The Onderdonk

What a great name for a boat! I stumbled upon the Preece and Onderdonk equations when learning about limits of electrical wires.

I’ve been designing the electrical system for our boat. Currently, we have a solar panel (60W), a lead acid battery (100 Ah), and a handful of navigation and cabin lights. We only use 12V devices on board and don’t have an engine, alternator, or shore power connection.

The battery box: charge controller, battery, fuses, switches all in one place.

The battery box: charge controller, battery, fuses, switches all in one place.

We will be increasing the capacity for new luxuries of a windlass, a laptop, SSB radio, cordless power tools, USB ports, VHF radio, etc.

My method for designing the system:

  1. Loads. Calculate your typical loads (amps) and duration (amp-hours) for a typical day. Not every device on the boat will be on at the same time!
  2. Battery capacity. Aim to have battery capacity of 3x that typical load, so that the batteries are only discharged by 30% per cycle.
  3. Solar panels. Estimate typical solar panel output on a “good” day, and on a typical day.
  4. Charge control. Without a charge controller, solar panels will overcharge and destroy a battery. The controller must be be rated for the charging current.
  5. Wiring. All wire will reduce the voltage and lose a percentage of power. Size the wiring to minimize voltage drop and power loss.
  6. Safety and distribution. Add sufficient fuses and circuit breakers, and an ability to switch circuits on and off.
  7. Iterate. Go back through these steps and make sure it still makes sense. Pricing provides the final decision.

What has been decided?

  • The batteries will be 12V AGM or gel with 160 to 220 Amp-hours capacity.
  • 400 W of solar panels which I estimate to provide 60 Ah/day to the batteries. The panels provide a peak 24 amps.
  • The charge controller will be a Flexcharge NC25A and is capable of handling AGM or gel batteries at a charging current of 25 amps.
  • The wiring will be 2/4 AWG for the main distribution, 10 AWG for the solar panels, and 14 AWG for general instruments.

More updates as we begin ordering and installing the parts!


Composite LPG Cylinder woes

After decades of a Primus kerosene stove, Piggy was upgraded with a propane (LPG) stove and oven. Propane requires pressure vessels and these must follow strict safety tests and lifespan. The typical barbecue tank is steel; the salty air around a boat created a market for aluminum tanks which are lighter, won’t leave rust marks and will have a longer lifespan. Unfortunately these are 5- 10 times the price!

A third alternative, composite tanks made of fibreglass, have entered the market. They are priced around 2 to 3 times more than steel, are half the weight, will never corrode, and are translucent to see the propane level.

I have found three manufacturers: Hexagon Ragasco in Norway, Lite Manufacturing in Tennessee, and Trident Marine in Pennsylvania. We purchased a Lite tank, which has now been recalled and the company has become insolvent. Oh no!

Is it really so bad? Can we risk using the tank? The company did not report the following issues:

  • 3 ruptures resulting in injuries or damage to property.
  • 19 cylinders returned due to sidewall and bottom leaks.
  • Selling 1000 cylinders to Dominican Republic after a suspension notice was issued for that model of cylinder. One cylinder failed during transport and injured occupants in the vehicle.
  • Selling prototype cylinders of with false safety certification.

In addition:

  • Did not proof test each cylinder at a high enough pressure (441 psi vs. 480 psi).
  • Did not randomly select cylinders for fatigue/burst tests, instead chose the first from each production batch. Did not follow up with burst tests after failures during production.
  • Insufficient maintenance procedures for the grinder/fitter.
  • Inoperable alarm system for running out of catalyst when gluing the two cylinder halves.

When the PHMSA shut down the company it found 4.6% of the inventory had leaks, and the previous 4 years had an increasing trend of failures!


Cylinder failures at Lite Manufacturing during proof testing (1.5x pressure during service) and leak testing.

Fortunately, it appears similar-sized tanks have just entered the Canadian-certified market. I’m planning to use Viking cylinders from Norway.

Where are we going?

Or perhaps, “where can we go?”

We are initially sailing for Hawaii  but the real destination is the South Pacific. Given the expected wind and ocean current, we expect to sail to Tahiti in the Society Islands. This will give us a safe port during the cyclone season (November to April), and relatively easy sailing when heading for New Zealand. See the map below for locations of the island groups.

Culutural regions of the South Pacific (click for bigger image)

My understanding is the region was settled by an Eastward migration several thousand years ago (mind-boggling), but that is the limit of my geographical knowledge. So here is a brief summary of interesting details for the different island groups:

  • USA
    • Hawaii: 8 major islands, most populous and largest area after New Zealand.
    • Johnston Atoll: An uninhabited, former navy base just south of Hawaii. Used for nuclear testing, now a national wildlife refuge.
    • Jarvis Island: An uninhabited island, claimed by the US in 1858 for guano mining. Production ceased after 21 years; the island was claimed by the UK, then the USA again, and has since become a national wildlife refuge.
    • American Samoa: A territory of 5 volcanic islands and 2 atolls, the smaller eastern half of the island group.
  • Samoa
    • In the 1890’s, a civil war between Samoans and colonial interests of Germany, America, and Britain was concluded after a cyclone destroyed warships stuck in a standoff. The Western half of the islands were given to Germany in 1899; this group became independent in 1914. Known for rugby skills.
  • Tuvalu
    • 4th smallest country in the world. 3 reef islands and 6 atolls with 10,000 people. Highest point: 4.6 metres above sea level. Known for how climate change is steadily submerging it.
  • Tonga
    • One of the very few countries in the world to resist European colonization (Kingdom of Tonga).
  • Pitcairn Islands
    • Technically a British Overseas Territory. Settled by mutineers from the HMS Bounty in 1790; population is now about 50. Known for being the most remote inhabited island in the world. Genetic diversity likely limited to 4 males of the original mutineers.
  • New Zealand 
    • Cook Islands: Population of around 20,000 spread over 15 islands, and sees about 100,000 tourists per year.
    • Niue: One of the world’s largest coral islands, 1400 people in 260 square km. The name translates as, “Look, a coconut!”
    • Tokelau: 3 atolls, population of 1400. Only a few metres above sea level.
    • Kermadec Islands: Uninhabited nature reserve.
  • Easter Island
    • Stone heads carvings and a population that deforested the island. Administered by Chile.
  • French Polynesia
    • Austral Islands: southernmost region of the group. The last region to be populated in the Pacific.
    • Marquesas Islands: easternmost group, experiences occasional droughts. After the Pitcairn Islands, likely the most distant island from a continent.
    • Society Islands: Two administrative divisions: Windward and Leeward Islands. Includes Tahiti and Bora-Bora, which claims to be the most beautiful island in the world.
    • Tuamotu Archipelago: the largest chain of atolls in the world; area of Western Europe.

Simplified regions of Polynesia. Click for Wikitravel information.


Welcome to the blog of our sailing adventures on Piggy. I will be updating both with progress of our boat preparations and live updates from the Pacific ocean!

The available pages are still half-filled templates. For now, here’s a recent picture of Piggy.

Piggy hauled out

Stay tuned for more!