Dan Ingersoll’s handbuilt avocado boat. This variation of the avocado boat shows where a two-inch band of clay was left around the slumped bowl portion of the form and then rolled down to create the larger rim.

Avocados are a big deal these days. So, who wouldn’t want a boat to show off this luscious and healthy green fruit? 

Creating the Hump and Slump Molds 

Start by making a paper pattern in the shape of a 6-x18-inch oval. Trace the pattern to a 1-inch-thick piece of rigid pink builders’ foam, then cut out it with a jigsaw (1). Repeat this process to produce two more pieces of foam. Glue the pieces together to create a tall stack (2). The foam structure will define the contour of the form and serve as a support during the construction process. 

1 Use a jigsaw to cut out forms for slumping clay into to create a bowl form. 2 Stack the foam pieces, then glue them together with spray foam adhesive.

Trace the same pattern from the foam onto a ⅜-inch piece of plywood, leaving a generous area of wood around the shape of the pattern. Using a drill (to make a starting hole) and a jigsaw, cut out the shape (3). Later a slab of clay will be slumped into the hole in the plywood to create the bowl of the form. 

Next, using paper or wood make a straight-edged pattern the width of the height of the wall sections of your form with extra length to allow for the joining of the wall sections around the foam support (see 6). If the straight edge is made from wood, use a table saw to cut a beveled edge, which acts as a guide to cutting bevels when constructing the form (see 4). 

3 Slump mold, beveled guide edge, and finished foam support. 4 Use a template to cut out wall sections with a beveled top edge.

Forming the Slabs 

Using canvas and a rolling pin with thickness gauges or a slab roller, roll out two fairly large ⅜-inch-thick slabs. Tip: To transfer the slabs without distorting them, lay a board on top of the slab, wrap the bottom piece of canvas around the edge of the board, and make a quick flip of the whole package. 

Spray water onto one of the slabs, stick a piece of butcher paper on to it, and flip it so it is paper-side down. Using a wooden or paper template (the pattern I use is 3-inches wide, the height of the foam support, and 24-inches long), cut out two clay slabs that will become the sides of the boat form. Be sure to cut the paper along with the clay. This results in paper-backed slab pieces that allow for easy handling of the wet slabs without distortion or finger marks. Cut a beveled edge on one of the long edges of each of the pieces of the sidewall (4). The beveled edges will face inward and will match the contour of the bowl form to create a smooth transition when joining the side walls to the bowl. 

Joining the Slabs to Create the Side Wall 

The use of the foam support and paper-backed slabs allow for working directly with a fresh slab and does not require you to wait until they are leather hard. I like the immediacy of working this way. Carefully stand the side pieces up against the foam support with the bevel side up and slanting inward (5). I do this while the slab is still wet. Join the two side pieces on each end by squeezing them together with wooden squares (6). This reinforces this seam on the inside when the piece is leather hard and removed from the form. Remove the paper backing and set this section aside, uncovered to dry to leather hard. During the construction process, I use Magic Water in place of slip with good results.

5 Stand the paper-backed wall section against the foam support. 6 Use two pieces of wood to squeeze the ends of the wall sections together.

Slumping the Top Bowl Form 

Place the plywood with the hole in it on top of the second slab. It should already have a board underneath it. Squeeze the clay between the two boards in sandwich fashion, then flip the whole work over. Remove the top board such that the clay is now resting on top of the board with the hole in it. Carefully pick this up and begin to slump the clay into the opening by gently tapping the edges of the board on the edge of a solid table (7). Rotate the board and continue giving it gentle taps on each edge until the clay has slumped uniformly into the hole. Caution: If you tap too hard you will tear the clay on the edge where it slumps into the void. 

Now place a board on top of the slumped slab, flip it over, and remove the slumping board (the one with the hole in it). Once removed, the slumped form will retain its shape. 

7 Tap the edges of the slump mold on the edge of a sturdy table to slump the clay. 8 Score and slip both pieces, then attach them together.

Joining the Two Forms 

After the side walls and the bowl portion of the form have become leather hard, reinforce the end seams on the inside and use a Surform to clean up the outside ends. Then, place a board on top of the slumped slab and flip it over, releasing it from the form. Score and slip all joining surfaces, then carefully set the wall form (with the beveled edge meeting with the bowl surface) over the convex (upside down) bowl form (8). 

Cleaning Up 

Score, slip, and reinforce all seams with clay coils. Use a fettling knife and remove the excess clay around the bowl form (9). With one board on top and one on the bottom, flip the joined pieces over (10). 

Use a pony roller, a soft red rib, a metal rib, a Surform, and a white Mudtools sponge to smooth the seams and refine and clean up the form. 

9 Add a coil of clay to fill in all the seams and refine the joined areas. 10 Use the two-board sandwich method to flip the form upright.

11 Make a paper pattern to alter the shape on the ends to create handles. 12 The completed form showing one of the tapered ends.

Finally, taper the ends of the boat to give the piece some flare and lift while it sits on a table surface. Cut out a paper pattern in the shape of a half circle. Trace the paper template onto both ends of the boat (11). Cut out the clay sections on both sides. Dry fit, cut out, then score and slip a new piece of clay into the openings on both ends to close up the form. Secure the joined areas with clay coils and smooth and refine the surface (12). 

The piece is now ready to carve, slip, decorate, fire, and glaze in way you desire. Then it’s time to make guacamole! 

Dan Ingersoll’s handbuilt avocado boat, built using the process written and illustrated in this article.

Guacamole Recipe

Dan Ingersoll taught K–12 art in the public school system for 30 years (17 of them teaching high-school ceramics). Following retirement, for 3 years, he was a lecturer in art education at the University of Wisconsin-Eau Claire. He is currently retired and pursuing his passion for clay in a small basement studio and wood firing with a fellow potter. His work has been shown on both regional and national levels.