The purpose of a custom electronics box is to provide a lightweight, accessible, easily modifiable, cool (temperature-wise), splash-proof housing for Fish ‘N Ships’ electrical components.

At first, we debated if we even needed a custom EE box. Off the shelf options are cheaper, require less labor from us, are rated to depths well beyond the design requirements of the box, and are already commonly used by RoboBoat teams. Modifying such boxes, while inelegant, is neither costly nor difficult, though it does make the box’s original pressure rating irrelevant. The question thus became: can we manufacture a box that offers a better weight to volume ratio than the leading alternative? And would it be worth the cost? We decided there was a high probability we could--and that the cost was more than justified by the learning experience.

Version 1:

The initial design of the EE box focused on accessibility, modularity, and thermals. It consisted of an ⅛” aluminum base, ⅛” acrylic walls, removable faceplates, a large “land” lid, and smaller “water” lids. This version of the box condensed the boat’s sensors and electronics into a single sub-assembly--i.e., its “brains”--that could be removed and tested independent of the hulls. The electronics were designed to mount to slightly elevated acrylic pegboards (elevated for subterranean wire management). Thermals were managed passively by aluminum “sleeves” that wrapped completely around the hulls and made direct contact with the box’s aluminum base. Overall footprint was roughly 32”x16”x6.5” (not counting the height of the sensor mast). This first design weighed ~13 lbs, roughly 12% of the team’s weight budget at the time, which we decided was far too much, which led us to make major changes in version 2.

Fig 1. EE Box version 1.

Version 2:

Design two features the elevated peg boards and removable faceplates of the first design, only this time they’re compressed into a footprint roughly a third the size (12”x16”x8”). To account for this compressed footprint the pegboards were elevated ~4” off the base (enough room to rotate the average human hand comfortably)--opening up a second layer for mounting components. The focus on weight reduction meant the old aluminum base with its heat finned cooling system was a non starter.. Fabric--engineered by a fashion industry focused on breathability, water resistance, and weight--was the obvious replacement. The new box was constructed almost entirely out of an ⅛” plywood frame, and the lid draped in PolyUrethane Laminate--a lightweight, durable, water resistant cloth commonly used for DIY diapers. Finally, fans, protected by 3D printed shrouds, were added for increased airflow.

Fig 2. EE Box version 2.

Version 3 (Current Design):

The current design retains many of the core innovations of the previous two--including the elevated peg boards, fabric lid, and removable faceplates. The primary driver of this iteration was usability feedback from the EE team: a self locating pin was added to make aligning the lid easier when latching the box shut and to prevent water from pooling during rainy tests; the number of mounting screws per faceplate was doubled to prevent water from entering the box when rogue waves swept over the deck; 1/32” aluminum L brackets were fastened to the edges of the acrylic pegboards to prevent the previous bowing/flexing/swaying behavior that made mounting components to the pegboards difficult; compliant hooks were added to keep the latches in the “upright” position while lowering the lid; and the Jetson was mounted on L-bracket stand-offs to allow for rapid insertion and removal from the box. Once the wooden seams of the base were caulked with a polyether adhesive the box proved watertight to 16cm (at which point water entered via the fan out take), well above design spec.

Fig 3. EE Box version 3.