The DW_Punt

by Peter Vanderwaart
Drawings
Bio

  1. Prefatory Generalities

    As I imagine the winning entry for this contest, it comes off the drawing board of the late Walt Kelly. There's a broken-down, hillbilly cabin, relocated to a leaky raft, moored to stakes in the soft mud of a leafy swamp. I see a fishing pole sticking out a window and a jug of corn liquor on the porch. For local transportation, a moss-laden, flat-bottom skiff trails at the side, oars in a jumble.

    Well, I haven't spent much time thinking about such things, I don't have any especially bright ideas in that line, and I couldn't draw them if I did. Scratching my head hard enough to engender a little creativity, I did investigate the possibility of mounting a store-bought, kit-built, geodesic dome on miniature barge. It seemed workable, but better suited to huddling against the cold of a New England winter than enjoying summer in the Okefenokee. I dropped the idea.

    The problem, I think, is that I didn't want to let go the idea of designing a boat, an actual vessel. So I decided to explore the possibilities of a minimum, liveaboard boat. One obvious possibility would be some variant on the New England catboat, a type of which I am fond. It could be made to work, without doubt, but construction of a catboat is a real job of boat building, and the spec calls for something quicker.

    Perhaps the most successful design of the intended type is Philip Bolger's Jesse Cooper. Several boats have been built, they have been used as intended, and owners have reported satisfaction. On the other hand, Bolger himself has noted a list of deficiencies, so we need not regard the design as definitive. I adopted the idea of a vessel along similar lines, but smaller (if possible), simpler (if possible), with interior improvements (if possible). For these benefits, I was prepared to sacrifice seaworthiness and performance. I gave long study to Jesse, and to Bolger's design for a live-aboard scow schooner.

    These drawings are my version of what Bolger would call a cartoon (his are hand-drawn), and what others might call the first cycle of the design spiral. In other words, this is the first try at getting the principal concepts meshed together. Chances are that everything would change a little in the next cycle, but the overall pattern is clear.

  2. Description

    The leading dimensions are:

    LOA: 22 ft.
    LWL: 20 ft.
    Beam: 7 ft. 8 in.
    Displacement: 5000 lb.
    Draft of hull: 1 ft.
    Draft of leeboards: 4 ft.
    Sail Area: 316 sq. ft.

    Lines: a punt underbody with very high sides, twenty-two feet long. The middle bottom comprises three full-width sheets of ply. Additional beam is obtained with a bilge panel. On the straight (in profile) and slightly raked upper chine, the upper sides are erected using three more sheets, also full width, slightly flared. The bilge panel tapers to a point at each end, so bow and stern transoms are each rectangular and vertical. Ballast will be required, even in a no-sail version, to balance the high, wide deck and the personal gear located in bins and cabinets built in the higher (i.e. more convenient) volumes of the cabin.

    Interior arrangement: the cabin is divided into three main areas. Forward, we have the dinette, pushed up adjacent to the open forward well. The dinette is 6 ½ feet long and can be converted to a double berth. Footroom diminishes going forward, but four should be able to sit comfortably, leaning against the flared side. Aft of the dinette is the work room, devoted to galley and navigation. The forward portion of this section, and the aft part of the dinette, are covered with a trunk cabin giving over six feet of standing room. The companionway ladder, which descends from the bridge deck on the port side, has more steps than shown and is about as steep as a step ladder. (The side-facing, vertical ladder on Jesse Cooper is one feature that would never be accepted by the tradition-bound geriatrics that I sail with.) Aft of the ladder and under the bridge deck is the head. The W.C is near centerline on the flat bottom to give maximum headroom. The floor area to starboard forms part of the head as necessary with privacy from the work room and aft cabin provided by a two-position swinging door and/or additional doors and/or curtains. Aft of the work area and head is the master suite, dominated by a double berth. The after portion loses headroom to the footwell above.

    Exterior arrangement: there are open wells at each end. The forward well measures 18 inches fore and aft. Wells like this seem to be popular in Bolger boats, used for anchors and wet line. The aft 30 inches are for a proper outboard motor well. There is the short trunk cabin, a fairly long bridge deck, and small foot well to form a cockpit. Around the footwell is a low coaming.

    Power: the specs do not require power, but I imagine that a well-used outboard of 10-15 hp would be very useful, nicely fitted with remote controls and steering in the cockpit. Possibly, a straight power version should have a skeg.


    Sailing rig: this is an all or nothing proposition. If you are going to sail, you need it all. If not, you don't need any of it, even the rudder. As I see it, the rig should be quite large. The blunt bow disqualifies this from being a heavy weather boat, so adequate sail for light weather is required. The 316 sq. ft shown is probably minimum. I think the gaff rig is about the simplest. The mast has a deep bury in the forward well. A boom gallows (not shown) will be welcome for keeping the rig tucked away and quiet while in residential mode, and also provide roll bar protection against the low-swinging boom for those seated on deck. Leeboards simplify the construction, and don't compromise the interior.

     

  3. Summary

    The basic boat is an efficient volume to build from ply sheets. Provision is made for a rich list of desirable features. However, the devil is in the details, especially the workability of the centrally-located head.

    The boat should sail and power well, except for conditions in which the blunt bow make it impossible. Properly built and ballasted, it should be safe in any reasonable conditions, even those in which it can't make much progress in the upwind (upwave?) direction.

     

  4. Appendix I – looking forward

    As noted above, this is the first look. What would be changed in the next refinement?

    These lines do not allow adequate displacement, and the ends, especially the bow, need to be higher. The fix is more rocker on a shorter waterline. The chine should be higher with more rake, which may help move the widest point forward, benefiting the leeboards. The whole boat can be at least 6" longer and still come out of three sheets, even allowing a loss of 6" per butt for overlap. Looking carefully at the requirements for the motor, the length of the well can be shortened from the 30 inches shown here. All of the additional length would go in the work area, easing crowding.

    The accommodation plan is based on the bridge deck (to give headroom in the head), but dimensions and details of the footwell/cockpit area deserve closer study.

    As for the rig, the greater rocker will allow a better shape and more area for the rudder. The ultimate sail area is dependent on stability calculations.

     

  5. Appendix II – an explanation

    The most observant of readers will have noticed that the curve of the bottom, as seen in profile, is not a single smooth curve, but has inflection points or "recurve" at each end. Let me explain how this happened.

    Thinking to get a nice curve without having to create one myself. I copied the coordinates for the chine line from a Bolger sharpie into my spreadsheet and used them to calculate the curve of areas. Then, dipping into my toolbox of analytic geometry gadgets, I calculated the chine coordinates for the punt to get a set of lines with the same curve of areas, adjusting to the desired displacement. It was only after I laboriously entered all the digits into my CAD program that I noticed the recurve effect. By that time, it was too late (and/or I was too lazy) to start over. Interestingly, since the concept calls for an upper chine and sheer that are straight in profile, the recurve is translated into plan view there.

    In a new lines plan incorporating the changes indicated above, the recurve would disappear. The episode illustrates a) the perils of design-by-spreadsheet and 2) the limitations of simplified hull shapes. Filling out the ends to a simple curve should increase the prismatic coefficient to the benefit of high-speed sailing.

Drawings:

Bio:

Peter H. Vanderwaart – a short biography.

Mr. Vanderwaart was born and raised in a land-locked town in New Jersey. He was introduced to sailing as a child by his father, a self-taught sailor. The family's boats were a home-built, plywood Sailfish and a GP-14 dinghy. Sailing vacations were passed on Cape Cod and in the Boothbay Harbor area of Maine.

Having developed a liking for Maine, Mr. Vanderwaart attended Bowdoin College, graduating in 1968 with a degree in mathematics. In December of that year, he was drafted into the U.S. Army and served a tour in Vietnam as an army bandsman. On return to civilian life, he attended Brown University and was awarded a Masters degree in mathematics in 1972. It was at Brown, that he discovered his vocation in operations research and management science.

In July of 1972, he married Janet Rush of Newark, Delaware. (Mrs. Vanderwaart is known to all as "Polly.") They settled in Connecticut, and have two children. Presently, Joseph is a graduate student in computer science at Carnegie Melon University, and Catherine is a senior at Swarthmore College.

Most of Mr. Vanderwaart's career has been spent trying to decide what boat or boats he would purchase if he became truly rich in some miraculous way. For the past several years, he has been sailing a Capri 22 sloop.