The specs for an Alajuela 38 claim a fuel capacity of 75 gallon. However, after emptying the tank into jerry cans, I measured the capacity to be 60 gallons. While measuring the capacity, I also calibrated a Simrad Fluid Level Sensor model 000-11518-001. The process involved adding ten gallons at a time and measuring the resistivity of the sending unit:
| Volume (Gallons) | Resistivity (Ohms) |
| 0 | 255 |
| 10 | 193 |
| 20 | 127 |
| 30 | 98 |
| 40 | 70 |
| 50 | 51 |
| 60 | 42 |
Note the change in resistivity is not linear. This is due in part to the non-linear behavior of the sending unit, but mostly due to the V-shape of the fuel tank. Without calibration, a “half tank” according to the mechanical gauge was probably in fact about a quarter tank. Having used five points to calibrate the Fluid Sensor (Empty, 1/4, 1/2, 3/4, and Full), it presumably gives a more accurate measurement of the fuel volume (highlighted in red).
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