A high attention has been paid for constant research on the preservation of materials in the marine environment. This includes all phases of design, development, applied engineering and economics which may influence the construction and operation of ships and underwater installations

Balasubramanyan, R.

Gopalakrishna Pillai, A.G.

Unnikrishnan Nair, N.

Aquatic Commons

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R. BALASUBRAMANYAN, N. UNNIKRISHNAN NAIR AND 
A. G. GOPALAKRISHNA PILLAI 
Central Institute of Fisheries Technology, Craft & Gear Division, Cochin-11 
World attention has to-day been drawn 
on the need for constant research on the 
preservation of materials in the marine. 
environment. This includes aU phases of 
design, development, applied engineering 
and economics which may influence the 
construction and operation of ships and 
underwater installations. 
The Indian fishing fleet comprising of 
innumerable indigenous sailing crafts and 
a large number of introduced mechanised 
boats have all assumed a greater responsibi-
lity to-day than ever before in the harves-
ting of the natural food resources of the 
seas around India. Of the 69 million tons 
of fish the world produces to-day (1970), 
India's annual contribution is about 1.7 
million tons. Besides feeding her own 
millions, India has also exported to world 
markets 38,271 tons of marine products 
valued at Rs. 58L7 million during 1972. 
The entire economy and the well being of 
the Indian fishing industry to-day lies, to 
a great extent, in the efficient, operation 
and management of her fishing fleet. 
Apart from the high initial investment 
on the development and the expansion of 
the fishing fleet, an enormous amount 
of money is b~ing spent annually on their 
proper maintenance for a prolonged trouble 
free and uninterferes with the smooth sailing 
of fishing vessels in Indian waters, is the 
intensive settlement of the marine fouling 
organisms on the boat hulls and their su-
ccessful prevention. While marine corro-
sion is restricted to metallic surfaces and 
marine woodborer distruction to timber 
structures, settlement of marine fouling 
organisms is common to all surfaces in sea 
-water may that be wood, steel, aluminium, 
fibreglass reinforced plastics (FRP or GRP) 
or even ferro-cement. 
The innumerable marine sedentry 
organisms comprising of both plants and 
animals that settle on ship's bottom con-
stitute the fouling complex and they seem 
to cause considerable amount of havoc to 
fishing boat afloat. The frictional resist-
ance of the hulls, the loss of efficiency 
of aU under water propelling devices and 
the frequent malfunctioning of aU under-
water electronic installations as a result of 
the accumulated fouling complex on them 
are too well known. Each and every boat 
has to be taken on the dry-dock periodi-
cally to get rid of all the unwanted fouling 
and again refloat them. This means a 
constant source of recurring expenditure, 
* Part of a paper presented at the 3rd International Congress on Marine corrosion and 
fouling held at Maryland, U. S. A. during October 2-5, 1972. 
!20 FISHERY TECHNOLOGY 
'Balasufnamanyan, Unnilhisllnan Nair & 9opalalhisllna 'Pillai: On tile importance of 
sfhp-vottom fouling 6y marine organisms -a tecllno-economic survey 
and less of fishing time, but however, 
fouling has to be prevented at any cost 
because of the al:lrming consequences. 
Though nearly 2000 species of plants and 
animals all over the world have been re-
ported to constitute to the marine foul.:. 
ing complex, practically only a restricted 
few of them become a menace to an 
crafts, boats and ships by their permane-
nt settlement ;;tnd massive growth on hulls 
underwater. The marine fouling comple:(( 
along the 5000 km length of coastal wa-
ters of India appears to be a true re-
presentative of the typical Indo-West pa-
cific -Tropical flora and fauna. The most 
common forms that are frequently met 
with during the dry-dock inspections of 
the hulls are npJrted. The Cirripede bar-
nacles, Lamellibranch bivalves, Annelidan 
tube.worms, Coelenterate hydroids, the en-
crusting colonial bryozoans, the water-line 
green-algae besides the ever present pri-
mary film of slime are the problematic 
forms of foulants. The project study, 
extending over a period of years, ,-inclu-
ded extensive survey and coB ;ction of the 
major fouling forms from different surfa-
ces from natural resources as wen as from 
raft exposures and laboratory studies. 
(Figs. l-6) 
A course of biological studies and 
investigations on the coastal foulants have 
revealed their quicker growth, early matu-
riry, greater fecundity and intensive settle-
ment within. a short tim~ and greater resis-
tance to adverse conditions under typical 
tropical Indian conditions. A supporting 
investigation on the hydrographical studies 
of the aquatic environment brought to light 
the greater influence of water salinity and 
lesser influence of water temperature on the 
fouling complex encountered. 
VoL X No 2 1973 
1. A close-up view of the perfectly ~lean 
ship-bottom at the time of launching 
2. A close-up view of the same ship-bottom 
showing the heavy fouli'ng during the 
am:ual docking. 
3. A newly fabricated floating buoy before 
exposure to sea-water. 
121 
'Balasulhamanyan, Unni~risilnan Nair & 9opala~·rislina 'Pillai: On tile importance ot 
sfiip-15ottom fouling f»y marine Organisms -a tectino-economic survey 
4. The same buoy after 8 months of expo-
sure to sea-water with accumulated 
fouling forms. 
5. An experimental Immersion rack for 
the collection of the marine fouling 
forms (before exposure to sea-water). 
6. The same rack after 8 months of expo-
sure to $ea-water with heavy fouling. 
122 
As far as fishing boats are concer-
ned; the intensity of settlement was con-
fined to few restricted zones like below 
the keel, at the turn of the bilge, rudd-
er surfaces and waterline areas. Displa-
cement hulls with deep draughts had co-
mparatively more fouling. An overall 
quantitative study has revealed an accu-
mulation of 1 to 1.5 kg per square foot 
(dry weight) of hull surface during a pe-
riod of 7 to 8 months of active service 
of fishing boats (Fig 6). Fouling was he-
avy when boats were inactive and lying 
at anchor inside harbours, river mouths 
and estuaries. Intensive fouling by shell 
forms not only has caused surface dama-
ges to wooden structures but also acce 
lerated corrosion on steel hulls. Copper 
and copper based alloys were free from 
fouling under normal conditions of imm-
ersion but were fouled as usual under 
galvanic inactivation. External installation 
of cathodic protection sometimes interfe-
rred with the efficient performance of an-
tifouling coatings. 
Periodical coating of antifouling pai-
nt on the hulls while the boats are on 
the docks, is the only method of preven-
tive measure, the Indian fishing fleet is 
adopting at present. Studies on the bio-
logical evaluation of commercial antifoul-
ing paints have indicated much scope for 
thdr improvement as regards design, for-
mulation, toxic leading and actual per-
formance. The Insiitute (C. I. F. T) bro-
ught to light the efficiency of copper-aceta 
-arsenite as a toxic pigment in the anti-
fouling composition in place of cuprous 
oxide. For the first time in India, a 
laboratory formulation of antifouling paint 
incorporating orga::1o metalic tin (Tri-butyl 
-tin-oxide) was formulated and put to test 
successfully. The newer construction ma-
terials like aluminium alloy, FRP or GRP 
and Ferro-cement and their surfaces wiU 
in no way be free from fouling in Iridian 
FISHERY TECHNOLOGY 
Balasu5ramanyan. Unnilirislinan Nair & 9opalalirislina 'Pillai: On tlte importance off 
sliip-6ottom fouling fJy marine organisms - a tedino-economic survey 
waters. Such new surfaces require not only 
an efficient antifouling paint but also an 
elaborate surface preparation, priming and 
anticorrosive under coats as is for wood 
or steeL 
Indian fishing fleet is fast expanding 
in size as well as in numbers. In the 
absence of adequate dry docking facilities 
at present, the only way is to enhance 
the life of antifouling paints with b;::tter 
formulations. It is roughly estimated that 
the Indian mechanised fishing fleet alone 
may require approximately 3,00,000 litres 
of antifouliug paint valued at Rs. 45,00,000 
annually to keep their hulls free 
from fouling and to have a smooth sai-
ling. This estimate, however, does not 
.include docking charges, labour and ex-
penditure on other ancillary items. Ma-
VoL X No 2 1973 
rine fouling is not just a growth of pla-
nts and animals but ''pins and needles" 
to boat owners. 
To-day studies and investigations on 
the phenomena of marine fouling are being 
carried out by a number of organisations 
and various agencies apart from Colleges 
and Universities all over the world. Stu-
dies of this type can no longer be con-
sidered as of mere academic interest but 
have immense industrial applicability. The 
subject of marine fouling and the various 
methods of their prevention have become 
a technology by themselves. The Central 
Institute of fisheries Technology at Cochin 
is at present actively engaged in similar 
studies and has infact been suggesting 
improved remedial measures from time 
to time. 
123 


On the importance of ship-bottom fouling by marine organisms: a techno-economic survey

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On the importance of ship-bottom fouling by marine organisms: a techno-economic survey

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