The Preservation of Fibre Ropes for Use in Sea-Water

Extract

1. For the preservation of ropes the importance of the preservative against bacterial decay being also an internal lubricant for the rope fibres must be remembered.

2. Tests have been carried out for one year in sea-water, which was much contaminated by sewage at times, under Plymouth Pier and in cleaner water of a tidal basin outside Plymouth Sound Breakwater for 10½ months, using 2-inch and 0-6-inch ropes respectively; the latter was manila, the former were manila, hemp, sisal and coir.

3. The preservatives included cutch, cutch bichromate, cutch ammonia copper sulphate, coal tar distillates, including those of the Coalite process, also hardwood and softwood tars. The tars and tar oils were tried alone and mixed with copper soaps, naphthenate (Cuprinol and Shell products), oleate and resinate, also zinc and iron naphthenates (Cuprinol). The naphthenates and oleate are good lubricants.

4. Very good results were obtained with green Cuprinol containing tar and with 10 per cent copper oleate in a light coal tar; slightly inferior were 10 per cent copper resinate in Coalite heavy oil or in creosote oil as now used largely in Plymouth; also 10 per cent copper oleate with 20 per cent of Coalite tar in Coalite neutral oil, b.p. 100–245° C, which i s a very cheap solvent. All these maintained the thin manila rope at or above 70 per cent of its initial strength after 10½ months; the untreated control was down to 13 per cent.