Bronze Skin Fittings, or are they Brass?

While surveying a French sailing yacht today in Swanwick Marina near Southampton, built in 2001, I managed to break a seacock with a small strike from a hammer. The following photo was the result:

Take a look at the colour of the failed material - a bright rosy pink. I took a knife blade to the broken edge and could cut into it as if it were a soft plastic. The zinc has leached out of the brass/bronze, leaving a material with no strength. If the fitting had failed whilst at sea, there would have been a fair rate of water in-rush and it may have been some time before the crew would be able to find the source of the flooding. If it had failed at night, the batteries would have become submerged very quickly, losing lighting and engine starting capability. It is for this reason that all boat skippers should know the whereabouts of all of their skin fittings and seacocks. I always recommend in my report that each skin fitting should have an appropriately sized softwood bung lightly taped to the adjacent hose. If the seacock fails in this way, the bung can be quickly located and forced into the hole to stem the flow of water.

Moving on from the failed fitting, I aggressively pulled on the hoses of other fittings and hit the seacocks with a light hammer. The following photo shows the result:

Needles to say, my report will recommend that ALL skin fittings and seacocks below the waterline are replaced with marine grade bronze. The brokers were initially a bit displeased, but soon joined in with the breaking of a good number of seacocks.

I suggest that any boat owner checks their seacocks this winter, but only when the boat is out of the water. Give the hose a good sideways pull, strike the seacock body with a hammer. If in doubt, remove the skin fitting and inspect closely. It is not possible to visual differentiate between brass and marine grade bronze, although some seacocks and skin fittings have an identification mark on the body.

For further advice, find our contact details on our website and feel free to give us a call or write an email.

www.fieldhouse-yacht-surveys.com

Check your Plastic Skin Fittings!

Moulded white Nylon Skin Fittings: Millions of boats have them, many have them too close to the waterline, some even have them (incorrectly) under the waterline. The un-reinforced nylon material is tough enough in the right application, but they don't stand up to many years of exposure to sunlight.

The black ring is a crack

The one in this photograph has quite clearly cracked around the inner circumference. You can imagine that when this skin fitting was installed, the large nut on the inside would have been screwed on quite tightly. This puts the plastic between the nut and outer flange into tension, creating stresses in the material. Over a number of years, sunlight will attack the nylon and slowly weaken it. Eventually, a crack may develop in the weakest and most highly loaded area. The crack propagation will be accelerated by impact, such as when the boat rubs alongside a pontoon or mooring pile.

This Winter Lay-up:

Closely inspect all of your plastic skin fittings. Look for signs of cracking around the inner circumference. Look at the condition of the nylon on the outside: Is it crumbly or powdery? Consider replacing if you are unsure. From the inside of the boat, apply a sideways pressure to the skin fitting. If there is movement, look closely for external cracks or determine if the fitting needs to be re-bedded.

Consider an Upgrade:

If the nylon skin fitting is close to the waterline, say less than 250mm above, consider replacing the nylon fitting with a marine bronze one. To be extra safe, use two hose clips when securing the hose to the fitting. American Standards specify that any fitting below the 'heeled waterline' should have a seacock fitted. For further advice, feel free to call us. Our contact details can be found on our website: www.fieldhouse-yacht-surveys.com