Organisms in the water, especially saltwater, attach to slick surfaces like a boat's hull. It doesn't take long for a boat hull to become slimy with algae. Algae pave the way for adherence of other organisms. The general term for organism on a boat hull is fouling. Fouling makes boats drag, use more fuel and harder to maneuver. Invasive organisms spread by hitching a ride on the underside of a boat. Common marine foulers include barnacles, algae, shellfish, tunicates, ship- worms, gribbles etc. Wood borers are highly specialised animals which penetrate wooden structures such as boats, wharves, jetties, driftwood and even living mangrove trees. Many can digest the wood owing to cellulose-digesting bacteria or protozoa living in their guts. Only a few species can actually produce their own cellulose-digesting enzymes (cellulases).Wood borers are insects that chew their way into the solid trunk of a living tree or into a wooden structure, such as an old boat or house. Healthy trees are rarely attacked by wood borers, but a diseased or dying specimen can often host these kinds of invaders. The same goes for old houses and boats, where rain-soaked or rotten wood is more susceptible to invasion.

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Boat Foulers and Borers
A.Fouling
Organisms in the water, especially saltwater, attach to slick surfaces like a boat's hull. It doesn't
take long for a boat hull to become slimy with algae. Algae pave the way for adherence of other
organisms. The general term for organism on a boat hull is fouling. Fouling makes boats drag,
use more fuel and harder to maneuver. Invasive organisms spread by hitching a ride on the
underside of a boat. Common marine foulers include barnacles, algae, shellfish, tunicates, ship-
worms, gribbles etc.
The marine biofouling challenges are even greater for wooden-hulled boats since they tend to
spend more time near the shore and are exposed constantly to a wider array of fouling
organisms compared to larger commercial fishing vessels that go farther out to sea. Thus, small
wooden boats represent a sizeable market opportunity for marine paint companies because of
the sheer number. However, price considerations are important, particularly since the end
users are small fishing boat operators and artisanal fishermen.
The photograph describes the fouling conditions in unprotected wooden boats in South India.
Hard fouling tends to be site specific and comprise mainly of mussels (Perna sp.), Teredo worms
and barnacles.
1. Barnacles
Millions of tiny shellfish called barnacles form
a crust on piers, rocks and boat hulls.
Barnacles cut the speed of a boat by up to 50
percent. In days past, pirates would tip over
their ships on beaches to scrape off barnacles.
Barnacles cost modern shipping industries a
large amount of money every year due to
cleaning, loss of time, extra fuel and wear-
and-tear on machinery.
2. Seaweeds

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Invasive Japanese seaweed called "wakame" spreads to other countries via boat hulls.
Discovered on a hull in Cornwall England in 2010, its appearance resembles Elizabethan
ruffles. Although wakame is edible and commonly used in soups and salads in Japan, it is
invasive and disrupts the natural ecosystem, according to the BBC website.
3. Sea Squirts
Didemnum vexillum, a type of sea squirt, grows rapidly and smothers natural habitats. It
has a distinctive orange/yellow color and spongy texture that feels leathery but not
slimy. It resembles dripping wax when attached to surfaces. This sea squirt exists in New
Zealand, northern Europe, the U.S., Canada and Japan.
4. Polychaete Worms
Polychaete worms produce calcium carbonate coral-like structure on hulls, propellers
and rudders. The European fan worm is a polychaete that covers marine pontoons.
Along with polychaete worms, the gelatinous invertebrates salps and pelagic attach to
hulls and get drawn through the cooling water intake, damaging an engine. Thick
infestations on hulls can easily slow down a boat. Sometimes applying anti-fouling
paints to the boat can help reduce the number of fouling organisms.
5. Zebra Mussels
Zebra mussels attach to different types of surfaces, such as fiberglass, aluminum, wood
and steel. Microscopic larvae, called veligers, enter boat engines and settle in the
cooling system to grow into adult zebra mussels. Adults block intake screens, internal
passages, hoses, seacocks and strainers. When mooring a boat, it is best to lift the
engine out of the water and/or use a boat lift to remove the entire boat from the water
when not in use.
Prevention or maintenance of boat from fouling agents
Damage from shipworms is an old problem. It is believed that the Spanish Armada of 1643 was
destroyed in a storm because the hulls of the ships were badly damaged by these organisms.
Woods Hole Oceanographic Institution (WHOI) was funded by the US Navy during World War II
to develop effective controls to marine fouling. It was estimated that up to 1/3 of the fuel used
by war ships could be saved if fouling was eliminated. WHOI pioneered the use of compounds
containing heavy metal bottom paints (lead, copper etc.). These chemical preparations worked
very well acting as general “biocides”. Later research has shown these heavy metal compounds
to be hazardous to all life in the sea, especially in shallow bays and harbors. Less toxic and more
species specific controls were needed as use of heavy metals was regulated.
TBTO (tributyltin-oxide) or TBT (Tributyl tin), a heavy metal antifouling compound is one of the
most toxic chemicals used in the marine environment. Scientists and engineers have strived for
decades to find effective solutions to antifouling paints and coatings which have been found to
cause adverse effects on the surrounding environments.
Copper Free Hull Paints

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New alternatives to copper base d antifouling hull paints have been developed in response to
water quality concerns, although not all alternative coatings have been registered by the
California Department of Pesticide Regulation. Non-toxic paints will not need to be registered.
The purpose, frequency of use, and storage location of a boat will determine what type of hull
coating is appropriate. Alternative hull coatings can be classified into two categories: biocide
and non-biocide hull coatings. Biocide coatings are designed to slowly release toxic substances
such as copper, zinc pyrithione, fluorine, chlorine and various organic biocides, including a new
organic biocide called Econea. Non-biocide coatings can be further classified as soft or hard.
Soft non-biocides may contain silicon or fluoropolymers that result in a slick surface making it
difficult for organisms to attach. Hard non-biocides may be ceramic or epoxy and are generally
used on racing boats and boats stored out of water. Non-biocide products generally last longer
than copper-based and zinc oxide paints
Hull Cleaner BMPs
Wait 90 days after applying new paint. Paints release more toxicant when new. Soft sloughing
or ablative paints release toxicant & paint to water when cleaned. On these boats, clean only
running gear and zinc anodes. Use only a piece of "carpet", sponge & other softmaterials to
clean the hull. Use soft nylon or similar material on rotary brush machines. Use stainless steel
brushes & pads on nonpainted, metal areas onlyUse more rigorous cleaning pads onlyas
needed to remove hard marine growth. Do not sand or strip hull paint underwater. Bring zinc
anodes back to shore; recycle or dispose properly. Clean gentlyto avoid creating a plume or
cloud of paint in the wate
Maintaining the Hull and Paint
Properly applied and maintained paints protect the hull from fouling organisms & improve
performance of the boat.Correct application also extends paint life by reducing amount lost to
harbor. Allow 90 days after applying new bottom paint before cleaning underwater. Regularly
scheduled hull cleaning and Maintenance reduces hard marine growth and hull dragRepair
paint bonding problems at haul out to avoid further chipping and flaking of paint into the water
Protection from Fouling Growth
Toxicants in some hull paints limit cleaning options & increase toxicant amounts in marine
waters. The following may be helpful to clients in choosing antifouling strategies. "Soft"
sloughing and ablative (self polishing) hull paints release copper when cleaned underwater.
Refrain from underwater cleaningHard finish, conventional antifouling paints release less
toxicant with underwater cleaning. Polyurethane and silicone paints contain no toxicant & do
not rub off during cleaningDon't leave most polyurethane painted hulls in water over 72 hours.
Store infrequently used boats on land. Check local requirements & facilities for storage
locations. Floating hoist systems hold the boat out of the water in the slip. Ask a repair facility if
your hull paint remains effective after boat is stored out of the water

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Some common fouling agents
Diatomacea Cnidaria
Garveia franciscana
Garveia franciscana
Cordylophora caspia
Bowerbankia sp.
Canopeum sp.
Polydora sp.
Corophium sp.
Mytilus sp.
Ulva sp.
B.Borers
Wood borers are highly specialised animals which penetrate wooden structures such as
boats, wharves, jetties, driftwood and even living mangrove trees. Many can digest the
wood owing to cellulose-digesting bacteria or protozoa living in their guts. Only a few
species can actually produce their own cellulose-digesting enzymes (cellulases).Wood
borers are insects that chew their way into the solid trunk of a living tree or into a wooden
structure, such as an old boat or house. Healthy trees are rarely attacked by wood borers,
but a diseased or dying specimen can often host these kinds of invaders. The same goes for
old houses and boats, where rain-soaked or rotten wood is more susceptible to invasion.
1. Shipworms (Teredo)
These wood borers swim through the water and look like worms, but in reality they are
a form of crustacean, classified as Bankia setacea. Their choice of host consists of
wooden ship hulls and other types of submerged wood, including driftwood. This
unusual clam usually finds a suitable host during the fall or winter months and begins its
wood-boring activities at that time. This invader tunnels through bare wood, secreting a
white substance after it is safely inside. Shipworms can ruin the wood of a ship, yet
remain undetected from the outside of the hull. For centuries they have been the
scourge of mariners, but recent use of fiberglass, high-tech paint and metal hulls have
reduced their presence in ship hulls. Shipworms will attack any untreated wood
submerged in salt water. The greatest injury is done to pilings and wooden boats.
Untreated pilings may last less than a month in the Gulf parishes. The replacement cost
of pilings destroyed annually by shipworms is tremendous. These animals prefer warm
salt waters. More than one-half of the volume of a pile may easily be destroyed without

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any evidence of injury being apparent on the pile’s surface. Only by cutting into the
piling can its condition be ascertained. The greatest damage in a piling usually occurs
just above the mud line, although entrance holes may be found throughout the
submerged area. Entrance holes about 1/16 inch in diameter are bored into the surface
of the wood by the larvae.
2. Wood Piddock (Martesia striata)
These bivalves drill holes into wood, usually at very high tidal levels. They can cause extensive
damage to structures like floating fish farms. They drill through mechanical action, using the
two shell valves as abrasive surfaces. (Length 1-2cm)
3. Wood-boring Isopods (Sphaerom terebrans)

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Wood-boring isopods drill holes by mechanically scraping their way in. It is not certain if they
actually feed on the wood or are detrital/filter feeders. Many of the species also drill into soft
rock. They often concentrate in great numbers, giving the wood a honeycombed appearance.
(Length 0.5-1 cm).
4. Limnoria (Isopod)
Limnoria is the genus commonly known as gribbles, and they do considerable damage along
coastal waters. They are confined to clear salt water and cannot endure fresh to turbid water.
They can tolerate low temperatures. When these crustaceans attack a piling, their tunnels
almost touch, so the thin walls between them are quickly worn away by wave action, leaving a
new surface of wood ready for reinfestation.
Control or prevention
I. Limnoria Control
The protection of wood from Limnoria attack is much more difficult than from shipworms.
Some species are resistant to creosote, partially because of the deterioration and leaching of
creosote in warm waters. The use of certain copper salts (chromated copper arsenate and
ammoniacal copper zinc arsenate) provides effective protection from Limnoria attack. A heavy
retention (2.5 pcf) of CCA or ACZA works well. Copper or tin salts, fungicides and insecticides,
especially the chlorinated hydrocarbons added to creosote, have shown various degrees of

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effectiveness in preventing Limnoria attack, but their use is limited by environmental
regulations.
In areas where severe attack by both types of marine borers is present, or if creosote-resistant
species of Limnoria are present, use a dual treatment. This method calls for pressure treatment
with the copper salt (1.0 to 1.5 pcf of CCA or ACZA) followed by a pressure treatment with
marine-grade creosote (20 pcf). Movable wooden structures and boats can also be protected by
an unbroken covering of marine paint. When borers have gained entrance to wooden vessels,
they can be killed by running the boats into fresh water or dry dock for at least 30 days.
II. Shipworm Control
Metal sheathing around a piling is effective but expensive and not very durable, unless it’s
galvanized or made from noncorrosive metal. Cement casings are unsatisfactory because cracks
develop as a result of expansion, contraction and wave action. Plastic and fiberglass coatings
have been used with some success. A very successful method of protecting pilings against
shipworms is impregnation with marine-grade creosote treatments of 20 to 25 pounds per
cubic foot (pcf). Also, 2.5 pcf of chromated copper arsenate (CCA) or ammoniacal copper zinc
arsenate (ACZA) may be used. Surface treatment is not sufficient, so the preservative must be
pressure applied to obtain good penetration. Deep penetration is difficult if not impossible with
many dense hardwoods. A softwood, such as Southern yellow pine, with a wide sapwood zone
is preferred. Applying marine creosote is still the preferred treatment. Noncorrosive metal caps
and coverings on pilings are beneficial because they protect against structural injury and
entrance of shipworms.