By Joe Espiritu
A few weeks ago, a wooden vessel modeled after an old boat dug up from the shallows of Masao, in what is now Agusan del Norte docked in Jagna. The boat named Diwata ng Lahi roughly translated as Spirit of the Race was crewed by climbers of Mt Everest and some naval personnel intended to tour Philippine ports before embarking on a voyage that will trace the route of ancient Malay seafarers.
The voyage will have to be postponed. When the balangay, the native name for the vessel docked in Manila to undergo check up, it was found out that the ship borers had been busy. Teredos or ship borers had taken up residence in the dug out keel and planks reached by sea water.
To a non seafarer, the affected boat seems to be intact or unaffected by those marine pests. Entrances to their holes are very small like pin pricks that they could hardly be noticed. Beneath the surface however is riddled with tunnels. The hull will leak badly that sailors will be aware of the infestation before the planks stove in due to weakness.
Anyway, the balangay named Diwata must be dry docked for teredo infestation, repairs and waterproofing. Otherwise they will be bailing out water on the high seas. It would be a ridiculous situation for the conquerors of Mt Everest clinging to a swamped vessel waiting for rescue.
Marine borers called teredos; tamasok in the vernacular had been the problem of wooden ships plying the tropics. Ship borers are not worms but mollusks, which destroy pilings docks and ship hulls. Their lifespan is 2 to 10 months and will grow up to 3 inches. Sub specie the tamilok will grow up to 3 feet. They bore cylindrical burrows. The hulls of the British wooden Men o’ War are sheathed with copper to prevent teredo infestation.
Apitong, the timber used on the Diwata cannot prevent teredo. Old wooden boat builders use the tipolo or wild breadfruit tree for casko and planks. Some use the balobagtuk a timber tree, which sap irritates the skin. However, when the resin is eventually leached out or dissolved by seawater, shipworm infestation sets in. To prevent osmosis - seepage of seawater into the wood - boats are beached or kept out of water when not in use. But this is only possible for smaller boats.
Ancient boat builders daub their hulls with resin. However, resin surfaces do not stand hard use. Later they used coal tar locally called alketran or barnis a corruption of the word varnish. Coal tar is smelly, like resin, it is initially sticky but dries to a hard finish and can withstand heavy usage. But coal tar is always black and old boats are derisively called Black Hawks.
At present boat builders use marine paint. To waterproof their boats and ships they use marine epoxy. Aside from that, they can choose any color they fancy. This time, sailboats and boats powered by four stroke gasoline engines sport all colors of the rainbow. Only tightwads, those who skimp on marine paints find their boats riddled by teredo holes.
Shipworms do not like freshwater. As mollusks, they may tolerate low salinity, as low as 10 part per million salt on freshwater. There had been stories that in Loboc some people cut open submerged logs for tamilok. The story teller may be pulling our leg. However, though Loboc may be some few kilometers up river it seems seawater penetrate upwards when the Loay River flow weakly. Freshwater may flow on the surface but seawater being heavier may be beneath the fresh.
Linkback:
https://tubagbohol.mikeligalig.com/index.php?topic=24270.0