On DECK: A Look at Lifelines and Stanchions

Having a lifeline or railing system can reduce the possibility of a fall overboard but the systems on many boats are poorly engineered and alarmingly inadequate. Such a system gives a false sense of security against the consequences of going overboard. How does your boat fare?

Story and photos by Jan Mundy

Lean against some “lifeline” systems and you’re apt to snap a fitting or worse, dislodge a stanchion from the deck. Lifeline is a misnomer. A well designed “no overboard” system won’t guarantee that you stay onboard, but it’s better than nothing and may limit the possibilities.

Lifelines must be engineered and installed to withstand both static and dynamic loads. Three 90.7kg (200lb) guys leaning against a lifeline equates to about 272kg (600lb) static load. If one of these guys falls overboard and grabs a lifeline or stanchion, this doubles the loads. Few overboard protection systems can hold up to a 181kg (400lb) dynamic load! The key to keeping people onboard is to have a system that is sized, constructed and installed properly, and never having to rely only on one system.

Examples of stanchions fuse-welded to bases. Small welds with minimal surface contact to bases are easily fractured from loading, causing stanchions to sheer off. Welded stanchions also prevent removal when installing a storage cover. Bases are either fastened with screws, or on better-built boats, they are thru-bolted. Though bolts are stronger, if the stanchions fracture removal of bases is often hindered by lack of underdeck access to the nuts.

Comparisons

ABYC recommends a minimum rail and lifeline height of 61cm (24”), though higher rails, 91cm (36”) even 1.06m (42”) are better for adults. The suggested height of the lowest rail or lifeline is 23cm (9”) above deck to prevent adults from rolling underneath. This won’t stop small children or pets, so with these onboard, install lifeline netting that fills the gap between the top rail and the deck. Fasten the netting securely to the deck with nylon wire ties to a separate line or you’ll defeat its purpose.

Stanchions and bases are made of cast or welded aluminum, stainless steel or rarely bronze. Lifelines are commonly 300-series 7x19 stainless-steel wire, usually vinyl coated. (316 is best if the wire’s being shiny is your priority or in coated applications; 304 is stronger.) Since stainless steel needs oxygen to maintain it’s corrosion resistance, when wrapped in vinyl, it’s starved for the essential oxygen and rusts. The coating also makes it impossible to examine the condition of the wire. Typically, the coating chips or chafes where it passes through the stanchion, but all stainless steels will show some surface rust in a saltwater environment. If you don’t like the look or feel of bare wire, consider rope lifelines. Made of 9mm (3/8”) line, it’s only subject to UV degradation and makes a more comfortable handhold when falling or being hoisted back onboard.

Backing Plates

Backing plates are all too often lacking. Backing plates (larger than the stanchion base) spread out loading on each stanchion base. Obviously, if the plate is too small, loads are distributed over a smaller area and the stanchion may fail at its point of attachment. Some systems have a subplate under the deck of the same dimensions as the base. While this is better than no backing plate, it limits the structural advantage.

A proper backing plate is made of 3mm (1/8”) stainless steel or aluminum, plastics or other rigid composites like fiberglass, 5mm or 6mm (3/16” or 1/4”) thick. Dimensions should be two to three times larger than the base. If you cannot mount a plate of this size because of the close placement to the deck edge, go with the largest size possible. Always bed stanchions with a polysulfide or polyurethane adhesive sealant. On cored decks, John Bamford of Stainless Outfitters (Tel: 800/268-0395, Web: www.stainlessoutfitters.com) advises the use of a compression tube as well. Without it, compressive loading on the backing plate and stanchion base will eventually crush the core.

Weak Link

Terminating stanchion mounted in a socket base is the preferred installation to one welded to a base. Machine screws holding stanchion are preferred to Allen screws.

Tests conducted by the US Naval Academy onboard a Navy 44 sail training vessel, presented by assistant professor Paul Miller at IBEX (a marine trade exhibition and conference held in Ft. Lauderdale), concluded that stanchions and pulpits where the first to fail at a 453kg (1,000lb) load, wire terminals and gates failed between 1,360kg and 2,268kg (3,000 and 5,000lb) load and wire lifelines maxed out at 3,175kg (7,000lb). The system is only as strong as its weakest point.

An overboard prevention system works best when tight and securely fastened. Stanchions and pulpits must be strong and rigid. Albeit too much torque, especially on upper lifelines, overloads the pulpit and can pull it out of its bases or rip open the deck if it’s a one-piece pulpit. A typical installation has swage or Nicopress fittings connecting the lifeline ends to the pulpit bail. Often a turnbuckle is provided to enable lifeline tension adjustment. A better solution is a rope wiping (use #4 polyester cord or equivalent) at all terminal ends. Should someone fall overboard, you instantly cut the line, hoisting him or her back over the rail without having the extra lift above the lifelines. This, of course, presumes that the person overboard is connected to the boat (harness) and is conscious. Pelican hooks on gate openings are a weak link and should be eliminated, where practical. Examine all connections and mounting hardware for corrosion and looseness. Also inspect nuts and washers underneath the deck at the stanchion base mountings, if possible.

Crew leaning against lifelines puts tremendous loads on stanchions and bases. On a taut system, the loads are pushing outboard loading the entire system. Where lifelines are loose and sloppy, the load is focused on the closest stanchion and base. For this reason, attaching “backrests” to lifelines only adds a comfortable perch but dramatically increases needless loads on the system. Also, don’t clutter the rails with boat hooks, whisker poles and other gear. Keep your boat’s overboard protection system independent of all other equipment.

Never rely solely on your boat’s lifeline system to prevent falls overboard. Provide good deck traction (redo the non-skid if needed) and eliminate any tripping hazards. Wearing a safety harness that attaches crewmembers to the boat at all times when onboard is your best bet, even in calm conditions.

Pre-Loading

Always replace a lifeline system fitting that is suspect. “Heaving” on stanchions is not a worthy test. Testing a new system requires the tested components to withstand the test requirements of ABYC H-41, Reboarding Means, Ladders, Handholds, Rails and Lifelines. That test subjects the equipment to withstand a “400 pound (182kg) static load at any point, in any direction, without failure such that they no longer perform their intended purpose. If the system includes a gate, the system must pass the test with the gate open.”

Combining aluminum bases with stainless-steel tubes is the ideal formula for corrosion. Aluminum causes the stainless steel to become brittle over time, resulting in stress corrosion cracking. (left top) A strong sideways force could easily fracture the screws that mount this socket base on the rail. (left bottom) In addition to the common Allen screws, this owner has installed machine screws to permanently secure stanchion to the base, though a better install is bolts with lock washers or nuts.		Stanchion welded to shaped stainless-steel plate mounts with cap screws to the toerail. This three-point mounting is better than a single fastening to the rail, but lacks the strength of a stanchion thru-bolted to a socket base.	A better stanchion-to-base fastener than Allen screws is a thru-bolted clevis pin. A cotter pin is preferred over the split ring, which deforms and can come adrift. Even better is a bolt with a lock washer or lock nut.	Socket base relies on welded brace for support. Brace helps to prevent a bending failure, but adds a trip hazard that can send one overboard.
What appears to be a strong socket base relies on a single screw to hold the stanchion and though it shows evidence of bedding compound, in all probability, is only fastened to the deck with wood screws.	Stud bolt fastens this terminating stanchion to the deck. If the stanchion becomes loose or breaks, there is often no access under the deck to repair it. (right) This manufacturer applied some sealant but not enough to seal the stanchion base, providing an entryway for inevitable water damage to the deck laminate and cabin interior.		If it’s necessary to remove welded stanchions for a storage cover or when doing repairs, cut stanchions away from bases, install socket-type ones and thru-bolt stanchions to bases.	The stanchion welded to a base plate is a weak installation that depends on a welded brace and base fasteners (hopefully bolts) for strength.
Well-secured lifeline netting ensures small children and pets stay onboard. The oversize squares of this product from Johnson Marine provide ample room for passing small objects and lines through the netting.