There are other measures you can take to further dampen the movement of your boat.
1 UTILISE A SMALLER FENDER
Lodging a slender fender beneath a line under load can provide a surprising amount of cushioning with the fender absorbing the shock.
The line becomes quiet despite the movement. You can wedge one beneath a rope anchor warp if you have sufficient length between the bow roller and a foredeck cleat, or beneath the springs on the side decks. It is a simple solution and surprisingly effective. I carry a couple of smaller, slender fenders which are easy to stow, specifically for this job.
When the spacing of the pontoon cleats creates an imperfect line to my deck fitting, threatening to scuff my topsides, then I insert a deflection fender. This is usually either to preserve my new vinyl strips, or to protect our teak toe rail from chafe. You may have to secure and lash each end of the fender in order to keep it in place.
2 THREAD ON RUBBER SNUBBERS
The shorter bow and stern lines benefit greatly from the rubber snubbers which you thread onto the line. The snubbers make the line more clumsy to coil and stow but they immediately take the shock load and quieten a noisy fairlead. Being rubber they degrade over time and eventually perish, but they aren’t excessively expensive and they spare the life of the (more expensive) warp which would otherwise be chafing in the fairlead. Plastic hose sleeving will also mitigate chafe.
3 SORT OUT YOUR DECK FITTINGS
Stainless steel compensators also work well. They are bulkier but do not degrade in UV like rubber, so owners are inclined to use them on a long-term basis when their yacht is permanently berthed in a marina subject to surge.
The stainless ones don’t have such springy properties as galvanised ones, which have a greater tensile strength, but these succumb to rust. Fishing boats sometimes use tyres suspended between chains but if you value clean topsides and have limited stowage, this is not a very yacht-friendly solution.
The power generated by snatching is greatly magnified from the normal loading of what a deck fitting is designed for, and the subsequent damage that can result shouldn’t be underestimated. Cracking in the gelcoat visible around cleats and fairleads is a tell-tale sign that the boat has been snatching at her lines and experiencing shock loads. Some deck fittings merely have penny washers beneath them, and it is worth replacing these with a more serious stainless backing plate. Those fittings with proper pads distributing the load on the underside have a better chance of withstanding sudden and unexpected loads. Genoa winches have several bolts securing them, usually with pads, and are much stronger than a cleat which may only have a couple of bolts through it and penny washers below. Cleats should be loaded in a fore and aft direction. Side-loading on a cleat can capsize it.
If your boat is noisy it will not only affect your sleep but also, ultimately, your wallet. Noise equals friction. Friction equals chafe. Chafe will result in expensive repairs because it is chewing its way through your cordage which will have to be replaced. It also has a price for your peace of mind.
If a line securing you to a pontoon is chafing through in a gale your safety or that of your boat is at risk. If all is quiet as you lie in your bunk you can slumber on smugly, content in the knowledge that you are properly secure.