We rely on bow rollers and cleats without giving them a second thought. Should we be paying them more attention? Alastair Buchan investigates
Are your bow roller and cleats strong enough?
When a yacht suffers gear or engine failure off a lee shore, her crew’s last lines of defence are getting a tow or throwing the anchor overboard and hoping it holds. However, even the world’s best anchor and strongest chain count for nothing if your deck fittings are not up to the job. Often overlooked and rarely included in the annual maintenance routine, your cleats and bow roller could be your weakest link that let you down when you need them most.
Unless you’ve had the boat from brand new or replaced your bow roller or cleats, it’s impossible to know what forces have been exerted on them before you bought her – or even if they were really up to the job in the first place. There is no guarantee that they are the right size, correct design or able to safely take the considerable loads imposed by winds, waves and swells. Additionally, when used as a fixing point for forestays, bow rollers must cope with the mast whipping about too. Finally, they must take high downward loads when you break out the anchor.
Taking the loads
The loads on deck gear vary according to whom you ask. The American Boat and Yacht Council (ABYC) has a table of anchor loads from the combined effect of wind and seas for various boat lengths and Professor John Knox, inventor of Anchorwatch, reckons that the force on an anchor in kilograms is (1/500) x (boat’s overall length in metres)2 x (wind speed)2, but this doesn’t take into account freeboard and gives different answers to the ABYC.
Well-designed bow rollers share a number of common features that make them suitable for anchoring, lying to a mooring and towing. A lot depends on the size of the roller in your bow fitting. In turn, that depends on the diameter of your anchor cable, be it chain or rope. Since choice of anchor cable is a personal preference, boatbuilders ought to fit the option demanding the most space, which is rope. The rule of thumb is a anchor rope should have 1.5mm diameter for every metre of the boat’s overall length, with a minimum of 10mm. Chafe protection doubles this and adding some extra space for a comfortable fit means that even the smallest bow roller should handle a 25mm rope with ease, but many can’t.
The cheeks of the roller that hold the cable in place as the boat yaws around must be strong enough to resist bending or breaking from side loadings they’ll experience. Bow rollers overhanging the bows create frightening horizontal and vertical loads, but the forces are manageable by taking them onto the hull via a tang on the yacht’s stem. This arrangement has the bonus of eliminating the hinge effect caused by using the fitting as the fixing point for the forestay. Even if your bow roller does not overhang, a tang to the stem is still a good practice.
When anchoring on rope, chafe is always a clear and present danger. Wrapping a rag around the line helps, but not for long. A short length of plastic tubing slipped over the line is better but, depending on the material, it may harden and need replacing.
Beneath the surface
Your bow roller fitting is only part of the equation. The fastenings keeping it and your cleats in place are just as important. Marine surveyor Ben Sutcliffe-Davies points out: ‘While fittings can fail, the fastenings cause more problems: crevice corrosion, lack of backing pads and small washers.’
On solid GRP decks, it’s best to tighten fittings down onto a large a marine plywood backing pad – at least one and a half times the footprint of the fitting, with large washers under the nuts. On some boats you may find just penny or even halfpenny washers.
The core problem
Balsa or foam cores make for lighter, stiffer decks but through-bolting deck fittings, besides crushing the core, may also allow water to seep in. This can rot a balsa core and saturate a foam core causing delamination.
In modern yacht construction the foam core stops before most of the deck hardware and aluminium or stainless steel backing pads are glassed in during manufacture. If not, cutting out the foam around the holes either by making the hole larger or by putting the long end of an Allen key in a drill chuck and the smaller end in the hole, moving it around before carefully starting the drill to mash up the foam core, then filling the voids with epoxy. For non-GRP decks, backing pads like those for solid GRP are recommended.
If installing your own fittings, always gently countersink holes drilled in glassfibre. This helps prevent stress cracking round the hole and allows the bedding compound to form an O-ring when the bolts are tightened. Use locking nuts, cut off excess lengths and burr the ends to ensure the nut won’t work loose.
Never put sealant on the below-deck backing pads. Under-deck sealant holds the water in the core, or the glassfibre laminate itself, without you being aware of a problem. A combination of metal, water and confined spaces is a great recipe for rotting cores and encouraging corrosion. Bolts, even of stainless steel, can rapidly corrode. You may not even see a rust mark before they fail and the deck delaminates. A quick inspection with a digital camera or camera phone can help you see hard-to-get-to places.
Do not rely on an anchor windlass to hold the cable fast, all windlass manufacturers recommend tying or cleating it off – the windlass clutch isn’t designed to take the loads. If your cable is all chain, use a long snubber that passes out through bow roller; this lessens the snatch load on both cleat and roller and will also give those in the forecabin a quieter night’s sleep.
After the bow roller, the final possible weakest link are the cleats themselves. The loads on them are very high when the boat’s moored in a blow or if they’re used for towing, made worse by snatch loading.
The rule of thumb for sizing cleats is 25mm of length for every 1.5mm of warp diameter. A 15mm diameter warp needs cleats 250mm (9.8 inches) long. Many boats come with undersized cleats. There are always problems providing decent backing pads to fittings on the toerail or close to the edge of the sidedeck, including chainplates. Even using penny washers can be difficult.
Even though they have no moving parts, deck fittings are not maintenance-free. If a fitting is pitted, it is suffering from electrolysis. If it has rust streaks, it’s leaking. Likewise, dampness below decks warns of leaks. Smearing sealant around never really works, and besides, wouldn’t you want to check the bolt now, before it’s too late? The only real solution is to remove the fitting and its backing pad, clean everything thoroughly and then refit and reseal it properly.
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