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Project Log:  Thursday, November 11, 2010

My down and dirty tank mockup for the new engine room tanks served its purpose for confirming basic dimensions, but its fit also suggested the need for certain changes and improvements.

Disassembling the original mockup, I held the forward and after ends in place against the hull; the simple triangular shape left large amounts of wasted space against the curvature of the hull, space that I could gain back by changing the shape of the outboard side of the tank.  I also determined I could add four inches to the height of the tank.

With a compass, I scribed the shape of the hull onto the cardboard.  Then, down on the bench I used these rough templates (one for each end) to lay out a polygon on new cardboard that better approximated the shape of the hull at each end of the tank space.

Aft End

Forward End

My initial layout featured a four-sided outboard edge, but I later simplified the shape by combining the top two sections on each piece by connecting the top corner with the bottom of the second segment, leaving a three-faceted edge.  This three-faceted shape is what you'll see in the remaining photos of the tank mockups.

With the shape of the forward and aft ends of the overall tank space thusly determined, I proceeded to connect the two pieces with a top and inboard side, using the full length of the space as a measurement.  Although I had about 48" to work with, I used an overall dimension of 47" length for the tank to provide ample space for the two tanks.

Once I had this three-sided, backless shape in place, I had to divide it in two to create the pair of tanks I intended for each side.  I wanted the tanks to be roughly equal in capacity, so rather than cut the mockup in half midway along its length, I made marks 20" aft of the forward edge, leaving 26-3/4" length for the after tank, since the forward section was deeper and therefore could be shorter.

With some layout lines drawn square to the tank, I used a long straightedge spanned between the forward and after ends to simulate the back (outboard edge) of the tank at each of the three corners defining the facets, and then measured straight up from the "tank"  to each corner, providing me with the measurements I needed to cut the shape of the tank at this cut location.  I made a pair of templates this size since the aft end of the forward tank, and the forward end of the aft tank, would be identical.

After cutting the main mockup in two along the pre-determined line, I assembled the final mockups for the forward and after tanks, incorporating back  panels as needed.



The new tank shape was now too wide to fit through the 19" wide pilothouse doorway, but they fit easily through the large overhead hatch in the pilothouse.


I decided that I could further simplify the tank design by combining the two lower facets into one, with minimal loss of tank capacity, so I planned to make the appropriate changes when I drew  up the final tank design.  I found that these extra facets--besides making the tank more complex to build--also interfered with the hull, particularly on the aft end of the after tank, and in the interest of the best fit and most realistic simplicity, as well as seeing how the tanks truly fit in their full three dimensions, it seemed clear that this was the right course.

Later, I continued work on deck and sanded the port sidedeck, cabin trunk, pilothouse, and bulwark with 80-120 grits on my vertical axis random orbit (VARO) sander.  Then, I similarly sanded the foredeck, forward end of the cabin trunk, and the remaining bulwarks up to the tip of the bow.



Total Time Today:  6 hours

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