The "NANCY G" a surfboat /lifeboat to motorsailer conversion build in progress

Discussion in 'Boatbuilding' started by viking north, Feb 11, 2011.

  1. viking north
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    viking north VINLAND

    (ALL VIKING POSTS ON THIS THREAD SUBJECT TO ONGOING EDITING FOR CLAIRITY AND UPDATES) To allow a continious flow of presentation and any feed back or questions I thought it more convenient to start a dedicated thread on this build rather than present it thru Boatbuilding underway.The problem being is this will take place over the next two years and it would become lost over that time. Under this system i can re post from a buried page back to a more recent page as a "continuation". The idea being it will provide a give and take on ideas and hands on building related to both conversions of a given hull into another use and aid in modifications of an existing use hull. This build in a way is a continuation of the info on the reverse engineering thread posted under the "Boat Design Heading," plus the great input of other threads related to this specific build and i will point them out as the build unfolds. Before we get into the meat and potatoes, I should post a disclaimer, that this is an example of how i did the build and that in no way is it to be used as an engineered reference on how to do it. If you decide to do a similar project i recommend you do as i have done, engage the expertiese of a professional as you deem necessary. Having said that all questions and input are welcome. Once again I thank all the forum members who have provided of their time and experience thus far to help me make this build more than just another back yard project. Thanks . Ok photos and some info on the past history of the hull.
    The hull is a former heavy hand laid fiberglass surfboat style Ships Launch/Workboat/Lifeboat off a cable laying ship.LOA 27ft. 6in x Beam 7ft. 6in. weight as purchased not stripped of non essentials 4500lb. Thus far i have stripped out approx.600lb. of non essentials. present weight 3900 to 4000lb.
     

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  2. Scunthorp
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    Scunthorp Hull Tech

    Nice work george I think I will be quite intimate with this project by the time you are done.
     
  3. wardd
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    wardd Senior Member

    if you don't mind what was the purchase price?
     
  4. viking north
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    viking north VINLAND

    Sorry Wardd, i meant to include that info, $3500 plus $500 to have it trucked to my shop. Correction my accountant (wife) informs me it was $3000 plus $500 for transport, total $3500. Geo.
     
  5. wardd
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    wardd Senior Member

    did it have a usable engine, if so what was it?
     
  6. viking north
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    No engine it had a big 4cyl. i think water cooled Lester origionally but was removed before i bought the boat. Much too big and heavy with gearbox must have been close to 1000lbs. geo.
     
  7. viking north
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    viking north VINLAND

    Taking Off The Hull Lines

    If your hull does not contain any superstructure as most lifeboat hull's don't, it is physically easier to do this with the hull inverted, however either way will get the job done. For an accurate outcome the key is preparation and patience.Allow a week part time to do the job, it is much more relaxing. You can do it in one or two days but it will drive you nuts.

    You will need the following tools and materials.
    BLOCKING--6x6, 4x4, 2x6, 2x4
    WEDGES---2X4X18 cut diagionally on it's flat corner to corner(makes 2)
    BIG HOME MADE SQUARE--legs longer than 1/2 beam of the hull ( use 3, 4, 5, ratio to build your square)
    STEP LADDERS-- one 6ft. and one 8 ft. would be good
    LEVEL--- 4 or 6 ft long
    PLUM BOB -with a string reel that has a string lock-chaulk line reel excellent.
    MEASURING TAPE--a good 1in. stiff foil unit.
    Hydrolic jack-- 2 to 5 ton low profile
    COLD BEER -- to attract a weeks supply of a helper

    My first step was inverting the hull and levelling it longitudionally with the run of the existing keel and transversely gunnel to gunnel somewhere close to midships, This is where blocking and wedges come in handy. It is not necessary to invert the hull but in my case i dealyed taking off the lines until i was ready to install the keel. It depends on when you require the lines to be taken off for design purposes.

    To be continued, Thanks for visiting and for input,--Geo.
     

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    Last edited: Feb 15, 2011
  8. Scunthorp
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    Scunthorp Hull Tech

    What is the best material for the "Hat section" to support the keel bolts. Teak, white oak, some kind of polymer? Why would layers of plywood which is strong due to the orientation of the plies not be better than say a solid oak????

    check this out...http://www.angelfire.com/tn/santana525/525_keel_bolts.html
     
  9. viking north
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    viking north VINLAND

    John, really good questions,especially the use of ply.Would like to hold off for a week or so when we get to that stage all forum members can have a good old discussion on it.It will flow better as a topic relating to the photos that will be posted and the stage of construction involved. I also ask forum members to hold off on related input to Johns question until then. Thank You for everyones understanding Geo. ( John would you re post once i have gone thru the floor timber and and associated keel bolt holes drilling, as i am particularily interested in the feasilibility of ply laminations for floor timbers, Tnx. Geo.)
     
  10. viking north
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    viking north VINLAND

    MISC. PHOTOS, Levelling and Blocking, the shop,

    Just a few photos on levelling and blocking, My workshop where the hull with the actual keel and ballast installed and mounted on a cradle will be moved to in the spring for the continuation of the build. Note the use of stainless beer kegs for blocking supports. Why throw them away after ther're empty :) Also Note the line level on a string across the hull at midships,in addition to checking the fore and aft level along the existing keel also check this daily before taking lines to make sure she's level beam wise. Be patient in getting it all levelled up and keeping it level (wedges)it pays off in the long run.
    To be continued, The actual process of set up and taking off the hull lines in a couple of days. Tnx. Geo.
     

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  11. viking north
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    viking north VINLAND

    TAKING OFF HULL LINES(setting up the tools)

    NOTE EDITED(Partly rewritten for clairty since first posted) These photos show a long piece of box alum. temp. fastened to the existing keel with it's edge aligned along the longitudional centerline of the keel. This provides a working edge referenced to the orig. keel's longitudional center line and simplifies lining up the big square so it's transverse leg is at 90deg, to the longitudional center of the hull. We'll call this the "Longitudional straight edge" for want of a better name. Any long straight piece of wood will also suffice but fix it in place to keep your measurements accurate.( If the hull was in the upright position a similar set up can be used with your longitudional straight edge run along the side of the keel but parallel to it's longitudional centerline at some fixed minimum distance out. You simply add this distance to the first out measurement on the transverse leg of the big square at each station. Example if your first out measurement on the transverse leg on the square is at the 0 in. location(corner of the square) and at that station the Straight edge is 8in out from the cent. of the keel your actual distance from which you measured is actually 8in. out from the keel longitudional cent. line.Following that same process if your next measurement is taken at the 6 in. out location on the leg of the square, that measurement is actually 8 in. plus 6in. for a total of 14 in. out from the longitudional cent.of the keel and so on for all consecutive measurements.) Note the big square with it's 90 deg. corner set on a station mark,( this photo station #9) one leg aligned and set tight to the Straight edge and the other transverse leg levelled using blocking on top of one of your stepladders. Also note the transverse leg marked off in 6 in. segements.We are now set up on a station and ready to take the hull trans curvature measurement numbers using our plumbob and measuring tape.

    Next post,taking the measurements using the plumbob and measuring tape,marking the locations on the hull and recording on paper.
     

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  12. viking north
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    viking north VINLAND

    Hull Lines Taking The Actual Measurements

    Ok we have the hull level in both directions, The straight edge in place along the keel centerline. We now have to divide the boat into stations. If you are using Simpsons rules to produce hull line drawings set up 10 equally spaced reference points (stations) longitudionally along the hull, in this case along the Straight edge. If you are plugging your numbers into a computer program it is not necessary they be equally spaced but it is always a good habit to do so. In my case most are equal but not all as i will be feeding them into a computer. Ok having done that lets continue; With the big square set up and levelled on a station we measure out from the Straight edge(long. cent. of the keel) to the keels edge, make a note of this distance as it is 1/2 the width of the keel at that particular station.(At station #9 in the photos this distance is 4 5/8 in.) Then measure from this point (bottom of existing keel) down to the hull surface(turn of the keel)( on a wooden boat this is where the garboard plank edge meets the keel i.e. the garboard seam) Make a note of this measurement as it indicates the external dept. of the keel at the station you are working on.( At station #9 in the photos this distance is 5in.) You will need both of these measurements as starting points when drawing the hull lines of the station you are working at. Now we will start working our way out along the transverse leg on the big square using our 6 in. reference points with the plumb bob, the measuring tape and a carpenters graphite pencil. (do not use a felt marker, it will leave a permanent mark and bleed thru paint and gel coat). In the photos I am working on station #9 and have taken measurements at the 6in., 12in., 18in., 24in., ref. points on the transverse leg of the square and am presently taking measurements at the 30in. mark. All the prev. 6in. spaced measurements were done exactly as described and shown at the 30in. point. I simply lined up the plumb bob string on the 30 in. mark let it out until the plum bob tip is just barely above the hull surface(not touching) When it stops swinging using you graphite pencil mark an X on the hull directly below it's tip. Remove your plum bob and using the measuring tape set on the 30in. mark, measure the distance from the bottom edge of the big squares leg to the X mark on the hull. In this case 11.75 or 11 3/4 in. Congradulations you have just made your first of 1000 measurements of you hull lines. :) You will see the following numbers written on the hull in the photo. 9(Station #9) below it 30 (30 in. out from the keels edge) and 11.75 or 11 3/4 in.(the distance from the bottom of the big squares edge to the hull surface which by the way is also the distance from the bottom of the keel to the hulls surface)( the big square has been leveled from the keels bottom face) By taking these 6in. spaced reference measurements at right angles to the longitudional center line of the keel you are obtaining X & Y axis plotting numbers that represent the curviture rate of the hull at the particular station along the hull you are working at.( In the photos station #9) Now one final important piece of info, As I worked out past the 30in. point say to 36in. then 42in. then 48in I reached a point between the 42 and 48 in. where i ran out of hull surface to drop the plum bob down to. So in this case simply find a point where the plum bob just hangs above the hull's edge. Using your pencil mark where the string sits on the leg of the big square. Measure your distance from the 42in. mark and add that amount to 42in. In my case it was 45in. out or 1/2 the beam of the hull at station #9. Continue this process of obtaining your hulls X&Y plotting numbers at all the stations you have set up along the longitude of the hull. Next post we'll get into plotting station #9 on paper. P.S. in the center photo you will see a hunk of lead placed on the string holding it in place freeing up a hand.

    A yacht is not determined by the vessel but by the care and love of her owner.
     

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  13. viking north
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    viking north VINLAND

    Transferring hull measurements to paper

    Wheather or not you are feeding your hull takeoffs to computer,I recomment you go thru the process of transcribing them to paper. As a builder this process has always built the hull in my brain. I can't express how this small step will aid you both in your build and a more complete connection with them once they are plugged into the computer. You get to know both the good and not so good qualities of it's form so much better from working manually with those numbers and their plotted lines. The transfer of the info is nothing more than your X & Y graphs from school. So many units horizontal along the X axis and from that point so many units vertical up the Y axis as the following photo illustrates. All the hull line info from each of the stations will be transcribed in the same manner. Once you have completed the taking of your lines at all the stations you have selected the next step is a set of lines that I approach and do in a seperate step. That is the taking off of what i call the profile info representing the curviture of the existing keel commonly known as "Rocker" and info representing the bow and stern curivature profiles. I will show you how I do this in the next postings. Geo.

    A yacht is not defined by the vessel but by the care and love of her owner
     

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  14. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Bow, Keel and Stern profile lines

    In the photo the Straight edge is still lined up with the longitudional cent. line of the keel, extended out over the bow and kept level with the bottom of the orig. keel by a support pole. A similar setup is also used to obtain the profile of the stern. If the hull was in the upright position you would use the same set up in reverse. Working out toward the stem head, simply set your plum bob at each station, let it settle on it's respective spot over the stem, mark that spot and measure the distance. I selected my stations at 20in. intervals from midship station #8 forward and was left with a distance of 23.5 bewtween station #1 and station #0 which was ok as the bow curvature was pretty much a continious curve. I.E. no abrupt changes or reverse clippers. The info numbers for the Bow, Keel and Stern was then transcribed onto paper in the same manner as it was with the transverse sections. Notice from station #8 to the end of the existing keel at station #16 the irig. keel is flat, however from station #8 forward to the base of the stem say statation #4, the keel has curvature (Rocker). This info on the flatness or curvature of the orig. keel is important to have in order to build the mold (Plug) for the shell of the new keel. Next post, info on bow and stern measurements that will finalize the hull lines in prep for input into the designers computer.
     

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  15. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Bow & Stern End Shapes

    The purpose of taking measurements to represent these shapes is to allow the designer to develop(blend) the hulls lines into a closer representation of the actual bow and sterns actual profiles and not just bringing them to a point. In this hull without this info it would have required alot of modification (adjustment ) and not be a proper model of the actual hull.The measurements and drawings speak for themselves. Next post i hope to present the actual hull lines as produced by the designers computer from the input measurements we have taken. ---geo.

    Edit P.S.The term "parabolic" is used for want of a better description of the edge shapes of the bow and stern.
     

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    Last edited: Mar 5, 2011
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