Steve D'Antonio This vessel has four eight-person rafts, two on either side of the flying-bridge-hardtop supports and two on the hardtop, providing a good mix of access and protection.
I’m convinced that the reason so many life rafts are poorly or improperly installed and maintained is because they are seldom tested by true necessity. Like seat belts and insurance policies, you hope you never have to count on them, but when you do you want them to be flawlessly effective. That’s why correct initial installation and routine maintenance are essential.
I’ll limit this discussion to weather-deck-installed canister life rafts because valise-style models have fewer installation options and thus opportunities for error. Provided that valise life rafts are routinely serviced and kept dry, you can drag them on deck, secure the painter, manually deploy them (by no means givens), and expect them to work.
Steve D'Antonio Install life rafts in the open on a weather deck where they can be manually or automatically deployed. They often require custom brackets and rails to ensure that they will float clear of obstructions
Location
Choosing a canister raft and cradle has several requirements—manual and automatic/hydrostatic deployment and deployment in the event of fire, along with the most economical use of the limited deck space on most small craft.
For rafts equipped with hydrostatic release units (HRUs) triggered by water pressure, it’s important to avoid unprotected locations such as the foredeck of a sailing vessel, where the raft may be struck by boarding seas, which could trigger the unintended and undesirable release of the raft. Even when an HRU is not used, a raft canister in any location exposed to heavy spray and green water is more likely to be penetrated by water, damaging the raft and its inflation mechanism stored within.
Steve D'Antonio This raft’s location, away from green water and high traffic, is ideal, except for the entanglement hazard from rigging and gear above and around it.
Steve D'Antonio | Professional BoatBuilder Magazine Seas could trigger the hydro release of this raft mounted under a catamaran’s deck; water entry into the canister is likely; and the davits could hinder deployment; but the raft could be deployed if the vessel capsizes.
You must first determine if the raft will be deployed hydrostatically or manually. For the former, the raft should be stored in an unobstructed space so it can float free from a sinking vessel (assuming it sinks on a relatively even keel). Do not locate it under overhangs, canvas, standing rigging, or hardtops. For manual-release scenarios, pay more attention to eliminating obstacles between the raft and the water while the boat is still afloat. Because a containerized six-person offshore raft can weigh close to 100 lbs (45.4 kg) and is unlikely to be lifted or carried by even the most fit crew member, especially in rough seas, a single person should be able to slide or tip it overboard. If it’s mounted inboard of a life rail or lifeline, or in a standard cradle in some cases, make certain it can be slid under the rail, or tipped over the edge of the cradle. If this isn’t possible, it may be necessary to make a section of the rail easily removable. Rafts mounted outboard of, or integrated into, rails, or those mounted outside the envelope of the vessel, are more easily released; they are also more exposed to heavy weather; and in my experience, vertically mounted canisters are prone to water leaks through the seam between canister halves, and through drain holes. No raft, when mounted, should stand proud of the vessel’s rubrail, where it is vulnerable to docking damage from a bulkhead or piling.
The top of a motoryacht’s or trawler’s cabin, flying bridge, or hardtop is another suitable storage location where the raft is not a tripping hazard, does not take up valuable deck space, and is protected from boarding seas and spray. The high perch also makes it less likely to be stolen. Drawbacks include difficulty in accessing it in heavy weather, for service/inspection, or in the event of a fire. Nevertheless, considering all options, cabintops are often the best of all installation compromises.
Steve D'Antonio Rafts stored outboard in cradles are the easiest to deploy and least likely to be entangled but are vulnerable to damage from pilings and bulkheads.
Steve D'Antonio While a cover will extend the life of a canister and its rigging, it must be removed when the vessel is under way.
You should be especially vigilant and critical of custom-made sandwich-type rail mounts, where the raft is cradled vertically in a hinged life-rail latticework designed to open when triggered manually or hydrostatically. I have seen a few of these designs where the geometry of the hinge, or the release’s means of engagement, hinders smooth, unobstructed canister release. Also, consider how such a support and release mechanism will work if the vessel heels, either in the direction of the raft, causing it to face the sea surface, or skyward. Either could make deployment problematic.
Keep in mind that many raft canisters have drain holes in the bottom for quick drainage with the raft installed horizontally. If you install the raft vertically, these drains are no longer on the bottom of the canister and allow water to enter but not to exit. Water trapped in a canister can lead to raft deterioration and a malfunction when the raft is deployed.
Steve D'Antonio The seals on vertically mounted rafts, especially those outboard of the superstructure, must be maintained to keep water out, and drain holes should be appropriate to the vertical orientation
Steve D'Antonio Most canisters are designed for horizontal installations. In vertical installations, upward-facing drain holes must be plugged and those at the lowest point left open.
When you order a raft with a vertical mount from a dealer, they should plug upward-facing holes. However, based on the many canisters I find with holes not plugged, never assume this has been done. All vertically mounted rafts should be closely inspected for this oversight.
Installation
The most common mistakes in cradle installation occur where the brackets fasten to the boat. Because these rafts are exposed to the elements and potentially to boarding seas, their cradles must be secured to the deck or other surface so they won’t come adrift or be swept away.
Steve D'Antonio Penetrations for through-bolts must be properly closed out with epoxy.
The preferred fasteners are stainless steel through-bolted machine screws. This method requires access to the opposite side of the mounting surface, which might be a saloon, stateroom, cockpit, or another hardtop overhead. Depending on the interior finish structure and method in the area, that access may require removal of a headliner; and for weather deck areas you might need to install access ports for the backside of the through-bolts.
Make the proper closeouts around the penetrations when installing the hardware through cored composite structures. The core must be reefed out and backfilled with thickened epoxy around each bolt, and nuts should be amply backed with thick (not easily distorted) washers and/or backing blocks or plates (see “Installing Hardware in Cored Composites” in Professional BoatBuilder No.189). The inside of the backing plate/block and nut/washers should not be bedded. Doing so will only trap water in the penetration against the fastener shank, where it will promote crevice corrosion, and the water will continue into the core even if properly closed out.
The threat of leaking through-bolt installations and the daunting demands of correct through-bolted cradle mounts often lead boatbuilders and owners to opt for tapping or lag screws. Under no circumstances should the installation of lifesaving equipment be entrusted to tapping screws, especially in a cored fiberglass substrate. Not only is this an inadequate mechanical attachment for any piece of gear but also guarantees water intrusion into the core, with all its unpleasant and expensive consequences.
Steve D'Antonio A moisture meter reveals whether raft attachment points have allowed water into the core.
Steve D'Antonio Tapping screws and limited bedding compound are inadequate for securing life rafts and other equipment to cored or solid deck or cabin structures
After the raft is installed, make certain its painter is secured to either the HRU’s designated “weak link” (specifics below) or to a hard point such as the cradle or a pad-eye, because this connection will need to withstand considerable upward force. Fastening a pad-eye with tapping screws or to a nonwelded life rail are poor choices. If this connection fails, a raft floating free from its cradle will not deploy, because the painter is never subjected to the requisite force to trigger inflation.
After the raft is installed, route the painter to include a drip loop to keep water from running in where the line enters the canister.
Hydrostatic and Manual Releases
Steve D'Antonio | Professional BoatBuilder Magazine The red weak link the painter is attached to is sized to withstand the tug required for inflation and then to break under the strain from the fully inflated raft as the vessel sinks.
Steve D'Antonio Hydrostatic releases are pressure sensitive. This one will automatically free the raft at a depth of 4′ to 12′ (1.5m to 4m).
The familiar yellow (or less common green) label HRU, made by Hammar AB, in Göteborg, Sweden, utilizes a pressure-sensitive diaphragm and spring-loaded stainless-steel knife, housed within a glass-fiber-reinforced nylon cover, along with a weak-link feature. The Hammar H20 HRU is designed to be triggered by water pressure at a depth of between 4′ and 12′ (1.5m and 4m) for the yellow, and 12′ (4m) for green label models, at which point the spring-loaded knife is released, cutting what Hammar calls the red and white “strong rope,” which in turn releases the raft to float free and upward. As it floats to the surface, its painter, usually between 30′ to 50′ (10m to 15m), pays out. This line should be secured to the hydrostatic release’s red weak-link-labeled “painter.” When the raft’s painter is fully deployed, it triggers the raft’s inflation mechanism. As the vessel continues to sink, the buoyancy of the raft creates enough tension to cause the weak link to shatter, releasing the inflated raft. While some raft painter lines include a weak link, if the painter is lashed to something other than the hydrostatic release’s weak link eye (the raft cradle, for instance), it’s possible the raft could be damaged before the painter parts. Hammar H20 weak links are designed to shatter, releasing the raft at about 500 lbs (2.2 kN) of upward lift for the yellow-label, and 270 lbs (1.2 kN) for the green-label model. Less buoyant smaller rafts, for fewer than four people, should use the green-label unit.
Hammar hydrostatic release mechanisms are designed to be replaced every two years. When the unit is installed, the date decal should be scratched away (not simply marked with a felt pen) to indicate the expiration date, two years after it is placed in service.
Steve D'Antonio Hydrostatic releases are labeled with dates to specify when to replace them.
Steve D'Antonio A set of raft release hardware must include a simple manual snap shackle with a lanyard, at far right, that can be easily released under tension. Test this hardware on a completed installation.
Beware: Counterfeit hydrostatic release mechanisms have made their way into the supply chain. To the untrained eye, the fake units look almost identical to genuine Hammar H20 release units. But every Hammar release has its own serial number, which can be verified by contacting Hammar. Additionally, the underside of a genuine Hammar H20 unit includes five fabrication marks on all units produced since April 2006. The fabrication mark on the upper side of the unit should point directly to the rope. If you are servicing a raft and the Hammar H20 hydrostatic release needs replacement, ask the dealer to give you the box the unit was shipped in, as well as the enclosed instructions; reports indicate counterfeit units are not shipped in Hammar-labeled boxes and do not include instructions.
Every raft should have a means of being easily released manually, whether or not it’s equipped with an HRU. This can take the form of a common snap shackle or a proprietary release mechanism such as Hammar’s “Easy Release,” which uses a simple fulcrum design or a Senhouse slip or pelican hook (these are available generically as well as from Hammar). Most raft manufacturers that offer canister cradles include straps with built-in release mechanisms. Chief among the requirements for manual release mechanisms are absolute reliability (the mechanism must be trouble free after years of inactivity and exposure to the elements) and simplicity (singlehanded activation in the dark, even in rough conditions, and it must not jam under tension). The release actuation mechanism should be equipped with a lanyard that is either clearly labeled or at least color-coded red or yellow, to distinguish it from other lashings or raft security devices. I have encountered manual release shackles with lanyards whose geometry would prevent them from being released when pulled in all but one very specific orientation, or not at all. I have also found release lanyards that were so badly deteriorated by UV exposure that they parted when tested.
Steve D'Antonio This raft was inadvertently fitted with two straps, one equipped with a hydrostatic release and one without, which could catastrophically prevent manual and automatic deployment.
Note that HRUs are not mandatory for recreational craft, which leads owners to question whether one is really needed. On my own vessel, I would never install an on-deck canister-type raft without a hydrostatic release. The only exception might be on a small vessel where a boarding sea is likely to trigger the release in a nonemergency. But even in that scenario, the green Hammar HRU, which will not trigger until the raft sinks to a full 12′ , could be used to prevent such accidental deployment.
A Tale of Two Straps
On a recent new-vessel inspection, I noticed that the life raft canister, supported in a vertical mount, was retained by a lashing connected to an HRU. Carefully looking it over to ensure that it was properly routed, I noticed a puzzling detail: the raft was also retained by a separate lashing of a different color and equipped with a manual release. It seems the builder ordered a raft with a hydrostatic release, and the raft dealer shipped a cradle with a manual lashing and the hydrostatic release, while neglecting to remove the manual release lashing. As installed, if the user tried to deploy the raft manually, it would not have dropped out of the cradle unless both lashings were released. Compounding the problem, the release on the manual lashing was not immediately obvious. In the dark and under stress, deployment must be quick, easy, and intuitive.
More importantly, if the vessel sank before the raft could be deployed manually, the hydrostatic release mechanism would have triggered, but the raft would go to the bottom with the sinking vessel because the manual lashing held it firmly in the cradle. I sent photos of this setup to the raft manufacturer, and they initially said it was correct, and the manual strap had a weak link that would break. I examined the strap and could find no weak link. I sent more photos and pressed the issue. It took four exchanges for the manufacturer to understand the issue and identify the problem—two sets of straps had inadvertently been installed.
The lesson is: read the instructions for your raft and its release mechanism and then inspect the installation, and make certain you fully understand how the retention and release mechanisms function. If something doesn’t look right, be critical and trust your instincts, query the raft and/or release manufacturer (I prefer going directly to the manufacturer, as the dealer may have made the error and may not understand the problem, or may be unwilling to admit fault) until you get a clear, logical, and unambiguous answer.
About the Author: For many years a full-service yard manager, Steve now works with boatbuilders and owners and others in the industry as Steve D’Antonio Marine Consulting. He is an ABYC-certified Master Technician and sits on that organization’s Engine and Powertrain, Electrical, and Hull Piping Project Technical Committees. He is also technical editor of Professional BoatBuilder.
