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- A typical panel after 3 months in static
immersion, with minor algae fouling.
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- Panel with heavy barnacle fouling, tube worm
and the boring sponge, Cliona celata. There are 32
species of Cliona in the Mannar Barrier and they are responsible
for considerable damage to pearl oyster beads.
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- A PVC panel totally covered by oyster fouling
after 1 year of immersion.
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Wood structures are heavily fouled by barnacles.
Inside the submerged wood are channels created by Teredo worms.
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Static Immersion
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Although there is a wide range of sophisticated testing available
now to evaluate the performance of experimental paints under
laboratory conditions, there is still no replacement for field
testing of finished coatings in actual marine fouling environment.
Static immersion remains a necessary step to validate the efficacy
of coatings against fouling. Our primary test site for
immersion testing is at SHMRC's marine station in Karrapad Cove (Tuticorin
Bay) in South India.
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- SHMRC Beach Laboratory
Why conduct immersion testing in Tuticorin Bay?
- Stable tropical environment with continuous barnacle
fouling. The primary fouling organism is the barnacle,
Balanus amphitrite amphitrite Darwin. This is also the most
common fouling organism found in most parts around the world and
likely distributed worldwide by seagoing vessels for many
centuries. The seawater temperature remains above 200C
all year and reach as high as 350C.
The salinity remains oceanic, except during short monsoon season,
when it drops precipitously (see figure below). However,
barnacle fouling remains unaffected by the brief decline in
salinity.
- Two-year salinity and temperature profile
of Karrapad Cove (Tuticorin Bay, South India)
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In collaboration
with SHMRC, the shore laboratory built in 2003 is dedicated
exclusively to support the field research on biofouling.
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The research staff
is comprised of marine biologists working on biofouling R&D.
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The location is
within a protected cove and restricted from commercial use, thus
avoiding damage on the platforms by commercial vessels.
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The adjacent Port
of Tuticorin is the second busiest container port in India and
therefore harbors the same fouling organisms that can be found in
Singapore and similar warm water ports.
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Fouling is very
aggressive. An unprotected surface becomes covered by
juvenile barnacles within 2 weeks. A low copper coating,
such as shown below, will foul within a month and show massive
fouling from barnacles, algae and sponges as the immersion
continues.
- EXAMPLES OF FOULING CONDITION
The progression of fouling in Karrapad
Cove on PVC rods coated with low level of cuprous oxide in
the absence of co-biocides. By week 4, juvenile barnacles are already covering
the entire surface. By week 8, green algae begin to cover the barnacles
followed by sponges in the weeks that follow. Sponges occur seasonally, normally
from October to November.
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Static immersion testing is conducted on flat
panels and PVC rods at Poseidon's test centers. Please click on the
link below to see a slideshow on how immersion testing is conducted
on coated rods at Poseidon's facility at the
Sacred Heart Marine Research Center in southeastern India.
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FOULING IN AQUACULTURE NETS
Near SHMRC is a shoreline with active
aquaculture of macro-algae, usually Kappahycus, on floating
nets by fisherfolk communities for income generation. Fouling
on the nets is also a significant problem that reduces the yield and
damage the value of the crop. Below are some of typical
fouling organisms. Poseidon-SHMRC also conduct tests on
antifouling systems for nets using this aquaculture area as a test
environment.
- Photos above show bryozoan and other foulers on
aquaculture nets in the open ocean.
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TOTAL IMMERSION TESTS
In total immersion, the panels are immersed below 2 ft
from the surface. Fouling challenge tends to vary from site to site. It is
therefore important to characterize the fouling conditions and the ideal
depth of immersion. The data in the figure below show that fouling is
heaviest at the 2 ft. depth. For this reason all total immersions are
conducted at this level.
 
The graph shows the weight of fouling on
PVC coupons at various depths after 2 months of immersion at Tuticorin bay.
The photos demonstrates the degree of barnacle fouling on the panels at
different immersion depth.
- Panel specifications: Maximum
width, 6 inches
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Maximum length, 12 inches
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(Panels
of larger sizes can be accommodated but will be subject
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to surcharges for extra space)
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Two mounting holes (1/8th inch diameter) on top left and
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right of the panel
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- Inspection Report: Monthly,
quarterly or biannually subject to project sponsor
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specifications. Please click
here for an example of a
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digital report submitted to project sponsors.
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WATERLINE IMMERSION
Fouling is most visible to the end users along the
waterline. Many of the obvious coating failure occur along this interface
because of UV damage and constant wave action. The waterline immersion test
is designed to test the integrity of the paint from wave induced erosion and
wave damage. In this test, half of the panel is submerged and the other
half exposed to the surf and sun.
Photo on left shows waterline damage to the coating.
Photo on the right shows barnacle fouling which appeared much earlier
compared to total immersion test of the same coating that showed no fouling
issues.
- Panel specifications and inspection reports same as in total immersion.
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