7.5m boat idea (beginner)

Discussion in 'Sailboats' started by tscanlon08, May 23, 2007.

  1. tscanlon08
    Joined: May 2007
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    tscanlon08 Junior Member

    I am interested in building a small racing style keel boat and have been looking at the Thompson t750 as an example. I was wondering if anyone could give an idea of the cost to build such a boat. I am also interested in designing the boat on my own and believe that this might allow me to reduce the cost. I have a feeling that I will have a lot of other questions so if anyone has experience or relevant information about this type of project I would greatly appreciate it.

    Thank you
    -Tim
     
  2. frosh
    Joined: Jan 2005
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    frosh Senior Member

    Are you sure that you are serious?

    You admit you are a beginner and want to build a T750 keelboat. f----n crazy, and then you want to design one just like it to save some money. Sawdust in the head would be better than what you have currently. :eek:
     
  3. tscanlon08
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    tscanlon08 Junior Member

    Thank you for your suggestions. I understand that this is a difficult project but i am ready to do the necessary work to make this possible. I won't be able to build the t750. But i hope to create a boat of similar size and purpose. Although i have not built any boats i have experience with fiberglass and building in general. I also have a relative who is a boat designer.
     
  4. tscanlon08
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    tscanlon08 Junior Member

    There seems to be very little information about building these types of boats and i am interested in what the cost of the materials needed to build the hull might amount to.
     
  5. Trevlyns
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    Trevlyns Senior Citizen/Member

    Hi tscanlon08 (or can I call you TS) ;)

    I know exactly how you feel as I been there myself. Don’t get discouraged by negative criticism; just pursue your dream vigorously and enthusiasm will win the day!

    Frankly, I don’t know anything about the Thompson t750 and also, I don’t know how much of a beginner you are, but I hope this can get you going in the right direction.

    1. Never loose sight of the basic concept of a boat. All boats are merely enclosed shapes that displace less water than their own volume – that’s why they float. It’s just plain old Archimedes principal at work. Of course some designs do a better job than others because of the way their hulls are shaped and how they are powered. Whilst modern design methods and CAD bring much to the design table, the Polynesians did a pretty good job of it too – 2000 years ago and without a computer in sight!
    2. Costs are a difficult one because the methods vary so greatly. You could go with something as simple as plywood that might set you back a couple of hundred dollars. Or a Kevlar composite perhaps… but you’d better sell your house now so you can pay for the rudder! :p
    3. Get started with some serious study of yacht design. The two “Bibles” are Elements of Yacht Design by Norman Skene (kinda like the Old Testament) and Principles of Yacht Design by Lars Larsson and Rolf Eliasson (New Testament!) I’m sure you’ll find both titles on Amazon.com. When I started, Skenes book was out of print, so I borrowed one from the library and photocopied the entire thing!
    4. Compare as many similar designs to the one you want to build as you can. There are many boats in the 7.5meter range. Some are F1 racers, some are dogs… Why? Comparison of key data such as displacement to length and sail area ratios will begin to reveal some secrets. Hull shapes, hydro and aerodynamics will also come into play.
    5. Keep your interest alive by soaking up these forums. They are an invaluable source of information from knowledgeable people who you can learn a lot from.
    Good luck to you lad! The mere fact that you ask such questions shows there is already a spark. Feed it all you can and, once complete, don’t forget to post your design for the rest of us all to see.
     
  6. nflutter
    Joined: Apr 2007
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    nflutter Junior Member

    hey tim sounds like a good project. i dont know where your located, but here in brisbane, australia there have been a number of people undertaking similar projects, those guys use the sailinganarchy forum, you might find out some specifics from them. The best (in my opinion) sportsboat slash weekender designs, in australia at least, have come from a bloke called alan carwardine, maybe google him. his designs are called the stealths, they look like this. this is the stealth 8. you may be able to buy plans from him, the boats are very quick. some mates of mine built (about 5 years ago) a stealth 8 off a jig from carbon and glass for something like AUS$ 40G. There is now a steath 7 with faired in wings that has been beating the Thompson 7s and sometimes the 8s i hear, and matches with the stealth 8 in the right conditions. should look that up. it takes out so much guesswork and time wasting if you get a tried and true boat from someone who knows how to build it.
     
  7. raw
    Joined: Jul 2006
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    raw Senior Member

    though he doesn't know me I am one of those nflutter was talking about.

    A few years ago, i had exactly (and I mean exactly) the same thoughts you are having now. The t750's are nice, but they didn't meet the local requirements and rules or needs.

    As a qualified NA, I set about designing my own and drew plans up for a 7.5m sports boat in foam/glass construction. We built using foam sandwich, over a cnc cut jig and made multiple moulds and small plugs to build the deck. Everything was built from scratch.

    then we built it, then raced it.

    I seriously suggest that unless you are experienced in fibreglass design, engineering and construction you are not going to end up with the product you desire. I design boats for a living, and even then there were times when I seriously had to put on my thinking cap to come up with solutions to apparently simple problems.

    Oh and the Aus $40k is pretty close to the money for a self build.

    raw
     
  8. tscanlon08
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    tscanlon08 Junior Member

    Thank you. That looks like a great boat and that price range is encouraging. Would you think such a design could be modified? I sail on a lake and don't need any under deck space. Also I’m interested in making a boat that is good up wind so is there any design considerations or trade offs that deal with a boats pointing ability. Not to say that in the end I won't build from professional plans but first I want to flirt with other more glorious ideas.
     
  9. raw
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    raw Senior Member

    I might not have been clear re the above, the boat in the link above is not mine, my design is closer to what you are thinking.
     
  10. frosh
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    frosh Senior Member

    Tim, sorry for the extremely harsh posting I made earlier on. I design and build boats for myself these days as a hobby. I had no formal training in any aspect of this. It is possible. Just remember, baby steps, one at a time. Best of luck
    Regards, Sam
     
  11. djwkd
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    djwkd Senior Member

    I am interested in building a smaller keelboat,of roughly 6 feet long,3 feet wide.But what would the depth of the hull be and the depth of the keel be?
    thanks in advance,dominic
     
  12. Guest625101138

    Guest625101138 Previous Member

    Tim
    If you have an engineering perspective than designing is an interesting pursuit. Building can be frustrating and actually using the end result is the reward for the effort.

    However unless you have very clear requirements I think you get the best value from buying something second hand to start with. Second hand boats tend to be good value if you take time to look around. The size of boat you are considering is trailerable and tend to be looked after reasonably well without too much damaging weathering. You get a lot of things with a boat that you do not price when you do initial estimating. Typically a basic hull is about 1/3 of the cost of a finished boat.

    A second hand boat might have some overstressed parts that need replacing but with care you can gain experience with potential to recover a good proportion of the costs.

    Owning and using a boat will give you invaluable experience when making design choices. If you set out to make a boat from scratch you could very well produce something that you enjoy but quickly outgrow and find it is near worthless to you or anyone else. Building a recognised design at least gives you a potential market providing it is well made.


    Rick W.
     
  13. Raggi_Thor
    Joined: Jan 2004
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    Raggi_Thor Nav.arch/Designer/Builder

    Building a boat like that may for example cost 50.000 USD if you buy drawings for maybe 1000USD. If you design it yourself you get something else, probably not what you want, and probably with no resale value.
     

  14. Trevlyns
    Joined: Oct 2006
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    Trevlyns Senior Citizen/Member

    Hi Dominic!
    Establishing your yachts dimensions is not an easy task!
    Rather than bore other members with maths and technical data, I’ve sent you a private e-mail explaining a few things.
    Take care!
     
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