Bot­tom Prob­lems

Soundings - - Just Yesterday -

as boats. Bot­tom foul­ing. It’s a prob­lem as old hulls with The Phoeni­cians and Greeks smeared it hot. pitch mixed with wax or tar and ap­plied tar in hot Or they mixed ar­senic and sul­fur with an iron — a oil and burned it into the hull with method the an­cients called “ship paint­ing.” a 1952 re“Marine Foul­ing and Its Pre­ven­tion,” In­sti­tu­tion port that Woods Hole Oceano­graphic on th­ese and pre­pared for the Navy, sheds light coverother meth­ods in the his­tory of an­tifoul­ing ings and coat­ings. with The Ro­mans used lead sheets fas­tened layer of cop­per nails over a cor­ro­sion-pre­vent­ing keep ship pa­per or cloth. While that process did the bot­tom; worms at bay, seaweed still fouled well into even still, the method re­mained pop­u­lar helped by the Mid­dle Ages. (Leonardo da Vinci lead.) in­vent­ing a ma­chine for mak­ing sheet an­tifoul - Christo­pher Colum­bus pre­ferred the were ing qual­i­ties of a coat­ing. His ship bot­toms ex­plorer “painted” with tal­low and pitch. Fel­low a depth of Vasco da Gama charred his hulls to “sev­eral inches.” 17th cenAn­tifoul­ing “paints” emerged in the

pow­dered tury. They were nox­ious mix­tures: glass iron, ce­ment and a cop­per com­pound; tin in a paste mixed with tar, oil and lime; molten salts of zinc; of zinc, lime­wa­ter, black soap and with var­nish. ar­senic, iron sul­fide and zinc mixed They did not have a good rep­u­ta­tion. cen­tury Then came cop­per sheath­ing. The 18th worms cure-all worked as a pro­tec­tion against “Old and didn’t foul. The USS Iron­sides,” was cop­per-clad. that. At The 19th cen­tury iron hull changed all from first, the cop­per sheath­ing was in­su­lated in tar; it the iron hull with a layer of felt soaked cor­ro­sive, didn’t work, and the de­mand for a non- 20th cen­tury an­tifoul­ing coat­ing in­creased. The a coat­ing pro­vided it. In 1908, the Navy ap­proved grain alus­ing red mer­curic ox­ide in gum shel­lac, ox­ide, zinc co­hol, tur­pen­tine and pine tar oil. Zinc dust and “In­dian red” were fur­ther ad­di­tives. the re­port It and other 20th cen­tury coat­ings, mod­ern paint states, “led to the de­vel­op­ment of the here is sys­tems.” (For the record, the ad­ver­tise­ment from a 1959 is­sue of mag­a­zine.)

Con­sti­tu­tion, Mo­tor Boat­ing — Steve Knauth

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