Reverse Engineering (conversions And Modifications)

Discussion in 'Boat Design' started by viking north, Dec 25, 2010.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    With respect, you have just proved my point, and several other posters above too, like PAR.

    The reason why it doesn’t drive the process forward, is because everyone with the required knowledge in said topic has told you don’t do it. In other words, it is your dogged instance that is preventing you from listening to the advice, you WANT it to go forward, regardless what advice is being.

    And again here….every boat, whether it is a small canoe all the way to a super tanker, has an SOR. This is a Statement of Requirements.. It defines the performance envelope of your design. It is not a wish list…it is real practical list of what the design shall, repeat shall achieve, ie not a dream of I wish to achieve.

    The design of a boat, any boat is greater than the sum of it individual parts. Only a naval architect understands this, despite the bleating from the masses. Only a naval architect will look holistically at the whole concept rather than individual parts such as…is round bilge better than hard chine. This is a small individual part of a very very large sequence of decisions which all interact with each other based upon performance and cost.

    If you wish to consistently ignore this…that is your prerogative.
     
  2. Steve W
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    Steve W Senior Member

    Im not going to get in to debating wether you should or should not pursue these projects but Gonzo is right,there are so many boats available so cheap its worth a thought.To the OP if you dont know if the hull is a power or sailboat hull dont waste your time,if you are sure it is a sailboat hull but without the apendages then you need to take the lines off it and do the calculations and Ad Hoc has given you a start on how to do that,if it does not have a waterline marked on it however you will need to draw one on the lines drawing that you will create from your table of offsets in order to do your calculations.You will also need to weigh the hull and then figure out a miriad of other weights that will go into the finished craft and their locations before you can come up with the weight of ballast and where it is located,it is a long process which is why it is likely not worth it,you can almost certainly by a complete boat cheaper and save years of work and a busted marriage. To the other chap with the lifeboat there is a guy in Florida who manufactures the Bauer 8 and 10ft dinghies who has done exactly what you want to do with the lifeboat, he did it in Germany i think and sailed it to Florida, it looked good in the pictures i saw so you may want to contact him,he will know more than any of us on this particular subject.
    Steve.
     
  3. viking north
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    viking north VINLAND

    Wow,maybe i didn't word it properly my idea in starting this post was to create a scenario( not real but educational) in which Mr. X had obtained a hull of which there is no design info available but had visions of a conversion or a continuation of an interrupted build which was also lacking design info. The scenario also stated money was tight but Mr. X wanted to work with a qualified design person using sweat equity where possible to supply necessary info to determine if the hull would be suitable as a sailer,motorsailer or the hull is 100% unsuitable for either. The question was if he approached you as a qualified person in boat design what would be the first step in the process. From reading the replys there are, i think several answers. Good photos or actual viewing of the hull would be step one. Step two is taking the lines off the hull as indicated by a reply.From my past experience and from the instructions in that reply i think (correct me if i,m wrong ) that this is something Mr. X can do. Ok now here is opportunity to provide some education and i would like to pose some questions on the process. #1 How many stations along the hull should one make measurements from ? #2 Is it important that these be exact distances apart and what tolerance if any would be acceptable ? #3 would these recommended number of stations work equally well with calculations by long hand (simpsons rules) and fed into a 3d computer program ? I thank all the positive thinkers out there and can appreciate the concerns of others regarding people wasting time and money on a dream but many out there have only one option and thats to work with what they've got in order to get out on the water(Slocum and many others did it). I thought it would be fun and educational to go thru the process of what route a person should take, what to expect, and from that determine if they should go forward. Question #4, Once the lines are taken off would it be necessary to weigh the hull, say by hiring a crane to do so in order that the designer could estimate the completed boats displacement waterline and from that get the magic numbers to determine if the hull has potential.(Remember in the opening of the thread i mentioned the hull looked like a good canidate for conversion). So four new questions and once answered I would like to ask a few more questions on behalf of Mr. X and once debated and answered this thread should have given a good indication of what a person is facing, considering a hull conversion or completion of a sailboat of which neither has design info.
     
  4. Bruce46
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    Bruce46 Junior Member

    I am of the opinion that when gender changes are attempted the results always leave something to be desired. However, if the proposed project is to complete the construction of a vessel started by another and documentation is lacking, it would be a very good idea to consult a professional as to the best way to proceed. In some cases the professional might advise you to buy a gallon of gas and a match. If that is the advise given cut you losses and take his advise, on the other hand if there is rational hope of creating a succesful outcome it would a good time to plan your next steps.

    If you don't alreay have books on yacht design and constrction now would be a good time to buy them and study the information carefully. Actually it would be a great idea to do a lot of reading before you sit down with a professional, as you will be able to speak the same language as the professional. These same books would answer the questions you have asked here much better then can be answered on any forum.
     
  5. Scunthorp
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    Scunthorp Hull Tech

    Opinions are lie *** holes

    I suppose it was a flawed expectation on my part to assume that everyone would respond in a mature and professional manner. I am really grateful to the people who have and I am putting forward your ideas and concepts which will further my understanding of engineering practices. How we get from boatbuilding to the bigotry of sex changes and lip stick on pigs was quite a surprise. Along with scantling rules and such like I find that “opinions are like *** holes” everyone has one. It is apparent that seriousness and confidence might be required to further this conversation.
     
  6. gonzo
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    gonzo Senior Member

    If Mr. X doesn't have the money to pay me for a survey so that I can inspect the boat, take the lines off and work with a NA, do you expect my answer to be: There are bored professionals that will work for free? Reverse engineering is expensive. You either have deep pockets to pay for the project or it is an unrealistic expectation. Any boat project can be completed, providing you can come up with enough time and money to put into it.
     
  7. breschau
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    breschau Junior Member

    Is this thread about reverse engineering an unfinished hull or converting a grp lifeboat into a motorsailer?
     
  8. Bruce46
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    Bruce46 Junior Member

    Scunthrop - hull tech: I'm sorry that my choice of words upset you. However, the analogy I used pretty much on target. When you try to change something from what it was to something completely different the results rarely meet expectations. Your engineering questions are best answered by reading books like "The Elements of Boat Strength, Skene's Elements of Yacht Design" or others. If after doing some background studying you still have specific questions, knowledgeable people on the froum will gladly answer them.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Yes, you can reverse engineer a hunk, but most professionals will refuse the commission, for several reasons, but mostly out of lack of control over things that haven't any over, such as (again) knowing the decisions made on in the original SOR to meet specific goals. Some of these things can be reasonably guessed at, but others not and this is a huge issue with an engineer (guessing). This presents a professional liability that most would rather not pursue, so you'll get the door slammed in your face a the mentioning of it, which is what's happening here.

    On the other hand you can find a small percentage that are desperate enough or inexperienced enough to take on a project like this. A student fresh from WestLawn may be the ticket and hopefully you'll get lucky as a team.

    Lets go back to the original post;
    This is the first indication that the poster is out of his realm of experience and should hire a professional. Two sentences later the following;
    which clearly suggests my observation was correct and their assumptions where precisely that. The very next (and last one of the post) sentence is;
    To me this is the end of the discussion in most practical terms, with the exception of the academic allowance seen here.

    In short Viking North, you need design and scanting specifications, retro fitted to your project. Yes, this can be done, though you'll find considerable resistance among the qualified people, that may entertain the prospect. The first aspects of the project can be handled simply and inexpensively enough by a reasonably skilled owner, which is to block her up properly, get her level in both directions and have the hull form evaluated. The next part of the project could be difficult, which is finding a skilled professional willing to place their reputation on the unknowns of an undocumented design. I've done this sort of thing in the past for clients, but it's not an easy nor inexpensive process, which is the last point I raised about it's academic value in a discussion.

    If you are serious about going on with the project, you should strip the boat of everything that is bolted or screw on, of course noting with photos where everything was. With a completely stripped hull, that is blocked and leveled, you can hire out it's evaluation and lines being taken off. You could perform this task yourself, though considerably study on the methods would be necessary, because the line taking process needs to be understandably accurate.
     
  10. viking north
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    viking north VINLAND

    OOps, long day yesterday and for some reason late last night i missed Steve W's reply(sorry) that has answered question #4, Yes the hull has to be weighed, again something Mr. X can do and provide this info to his chosen designer. From this the designer can estimate the additional weights of superstructure, equiptment,interior, sails and rigging and of course the all important waterline from which all the big magical numbers and locations of engineering/building reference points on the hull are located. At this point the designer can answer the all important question,what the hull is most suitable for and roughly to what degree it will be successful if equipped with proper driving systems. Lets assume the hull shape and displacement places it more into the motorsailer 50/50catagory and as a result MR.X decides to go with a full keel with say Brewer bite cutout a rudder/tube set up(not aft hung) to allow him a quadrant. He also decides to go sloop rigged with a typical wheelhouse/ trunk cabin super structure.Given that Mr.X is a pretty good back yard boat builder or has a friend that is, other than the following input from his designer am i correct in stating he should beable to complete the build.(providing he has not run out of money thru a divorse and we all know the result of a spouse that is not into motorcycles or boats)
    He will need his designer's help with the keel,rudder,ballast and location of the mast. An approxmation of sail area and engine size. We all have a good idea that once the designer has the hull lines fed into the computer it is fairely straight forward for him to provide most of the data that Mr.X will need for his conversion or continuation of a part build. Based on a 30ft. hull and a budget of $25000 ($4000hull)(1000transport and shed)($3000 keel,ballast,rudder)($2000used engine)($250used shaft and prop)($200used hydrolic wheelhouse steering) ($1500used mast,rigging and sails)($4000 to complete superstructure and interior)($1000used winches,misc. hardware,anchor,cordage)($1500 thru hulls,fuel/water tank, exaust, head, basic galley,cushions)( $250,compass, vhf, gps,)(designers engineering fees $2000) and $3500 to cover misc. The idea is that by obtaining a solid hull and investing $25000 one would end up with a either a good heavy crusing sailer or motorsailer. Is it reality yes, are there pitfalls definately yes, but it is an option to be considered and one where the all the cost isn't immediate thru a bank loan but can be spread out over time making use of sales, used items,and good wheeling and dealing. The main point here is to stress the input of a qualified person in the field and from that determine if the project is feasible and the outcome acceptiable. No boat is perfect and as a famous man once said a yacht is not determined by the vessel but for the care and love of her owner. All and any responses welcome,Geo.
     
  11. Tad
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    Tad Boat Designer

    Before any survey or taking of lines is undertaken the feasibility questions (as alluded to by Ad Hoc) must be answered completely and realistically. This seems to be the most difficult part for both amateurs and professionals.

    Amateurs are usually the owner/builder type, may very well be can-do people who have accomplished much in their life but never built a boat. Due to a lack of experience (a boat is just a floating house) they don't understand (vastly underestimate) the scope of effort required in a refit/conversion/rebuild. They do not understand the implications when they casually mention maybe a trip to Mexico, or four freshwater flush heads with holding tanks to suit.

    Professionals are in a quandary because the owner comes to him or her with the project already underway (almost invariably). They just bought this boat and they're going to go into the high-end charter business. "I just need an interior plan and a rig design".....oh boy! So the professional (me) takes this seriously, spends several days thinking about this, doing research on the boat, and answering and asking questions of the owner. Eventually he or she (our intrepid and hungry NA) comes up with an estimate of the design work involved and gives the owner (Mr. Nube) a realistic price. He also is honest enough to tell Mr. Nube that his projected budget isn't going to do it, of course backed by a projected cost analysis (done for free).......The result is that our NA will never hear from Mr. Nube again.......but the project will go ahead with some input from various people of little experience....and thus become a nightmare for the owner when all the money's gone and his boat is worth less than he paid for it........

    So should (As several posts above have done) the experienced professional say forget it at the start, or say "I'll bill you every two weeks" and hope that he gets a little work?

    So you start with the feasibility questions.....
    1) Are my goals in sympathy with the existing hull?
    2) Will this boat do what I want it to do when we're done? This includes performance, aesthetics, safety, accommodation, satisfaction, seaworthiness, range, etc.....
    3) What are the economic goals? Save money, produce resale value, investment value, use value, etc?
    4) Can the goals (of 1, 2, and 3) be achieved in some other way?

    Realize that the bare hull is probably 10% of the cost (materials and man hours) of your completed boat. Amateurs often believe they are almost done when they buy a hull. Worse is when they buy a complete boat at market price and then gut it....reducing their investment value to nil.....unless it's a very special boat this is a losing proposition. Many often realize near the end of the project that it would have been quicker and cheaper to start with a more suitable design and build from scratch.
     
  12. Scunthorp
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    Scunthorp Hull Tech

    Trying to post some Photos The Green Hull is mine it is an ex polish lifeboat 28ft long 8ft wide and 5ft deep. It came with a 45hrs Lister 3 cylinder
     

    Attached Files:

  13. viking north
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    viking north VINLAND

    Ok while writing the above response, entertaining visitors, filling the fireside woodbox, answering the phone, then returning to complete my post and after posting it i was astonished to view a whole bunch of new postings and some firey ones to boot. Boys, this is not a real build this was just to present a scenerio of possibilities, stages, proceedure, and throw in some costs, to explore what a person might expect if they wanted to persue their dream thru a conversion or continuation of an interrupted build where no design paperwork was available. Man mostly BUT NOT ALL,what i hear from the forum input is negative and attack,personal attack,attack against fellow professionals who would dare take on this sort of project , attack against Westlawn grads. Other than being just plain negative the other concern seems to be,liability, being sued, well there must be a waver your lawyer or association has available that a customer can sign re, modifications on a new boat, continuation of a custom build where the origional designer has passed away, or a conversion. Anyhow it really doesn't matter it was just an idea for a thread, something new to try. As for my knowledge and background which has been questioned, I have built in all mediums, wood, metal and glass and have completed three conversions one of which has sailed across the Atlantic, and am presently working on conversion #4 my own personal boat and yes hired a qualified person to aid me on the engineering part of project. I have sailed on and in everything from a 18ft. dory to 72ft Henckleys and no i didn't just fall off the turnip truck. The idea of the thread once again was to create a scenerio, ask some common questions to get input and maybe pass on some info on the topic. Regardless, Merry Xmas Everyone, Geo.
     
  14. Tad
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    Tad Boat Designer

    viking,

    You state the designer will do a weight study based on the existing hull weight plus "superstructure, equipment, interior, sails and rigging", you didn't mention tanks and machinery and ballast.

    To do this your designer must know the location of these items and the weight of each.....thus he or she must design the boat.......to know the size of an item one must do the structural calculations and calculate minimum scantlings.

    This is what few seem to understand, the professional has to maintain his reputation, $2000 is not worth it....there is no incentive for the professional to get involved...it's not his design, you're offering three days work and the professional wants a couple of weeks to be sure all elements will hang together. Few if any experienced and prudent designers will become involved unless they know the outcome.

    So the amateur is on his own, build some stuff, throw it in the water, use ballast to correct your mistakes, the boat is a dogs breakfast because you do not see any value in high quality fully integrated design.....thus you end up with a boat of little value in the marketplace, though she may be of immense value to you......

    And no, feeding the hull lines into the computer and then creating a usable hull is just the beginning. Beyond is an endless series of "what if's" and "but could we's".......who's engineering the mast step? How does it integrate into the main bulkhead? What's the rig load? Well...what's the stability? Well....What's the ballast and what supports it?......on and on. A 30' boat requires roughly 3-400 design hours to get right, no one can come close to right in 30 hours.......

    As to your budget estimates no professional will go along with those....way too many unknowns.....how much was that used rig stretched? How close to failure is it? I would guess your numbers are off by a factor of 2-3......I'm going to specify $5k worth of epoxy and another $5k in bolts, ignore this and I wash my hands of the project.........
     

  15. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    Viking North,

    Hey mate, do not take what we are saying personally as an attack, or read into our comments as being so in any way, shape or form......take another read of the material so far provided and try annalytically to see what you are being told.....do you see a pattern existing.....it seems to me that the majority are saying be very careful of falling into the lost boat project team, nothing more and nothing less. Whether this is in theory or in practice, the end result is the same, very few end up with anything worth while, if at all anything.
    There are many "theoretical" questions asked on this forum, some become reality, some appear to mystically become a current project, and some are just dreaming, but they are generally all the same anyhow, read up on a few of them and try to find the ones that actually were completed successfully.......
    Unfortunately, an ocean going vessel is not a boat but an entire city, with power generation, electricity grid, engine and mechanical systems, sewage, accomodation, garbage disposal, rigging and maintenance considerations,safety considerations etc etc. They all need to be understood and world best practice codes implimented and controlled
    if you seriously wish to have an end result that is both safe and resalable (or at least suitable for the purpose intended).
    ...anyhow, have a nice holiday, please feel free to ask any questions that we here may be able to answer for you, but do so with the understanding that answers may not necessarily be to your liking, we may all have arseholes and sometimes be one, but, actually, the ******** does a very important job......
     
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