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Hitch Pin Securement Illustration

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Sea Catch Hitch Pin Securement

To prevent the loss of the hitch pin, two methods of securing it to the release line are suggested as follows:

FIG. 1. The first option is to tie the hitch pin to the outer end of the release line.

FIG. 2. The second method is to secure the hitch pin at a point near the inner end of the release line as shown. This method not only provides hitch pin securement but may facilitate removal of the hitch pin at the time or release.

Sea Catch Over-Center Pressure Adjustment

FIG. 3. Ample material has been left at the tip of the movable jaw (see arrow) where the jaw and body come in contact. This aids in holding the device securely over-center in the locked postion even when no load is applied to the device. It also helps prevent inadvertent release of the device.

Call John McMillan at 253-858-1985 for further questions or comments.

Sea Catch TR3 Photo


What is Sea Catch made of?

All Sea Catch toggle releases and retrieving hooks are made from aerospace-grade PH15-5 stainless steel plate heat treated to 1025. See the certification page for more details.

How hard is it to manually release it under load?

Under capacity load of 7,000 lbs. the effort to release a TR7 is around 40 lbs. See the effort chart for other models.

Can I use a looped line instead of a shackle as the connected item to be released?

Yes, if precautions are taken to prevent line wear, such as adding protection to the line. See the Sea Catch "M" Series for units designed specifically for use with line or cable.

What is the Sea Catch used for?

Most are used in ROV (remote operated vehicles) and instrument deployment in ocean research operations. This is followed by uses in the offshore industry, seabed flowline installations, geophysical surveys and maritime uses including tug and tow applications, mooring deployment and port facilities. Next comes aerospace use in ground support equipment releasing, US Navy and US Coast Guard deployment of rescue boats. Commercial fishing applications follow with uses such as skiff releasing in purse seine operations (where the first Sea Catch was used). Then comes the testing industry where items are drop tested, followed by general consumer uses and object dropping in movie special effects. See the uses page for more details.

What is the history of the Sea Catch?

As with most innovations, Sea Catch was spawned from a problem solving effort.

In this case, the problem presented itself first to Bob Schmidt and then to John McMillan on the eastern shore of Alaska's Cook Inlet in the mid-1980s. This region is known for its large tidal fluctuations, at times up to 22 feet from low water to high. All commercial salmon fishing set-net sites are located on the beach or near the shoreline and all are anchored at each end to the bottom. Generally, the nets are set at specific times, picked at slack tide and pulled out at specific times by fishermen using skiffs. At certain times during the summer fishing season, fishermen are required by law to remove their fishing nets from the water before 9 PM. Although there are large floats at each end of the net and corks along the full length of the cork line, the entire net and its floatation system is prone to being submerged when high tides and heavy currants are combined with high winds. If such conditions are anticipated at the 9 PM pull-out time that would prevent access and removal of the gear, fishermen would go out at the 6 PM slack tide, pick the fish out and remove their gear to avoid the high tide hardships and a possible citation by the Alaska Department of Fish and Game. While picking up the gear at 6 PM would seem the wiser approach, it would also mean that 3 hours of valuable fishing time would be lost. Quite valuable in fact, since in most cases, the heavy salmon runs occur during these high tide situations.

The question then arose, "For these conditions, how can we leave the gear in the water right up to 9 PM and still access the gear and pull it out on time?" Not only would you get 3 hours of extra fishing time, but you would also have access to all the fish along the beach for that whole time period since the competitor's fishing sites upstream would have been pulled out at 6 PM.

Finding a way to release the net from the anchor while it was under load was not easy. After months of experimenting unsuccessfully with pin shackles and pelican hooks, the only thing that worked best was a primitive device based on a modified set of Vice-Grip® pliers. These devices use what is called a four-point toggle linkage principle to grip and lock anything within its jaws. The jaw was replaced with one that encircled a metal ring rather than gripping it. The body of the device was fitted with a hole where it could be connected to the net. The release lever was modified with a hole where a release lanyard could be attached. Two units were required, one for the cork line and one for the lead line. The release lanyards were spliced together to form one line (20 to 30 feet) that went to a cork that stayed afloat regardless of the weather and current conditions. These devices were installed in the lines during the 6 PM slack tide period whenever heavy seas were anticipated during the 9 PM pull out time. They worked amazingly well. A crewmember in the skiff merely pulled on the release line floating at the surface. This released both devices and disconnected the cork line and lead line from the anchor. While the gear flagged out with the current, the crew then pulled the gear, fish and all, into the skiff. It may have been one of the first times in history that four point toggle linkage was used for a locking and releasing function!

In the summer of 1990, John took a primitive four-point toggle linkage quick release made of silicon-bronze to Prince William Sound and used it to release the skiff during sets on a commercial salmon purse seine operation. It worked so well that it was used the entire summer and replaced the old pelican hook whose design has yet to be proven as an efficient release mechanism.

For the next several years John worked relentlessly to design a more efficient and stronger quick release that used the same toggle linkage principle. Commercial fishing was the targeted market and several devices were designed and sold that were built of cast silicon bronze. Finding these inferior in strength, he eventually found a special stainless steel plate material better suited to the locking and releasing functions of the device. The first commercial production Sea Catch units of the current design were sold in October 1994 to the sea technology industry. This is still a strong market area for the device as is drop testing, offshore petroleum, general maritime, and military applications. He then received a patent in 1999 for what is now known as the Sea Catch Toggle Release. The Sea Catch is the only known quick release device in the world that uses the toggle linkage principle to both lock and release lines or objects under load.

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