AN APPARATUS FOR CLEANING THE BOTTOMS OF IRON SHIPS WHILE AFLOAT
Year: 1857

page_text: application for Letters Patent was not given within the time prescribed
by the Act.)
PROVISIONAL SPECIFICATION left by Charles Robertson at the Office
of the Commissioners of Patents, with his Petition, on the 3rd June
1857.
I, CHARLES ROBERTSON, of London, Master Mariner, do hereby declare the
nature of the said Invention for "AN APPARATUS FOR CLEANING THE BOTTOMS
OF IRON SHIPS WHILE AFLOAT," to be as follows:
This Invention has for its object a simple arrangement of apparatus for
scraping the bottoms of iron ships while under way or laying in a stream,
for the purpose of removing any accumulation of barnacles or seaweed that
may have adhered thereto, and without the necessity of using boats, the whole
operation being performed by the crew from the deck of the vessel.
To construct an apparatus according to this Invention, take two or more
plates of metal of, say, 14 inches long by 4 inches broad, having their
edges hardened and sharpened like the edge of the common ship scraper
now in use. These plates are laid upon their edges, say, about 6 inches
apart; between the plates introduce a block (or blocks) of wood or metal,
or an air-tight box (or boxes), of a less size than the edge plates, so that
the scraping edges of the plates will stand up above the surface thereof.
The whole is firmly braced together, and eye-bolts pass laterally through
the edge pieces, to which is attached a bridle of (say, inch) chain, and
on each end of the plates are smaller bridles. To the front or larger bridle

page_text: a small chain of any ordinary description is connected, and to the side
bridles are attached flat chains, formed so as to present sharp edges to
the sides and bottom of the vessel; or ordinary chains or rope may be used,
and which may have triangular pieces of metal slipped on to them like a
string of beads, but it is prefered to fix them to the chain or rope, so as to
keep them a little apart to allow flexibility in the chains or rope. To the
bowsprit attach a block, through which reave the chain or rope attached to
the middle bridle. On to the side bridles bend the chains or ropes, as
described above. Carry one of these side lines or chains over one of the
bows and under the bobstay, and up the other bow on to the deck, then haul
away upon. the chain or rope of the fore bridle which is rove through the
block on the bowsprit. Then slack out sufficiently to allow the scraper to
drop under the fore foot, and then haul moderately taught the chains of the
side bridles; gradually slack off the chain of the fore bridle, and pass the
chains of the side bridles aft to the distance required; then haul in the for-
ward bridle line and pass the side bridle lines forward again, and repeat this
operation as often as required. Then slack one of the side bridle chains and
haul in a little upon the other, so as to remove the position of the scraper;
then repeat the operation of slacking the chain of the fore bridle, and so
forth, as before, and so on until the whole of the vessel's bottom has been
scraped. The action of the vessel, when going through the water only at the
rate of two or three knots, will be quite sufficient to cause the scraper and
side chains, when kept hand-taught, to be in close contact with the vessel's
bottom. The same effect will be produced when the vessel is at anchor in a
current running at about the same rate.