Technical Note: Rig Tension Sensor series of Dead-Eyes
Strain Measurement Devices, a world leader in thin film strain gages, introduces the world’s most highly engineered group of Dead Eye and Rig Tension Sensors. Using our sensor and strain gauge design experience SMD crafted a sensor and circuit that is designed to measure tension accurately in a sailing rig by adding a custom thin film strain gage sensor into an Aluminum 6061 deadeye with a wireless circuit. Testing each design iteration and measure performances of individual mechanical designs or machined features, makes this the highest engineered Dead-Eye available. This Patent Pending Design uses unique machining features that allow the rigging lines to run with minimum stress concentrations and improve Hysteresis in the system, also offering a waterproof, wireless and solar powered system.
Two ranges of dead-eyes are available currently to suit either the 15-17 mm or 11-13 mm Dynema. The former having a safe working load of 25 Kpounds and the smaller at 15 Kpounds.
Mechanical Accuracy of the Sensors are defined as the sum of Non-repeatability, Non-Linearity and Hysteresis. Non-Repeatability and Non-Linearity are typically better than 1%, while Hysteresis is rigging line dependent and can contribute up to a 5% for full load excursion.
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Specifications:
| Sensor Mechanical | |
| Non Repeat-ability | 0.2% FSO |
| Non-Linearity | 0.7% FSO |
| Hysteresis: Line Dependent | 1-6% FSO |
| Thermal Errors | |
| Temp. Co of Offset (TCO) | +/- 0.01 FSO/C |
| Temp. Co of Span (TCS) | + 0.03% FSO/C* |
| *Typical, Improved TCS available | |
| Cicuitry | |
| Bluetooth | Unpaired |
| Update Rate | 100 Millisecond |
| Battery Life | No solar charge available: 28 Days |
| Solar Panel | Full recharge in 30 mins, full sun |
| Range | 50′ line of sight |
| Hermetic On/Off rotary switch included for known down times | |
| Mechanical Details | |
| 15-17 Dynema Dead Eye | 25,000 lbf Safe Working |
| 50,000 lbf Breaking Strength | |
| 5/16″ [8 mm] Lashing Line | |
| 11-13 mm Dead Eye | 15,000 lbf Safe Working |
| 30,000 lbf Breaking Strength | |
| 1/4″ [6.4 mm] Lashing Line | |
O’ring sealed to IP67