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 TB 55-1900-201-45/1
fittings. It is impossible to list each area of trouble in each type of vessel. In general, areas which are hard to maintain,
have poor ventilation or, are subject to heavy stresses have the most deficiencies.
2-7. Inspection for Decay and Marine Borers.
a. Serious deterioration of a wood hull goes on within the wood itself with little or no outward sign until it is well
advanced. In order to spot decayed (dry-rot) wood, which has not progressed to the point where the wood appears eroded
and spongy, sounding with a hammer can be of use. Unsound wood will give a dead or dull sound. Heavy timbers
whose interiors are rotted may give a distinctive drum-like tone. Where the sound is not that of good solid wood, the
member is suspect. A probe or drill can then be used to determine the extent of decay.
b. It is imperative that unnecessary probing and boring be avoided. Holes made by a probe or drill in the hull ex-
terior are potential entry ways for marine borers. In the hull interior they allow easier moisture penetration and thus aid in
starting decay. Probing and boring should be done carefully and only when there is an indication that the hull is unsound.
Holes made by boring should be plugged with dowels or plugs which are glued in place, not merely driven into the wood.
Plugs and dowels should preferably be treated with wood preservative to prevent future trouble. Areas which have been
probed should be filled with a suitable compound. When covering boards or other obscuring construction is involved, it is
often difficult to locate deteriorated members by probing. In such cases, when bolted or screwed fastenings are involved,
check for tightness of randomly selected fastenings. If a member is solid, the fastening will take hold at the beginning of
the turn. If serious decay is present the fastening will turn freely and fail to take a bite, indicating soft and spongy wood.
c.
Decay (dry-rot) is most often found in the following locations.
(1)
In the wind and water area.
(2)
Around overboard discharges and other fittings.
(3)
In the stem area.
(4)
At the transom.
(5)
All areas that are poorly ventilated (especially the forepeak).
(6)
In the bilge (especially at the turn and along the keel).
(7)
The lower courses of bulkhead planking.
2-10
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