Project #3 Sailing Outrigger Canoe

    My lowest priority project at the moment, one that is still strictly in the planning stages, is to construct an outrigger, sailrig and sprayskirt to adapt a tandem tripping canoe for coastal sail travel.   

Adapted to a 17' abs or poly prospector-style canoe, the full rig would be:

• car-toppable
• relatively fast (estimate about 8 knots travel speed under decent wind)
• capable of carrying two people and enough cargo for extended wilderness trips
• quickly assembled or disassembled
• easily packed and unloaded
• much more seaworthy than a regular canoe
• durable enough to withstand running aground, landing and launching on beaches or rocks

The ama (outrigger) and akas (spars connecting the main hull to the outrigger) will be designed first, followed by the sail, leeboards and rudder.  The spray deck will be built last to accommodate the modifications that protrude above the deck line.  

The ama would be constructed from plywood, glassed over and fitted with Kevlar rub strips along the keel line.   The bulkhead within the ama will provide cargo storage space, accessed through a watertight hatch.     

 

Akas will be constructed from sheets of fir or sitka spruce laminated in a curved form.

I am using Solidworks a lot for this project.  It provides a quick, accurate method for determining displacement volumes and wetted surface areas of hull shapes under varying weight loadings, and bodies constructed of curved sheets (the plywood ama) can be unfolded to resolve the sheets' flattened shapes.




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Project 1 - Water Quality Data Logger - Progress

A little bit of progress on the data logger project.  The first prototype circuit is constructed:

The rear breadboard is just the voltage regulator circuit.  It is a 1.5 amp smps buck converter with a 3.3v output.  It is way bigger than this application needs, and I'll use a smaller cheaper one for the final design, and probably use this one for a bench power supply.

The front breadboard has the 18F4550, 20mhz ceramic resonator, and a SD card socket.  The SD card socket is homemade from header pins following this instructable:
 Cheap-DIY-SD-card-breadboard-socket

For starters, I'm going to forgo adding any peripheral sensors, and put together a program code that saves a dummy sensor reading and time stamp to a text file on the SD card for every three second interval.  Once that is working, I'll start to add sensors.

I've decided to use microchip's Memory Disk Drive File System software library, rather than PetitFatFS, since it should be easier to port to my chip.


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Project #2 - Subsurface Flow Wetland for Household Greywater Treatment

       I've begun designing a constructed wetland to treat kitchen sink and laundry greywater from the house I'm currently living at.  The system will reduce BOD, nitrogen and phosphorous levels from the influent greywater before it's released to the environment, where it will be used for garden irrigation.  It should be a fairly straight-forward project, as lots of documentation and guidelines for similar projects are available online, and the construction looks fairly simple.


      A popular source of diy greywater information is Art Ludwig's book Create an Oasis with Greywater, and his website, Oasis Design.  If you're looking for background information on Greywater, his website looks like a good starting point.  Another is the well-named Greywater Guerrillas (Because greywater treatment is clearly pretty subversive stuff. I find the anti-establishment side of DIY culture kind of funny).  Both seem to advocate simple designs that route the greywater through drainage pipe laid in mulch basins adjacent to plants with high water uptake (mostly fruit trees).  While this looks to work quite well in mild climates, I expect the winter performance would suffer in areas where plants are dormant for much of the year.  I think a wetland system would be better suited to colder climates.


      Two types of constructed wetlands exist: surface flow and sub-surface flow.  By keeping the water surface below the soil/gravel surface, the subsurface design avoids odour and mosquito breeding issues that may arise with surface flow systems, while also minimizing potential for human contact with pathogens in the untreated water.  For these reasons, I'll be building a sub-surface flow (SF) wetland.  


The US EPA has made available a lot of information about wastewater treatment with constructed wetlands, including specific design and construction guidelines: 


Handbook of Constructed Wetlands [pdf]
Subsurface Flow Constructed Wetlands for Wastewater Treatment [pdf] 

The EPA SF design guideline models the system as a first-order plug flow reaction, and provides an empirically-determined rate constant.  Sizing a wetland  using these guidelines is a simple matter of entering the influent flow rate and BOD, desired effluent BOD, bed depth, media (gravel) porosity and water temperature into the supplied equation, and solving for the wetland's plan area.  The maximum length-width ratio is limited by the hydraulic capacity of the bed, and must be considered to prevent the water surface from rising above the media surface.

I've roughly calculated the wetland size for my application using published domestic greywater flow, BOD, N, P, K and TSS characteristics  listed in a few different studies I found online. To achieve 97% BOD reduction from kitchen sink greywater in winter (design temperature = 4 degrees C), it looks like my system will need to be about 2.5m long x 1.5m wide x .6m deep.  During summer (design temperature = 15 degrees C), the reaction rate is much higher and the same wetland should be able to handle the additional flow from a washing machine.

   I intend to build a rectangular wetland, as pictured below:

• Inlet and outlet structures will each be constructed of PVC or ABS drain pipe, connected to respective sumps. 
•  A height adjustable standpipe in the outlet sump will allow control of water depth, which is useful for conditioning root growth of wetland plants
• Liner will likely be PVC or EPDM
• Basin will be partly dug, and partly built from retaining wall 

    I'm presently doing some foundation waterproofing work on the house I'm living in and will soon be ordering drain rock.  When I do, I'll assess the porosity of the available material, come up with a final design for the wetland and order enough extra for the wetland project.


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