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‘FOULING OF SHIPS’ BOTTOMS:
IDENTIFICATION OF MARINE GROWTHS

MARINE CORROSION SUB-COMMITTEE
CORROSION COMMITTEE

A. JOINT COMMITTEE OF
THE IRON AND STEEL INSTITUTE
AND
Tue Brirish IRON AND STEEL FEDERATION

WITH EIGHT PLATES - _

Published at the Offices of
THE! IRON AND STEEL INSTITUTE
4, Grosvenor Gardens, London, S.W.1.
pe! , 1944

eee kee

A '

5

ee). ers : =

This booklet which is published hy the
iron and, Steet imstitute, has been prepared.
in collaboration with the Admiralty Corrosion
Committee. Worist its: eontents may ‘appear
to be of a somewhat academic nature, it is
considered that it will be of use to all
those who are concerned in the fouling
problem of ships, or interested in natural

history.

The suggested docking form ae this
pamphlet is for the Mercantile Marine, and
must not be confused with the official dock-
ing form D.495, which is required for Naval

Wessels.

Attention of all Naval and Dockyard

- Authorities is called to the Activities of
the Admiralty Corrosion Committee vide |
ool ea 2 2923/43 « Any examples of fouling

or queries arising therefrom should be |
referred to the Secretary of the? Admini tes
Corrosion Committee, Portsmouth Dockyard,

and not to the officials of the Marine ~

Corrosion Sub-Committee.

FOULING OF—SHIPS’-BOTTOMS: IDENTI-
FICATION OF MARINE GROWTHS.!

By THE MARINE CORROSION SUB-COMMITTEE.?

(Figs. 2 to 45 = Plates I. to VIII.)

Paper No. 14/1944 of the Corrosion Committee (submitted by the Marine
Corrosion Sub-Committee).

CONTENTS
PAGE
(1) Objects of this Booklet
(2) The Significance of Fouling
(3) The Growth of Fouling
(4) The Anti-Fouling Problem
(5) The Fouling Organisms
(a) Slimes . 2 2
(0) Plants (‘‘ Weeds ’’)
(c) Animals ‘ . ; a ids
6) The Identification of Fouling Organisms
7) Dry-Docking Report and Key i i hh wil ela ,
8) Notes on the Recognition of Specific Organisms. ‘ 14
(a) Diatom Slimes : : : A : -
(6) Plants . : ; : : : ; : : i4
‘(c) Animals : ; . " Riek HE ee : 16 |

OOO OIwW iH

(
(
(

(1) OpsEcTS OF THIS BOOKLET.
The objects of this booklet are :

(1) To emphasise the deleterious effects of fouling on the
operation of a ship,

(2) to give a brief account of the settlement and growth of
the marine organisms which are mainly responsible for fouling,

(3) to discuss briefly the methods of anti-fouling research,
and the means of preventing fouling, and

(4) to describe the characteristics of marine growths in

sufficient detail so that they may be correctly identified when

present on ships.

A questionnaire in the form of a dry-docking report is provided on pp.
11-12. This form, additional copies of which may be obtained from
the Secretary of The Iron and Steel Institute, is intended to serve as a
research tool in furthering our knowledge of the growths on ships in
relation to the various factors concerned. It is hoped that as many
shipowners as possible will make use of this docking report.

1 Received November 16, 1943.

2 A Sub-Committee of the Joint Corrosion Committee of The Iron and

Steel Institute and the British Iron and Steel Federation reporting to the °
Iron and Steel Industrial Research Council.

FOULING OF SHIPS’ BOTTOMS:

ho

(2) THE SIGNIFICANCE OF Fourie.

The fouling of ships by marine growths Is a. matter of very brent
importance in both the performance and the upkeep of the Royal
Navy and merchant fleets.

For design purposes it is the practice of the Admiralty to allow
an increase of frictional resistance of 4% per day out of dock in
temperate waters and 4°% per day in tropical waters. These figures
are based on the results of experience over a number of years, and

may be regarded as covering the worst conditions of fouling that
are generally experienced in warships in peace-time, when a rela-
tively large proportion of time is spent in harbours. The possible
effect of fouling in producing increased fuel consumption and loss
of speed is shown in Table !., which is calculated:on the basis of
this Admiralty allowance for various types of ships in temperate
waters. The corresponding figures under tropical conditions would
be approximately doubled.

TABLE I.—Effect of F ee for Six Monihs out of Dock in Temperate
Waters.

Frictional resistance assumed to rere 1; per day.

Percentage Increase in Fuel |
|

!
|
eer Loss of Consumption * to Maintain
A
Ue raciusnie Maximum w- ..@ Speed of —
Pype of Ship ee as ee Mi as a
no
| | 10 Knots. 20 Knots
Rr i LE TN aA i | I i ee eee
: if | |
' Battleship j 39,000 13 45 40)
Aircraft carrier | 23,000 | 1} 45 | 4)
- Cruiser (10,000: it 59 | 45
Destroyer : 1,850 | 2 | bu rel |
| | |

oe NS ee |

S40 BPE © Reis Leh 8 ee OP ee ees
* These figures are based on the fuel consumptions for propulsion only,
i.€., auxiliaries are not included.

The foregoing examples refer to warships under peace conditions.
The corresponding figures for merchant ships will in general be less,
because they spend a greater proportion of time at sea and are there-
fore less exposed to fouling conditions. During the war, however,
many serious cases of fouling of merchant ships have been reported,
particularly on vessels operating in the tropics. As a result, the
Ministry of War Transport and shipowners have been considering the
possibility of using more efficient compositions to meet these con-
ditions.

Whilst it is difficult to give a reliable estimate, it is probable that
at least 20% of the total quantity of fuel used for ship propulsion is
expended in overcoming the increased resistance due to fouling.
When to this is added the cost of the more frequent dry-dockings
necessary for cleaning and coating bottoms,some idea can be obtained
of the enormous expenditure attributable to foulmg. Apart from the

PD ENA ERTION OF MARINE GROWTHS. 3

purely economic aspect, the problem is one of vital national import-
ance in war-time from an operational point of view. The outcome
of a naval engagement might well depend on the increased endurance
and higher maximum speed that would result from a reduction of
fouling.

(3) THE GRrowTH oF FouLine.

When a plate painted with a non-poisonous paint is immersed in
the sea at certain times of the year, a community of organisms
rapidly settles upon it. Included among these organisms are :

(i) Marine bacteria, some types of which secrete a coherenv
slimy film over the surface.

(ii) The young stages (spores) of seaweeds, microscopic in
size, but many of them rapidly developing into typical seaweed
form.

(iii) Diatoms, which are minute plant cells bccurring singly,
in chains or in masses. These may form a brown slimy layer
over the surface or long trailing brown threads similar in
appearance to certain seaweeds.

(iv) The larval forms of many sessile marine animals.
These are all microscopic free-swimming organisms capable, at
a certain sharply defined stage in their development, of settling
on a suitable surface, to which they attach themselves by a
cementing organ. Attachment precedes a metamorphosis pro-
ducing the adult organism. As the animal grows, more cement-
ing material is laid down, ever increasing the security of attach-
ment. This sequence occurs with the common animal fouling
organisms such as barnacles, calcareous tubeworms, ascidians
(sea-squiris) and polyzoa. The attachment and growth of
hydroids (which belong to the animal kingdom) follow a more
plant-like pattern; the larva settles and grows out over the
substratum as a series of branching tubes, from which at intervals
arise the stalks bearing the main body and feeding organs of the
animal. |

A heavily fouled surface may show a basal “ carpet ”’ of bacterial
and diatom slime from which project the “ stalks ’’,of hvdroids as
~ well as diverse seaweeds, and sometimes the trailing brown filaments
of certain diatoms. Barnacles, tubeworms and many other animal
forms attach themselves very firmly to the paint surface, for this
purpose penetrating the slime, and often the surface layers of ysaint,
if this is fairly soft.

A very heavy growth of one type of organism is frequently
accompanied by the more or less complete absence of rival forms
both plant and animal, so that a badly fouled surface can usualiv be
described in terms of a very few animal or plant types. This
phenomenon is known as biological exclusion.

4 FOULING OF SHIPS’ BOTTOMS:

Plants grow predominantly at and near the water-line, and if
they .are abundant there they tend to discourage most types of
animal life in that area. Well below the water-line, and particularly
under the turn of the bilge, lack of light prevents plant growth and
the population is largely, if not entirely, animal.

Several factors influence the degree of fouling which may appear
on a non-toxic surface; the more significant of these include the
season of the year, the amount of light reaching the submerged
surface, the temperature of the water, and, perhaps the most import-
ant, the geographical location of the waters concerned. The colour
‘of the painted surface is relatively unimportant.

Many fouling organisms have a restricted breeding period; this
is illustrated in Fig. 1, which has been compiled at two observational

Barnacles Ys ny

Hydroids
Ascidians
Polyzca
Musse/s SS

Mussels |

Lo
Seaweeds WILLE = 53 a7 By
22a): Wi ee wy WV’Vll-*

Fic. 1.—The Fouling Season at Caernarvon and Millport 1941-49, Heavy
settlement is indicated by cross-hatching, the period of lighter infection
by single hatching. (Ascidians = sea-squirts. Diatome correspond chiefly
to those inhabiting the slime layer on Snes )

stations, Caernarvon and Millport, during the two years 1941-42.
The seasonal settlement of fouling organisms naturally varies
according to the locality, but the diagram may be taken as being
indicative of behaviour around the coasts of Great Britain. In some
tropical ports, it is known that the’ seasonal variation in settlement
is much less marked than in home waters and that extensive fouling
will occur nearly all the year round.

Fouling octurs when ships are in port or at anchor’ in shore waters,
since the usual fouling organisms live in or near shore waters. The
ports of the world vary considerably in their liability to produce
fouling. As a rule, ports in the tropics are more troublesome than
those in temperate climates. Most marine fouling organisms will
not survive in fresh water, and hence in ports into which river
waters run the variety of plant and animal life that may appear is
curtailed or that acquired in a sea-water port may perish and sooner
or later fall off. The shells of barnacles and tubeworms remain
attached to the ships long after the animal is dead, but become very
brittle. One species of barnaele (Balanus improvisus) is reputed to

IDENTIFICATION OF MARINE GROWTHS. 5)

have caused severe fouling in almost fresh water (e. q., the river
Plate).

(4) Tue Anti-FouLinc PROBLEM.

The present-day method of combating fouling on the under-
water plating of ships is the use of anti-fouling compositions applied
just prior to undocking. These compositions may contain as
poisons copper and mercury compounds and organic substances.
In water, these poisons leach out of the paint medium, so that a
more or less continuous supply of poison is available at the surface of
the paint film. The value of an anti-fouling composition depends
_on the rate of leaching of the toxic ingredients, which in turn is
a function of the type of medium employed to bind the paint and
of the percentage of toxic ingredients present. All anti-fouling
compositions thus have a limited life, which for most commercial
products is of the order of 4-12 months. Thus, periodical renewals
of anti-fouling compositions are determined by this limited life.

The actual anti-fouling mechanism is being actively investigated
at the present time. Available evidence indicates that the toxicity
of a surface has little effect on the growth of an organism once
attachment has taken place, so that the main line of attack lies in
the prevention’ of the initial attachment. The constituents of the
anti-fouling composition may thus include substances which exert a
repellent or lethal action on the larve and spores, or alternatively
substances which prevent the adhesion or setting of the cementing
substances produced by many of the organisms for effecting the
attachment. ‘It is also possible to eliminate attachment by exfolia-
tion, 7.e., the continual shedding of the surface layer of a suitably
compounded paint.

A brief summary of the Sub-Committee’s investigations which
are now in progress on this matter will be appropriate. Tests are
being made on formulated anti-fouling compositions containing
inorganic and organic poisons. It has been found that mercury is
approximately twice as effective as copper against weed fouling
(weight for weight) and three times as effective against barnacle
fouling. Inorganically combined arsenic is almost ineffective.
Although many organic poisons have been found which are very
much more potent than copper and mercury when in solution in.
sea water, unfortunately in most cases this toxicity is difficult to
bring into effect when the organic poison is incorporated in a paint
film. There are, however, certain promising developments in this
connection. A new technique has been developed for studying
the leaching rate of poisons from paint films immersed in sea
water.

An important aspect which is receiving consideration is the paint
medium in which the poisons are incorporated, due regard being paid
to the conflicting requirements that the poisons shall be readily and
continuously available whilst the coating shall be as durable as

6 FOULING OF SHIPS’ BOTTOMS :

possible. In all this work the importance of providing efficient
protective undercoats has been stressed, since premature failure of
the underccats invariably leads to unrestricted fouling, apart from
the incidence of corrosion troubles.

It will be realised that the problem of fouling is indeed a complex
one requiring the collaboration of the marine biologist and other
specialists. It is equally desirable that all those who are concerned
with ships and shipping at sea or in dock should be familiar with the
broader aspects of the problem and the methods by which it is being
tackled. It is hoped, therefore, that this booklet will serve a useful
purpose in stimulating the interest and co-operation of all concerned,
and at the same time provide a useful guide to the identification of
the marine organisms which cause fouling. |

(5) Tor FouLtine ORGANISMS.

On a ship that has remained for a long period of time in a har-
bour and js then dry-docked, perhaps in that same harbour, without
an intervening sea voyage, an enormous number of different types
of organisms may be found growing. Not all of these forms are
attached to the surface of the vessel, for in the miniature forest of
growth all sorts of creeping and swimming forms find a comfortable
berth. In addition, many of the attached forms have anchorages
which will not stand up to the rapid motion of a ship at sea. In this
booklet attention will be concentrated on those forms which are
likely to be found in the normal course of a vessel’s work, when she
is dry-docked at the end of a trip with relatively little opportunity
for the settlement of the temporary lodgers which may occur in the
harbour and approaches to dry-dock’ areas.

The limitation of the description to the “‘ permanent ”’ lodgers
has two advantages: There are surprisingly few types to describe,
which simplifies the problem of identifying them; also, since the
temporary inhabitants will all be rapidly washed off when the ship
puts to sea, they are not important in causing resistance to the
motion of the ship. |

Marine fouling growths appear either as slimes, as tresses of
marine plants or in the highly individual forms shown by the marine
animals. The animals and slime may occur over the whole sub-
merged surface ; the tresses produced by plant growth rarely extend
more than a few feet below the water-line.

(a) Slimes.

The nature of the slimes that occur on ships can be recognised
only by microscopic examination. Commonly they appear structure-
less under a magnification less than x 100, and such slimes are
probably formed by bacteria. Others, which are usually rather
tougher, are formed by one-celled plants called diatoms. They live

IDENTIFICATION OF MARINE. GROWTHS. 7
in countless numbers, often closely packed together, within the
slime which they themselves produce (see Fig. 40). The contents of
the cells are brown or olive-yellow in colour.

(b) Plants (“ Weeds ’’).

The seaweeds that form the “ grass’ on the upper parts of the
underwater plating are of diverse kinds like the seaweeds found
in rock pools on our own shores. They may be green, light or dark
brown, bright red or purple in colour (Figs. 2 to 8), and may reach a
length of several inches.

(c) Animals.

The best-known of all the animal fouling organisms (Figs. 9 to
16) are the barnacles. The form of these, with their conical shells
adhering firmly to the hull surface, is almost too well-known to need
description.

The common type of barnacle, the “‘ acorn barnacle’’ (Figs. 12
and 21}, is most usuaily encountered, but occasionally stalked or

‘goose barnacles’”’ occur. The latter are attached to the hull by
a thick muscular stalk up to 3-4 in. in length, at the end of which is
the body with its shell (Fig. 22), which may be inconspicuous.

The shelifish (molluscs) which foul ships are represented by the
mussels and oysters (Yigs. 13 and 14). They are not likely to be
mistaken for any other forms, since the shell is always formed from
two halves called “ valves.” They frequently occur in large num-
bers on the various underwater gratings of the ship; when they
_ grew on the hull itself they show that the anti-fouling coating has
completely broken down, since they are very easily poisoned.

Tubeworms, as their name suggests, appear as white or greyish
limy tubes, which may be much coiled, lying flat against the surface
or sometimes projecting outwards from it (Figs. 11 and 17). They
often occur in patches on the hull surface (when they are frequently
but incorrectly called “ coral patehes ’’). They are of considerable
importance in the fouling of propeller blades (Fig. 18). Their very
long and firm attachment anchors them well even on a rapidly
rotating screw, where they may occur along almost the whole
length of the blade, causing a very serious reduction in the pro-
pulsive efficiency. They are fairly sensitive to poisonous paints,
and hence their settlement on the huil indicates poor anti-fouling
properties.

All the above forms possess shells which remain on the hull even
when the animal is killed, e.g., by steaming through a fresh-water
zone. Other animal forms without limy shells can occur either as
Pees -like branching growths (e.g., hydroids) or jelly-like soft-bodied
orms

Hydroids (Figs. 9 and 10) are often important fouling organisms,
since they are firmly attached and some are very resistant to anti-

8 FOULING OF SHIPS’ BOTTOMS:

fouling paints. The most usual forms occur in patches or clumps
of knobbed stalks, which are much stiffer than those of fouling sea-
weeds, so that they stand out from the hull surface even when in
dry-dock. The tresses of seaweeds almost always collapse against
the surface when the water is withdrawn. One of the commonest
forms of hydroid in British waters (Tubularia, Fig. 10) has a very .
striking bright pink head to the stalk. These heads disappear
under unfavourable conditions (e.g., fresh water, low temperature,
&c.), but the stalks persist and form characteristic sult, wiry grey
clumps.

The soft-bodied forms include the sponges (Figs. 19 and Piss
sea- es (Figs. 20 and 25) and sea-anemones (Fig. 27).

(6) THE IDENTIFICATION OF FouLINe ORGANISMS.

It is impossible to give an absolutely hard and fast rule for the
identification of any particular type of fouling organism. The key
in Section (7) gives a reasonably accurate method of establishing
the principal groups without going into detail, which can be seen only
under‘a hand-lens or microscope. Whenever doubtful cases occur,
a small sample can readily be preserved in water to which a few
drops of formalin have heen added. The Marine Corrosion Sub-
Committee will gladly examine and identify any specimens sent
to them, and will supply tubes of formalin to anyune wishing to send
samples; correspondence on this subject should be addressed to the
Secretary of The Iron and Steel Institute. |

In using the dry-docking report, the following general remarks
should be borne in mind. Seaweeds are almost always. confined to
the water-line area; if a plant-like growth occurs over the whole or
the darker parts of the hull it is probably a hydroid. A green colour
is an almost certain mark of a seaweed, but the latter may also be
red or brown. A red seaweed is usually of a fairly rich deep colour,
‘the stalk as well as the “ branches ”’ being all of one colour. The
red colour of some hydroids is limited to the knobbed head alone;
the stalks (which may not bear any head at all) are usually ereyish,
brown or white. A diatom slime may look like a patch of brown
oil; it is not, however, greasy, and washes off the fingers easily
with water ; when dry it often appears as a grey or greenish-grey
film.

The recognition of the various kinds of plant growths, both
diatoms and seaweed, that occur on fouled vessels is most satis-
factorily accomplished by the use of the microscope, a magnification of
100 diameters being adequate for this purpose. Some seaweeds are,
however, difficult to distinguish from one another except by an expert.
Some identification is possible by examining plant growths with a
good hand-lens; for this purpose it is advisable to spread them out
thinly on the fingers or in water between two small sheets of glass,
examining them against a strong light.

PuaTE J,

SEAWEEDS AND HyprolIpbs.

Rather less than Natural Size.

Green Seaweeds Brown Seaweeds Hydroids
Fig. 2.—Enteromorpha. Fig. 3.—Ulva. Fig. 4.—Cladophora. Fig. 5.—Laminaria,
Fig. 6.—Ectocarpus. Fig. 7.—Ceramium. Fig. 8.—Polysiphonia. Fig. 9.—Various
hydroids. Fig. 10.—T7ubularia (a common hydroid),

[Fouling of Ships
[To face p. 8.

PuaTeE II.

VARIOUS ANIMAL FOULING ORGANISMS.

Rather less than Natural Size.

Fig. //
Mussels and Oysters

| Barnacles” | , Bases of Barnac/les

Fig. 11.—Tubeworms. Fig. 12.—Barnacles. The coloured type is a tropical and sub-tropical form ;
the white ones are a typical British species. The elongated form assumed when the barnacles are tightly
packed is also shown. Fig. 13.—Mussels. Fig. 14.—Oysters. Fig. 15.—Patches
of encrusting Polyzoa. Fig. 16.—Bases of barnacles after the barnacles themselves have fallen off

or been removed by scraping.

[Fouling of Ships.

PLATE III.

ACTUAL FOULING OBSERVED IN DrRy-Dock.

Fig. 18.—Fouling of propeller of H.M.S. Fowey by calcareous tubeworms. (Reproduced, by courtesy, from
G. D. Bengough and V. G. Shepheard, ‘‘ The Corrosion and Fouling of Ships,’’ Transactions of the
Institution of Naval Architects, 1943, vol. 85, p. 1.)

{ Fouling of Ship:

PuatTe IV.

*410dS0r)
j@ Ppo[noj faued e fo sjzinbs-ees Aq

uoljoozut AAVOTT W—"08 “SIF wiorj psonpoidoyy

“SIANVd IVINGWINAdXY NO GHAXASAO

ONITNOY

‘ydergojoyd anojoo
*‘yanbs-e9s [etuojoo & pue sosuods ‘ sjeulue perpoq-]JOS—*6] *BhF

quinbs

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88S seruosog

Se

g of Ship

Foulin

L

PLATE V.

VARIOUS ANIMAL FOULING ORGANISMS.

high
rte
WUEE LMR

Fig. 24.—“ Acorn barnacles,”? showing the con:pressed forms found in crowded colonies.

Fig. 22.—The ‘‘ goose barnacle.”’ Fig. 23.—Patches of an encrusting Polyzoan, showing how
it may grow over the shell of a dead barnacle. The structure is honeycomb-like. Fig. 24.—
Barnacle bases, showing the type of markings which distinguish them from Polyzoa patches.
Fig. 25.—Various sea-squirts, showing two different forms of single animals and a colonial form.
Fig. 26.—Sponges, showing (Jeft) a colony of single individuals, and (right) a colonial ‘‘ encrust-
ing ’’ sponge. Fig. 27.—A sea-anemone in its contracted form as seen out of water,

[Fouling of Ships.

PuatTeE VI.

STRUCTURES OF VARIOUS PLANT FOULING ORGANISMS.

©

Fig. 28.—Branch of an Ectocarpus, with four of the characteristic reproductive organs; cell contents
only shown at the base. x 100. Fig. 29.—Portion of a thread of Ulothrix flacca. xX 180.
Fig. 30.—Two individuals of Licmophora, seated on the end of the branches of the mucilage
stalk and seen in different positions. x 300. Fig. 31.—Single individual of Schizonema.
x 700. Fig. 32.—Cell of Achnanthes at end of mucilage stalk. x 250. Fig. 33.—
Tip of a Cladophora, showing shape of cells and manner of branching. x 100. Fig. 34.—
Two tiers of a Polysiphonia, with four peripheral cells surrounding the single centralone. x 400.
Fig. 35.—Small part of a Cladophora at a point of branching, showing cell contents and the thick
walls. x 350. Fig. 36.—Small part of a strand of Enteromorpha. x 150. Fig. 37.—
Tip of a thread of Urospora; the two uppermost cells with reproductive cells. Xx 150,

| Fouling of Ships.

Puate VII.

PHOTOMICROGRAPHS OF VARIOUS SEAWEEDS.

$

SESE ee ee

=

bos

Fig. 38.—A number of strands of Enteromorpha. Fig. 39.—Part of a plant of Cladophora, showing
Sas the elongated cells. x 30.

i 2 “

ers

TAR the

Fig. 40.—The diatom Schizonema in its mucilage Fig
tubes. X 70, a number of the reproductive organs. x 30.

[Fouling of Ships.

Puate VIII.

PHOTOMICROGRAPHS OF SEAWEEDS AND POLYZOA.

Fig. 42.—The red seaweed Ceramium, showing the Fig. 43.—The red seaweed Polysiphonia, showing

characteristic banded appearance and pincer- the tiers of cells. x 30.
like endings. x 15.

6

Fig. 44.—A branching Polyzoan. X 3. Fig. 45.—The same organism as in Fig. 44, showing the
typical honeycomb structure of the Polyzoan. x 4,

(Fouling of Ships
[To face p. 9.

IDENTIFICATION OF MARINE GROWTHS. 9

(7) Dry- Macierka REPORT AND: Key.

A reduced facsimile dry-docking report, which has been filled in
for purposes of illustration, is given in the following four pages.
Blank copies of this report, ‘printed foolscap size and incorporating
the appropriate keys for identification of the organisms, are issued
separately and may be obtained from the Secretary of The Iron
and Steel Institute.

(a) Conical shells with an opening at the top

10

FOULING OF SHIPS’ BOTTOMS :

Key To Section A or Dry-DockiInG REPORT.

(1) Organisms with a Shell.

‘acorn barnacles’’) .
(6) Shells (formed from many plates) at the top of
a long fleshy stalk (‘‘ goose barnacles ’’) ;
(c) Small but long tubular shells, lying flat or
projecting upwards at the open end, often
coiled :
(d) Paired shells (like mussels and oysters)

(2) Organisms with no Shell.
{e) Bag-like forms or slimy rounded masses .

Branching types :

(f) Steff stalks, dark brown, grey or white in colour, ,

sometimes ending in knobbed heads :
(g) Green, brown or red, often branched threads or
leafy growths, limp (7.¢. ee flat in oy dock)
and near water-line . :

BARNACLES.

TUBEWORMS.
MOLLUSCS.

Sort-BoDIED
ANIMALS.

HyYDROIDs.

SEAWEED.

The above key is sufficient for the identification of all the groups dis-
tinguished in Section A of the dry-docking report.

IDENTIFICATION OF MARINE GROWTHS. ll

DRY-DOCKING REPORT.

This form, together with any samples collected, should be sent to. The Secretary, The Iron and Stccl
, Institute, 4 Grosvenor Gardens, London, S.W. 1.

Naime of Vessel : it. HESPERYS Date of Dry-docking : 20. Nav.. LG43
Place: ... BPA ENMAEAD..... ccc.

Secrion A.
The whole of this section should be completed as fur as possible.
Last Dry-Dockine.
Date :.(8..4O0G?..1944...... Place : - GLAS GON. STO GAN MAIER (AC) SPE I VETS ae |
Anti-corrosive coat : *..S7UAS. He. proticlive.... Touch up/one-eoat /twe-voats.
Anti-fouling coat : * Smith's. Adrrumnlly. ually. 207 "Fouche one full coat.

~

Weather when painted : . Gant... brut. frome. Sea PEARCE COSS.: sae, JoanuuTe d,s

VOYAGE. Foutrnc.
r

E De- Amount ft and Position.
Port of Call. areal parture Kind. - == x

Date. Sides | Bottom. | Propellers
Alexomata Caer awe AQ Mohd Parnacles ; ‘ eA Seeds ees | £X. RAS | bac ea |
Able pete i Cn AF- LAGS: Br: 44S, Tubeworms . Rysloetesidtih s 3 | nce ee 4 (
age heeeicbeannee| le a5 #3, MO 8- 43: Mussels or Oysters . |--.-.-+..+ a see ee | Deed ae awash
ET): ee Q- E-ed. (er8: eed. Soft-bodied forms . |....-------.-+- | ppoanponodd sod ss ceacadeeee
PIGOTIOY So... sey 2: 624A C2 TMI Hydroids, (007) s) [esccuatticesrcoteree p. Sete eh Bd
DAB ecco 2-9-4 6 - 9-H) Weed (gradityrh or SoM. | Rabel toilaan 2 e.
be tueelourn Des iaeioaees -.Q- 4d 1O-M0-. Weed (brown) —. [-...-- PERN ARON asl 8 aN

|
Athen fa POE nose rear resists. Weed (red). |

+ The waneunt of fouling should be show: pee x little ;

Paint ConDITION oy Botrom.

Port. STARBOARD. |
Amidships. | \> Aimidships:
Paint Condition. : :
Forward.| apove Below Aft. Forward.| apoyo Bclow Aft
Bilge- Bilge- Bilge- Bilge-
Keel. Keel. Keel. Keel.

Good ! = : :
Fair ? : . é é x
Bad? 4 : 2

NE x
Intact anti-fouling coating. °% * | 25 /

1 Good.—Paint generally firm and adherent, aabieas ee ait areas eas Mee exeeeding 29% of the total arca.
: Fair.—Rusted and bare areas from 3 to 9°;, of the total area.
3 Bad.—Rusted and bare areas 10°, or more of the total area.
Enter a X in each colunn. opposite the appropriate condition.
‘ Insert the percentage areas in each column.

Zinc Prorection Brocks }: Net-fitted /condition of zines : ...2aY.. Gaclly.. scam ltrast...
Lake Led BfpQhOAsd,.ON.. SE eran ON eee SE a Tocbh ap bannp- os

Omer COMMENTS : .. Wo pes ge AAAs, aici 09, OAD...

* Enter the name of the composition and cross out remarks which do not apply.
+ Cross out remarks which do not apply.

FE ie Pea ena

12

Theseaquestions are less important than those in Section A overleaf, but answers to any or all of them will
provide very useful information. i

SreciaL Notes on Fou.ine.
1. Slime.* Present /ebsent. Beeteriel diatom.

2
'
foe
een i
ees gas
eae
ee
|
|
ee are
bp at
|
|
1

. Barnacles: Size: * Large/medium/smed.. Colour: * Wsite/purple or blue.
. Molluscs.* Meesele/oysters. Bottem—pleting /gratings only

. Polyzoa.* Wat-onceustinetypes /branched forms.

. Soft-bodied forms.* Spongeeses-equistn

., Any other forms. (Give brief description and send sample tf possible.)

. Special Notes (e.g., if port and starboard sides very differently fouled or if fouling limited to certain

FOULING OF SHIPS’ BOTTOMS :

Dry-DockiIne REePort—Continued.

Section B.

Weed. (If individual types of weed can be identified (using the pamphlet on “ The Fouling of
Ships’ Bottoms’ or the key below) enter the names and amount (as X or * x) of cach in
this space.) ...... OTUAPAA...4K...0L... s .. Bp. Aah... o9

w= ONL. EMETCOR GIS, Kose sec itece reece ROM en OWA ARS r one mt Peay So ke 2,

Pe eee eT e ee oe e e e e eee r ry

vie .. fflate.5 + headlied.. fatans 7.280... CHUMIUTTARG 0... ce cecccccceceeseeeees it
a ... faangal... Me TS fly OT ee We doe, ce

PPererr rT eee rre er eee ere eee eee ee eee eee eee eee eee eer eee errr e ree er ee ee re

special areas. Any information as to where fouling was first encountered on the voyage, length of
weed or diumeter of barnacles on docking, etc.).:

Aneel. nuke. dreanrtinr.,.90.. and... hile, tifa. Ab.. 38" hong. ale........

Bere e cern meee ees eesssceren rn sees ee bess wererennee

Ree eee eee ORC HESS E REDE HHS ERE SONS OES EH OER OEE HES EDS EET EEO HEH SEH EOE EH SE ESO EH SHH SOHO H EHRs Ee HeHeaaarsenseeos ese eeerateees

Signature vB OMOG 2. Position in Firm or ship Bork... Supesrstin. deal

+ * Cross out remarks which do not apply.

IDENTIFICATION OF MARINE GROWTHS.

Key to Section B or Dry-Dockine REPORT.

(See also key to Section A if fer eatgie )
(1) Organisms with a Shell.
(h) Flat patches of a limy oR ett pan
comb in structure . : .
(2) Organisms with no Shell.
. (i) Branching types :
(7) Branches expanding from a single base or
forming a moss-like tangle; never possess-
‘Ing heads on the stalks and showing a
honeycomb structure under a ere lens
(7) Green weeds :
(1) Soft and flexible tubes, varying in

thickness from that of human hair to

about } in. or more, usually little
branched ‘

(2) Single threads, with a slimy feeling,
of the thickness of a human hair
or much narrower, the individual cells
in the wider threads just recognis-
able under a good lens .

(3) Richly branched threads, forming tufts
1-2 in. long, with a rather harsh feel-
ing, the long sor penent cells readily
seen with a lens ; 3

(4) Broad papery sheets

(k) Brown weeds :

(1) Threads forming short tufts or long
hanging tresses, usually extensively
branched, but the majority of the
branches much: narrower than those
of Cladophora. (N.B.—These growths
may appear green after a ey in
fresh water) .

(2) Similar branching threads, with a more
slimy and softer feeling than those
of Ectocarpus; under a microscope
are seen to consist of mucilage tubes
harbouring boat-shaped diatoms

(1) Red weeds :

(1) Branched threads, often repeatedly
forked, the two arms of the ultimate
forks often curved inwards like a pair
of tongs; threads with alternating
darker and lighter cross bands :

(2) Branched threads, in which the elon-

. gated cells are arranged in successive
horizontal rows, especially obvious
in the upper parts

(ii) Soft-bodied forms:
(m) Jelly-like masses or transparent leathery bags
(n) Opaque bag-like or spongy structures .

_ ENTEROMORPHA.

POLYZOA.

POLYZOA.

UROSPORA.

CLADOPHORA.
ULVA.

ECTOCARPUS.

SCHIZONEMA,

CERAMIUM.

POLYSIPHONIA.

SEA-SQUIRTS.
SPONGES. |

14 FOULING OF SHIPS’ BOTTOMS:

(8) NoTES ON THE RECOGNITION OF SPECIFIC ORGANISMS.

(a) Diatom Slimes.

Among the types of diatoms responsible for fouling are species of
Schizonema, in which numerous individuals live within a branching
system of mucilage tubes (Fig. 40). The individual ceils, according
to the position in which they lie, appear rectangular or more usually
boat-shaped, tapering from the middle towards each end (Fig. 31).
Other diatom slimes are of a different character, the cells being
situated at the ends of rather thick, simple or branched, transparent
mucilage stalks, which are themselves attached to the ship’s hull.
The commonest of these, due to a diatom called Achnanthes, is
readily recognised (x 50), because the individual cells either appear
oval or exhibit a marked bend in the middle (Fig. 32), according to
the side which faces the observer. Less frequently diatoms are
found with wedge-shaped cells borne on mucilage stalks. These,
Licmophora (Fig. 30), usually grow attached to other seaweeds.
Many other kinds of diatoms occasionally occur in the growths on
fouled vessels, but these are rarely abundant and could only be
identified by an expert.

(b) Plants.

Among the green seaweeds the commonest is. Enteromorpha
(Figs. 2 and 38), which possesses soft and rather flexible threads,
frequently unbranched, although a few kinds branch freely. Under
the microscope (x 50) the threads can be seen to resemble a hollow
green tube, a layer of small cells surrounding the central hollow.
The cells are commonly arranged in longitudinal rows (Fig. 36). In
some of the coarser kinds the tube-like character is recognisable
without microscopic examination.’ The strand of Hnteromorpha
may grow toa length of 6 in. or more. |

_ Less commonly the green seaweed Cladophora (Figs. 4 and 39) is
concerned in fouling. This occurs in dense tufts, which are richly
branched and usually from 1 to 2 in. long. They have a coarser
‘* feel’ than the growths of Enteromorpha, and with a good hand-
lens can be seen to consist of simple rows of long cells (Fig. 33), much
larger than those forming the surface of the Hnteromorpha tube.
The branches commonly arise in twos or threes at the same point
(Fig. 33). |

Occasionally green fouling is due to Urospora; this has un-
branched hair-like threads, which, when handled, have a rather
slimy feeling. Structurally (x 100) they show a single row of broad,
often barrel-shaped, cells with rather thick walls and dark green
contents (Fig. 37). The shape and size of the cells are very variable.

In the early stages of fouling very much narrower threads with
small cells are sometimes found; they belong to the seaweed Ulo-
thrix flacca (Fig. 29), and are recognisable only under a microscope
(< 100). Such threads sometimes occur within the diatom slimes.

IDENTIFICATION OF MARINE GROWTHS 15

Species of sea lettuce (Ulva) may also be met with on ships’ hulls,
although, so far as present experience goes, they always occur in
association with some of the other green forms. One of the common-
est kinds grows in broad sheets of about the thickness of tissue paper
and is readily recognised (Fig. 3), but some kinds of Ulva produce
relatively narrow ribbons that are not always easily distinguished
from some types of E’nteromorpha.

Of the brown seaweeds responsible for fouling one of the very
commonest is Ectocarpus, of which there are a number of different
kinds. Its tresses are usually dark brown, and when spread out
are seen to be richly branched (Figs. 6 and 41). Some kinds are
less than an inch long and, if there is a dense growth of Enteromorpha,
for instance, may be completely hidden beneath it. Other kinds of
Ectocarpus may grow to a length of several inches. Under the
microscope the contents of the cells appear brown or yellowish-
brown, although if the vessel has been for some hours in a fresh-water
port the brown colour will have leached out and the contents may
look green. Some or many of the shorter branches will be found to
end in oval or elliptical structures, consisting usually of several rows
of minute cells, much smaller than those composing the other parts
of the seaweed (Fig. 28). These distinctive structures are the
reproductive organs of Ectocarpus.

Other brown seaweeds that may occur on ships’ hulls are coarser
and less richly branched, but these are rare and have not usually
reached their full growth, and it would require an expert to name
them. The most frequent is Scytosiphon, with hollow strands
resembling those of Enteromorpha. The bladder-wrack (Fucus) and
the oarweeds (Laminaria) (Fig. 5) are likely to settle only on a
heavily fouled vessel which has made a long sojourn in port. They
would almost certainly become detached when the ship began to
move through the water.

Of the red seaweeds likely to occur on ships’ hulls the two most
easily recognised are Ceramium (Fig. 7) and Polysiphonia (Fig. 8).
Both appear as richly branched tresses, usually 1-3 in. long; those
of Ceramium are mostly bright red, those of Polysiphonia often dark
purple, sometimes appearing almost black. When the tips of the
threads of Ceramium are examined under a hand-lens (Fig. 42) they
usually appear forked, the two arms of the fork often being cur ved
inwards like a pair of ‘tongs. The threads themselves show numer-
ous cross bands which are of a darker colour than the intervening
portions. These two features are quite distinctive of ‘eramium.
Under a microscope (x 100) the banded appearance is seen to. be due
to the fact that the lar; ge cells forming the threads of this seaweed
are covered at regular intervals by sheets of smaller cells.

The threads of Polysiphonia are usually coarser. The upper
(i.<., younger) parts, when viewed with a hand-lens, show an
arrangement of cells in horizontal tiers which is: very characteristic
and is even more obvious at a magnification of x 50 (Fig. 43). The

16 FOULING OF SHIPS’ BOTTOMS.

individual tiers may consist of from four to twenty longish cells
(Fig. 34). The walls of the cells are usually thick. Sometimes some
of the branches are irregularly swollen and harbour a number of
very deeply pigmented cells, often in groups of fours; these are the
reproductive cells of Polystphonia.

(c) Animals.

When an acorn barnacle is scraped off the hull surface it generally
leaves a circular plate of lime still attached to the paint (Figs. 16
and 24). There is, however, one, type of fouling organism which
rather closely resembles a barnacle base and should be carefully
distinguished from it. This is known as a Polyzoan and produces
another form of “ coral patch ”’ on the surface (Figs. 15 and 23).

The Polyzoan encrustation has a fine net-like or honeycomb structure
~ composed of numerous small cells, while a barnacle base resembles a
fish scale. Me

Polyzoa also occur as flexible branching forms (Fig. 44), as well
as in the “ coral patch ” form. They are difficult to distinguish from
plant and hydroid growth, though their fine honeycomb structure is
generally visible under a hand-lens (Fig. 45).

Jelly-like masses, found usually on ships moored for a long time
in richly infested waters, may be sea-squirts (Figs. 19, 20 and 25) or
sea-anemones (Fig. 27). A thick leathery bag of jelly which ejects
water voluntarily or when compressed (sea-squirts), or a coloured or
white flattened blob of jelly, is typical of such animals.

Sponges, sometimes found under similar circumstances, are more
bag-like in structure with a rough surface. They have either a
single large opening to the bag or a very large number of such
openings from a colony (Figs. 19 and 26).

PRINTED IN GREAT BRITAIN BY RICHARD CLAY AND COMPANY, LTD.,
-BUNGAY, SUFFOLK.