Please visit our home site at www.TRILOBOATS.com.

Anke and I are building our next boat, and writing about it at ABargeInTheMaking.blogspot.com. Access to the net comes and goes, so I'll be writing in fits and spurts.

Please feel free to browse the archives, leave comments where you will and write, and I'll respond as I can.

Fair winds!

Dave and Anke
triloboats swirl gmail daughter com

Sunday, March 22, 2020

COVID-19: Why Nobody Likes Math


Double, double, toil and trouble!
-- Shakespeare


COVID-19: Why Nobody Likes Math
(Or at least, Mathematicians)

Um. The majority of people I speak with are busy making business-as-usual plans through summer.

COVID-19's global reach is doubling every 4 to 6 days resulting in explosive exponential growth. There's a lot of finicky issues in calculating these numbers... let's be optimistic and say it's only doubling every 10 days.

That is to say, the total number of people who have been infected with the virus doubles in every 10 day period. Let's roundly say that each month has three 10 day periods, so it will double three times every month. The total at the beginning of any month will grow by a multiple of 2... 4... 8 times by the end of that month.

As I write, today's global total is 300,000 who have been infected.

How many months ahead do you want to plan? Each month, the total grows by a factor of 8. Here's a convenient little planner:

  1. Mid-April ...              8 x 300,000   = 2,400,000
  2. Mid-May ...             64 x 300,000   = 19,000,000
  3. Mid-June ...           512 x 3000,000 = 153,600,000
  4. Mid-July ...         4,096 x 3000,000 = 1,228,800,000
  5. Mid-August ...   32,768 x 300,000   =  OOPS...
                                                              ...  exceeds human population.
  6.  
  7.  
  8.                          >>>  Here there be Monsters  <<<
  9.  
  10.  
  11.  
  12.  As I write, this is the earliest we might hope for a vaccine.

Things not cool today? So many months from now, the first number is how many times worse it will be at the present doubling rate. The math spotlights the urgency

If you can think in terms of doubling time (rather than days, weeks and months) it will help you with vital decisions.

*****

At the rates we used, the spread will peak sometime between four and five months out if it hasn't been flattened. That's the July? August? the President mentioned. 

While the CDC knows all this (their data, after all), they are coy about being specific. They urge, for example, that we have supplies on hand for "a period of time", or occasionally "two weeks". Yet stay-at-home orders implemented today are likely to be in place and tightening for months ahead.

China managed to flatten their curve and are seeing declining numbers of new cases. Whatever we might think of their politics, they moved relatively early and according to accepted epidemiological practice. In two months, they were able to locally flatten and reverse spread. Nevertheless, they may miss a case or two, or be re-infected from the rest of the world which has not taken strident measures to date. Then it's start over with the same 'draconian' measures.

Of course, this presently high doubling rate we're discussing won't sustain.

Social distance and travel restrictions will slow the rate of growth (won't eliminate it without unAmerican resolve). But these flattening measures also prolong the period of pandemic by spreading cases over time. Even if no measures are taken, the spread slows as a higher percentage of the population acquires immunity or dies.

Things won't turn on a dime. We are seeing measures ramp up late in the game, but early in the eventual spread. We hope to avoid the spike. At best, there will be tightening restrictions for months to come. Our best laid plans are all agley.

Meanwhile, the global economy is coming apart at the seams.


So provision up, batten down hatches and take a reef, me Hearties! 
Were in the storm, sure enough!!





The higher the dot, the slower the spread.
From Scientific American article


PS. Among the mitigation and travel restriction measures being implemented, travel by private vessel is being restricted in places around the globe. Even those of us who live aboard need to get where we want to be NOW, before rules and enforcement get around to our stretch of water!

Monday, March 16, 2020

COVID-19: Circle the Wagons

Important, but is it happening in time?
Treatment capacity lines seem optimistic, to me...
assumes healthcare is exceeded vs overwhelmed.

James gave the huffle of a snail in danger,
And nobody heard him at all.

-- A. A. Milne


COVID-19: Circling the Wagons

For those of you who don't know it, I've been huffling since the run up to Y2K about TEOTWAWKI - The End Of The World As We Know It.

Now I believe we're watching it unfold.

The basic factors are these
  • A fragile, Global Industrial Economy (GIE)... our tightly coupled, deeply indebted Complex Adaptive System (CAS).
  • A vast, overshot, human population which depends on a functional GIE for its livelihood.
  • Exponential spread of COVID-19 pandemic which will almost certainly overwhelm the healthcare system.
  • Failed containment and failing mitigation measures.
  • Exponential growth of associated problems.

Exponential growth of anything catches humans by surprise in almost every case. Windows of opportunity for meaningful action / preparation are snapping closed at a rate that's difficult for human beings to grasp intuitively.

NOTE: See here (~4 min vid... visceral impact of exponential growth) and here (~9min vid... exponential spread of COVID-19 vs flattening) to get a taste of the challenge.

David Korowicz lays out the general issues in his paper Trade-off (77 pages for the very interested) and specifically, pandemic based analysis in Catastrophic Shocks in Complex Socio-Economic Systems: A Pandemic Perspective (10 pages for the interested). Both are challenging reading, but, I believe, provide a foundation for viewing current events.

CAS's - such as the human body - have a range of stability. Within that range, they can be astoundingly resilient. But if events drive them beyond that range, a tipping point is reached and the whole system settles into a new equilibrium.

In the human body, an infection can lead to the loss of a critical function (breathing, say), and in a rapid cascade it collapses (and without rapid, correct intervention, dies). In a just-in-time economy, supply-chain interruptions block down-chain production and can rapidly paralyze the economy. In finance, disturbing the mountain of debt can bring currencies and institutions crashing down.

All of these are underway. [Or, for a less detailed and challenging glimpse of the problem, try this article.]

This is my long-winded way of saying that this is both serious and moving faster than we imagine.


 My Urgent Advice...

>>>  Get together with those you most love RIGHT NOW. Stay together for the duration.

>>>  Get together provisions RIGHT NOW (food, water, essential medicines, cooking/heating fuel) for a minimum of two weeks (CDC advice). Longer is better.

>>>  Make an isolation / infected plan and put it into action RIGHT NOW.

>>>  Don't panic, but GET MOVING.


Whether I'm right or wrong about larger consequences... even if the GIE manages to function beyond the crisis... even if your area has no known cases...  whether you are riding this out or hunkering down for trouble...

Containment and mitigation measures are shutting down travel and contact for unspecified periods. If flattening the curve is successful (our best chance), lockdowns will be in place for months, not weeks.

I say again, windows of opportunity are snapping closed.

Fair winds, health and happiness to all of us,

Dave and Anke




P.S. Here's some good advice from a guy who's been there.

Saturday, March 7, 2020

Ama AHA! Quick and Dirty Approach to a Small Multihull

Insurance for a narrow hull

My escape is to just get in a boat and disappear on the water.

-- Carl Hiaasen


Ama AHA! Quick and Dirty Approach to a Small Multihull

Let's say we can get our hands on a canoe, dory, kayak or other small craft. We enjoy paddling around, but are thinking a sail would really be kinda fun. But we're cheap.

What might we do?

To sail, we'll need some basic things:
  • Stability
  • Sail and rig
  • Lateral Resistance
  • Steering

Stability

I'll presume our little boat is narrow and tippy. We may get some stability from ballast, but that's awkward and complicates everything. So we look for ways to increase form stability.

The arrangement shown above looks quick and dirty to me.
Three features excite me...

A) The simple, bent ama shape... even with blunt ends, most of the time the immersed shape will be hydrodynamic. These look to be PVC which can be momentarily softened and permanently shaped with moderate heat (hot air gun, hair dryer or holding over a heat source). 

Small trees for cross beams and curved drift logs from the base of select trees would work as well, and can be quickly shaped with an axe.

B) The over and under arrangement with the cross beams... the aft strut could easily be eliminated with more curvature or an arced cross beam.

C) The whole affair can be lashed up... all we need is some line and a few holes bored below the sheer rail at mounting points.

This simplifies a scheme Anke and I have been wanting to try with our dory as well sas a planned, half-open beach cruiser, in which we can go into proa or tri mode using beachcombed crossbeams and akas. Using this approach, so long as the hull has xbeam mounting points, the whole thing can be lashed up with minimal carpentry. 
When done with a (windward) sailing stretch, we can disassemble and row/downwind sail off leaving the components in our wake. 

Of course, this works especially well in an area like the Cascadian Passage. Won't be so easy, in a lot of places where the beachcombing is limited.

Sail and Rig

A sail is a simple thing. Any flat fabric of the right size will do. Problem is, flat sails work (if you allow them to twist) but they are not powerful. A little shaping goes a long way. The trick is to get the right amount and proportion of extra fabric toward the middle of the sail.

Q&D fabrics include tarps of most any kind, house-wrap, awning material, sheets and so on.
Q&D solutions for shaping a sail:
  • Cut one or more perimeters with some curvature (curved away from the sail's center). When straightened along a spar or under tension, the extra fabric goes toward the middle.

  • Seize around one or more corners. This pinches the tied corner, tightens the perimeter and radiating cloth from the corner toward the middle.

  • Selectively dart the edges. This is a little fancier, and takes some knowledge or experience. But good in the tool kit.

Masts can be made from small diameter trees (chances are your guess at about right will be about right). If straight ones aren't available, consider a balanced lug rig, which sets well on a crooked mast.

They need at least two points of support - step (or heel stop) and partners with as wide a spread as you can manage (can always add stays). Since we're talking small boats, these needn't be too beefy. U-shaped pipe hangers have worked well for us as partners and stop. If the hull is thin, we'll add a small plate of plywood under the mast heel (bottom end of mast).

If you decide to go bigger, scale up as need be.
You'll need sheets to haul the sail in and let it out. A halyard is optional (sail may be fixed to mast). Some rigs will have their own extras. Consider rigs that keep the extras down (sorry Junk Rig!).

PDRacers are a racing platform with no specified rig. In short, you can see all manner of practical (and impractical) rigs for small boats here.


Lateral Resistance

The harder the chine (angle or radius between sides and bottom), the more lateral resistance from the hull. If we want to sail to windward, we'll need to add more.

Simplest means I know of is an Off-CenterBoard. Most just call them leeboards, but they work on both tacks. Of these, among the simplest is Jim Michalak's pivoting leeboard.


Steering

The simplest solution is no rudder. Balancing sail adjusted with sheets against lateral resistance adjusted by weight shifts (LR moves for and aft with crew weight). This is why sailboards need none.

An oar over the side or stern is next. A well placed pin or stern notch, respectively, help keep it in place and reduce fatigue.

A light kick-up rudder (bearing plate style is simplest of these) can be easily hung on strap hinges, and doesn't require mounting or dis-mounting when leaving or approaching shore.


*****

So there you have it. A bag of Q&D approaches that can have you sailing day after tomorrow! 
Don't forget flotation and life-jackets!






...

Full disclosure: COVID-19 has me on alert. If you may need to travel by water, it's a good time to be getting a boat in hand. Go small, go simple, get ready!