creating expanded panels for flat bottom skiff

Discussion in 'Software' started by ddoyle, Apr 3, 2014.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    Tell me he has sent you details via message. Pretty rude if he didn't !
     
  2. oceannavigator2

    oceannavigator2 Previous Member


    Thank you so much for this response. Truly fascinating for me (and probably would have been for Dick Newick), as locals. What is really getting me riled up., aside from the history, is just trying to picture where they used these.

    There are some of the largest estuaries there...but all subject to "unscullabe" currents.

    What were they hunting? You aren't likely to see any ducks there whizzing by at 4 knots while they think they are standing still. More likely to see very large, healthy seagulls and cormorants moving along at 4 knots. Or a seal.

    The only places you see ducks there is fresh water such as ponds in Durham, Dover, etc...

    So perplexing. :)

    As to building it, let me look closely.
     
  3. oceannavigator2

    oceannavigator2 Previous Member

    I do not have the free time to build any other boats, unfortunately. Have my hands full. But, it looks like at least one person successfully did the 3D to 2D panel shape in the thread. Hopefully they share that.

    I would probably just use stations and battens, but I know you are looking to get those panels cut from the start, just tying them together to arrive at the shape.
     
  4. ddoyle
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    ddoyle Junior Member

    Mr Efficiency, Nope. LOL.

    OceanNavigator:

    They used them everywhere. No such thing as "unscullable" currents. Scullers use tide, current, wind to advantage. This aint recreational kayaking. Of course no duck is worth dying for but grocery store meat will kill you as sure as hypothermia but alot more painfully so.......


    I think there is a video still on youtube of two brothers operating a scull float deep in New York Harbour in winter. It will give you an idea of what is possible. I am not encouraging stupidness or recklessness here but if you know your boat, your abilities, are thermally protected against repeated dunkings and have positive floatation in the boat things should be ok.

    EDIT: there is always room for one more boat is'nt there????? Keep your eyes open now that you know they exist you will notice them locally. There really is no more plesant way to spend a calm evening, laying down comfortabley and propelling yourself at a walking pace with a casual and effortless wrist motion. Ultimate boat for the lazy man who enjoys looking at birds and critters.
     
  5. ddoyle
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    ddoyle Junior Member

    Couple more pictures in case any boat modeling guru out there needs more inspiration. FYI the completed boat pics came to me in the mail from California no pedigree or any info on the builder. Complete and absolute fluke that I was lucky enough to find the boat in "American Small Sailing Craft".
     
    Last edited: Apr 9, 2014
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Hopefully that omission will be corrected ! :rolleyes:
     
  7. lewisboats
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    lewisboats Obsessed Member

    Here... try this as a basis. The after part will take a bit of cranking to get to shape but not too bad
     

    Attached Files:

  8. oceannavigator2

    oceannavigator2 Previous Member


    I suppose what i mean is that for (what seems like) the majority of the day there, you couldn't row a decent row boat and escape the current. It is so strong, you have to face away from the bridge you are waiting to open and gun it to maintain your position.

    One time, I had to go under one of the fixed bridges but the sign for clearance (as a function of tide) was broken off.

    In order to approach the bridge slowly enough to see if my mast would clear, I had to turn and face the bow away from the bridge, pushing 2800 RPMs on twin Yanmars to hold my position relative to the bridge. I backed the rpms down to about 2600 to start approaching the bridge, stern first.

    As i got to the point where I could see my masthead made it under, I put the port engine up to 3200 rpm in forward and the starboard engine at a similar rpm in reverse, spinning the boat 180 degrees as I passed under the bridge. I popped out the other side at around 10 knots over land to the cheers of a few commercial fishing boats. Made that maneuver up on the spot because it was either do that,or be smashed into the bridge if my mast didn't clear.

    I'm assuming that is "unscullable". It is not simole to control a boat with twin 30HP Yanmars in the conditions there. I doubt very much anyone could control a boat sculling there for a great portion of the day. I'm not sure you understand the current. It is the second strongest navigable current in the entire USA.

    It would be a lot like doing the luge in the olympics to take that boat out for a scull at most times of day there. :)

    Not trying to argue, just trying to understand how/where these boats were really used.

    Considering the lack of ducks riding the river rapids and the inability for the boat to do anything but act as a luge in the current there, I am inclined to believe these boats were used in towns like Durham, Dover, Newmarket and Exeter. So far inland, they didn't have to contend with the currents of the actual Piscataqua. That they would be used on the Oyster River, Cocheco River, Etc.... where the ducks are. Note these all feed Great Bay, which is what feeds the Piscataqua. All one large estuary.

    I'm really finding this fascinating. Thank you for sharing these boats and local history for me.
     
  9. XJ9
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    XJ9 Junior Member

    It looks to me like the half width and height of the chine shown on the offset table doesn't agree with the plan ...but I may be wrong???? If you follow the offset table, the boat shows a small transom bulkhead of about 2" high and the same width as station #8, but the plan seems to not have this shape, rather the chine and sheer meet at a width of slightly more that station #8. Maybe my eyes are playing tricks on me.

    Anyway, I have a Hull file with a bit of poetic licence used to make it look like the plan views. At least it might be a starting point.

    Simon
     

    Attached Files:

  10. ddoyle
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    ddoyle Junior Member

    Lewis and Xj9

    Huge thanks guys. I really appreciate what you have done for me. If either of you need a pound of bronze nails, a book for your shelf or any other token of my appreciation for your work please PM me a mailing address.

    I will study on your generous work this evening.

    Navigator,

    I agree I'd be happy to know the same thing regarding exactly where they were used. For certain there are currents that would defeat your ability to maintain steerage. I cannot guess about which sections of water they were used on. I can tell you however that if waterfowl raft anywhere on a hunk of water they are at risk of being sculled. The old boys that ran these boats for a living or to feed a parcel of kids went anywhere a seal could go. I hunted the Peace River, which runs at 7 knots, once. Doable but in no way to be construed as fun or safe!

    There is a scull boat specific to Both the Exeter R and the Cocheco R. I would have to do some digging but there is a family (name escapes me) which built the Exeter boats for at least two generations. The current son is not a builder (computer guy IIRC) but his father was famous in those parts for building very long lived skiffs. I have not been able to find a picture or a user of the Exeter sculls but it seems a number survive and are in service. A few people in Maine use Exeter and scull float interchangeabley. I think if you search Exeter skiff you might find a path to someone who knows the history of the boats. I had a mailing address for the family but never wrote.

    I'll browse thru some files tonight and see what else I have that is specific to your area and post them. If you want a raft of stuff to browse thru send a mailing address and I'll burn a disc for you with everything I have.
     
  11. ddoyle
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    ddoyle Junior Member

    Navigator:

    Some years ago these folks did some work/presentations on the history of sculling waterfowl in New Hampshire. They might be able to point you toward some hard and fast facts or at the least put you in touch with a member of the Whitham family who will be able to answer anything you can think to ask.

    http://www.newmarketnhhistoricalsociety.org/
     
  12. philSweet
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    philSweet Senior Member

    ddoyle,

    As far a developable surfaces go, start with Rabl's method. It supplies you with the curved shape of the frames to suit the panel shape. Ie., for ply on frame construction. If you are trying to stitch and glue, I have to tell you that the boat you have pictured is not an easy conversion candidate. It is going to require a very high level of accuracy to get the look right. The very flat bow plates and reverse curves are poorly suited to an easy stitch and glue conversion. It can be done, but it will be fussy and also will need a fair bit of temporary structure. I'd probably go with 7mm okoume ply (5 ply) in order to get control of the shapes.

    You will need to lap the sides over the bottom and drill the stitch holes precisely on the interior bottom line of the side panels. The sides can be cut 1/8 wild past the exterior line and trimmed to shape (because the angle is acute and the bottom will draw up to the stitches). The deck should overlap the side and the edge must be perfected before assembly (because the angle is acute in some areas and the deck will draw to the edge).

    In FreeShip, you get developable surfaces layer by layer. So assign the bottom, side, deck, and coaming their own layer. That way the plate development will give you something. It's no guarantee it is accurate, but the software does compare the area and perimeter of it's plate development to the properties of the actual layer surface. If you design a developable surface and model it in FreeShip, the plates should agree with the surface to four digits or so and convergence should happen in very few iterations.

    The trick in your boat is to make the result visually acceptable. Unless you want to paint it flat battleship grey or camo, then it is less of an issue. So basically, you need to design a new version of the boat on paper using Rabl's method, then bang it in to FreeShip and extract the plates, or just extract the plates manually off a largish drawing.
     

    Attached Files:

  13. ddoyle
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    ddoyle Junior Member

    Gee whiz guys, way to make a fellow feel gratitude. Phil, thanks a pile for your thoughts and thanks also for the Rabl document.

    I am on the verge of gluing some cardboard together and yes it does take alot of cut up chop sticks to get it right! On the plus side, despite my desire to get it 'right', the boat is destined to be painted "battle ship grey" and the myriad of pigments in a true battleship grey do go a long way to toward hiding wonkiness LOL. If things really went bad I am a bit of a student of cubism and "dazzle camoflauge" so that is the worst case scenario paint scheme. Unfortunatley for my long term contentment the boat is destined to live much of it's life on top of my vehicle and as we all know nothing shows off trouble quicker then displaying on top of a vehicle so that everytime you get in and out your eye follows a chine. My current scull float has an irksome bow and despite functioning fine drives me crazy.

    Again huge thanks all around it sure was a refreshing breathe of air to recieve such a welcome and such competent assistance.
     
  14. DCockey
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    DCockey Senior Member

    "There were a few, however, that were distinctive craft - on of which is shown in Figure 49. It is a form of ducker once popular on Great Bay, upstream on the Piscataqua River, a little above Portsmouth, New Hampshire."
    American Small Sailing Craft, p 132
     

  15. lewisboats
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    lewisboats Obsessed Member

    I thought that was what I did...
     
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