There are different types of materials used in structures and how structures are put together to resist the forces. All of the above has been based on the supposition that the materials remain and function in accordance with their normal properties. However, in practice all materials are subject to degradation over time from a variety of different sources. some examples of materials used for yachts noted in their several years of experience by constellation marine inspectors are as under:-
Wood and dhows Repair Inspection.
Timber that has been well seasoned and that is kept in a uniform state of moisture (neither too wet nor too dry) when properly ventilated will remain stable and with no significant degradation for many hundreds of years. However, as a naturally occurring material, wood has naturally occurring enemies which come in the form of fungus (mould), worms and beetles which need to be inspected carefully.
Common Rot noticed by constellation marine surveyors during detailed Yacht/Boat condition inspection and surveys.
This is manifested by the presence of external yellow spots on the ends of the timber and is often accompanied by yellowish dust especially where the pieces of timber are in contact. The main cause is poor ventilation of the timber.
Moisture, especially in the presence of warmth, will dissolve out some of the constituents of the cell walls and thereby cause decay. However, timber kept constantly immersed in water may soften but does not, in general, decay. It is the cyclical nature of wetting and drying that does the damage.
This is caused by the fermentation and breaking down of the chemical compounds of the wood when a certain fungus (merulius lacrymans) is introduced in the presence of moisture. The organisms as part of their normal digestive process excrete chemicals that dissolve parts of the cell wall structure of the timber and crumbling of the wood follows.
A swelling of the timber, a change in colour and the presence of threads or tendrils across the surface are all indications of the presence of dry rot. It also has a very distinctive, musty odour. Once present, dry rot is very difficult to eradicate completely.
What is meant by Toredo or Ship Worm (Toredo Navalis) and how can it be detected during dhow or Yacht/Boat repair inspection?
Of the various different types of “worm” toredo is by far the most destructive. It deposits its eggs on the timber that is immersed in water. The eggs then bore into the wood generally following the grain. The worm continually increases in size varying from 6 to 12 mm in diameter and over 2m in length (with length limited only by the length of the plank). Toredo prefers warmer water and is a particular feature of the tropics.
constellation marine is involved in independent pre purchase inspection of yachts, pleasure Boats,Tugs. We do come across a variety of interesting Topics, some of those are posted here in for the review knowledge.