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06 November 2013

Want, Need, Can Manage: Core Considerations

Problem-Space Diagram


The only rules that really matter are these: what a man can do and what a man can't do.
  -- Cap'n Jack Sparrow


Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away
  -- Antoine de Saint-Exupery



Want, Need, Can Manage: Core Considerations

Design always begins with what we want

How could it be otherwise? Some vision - the azure lagoon of a South Pacific Isle, a quiet slough up Lazy River, glaciated peaks towering over wind-torn waters - some vision arises of ourselves, on-board in some place.

This vision won't be ignored. It takes over our dreams waking and asleep, urgent to make itself real.

Soon enough, it takes over our very lives! We find ourselves doodling the vision onto the margins of the morning paper, on napkins, on any odd scrap we come across. Dreamy doodles - what a friend calls 'cartoon boats'. Beautiful. Impractical. 

But, deep inside, gears are turning. 

We frown at our latest; erase here and there and redraw. This or that could never work, but this could! Hmm... we invest in some graph paper and begin to scale things out, pacing them off in our front room. We start carrying a tape measure with us, noting the dimensions of spaces, furniture, ourselves. Some of our wants clash, pull in opposite or competing directions. We weigh them and write our lists of pros and cons.

We are designing the dream.

Under melody and counter-melody of want - need starts to thump out a base-line. We need a place to sleep (hammock, cot, single berth, double, rumpus room?). We need to prepare food. We need to carry stores and gear. We need to work the rig. We focus and refine our ideas.
 
And, finally, there comes what we can (or are willing to) manage. What can we afford? What physical resources are available to us? How about temporal ones? What skills do we have, and which to acquire?

It's the dynamic tension between these three that makes up most of design. In the Problem-Space Diagram (above), Each corner represents a limit: maximum want, minimum need, maximum ability to manage. A particular design is a point within the 'space' created by these three attractors.

 If you plotted successive solutions, you'd likely see that point wander around. Our paths through this space often loop, blooming from need toward want, then collapsing abruptly back toward need. Occasional spiky forays toward the higher end of what we can manage, too.

Eventually, this tendency to wander settles down. It starts to tread in very tight circles as the big picture settles down to details within it. Of course, some minor detail can blow a whole design and set us back on our peripatetic course. 

But we narrow in.




*****

Anke and I want the usual, huge on the inside, small on the outside. 

We sail year-round on rough waters, without an engine, so we like a simple form of junk rig and shoal draft (both are great safety factors). We have to be able to work it as we age, so long as we remain reasonably healthy.

We carry a lot of food (a year's supply to keep us out as long as we want), gear (anchor gear, jacks, clothing, books and tools). We want to add some collapsible field kitchen gear, SWAB style (SWissArmyBoat) and be able to carry several cases of canned goods. We'd love to be able to mount a winch big enough to haul us above the tideline.

We both love to cook, entertain and slug a-bed.

Budget is a major factor, for us. We only want to put so much energy into the boat, be it earning the money for it, putting it together or maintaining it. We don't want to skimp, but neither wish to be lavish.

Economy and hull shape considerations are complicated by our strong preference for copper-plated bottoms. While we believe the copper pays for itself, it's a hefty initial outlay. And, being sheet material, its inclusion constrains hull shapes.

Our current boat, SLACKTIDE (T26x7), meets our needs, and then some. We're building to push closer toward satisfying our wants. Fortunately (for us), we're simple folk, and many of our wants stick close to the need line. Generally speaking, we're looking for a minimum solution, and are not tempted by maxima.

But. There is that pesky issue of efficiency-to-windward.

When we have a schedule to meet (way more often than we'd like), we find ourselves pushing 'uphill', sailing against the wind and working the tides. Our strategy has been get there ASAP and play around at that end, if early arriven. But hoo-boy! Do we sometimes wish we could slice our way into it!!

Four solutions (which can be applied seperately or together):
  1. Ditch our obligations -- Easier said than done... family, guests, work, bureaucracy. 
  2. Windward Rig -- Trade simplicity, economy and quick-reef for improved efficiency.
  3. Longer WL -- Increased WaterLine = higher HullSpeed for a more easily driven hull.
  4. Curvi(er) Dog Hull -- Improved hydrodynamic efficiency relative to the box barge.
First two are non-starters, for us. The rig is sometimes tempting, but the simple junk rig satisfies our needs like no other (more on this later).

A longer boat is a consequence of our expanded wish-list. Come what may, our hullspeed is going up. So this will be more of a tipping factor between solutions competing for other reasons.

Curvier Dogs, eh? We've got the skills and the means...

 In coming posts, we'll take a look at some of our contenders.

4 comments:

  1. (Posting for JOHN)...

    You wrote:
    Four solutions (which can be applied seperately or together):

    Ditch our obligations -- Easier said than done... family, guests, work, bureaucracy.
    Windward Rig -- Trade simplicity, economy and quick-reef for improved efficiency.
    Longer WL -- Increased WaterLine = higher HullSpeed for a more easily driven hull.
    Curvi(er) Dog Hull -- Improved hydrodynamic efficiency relative to the box barge.

    I've long heard that flat-panel junk sails aren't too efficient when sailed to windward, but I understand that the newer cambered-panel junk sails are as good or better than many Bermuda sails in this respect. Do you have any experience with cambered-panel junk sails that would confirm or deny this?

    John

    ReplyDelete
    Replies
    1. Hi John,

      There's going to be a lot more coming on Junk Rig (and others) and how it can be fit to our next boat. But briefly...

      We don't have experience with cambered JR panels, fanned sailforms or gurney flaps, but are considering them. The JR Association (junkrigassociation.org) is a wealth of knowledge and experience, which we've only begun to tap.

      Consensus is that cambered sails are a clear improvement, as are fanned sails. Many of these are competing head to head against marconi rigs and holding their own.

      Fanned sails are tempting, to us, but they require a number of extra control lines for best results, and they need to be precisely designed to achieve non-fouling batten stagger.

      Our reservations about camber are 1) finding a place to lay out and build anything more complicated than a flat sail, 2) concern about flogging in slack panels (unconfirmed, one way or the other... NOT flogging is a big psychological boon when it's getting wild).

      Gurney flaps look like a cheap and easy way to up performance, but haven't yet found out much about them. There's a good article at http://www.duckworksmagazine.com/06/howto/junkrig/.

      Dave Z

      Delete
  2. I believe you could build a cambered fanned junk sail in separate sections which are then added to two outer ropes as wanted. It should be easy to stitch them together with 3 mm poly line in wide "stitches" along the battens, in pre-made holes or small loops of cord/belt or similar. With a fully modular construction you can change any damaged or worn out panel, or adjust the fan-shape or the camber in any single or multiple panels as needed and wanted.
    You could probably sew the sails in your boat with this approach.

    Cheers,
    Johasnnes

    ReplyDelete
    Replies
    1. BRILLIANT!!

      Battens could be passed right through the lacing between panels, otherwise attaching only at the ends. It could be roped or not around the edges of the assembled panels.

      And yes, each panel would be easy to sew up below-decks, eliminating our need for a large, inside space.

      I'm gonna pass this on at the JRA!

      THANKS!

      Dave Z

      Delete

About Me

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Anke and I live aboard SLACKTIDE, our T26x7 ketch. We sail by wind, tide and muscle in the waters of mid- to northern Southeast Alaska. We try to maximize the joys of life, and minimize the chores. ........ We live between the communities of SE Alaska, but drop in to visit with friends. Lately, we've worked, every other winter, care-taking Baranof Wilderness Lodge in Warmsprings Bay. This has given us a window on Web. ........ We're working toward a subsistence lifestyle, somewhat impeded by addictions to coffee, chocolate and cheese. ........ We think TEOTWAWKI is looming, and while we won't be ready, we'd at least like comfortable seats.