What can I do to protect my teak deck?

Many teak decks on modern yachts are a veneer of teak sometimes only 3 or 4 millimetres thick on a substrate of plywood or a scrim of epoxy cloth. The teak surface will naturally erode and the decks length of  life will be extended most efficiently by limiting this erosion.

A tree’s growth rings are made up of alternate bands of fast growing springwood and slower growing summerwood. The springwood, when the tree puts on most of it’s growth, is a wide band and is light in colour. It is relatively soft and has a thin walled cellular structure. Summerwood is a narrower, darker band and the cell structure is much stronger. In the autumn and winter there is no growth at all. It is these varying, alternating coloured bands that create the attractive grain pattern in the face of the timber.

The use of pressure washers or deck scrubbing has the affect of scouring out the soft springwood leaving the harder summerwood as weakened raised ridges. This raised grain will then be rapidly eroded by foot traffic. For this reason a teak deck should never by cleaned using a pressure washer or by aggressive scrubbing along the grain. When this is done the operator will see brown water coming off and assume that it is dirt. It is not, it is the wood itself. The operator is flushing his precious teak deck down his cockpit drains!

The colour of teak can be restored if necessary by a light sanding orbital or across the grain, or the use of a chemical oxalic acid cleaner. A teak oil should then be applied which will retard the dying off of the cells. These dead cells are the silver coloured wood which is how a well preserved deck will normally look. A deck which is regularly ‘restored’ to the original golden brown as seen at the boat shows is one which is going to have a short life.

What is electronic rig testing? how does it work? is it worth doing?

The principle of electronic rig testing is to pass a current through a swage terminal and measure the resistance increase caused by possible broken strands or corrosion hidden within the swage. As the tested conductor is stainless steel the resistance will be very low in the order of micro ohms and this requires a specialised 4 wire Kelvin Bridge micro ohm meter.

First the resistance is measured along a section of the wire stay approximately 5 cms apart, then a second reading is taken between the wire and the end of the swage terminal also 5 cms apart. In theory in the second test the swage itself is forming a perfect, almost zero resistance joint with the wire and so the two readings will read the same. Any wide variation may prove a possible fault hidden within the swage. In practice it is considered a pass if the two readings are within 10% of each other.

The majority of rig failures are at the joint of the swage due to the anaerobic corrosive effects of salt water settling in the open end. Also this section is most likely to suffer work hardening and embrittlement as any harmonic vibration in the wire will cause the wire to flex over its length but it will bend sharply at the joint as the wire is trapped within.

The test is not infallible as the resistances are very low and anomalous results can be generated by other factors. It should be taken as an additional indicator in combination with other tests, visual inspections etc to produce an overall view of the integrity of a rig. The test is most useful when made as a trend analysis where a test is carried out every year and the results recorded. In this way a progressive deterioration can be spotted before failure occurs.