Engineering Controls Database
Engineering Solutions for Winch Design
|
In 2008, over 8 billion pounds of seafood was harvested in the United States earning over $4.4 billion. There are approximately 115,000 harvesters in the United States using a variety of different fishing gear and vessels [NOAA 2010]. Species that contributed the most to this revenue include shrimp, Pacific salmon, pollock and lobster. Commercial fishing is one of the most dangerous occupations in the United States. Many commercial fishing operations are characterized by hazardous working conditions, strenuous labor, long work hours and harsh weather. During 1992-2008, an annual average of 58 deaths occurred (128 deaths per 100,000 workers), compared with an average of 5,894 deaths (4 per 100,000 workers) among all U.S. workers [DOL 2010]. In Alaska, fatal deck injuries are even more prevalent, accounting for 12% of all fatalities during 2000–2006 [NIOSH 2007a]. |
|
|
During 1994-2004, there were 51 fatalities among commercial fishermen in the U.S. that were caused by deck injuries [Dickey and Ellis, 2006]. Most (67%) severe nonfatal injuries occur on deck during the deployment and retrieval of fishing gear [Thomas et al., 2001]. Severe nonfatal injuries are defined as those requiring hospitalization and include lacerations, broken bones, severe head injuries, and smashed limbs. Many of the deck machines used on commercial fishing vessels lack adequate guarding and safety features and entanglement is a particular hazard. The National Institute for Occupational Safety and Health (NIOSH) found that during 1991–2002, 798 fishermen were hospitalized for severe nonfatal injuries, which is equivalent to an annual rate of 410 per 100,000 full-time equivalent fishermen. Of these injuries, 23% were due to being entangled or struck by lines or gear, or being trapped in a winch, pulley, or other deck equipment [Lincoln et al., 2006, Lincoln et al., 2008]. |
|
|
NIOSH conducted focus groups with fishermen that identified the purse seine capstan (Figure 1) as the most dangerous piece of equipment on deck [NIOSH]. NIOSH investigations identified two major safety hazards: no entanglement protection is provided by the winch and the hydraulic controls are usually out of reach of the person who is entangled. Injury epidemiologists from the NIOSH Alaska Field Station partnered with engineers at the NIOSH Spokane Research Laboratory to design a practical engineering solution to mitigate these safety hazards. NOTE: The information in this summary document is taken primarily from Lincoln et al., 2006. The NIOSH team of epidemiologists and engineers met with vessel owners, purse-seine fishermen, and winch manufacturers to discuss the various safety design options. It was quickly realized that standard machine guarding and “dead-man switch” solutions were either not feasible or applicable to the typical machine use. Pressure mats for the dead-man switch would be subject to false signals from lines being coiled on deck, or from fish as the net is dumped. Physical guards are impractical because lines are fed onto the winch from virtually any angle (Figure 2) using the fixed winch ‘horns' in combination with the rotating drums (complicated by the fact that both drums are sometimes used at the same time with lines from two directions). Rain or ocean spray would interfere with light curtains. Design considerations also favored systems that would be simple, affordable, unobtrusive, applicable to various winch models, use off-the-shelf components, not disable other vessel functions (such as the rudder or anchor winch), not interfere with normal fishing operations if the emergency-stop system failed, and — most importantly — have the capability to be activated by the person being entangled in time to prevent serious injury [McKibbin & Woodward, 2006]. The engineering design solution that was developed was an emergency-stop (“e-stop”) system that incorporated a robust, low-profile, momentary contact button mounted on the top port-side winch horn (Figure 3). This location was the preferred mounting spot for a fisherman pursing the net from the starboard side of the vessel (the most common scenario). When pushed, the button energizes a safety-relay that in turn de-energizes the solenoid of an electro-hydraulic valve. This valve, plumbed between the manual valve that controls winch rotation and the winch drive motor, closes the flow of hydraulic oil to and from the winch motor and locks the capstan drums in place. If the emergency switch is pressed in a timely manner and the hydraulic motor does not have significant wear in the vane seals, the winch drums will lock almost instantaneously. When the electro-hydraulic valve is de-energized, the valve-spool shifts to the default position to block the oil flow to and from the winch motor. This functions as a hydraulic brake on the winch enabling a Category 0 stop. If the electric power to the electrohydraulic valve is turned off for any reason, the hydraulic fluid flow stops and the winch will not operate until the power is returned and the e-stop circuit is reset. If the winch drum has significant external rotational force acting upon it, and the motor seals are in need of repair, back-spooling of the winch drums could occur after the hydraulic valve closes both pump and tank motor ports. The back-spooling drums could effectively unwind the victim from the entanglement. The time it takes the victim to strike the emergency switch is thus the controlling factor in arresting the drum rotation, not the valve response time. With the drums turning at a typical working speed (40–60 rpm), and considering a typical human response time (less than 0.5 sec), the winch drums could be stopped in less than 180° of rotation – sufficient to limit serious entanglement injury. A control box containing the safety-relay, pilot lights to indicate system status, and a system reset button, is mounted adjacent to the winch directional control valve. In the event someone becomes entangled, it is important that the winch directional control valve be returned to neutral before the e-stop system is reset; otherwise, further entanglement or injury could result by the rotating drum. On purse seine vessels, the manual winch directional-control valve is almost always mounted on the rear bulkhead of the vessel, usually about 5-to 6-feet forward of the capstan winch. The normal function of the manual valve precludes having a self-centering spool. The fisherman typically shifts the spool for either a forward or reverse winch operation, then leaves the winch running to execute his/her fishing duties. If there is a winch entanglement and the e-stop is used to stop the drum rotation, the safety relay requires a manual reset. If the prototype system was reset without verifying that the manual valves were in the neutral position, the winch drums may start to rotate again unexpectedly. The position of the reset function was moved from the position of the e-stop switch to the proximity of the manual valves. In the described scenario, this operating location removes the reset-switch operator from the possible hazardous area near the rotating winch drums. Yet, he/she is close enough to make a visual inspection of the clearance around the winch and to be able to observe the position of the manual valves, before resetting the system.    |
|
|
Dickey DH, Ellis Q P [2006]. Analysis of Fishing Vessel Casualties - A Review of Lost Fishing Vessels and Crew Fatalities, 1994-2004. Washington DC: United States Coast Guard, Compliance Analysis Division. DOL [2010]. Injuries, illnesses, and fatalities: Census of Fatal Occupational Injuries (CFOI)--current and revised data. Washington, DC: US Department of Labor, Bureau of Labor Statistics. Available at http://www.bls.gov/iif/oshcfoi1.htm. Accessed September 29, 2011. Lincoln JM, Husberg BJ, Mode NK [2006]. Severe injuries on commercial fishing vessels in Alaska. Paper presented at the Third International Fishing Industry Safety and Health Conference, Mamallapuram, India, February 2006. Lincoln JM, Luca DL, McKibbin RW, Woodward CW, Bevan JE [2008]. Reducing commercial fishing deck hazards with engineering solutions for winch design. J Saf Res (39) 231-235. McKibbin RW, Woodward CC [2006]. Development of an emergency stop system for a hydraulic deck winch. Paper presented at the Third International Fishing Industry Safety and Health Conference, Mamallapuram, India, February 2006. NIOSH. Commercial fishing safety and health research: Development of an E-stop for purse seine capstan winches. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Alaska Pacific Regional Office and Spokane Research Laboratory. NIOSH [2007a]. Commercial Fishing Incident Database (CFID). U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, managed at the Alaska Field Station. NIOSH [2007b]. The most powerful thing…deck safety awareness for purse seiners. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health. DHHS (NIOSH) Publication No. 2007-126d. NOAA [2010]. Fisheries Economics of the United States, 2008. US Department of Commerce. National Oceanographic and Atmospheric Administration. National Marine Fisheries Service. Available at http://www.st.nmfs.noaa.gov/st5/publication/fisheries_economics_2008.html. Accessed September 29, 2011. Thomas TK, Lincoln JM , Husberg BJ, Conway GA [2001]. Is it safe on deck? Fatal and nonfatal workplace injuries among Alaskan commercial fishermen. Am J Ind Med, 693-702. |
|
|
commercial fishing fishermen |
|
|
The e-stop has received strong support at industry trade shows. It has been demonstrated at Pacific Marine Expo in Seattle in 2005, 2006 and 2007, the largest commercial fishing trade show in the United States, and at Comfish Alaska in Kodiak in 2007. The e-stop has received an overwhelming positive response from fishermen, with many fishing vessel owners and operators requesting information on how to obtain the device for their vessels. NIOSH staff have also produced and distributed copies of a deck safety awareness DVD that illustrates the entanglement hazard and e-stop solution to the hazard [NIOSH 2007b]. The NIOSH intervention design has been licensed to a manufacturer. In November 2007, NIOSH entered into a Proprietary Technology Licensing Agreement with Emerald Marine Products, LLC (Seattle, WA) to develop the e-stop system for commercial use. Emerald Marine Products, in cooperation with Kolstrand Marine Supply (Seattle, WA), will be manufacturing a similar system based on the NIOSH research. They will be selling the e-stop exclusively through their distributor Go2Marine. |