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Project Log:  Wednesday, November 10, 2010

As I continued work on new tankage design, I decided I ought to build some basic mockups of the proposed tankage outboard of the engine room before I progressed too far in the basic design and concept.  Seeing the basic measurements displayed in three dimensions would go a long way towards confirming the overall sizing, or perhaps lead the way to some design changes.

To help keep weight distribution as even as possible, I planned to split each space (port and starboard) into two tanks:  one each for diesel and water on each side of the boat.  This arrangement would be necessarily more complicated, but I worried about the potential unbalance that might occur otherwise; listing boats are just unacceptable.  Still, I vacillated on this issue, and hadn't made any final decisions yet.  One ongoing goal I had was to keep things as simple as possible, though without sacrificing utility in the process.  "As simple as possible" doesn't always mean inherently simple; it just means avoiding undue complexity wherever possible.

Why this additional tankage, one might ask?  Convenience.  With this boat more reliant on engine power, and therefore fuel capacity, I didn't want to become a slave to the fuel dock while cruising.  Since we tend to prefer more isolated, out-of-the way anchorages while cruising, the last thing I wanted to do was end up being forced into ports with fuel docks more often than necessary--even if one was just around the corner.

To a lesser extent, the same issue applied to water.  The more we could potentially carry, the better, not only in terms of fewer fill-ups, but also in terms of reduced concern over consumption and rationing.  Fueling and watering are things I'd prefer to minimize at all times; having become used to cruising without a need to ever stop for fuel and water over a two-week typical cruise, I was loathe to give up that freedom.  So, more tankage it is.

For the moment, I decided to build a single mockup for the entire space, just to check my measurements and see what changes, if any, I might want to effect.  From scrap cardboard, I slapped together a rough mockup of the port-side tank using the basic measurements I'd taken earlier.  The side facing the bench in these photos doesn't even have a side installed.


The full-size mockup fit easily through the pilothouse door and into position on the port side.  I'd intentionally left a good bit of space above the proposed tank to allow me to access the underside of the deck, bolted-on fittings, and so forth, but my initial thought upon seeing the mockup in place was that I could easily add a few inches in height, which would have a significant impact on the tanks' potential capacities.

Also, the triangular shape of the ends of the tank left a bit of wasted space against the curved hull--more than I wanted.  So I thought my next design would include a two-sided edge against the hull to help utilize some of this space.


Note that there's empty space aft of this "tank" on this side.  Because I want to make the new tanks for each side identical (except, of course, reversed), I chose the smallest fore-and-aft dimension for the overall length.  The starboard side was configured a bit differently, with an enclosed locker  (originally for propane bottles) at the forward end of the cockpit that closed off the aft portion you see open on the port side.

The quick mockup served its purpose well:  it confirmed the basic dimensions, but also highlighted the potential for useful changes that would improve and increase the tankage.  I'd use the information gained during this brief exercise to construct more accurate mockups of the next designs.

Total Time Today:  .75 hours

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