some point near the middle of the hull the deadrise angle starts to increase, and in the designs I've looked at, it ranges from 42 to 54 degrees at some point near the bow. I do not know where these two points exactly are, and I do not know how these two points are determined. THIS is the kind of information I'm looking for at this point, so I can start doing the statics for buoyancy first, then I have to break out the old dynamics books..I *hated* dynamics in school.

    Another point-does anyone know any NA's who are willing to work with individuals? I've yet to have any of the ones I've called even pick up the phone over the last two months.
     
  6. Milehog
    Joined: Aug 2006
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    Milehog Clever Quip

    First you say, "Any information is helpful at this point!"
    Then you get a little prickly, "You all seem to think that I'm new to large fabrications..."

    I'm confused.
     
  7. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    It would be reasonable to simply increase the frame spacing of the 16' Orca a bit if you want to increase the length by a few feet - although then you would not have the full developed panel shapes for the hull plating. But maybe you can then do these yourself with a CAD package?

    Well, I think that you came to the right place here - there is a lot of experience on this forum, and I am sure that many on here will be keen to help you (myself included).
    Re the maths, and rules of thumb for laying out a design, do you know how to calculate buoyancy and do weight estimates of structures?
    One fundamental rule is that you need to have enough buoyancy to support the weight of your hull and outfit - plus the fishermen, coolers, gas tanks etc.
    Another would be to ensure that it will have reasonable stability - a beam of 8' on an 18' length should be fine so long as you don't have too much weight high up.

    For fishing, the ability to walk around the boat is very useful for sure, so if say your beam is 8' amidships, and your gunwhales are say 9" on each side, and you have say 2' of clearance on each side of the console, then you have a max console width of approx 2' 6" - not huge, but should be enough for a steering helm and basic instruments, and you could then have instruments in an overhead console under the T-Top.

    Do you have a CAD program which can give you buoyancy and hydrostatics / stability calculations?
    It is useful to have a reference vessel that you like the looks of, and develop your design form that - this is how most boat designs are created.
    That 16' Orca might be a good reference boat to start off with.

    You will probably find that you won't hit your perfect design at your first attempt - you might well find that you have to go around the design spiral a few (or more) times, as every time you change something, something else is affected, possibly adversely, and then you have to address that, and this can get rather frustrating, but persevere.
    There is no 'perfect' boat - every boat design is a compromise of all the various constraints that you have imposed.
    And once you have designed and built it, then you will no doubt want to make changes on the next one to 'improve' it (if you still have enthusiasm for a next one :) )
     
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  8. WolframM
    Joined: Jul 2022
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    WolframM Junior Member

    Any information *is* helpful. But, as I explained in the very first paragraph of the first post, I have worked in engineering and fabrication for years and own a fabrication shop. So, when the first few replies center around "you're going to spend way more money than just the plans" and "even if you do all the labor for free", that's not information, that's pay someone else to build your boat. I already know that the design time costs will be nearly the same as buying them. I already know that a 4x8 sheet of aluminum is not enough and that it will be between 6.5 and 8 thousand dollars in materials (assuming one 5x25 sheet of 5083 aluminum in .160" thickness and two sheets 5083 in 0.100" thickness) to start with and I am very familiar with the layout and nesting of CNC sheet cutting machines.

    I had thought I'd covered that base in the first paragraph, which is why I seemed prickly about the first answers being what they were.
     
  9. WolframM
    Joined: Jul 2022
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    Location: Kentucky, US

    WolframM Junior Member

    Yes, I can do this. I have several CAD/CAM packages available. Solidworks, anything available from Autodesk (educator's license so I can use *anything* they sell as long as it's not for commercial use) Freeship Plus, and Delftship.

    I do mostly remember how to calculate buoyancy, and can absolutely do weight estimates. Stability is something I'd have to rely on a NA or other additional support, and also things like swamped stability.

    The design process for a new "thing" can be quite long-I am ready to spend a few years on a boat design, before I even pick up the first cutting tool. I've built a few scrach-built cars, one of which I drive to work every day-and it's not bad, but could be better. Aerodynamics when you don't own a real full size wind tunnel is a whole new ball game-you have to have accurate models plus instrumentation of those models, it takes a LOT! And that's with air...that's available in my shop, where I don't have to drive out to the lake to test!

    Thank you, Bajansailor. I'll play with some of the CAD software I've got and when I think I've got a reasonable starting shape I'll come back around to figure out the next increment in the design refinement.
     
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  10. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Please do post your CAD drawings and thoughts on here - you will receive useful constructive opinions, and no doubt some will not be to your liking, but please do still take note of it - folk on here speak from lots of experience.
    Your CAD programs (some of) should be able to calculate basic stability as well perhaps?
     
  11. BlueBell
    Joined: May 2017
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    BlueBell . . . . .

    Oh, okay, now I understand, it's like that.
    All that experience combined with years of design development...
    You'll be fine.
    Best of luck.
    Post lots of pictures.
    (Silly me, what was I thinking.)
     
  12. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I recommend you leverage your fab and build abilities and either find a new design or pay the fee or contact the designer and negotiate.

    The problem with design is there are so many variables. The sheer is actually less important than the bottom, and easy to add a personal touch.

    There are so many developable 18' boat plans out there, I cannot imagine spending years drawing is a wise use of time.

    Here is a dev panel boat plan for about $100 bucks. I don't think they sell the cnc files, but this plan is close to what you described. Dev plans are generally always scalable up and so this gets you close at plus 7% to 7.5' and 18.2' and is a well proven design. Not sure he modded to ally, but there is your engineering.

    https://www.boatbuildercentral.com/StudyPlans/FS17_STUDY.pdf
     
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  13. Waterwitch
    Joined: Oct 2012
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    Waterwitch Senior Member

    A designer with a similar center console is Bowdidge marine. you might ask the designer about an aluminum conversion, they have a 16 and 18 ft model. Too much boat for lake fishing but if you ever do get to the coast... https://bowdidgemarinedesigns.com/sea-strike-16/
     
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  14. Dolfiman
    Joined: Aug 2017
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    Dolfiman Senior Member


  15. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    The Coryphene 20 is a Lucas designed boat and this arhitect has several other designs available for amateur construction in Al that fit your description.
    Diam 18' https://www.fr-lucas.com/-1692
    Steredenn 570 https://www.fr-lucas.com/steredenn-570-1704
    Trial 19 https://www.fr-lucas.com/-1631
    He speaks english, contact him for prices if the boats are to your liking.

    One word about designing yourself. This is entirely feasible if your main goal is to learn boat design. If it's not, then I recommend buying plans, regardless of how expensive they might seem. The reality is that you will spend a lot of hours learning how to do it, and if those hours are money to you then 1-2000$ for plans are peanuts. Commissioning a custom design is going to cost more then that, and it's probably the reason you don't get replies, the NA's know you will say 5-8000$ is to much. You have to actually walk into someone's office physically and ask how much for a consultation fee to signal you are ready to spend time and money before they will consider taking the time to talk.

    Designing yourself would be a lot simpler if the boat would have a displacement hull. For a planing hull you have to learn about how different shapes change dynamic behavior on the water, otherwise you end up with a boat that has bad handling characteristics on the plane. For example all V- shape boats experience chine walking to some degree, the trick is to determine at what speed and arrange things to minimize it (or avoid that speed completely). This depends on a lot of factors, from desired speed, weight distribution, installed power, prop size, etc.

    A fresh water boat does not have to be made from 5083, any cheaper weldable series can be used, you just compensate for the different properties in the scantlings.
     
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