Converting multichine alu hull to radius?

Discussion in 'Sailboats' started by urbansailor, Jun 22, 2015.

  1. PAR
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    PAR Yacht Designer/Builder

    Dudley has been doing some pretty nice designs for some time and resale value is good. They rate well if racing and you'll fair well if they're sailed hard too. Most folks that lack experience think they need an Ingrid or something similar. Maybe they've read Buehler's or Pardey's book, which makes things worse, without experience. If you're married to one of these puppies, there's lots to select from. If you lack experience BPW is correct, get some sea time, preferably on as many different boats as you can, so you can develop and evolve your ideas and desires, which will continuously change in the first few years.
     
  2. urbansailor
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    urbansailor Junior Member

    PAR, you are right about Bruce Roberts. I've never heard anything positive about him and his website is very gimmicky. I am going to go ahead and order the study plans for the Hout Bay 30 from Dudley Dix. He seems like a very approachable person. I called his office a while back, I though I would get the answering machine, but Dudley himself answered the phone and answered all the questions I had regarding the Hout Bay 30. Nice guy.

    BPW, my cruising experience is limited to mostly day sails but I have done a few 2-3 day passages in the Gulf years ago. Your right, I have read a lot of George Buehler's articles as well as the Pardey's. Larry or Lin wrote somewhere that all cruising boats under 40 LOA should have a full length keel-I'm pretty sure I read that in either one of their books or in an old article. I don't fall into that camp, but I do like the idea of a skeg/rudder combination for safety. Atkin's Inga is a really pretty boat! Is yours timber or grp? In any case, I'd like to thank everyone for the greatly appreciated responses!! I will keep you guys informed on my progress if you are interested.
     
  3. PAR
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    PAR Yacht Designer/Builder

    My Atkins was John's last commissioned design and cedar over oak, with cedar decks and coach roof. Inga is one of Billy's older designs and I know of a few, all complain of excessive leeward skidding. One recently took my advise and added a significant hunk of deadwood (several inches), below the existing keel and she points much better without as much skidding. Have a look at her sections and picture her heeled over at say 10 degrees. How much effective lateral area is reasonably perpendicular prevent leeward movement? Yeah, these puppies ride like a '53 Cadillac, but can't get upwind to save their butts.

    Full keels do offer protection, but so do fin keels, if well designed. You'll note that Dudley (yep, he's a nice guy) has the shaft and wheel well up on the back of the fin, so it's just as protected as it would be on a longer keel. A skeg mounted rudder is a little more vulnerable than keel hung, but if the skeg is stout, it'll fair well. Generally, if the skeg takes a bottom strike, you've already dragged the keel over the bottom too, killing much if not all of your momentum, so don't get too worried about the rudder on the Dix design.
     
  4. bpw
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    bpw Senior Member

    Our Inga is actually cement with plywood and glass decks. A bit strange but someone did a good job building her and she is a tough little boat. We are the ones PAR mentioned who added the to the keel and it made a huge difference. I am sure some of Atkins deeper draft boats sail quite a bit better, but still nothing like a modern boat.

    If you haven't cruised before I would strongly recommend buying a boat and sailing a few years before sinking the time and money into a new build. You will learn a huge amount in a years cruise that will translate into whatever you decide to build. Your ideas will change radically after sailing a bit. It's possible these days to buy a ready to cruise small boat for under $10,000 and get most of that back when by you sell, even a cheap build will cost multiples of that. Heck, our boat is about to go on Craigslist for a few thousand bucks and she just did a trip through Tierra del Fuego and a then 4700 mile non-stop passage. Sure She is cement and has no motor, but she is sorted and ready to go again. Whoever buys her will be able to buy a few bits and be ready to go Around the world for $7-8000 all in.

    We are actually about to start putting our new boat together from a bare hull, I am exited for the project but it will be my third cruising boat and we just spent 4 years cruising on Inga so we have a good of what we want on the new boat. Building would have been a bad decision before we lived aboard and cruised for a few years.
     
  5. tom28571
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    tom28571 Senior Member

    From the BR boats and owner/builders that I've met over the years, I can only agree with what the others have said.

    A good rule of thumb is to look first at designs from designers who have actually built and sailed their own designs. Dudley Dix certainly fits in this category and I admire both him and his boats. Some designers just sit at their computers and crank them out (some being close copies of others work) and let the first builders find the problems.
     
  6. urbansailor
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    urbansailor Junior Member

    PAR, I think you might have me convinced that even a balanced spade rudder might be a viable option on the Hout Bay 30. What do you think? Also, Dudley does not offer CNC cutting files for the Hout Bay 30. Do you have any idea how much it would cost to convert the plans/offsets to digital CNC files? If I were to pull the trigger on this project, In lieu of lofting, I would rather have all the parts CNC milled and the radius plates rolled at a local shop with a three roller plate rolling machine.
    Bpw, holy smokes, Tierra Del Fuego (no pun intended) in a ferro cement Inga!! That's amazing!! I bet you have some great adventure stories to tell! I don't think I'll ever make it down that far south...I'm totally jealous. Anyhow, I think you offer solid advice as far as buying an inexpensive boat and doing some cruising before making an investment in both time and money. It's true that my cruising experience is a bit limited, but I'm fairly certain that I know what I want, or rather, what I need. But, if I were to come across a good deal on a second hand boat, and if my better half approved, I would certainly consider making the purchase.
    Tom28571, I have decided to stay away from any vessel associated with Bruce Roberts; and yes, I think you are correct, I think Dudley Dix regularly races on his own designs.
    As always, I want to thank everyone for their advice and input!!
     
  7. PAR
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    PAR Yacht Designer/Builder

    Dudley would be best approached for the cut files on his design. He has some CNC designs in his drawer, so give him a call. If he can't, for whatever reason, any good CNC shop should be able to do the conversion from his DWG's, JPG's or PDF's.
     
  8. urbansailor
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    urbansailor Junior Member

    PAR, I contacted Dudley Dix in regards to CNC cutting files for the Hout Bay 30. He does not do the conversion but he works with an outfit that will. From soup to nuts it'll take 2-3 months and the cost is roughly 4k for the conversion. That's a lot more than what I was anticipating. Perhaps this is not the boat for me. So, the search continues...
     
  9. PAR
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    PAR Yacht Designer/Builder

    Contact your local CNC mill and see what they'd charge.
     
  10. bpw
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    bpw Senior Member

    Four thousand isn't much compared to total build cost if its the boat you want. Lofting is also not very hard, don't get too hung up on Cnc cutting.

    Have you considered the Didi 34, he has Cnc files and it shouldn't cost much more to build than a Hout Bay. More modern and faster as well.

    Edit: duh, you want to build in alloy, so Didi 34 won't work without lots of conversion. Forgot about that part.
     
  11. urbansailor
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    urbansailor Junior Member

    PAR, there are a few local CNC mills in the area, I'll call around and see if any of them can give me a quote with just the study plans as guidance.

    Bpw, are you building the Didi 34 yourself or having a yard build it? It looks very modern and fast. What do you guys think about Van De Stadt designs? The Vita 30 http://www.stadtdesign.com/designs/stock_plans_sail/vita_30
    is a very different boat from the Hout Bay 30. But, it also can be built in aluminum, comes with cutting files and has three keel options. It looks like a spade rudder is standard but I think I read somewhere that there is an option for a skeg hung rudder. I could email them to find out. It's also a multichine hull design, so no need to roll any plates, just cut and weld. I suspect that this would be a quicker build and less costly as well.

    What do you guys think?
     
  12. urbansailor
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    urbansailor Junior Member

  13. urbansailor
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    urbansailor Junior Member

    The picture above in the previous post is of an aluminum version of the Vita 30.
     
  14. bpw
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    bpw Senior Member

    We actually wound up buying an aluminum Alan Gurney design that was built by Royal-Huisman in the late sixties. The interior and decks are a complete mess but we are stripping to a bare hull and building from there. We plan to do quote a bit more high latitude sailing and decided metal construction would be a good idea. It's a fun keel boat similar to the islander 36 but a bit shorter and without the IOR stern. It is asked hung rudder but I am seriously considering converting it to a spade rudder.
     

  15. gonzo
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    gonzo Senior Member

    I think that spade rudders are not likely to hit on a grounding unless the boat is on its side over jagged rocks. Otherwise, only the keel will hit. I do like skeg mounted rudders because they won't get a line or net stuck between the bottom of the hull and the blade.
     
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