This paper brings out the difficulties encountered with the Bilge and sea water circulating pumps which are fitted and drawn in series along with a fresh water pump in the 17.5 m fishing trawlers

Ranjan, A.

Aquatic Commons

E E 
Ji G 
s 
LE 
A. RANJAN 
Deep Sea Fishing Station, Bombay. 
This paper brings out the difficulties encountered with the 
Bilge and sea water circulating pumps which are fitted and 
drawn in series alongwith a fresh water pump in the 17.5 m. 
fishing trawlers. 
INTRODUCTION 
The Deep Sea Fishing Organi~ation, 
Bombay have procured a score of Jingha 
type trawlers of overan length 17.5 m. 
constructed indigenously at various ship 
building yards. While operating these 
vessels this department faced various diffi-
culties and breakdowns and efforts were 
made to rectify these defects with suita-
ble modifications. One such difficulty 
was with the bilge and sea water circulating 
pump. These pumps, being of impeller 
type, were provided with imported seals, 
replacement to which . was difficult to 
procure. There have been frequent leakage 
through seals, breakage of coupling, im-
peller bearing, shaft bearing, air locking. 
Hence a modified bilge and circulating 
pump replacing the seal with a gland with 
provision to change the gland without 
dismantling the whole set was designed 
and successfully tried in one of the vessels. 
Details of modifications effected and 
results of trials are presented m this 
communication. 
64 
MATERIAL AND METHODS 
The set up of the pump 1s shown 
in figure 'A'. 
The sea water pump circulates sea 
water through heat exchanger wh· ch in turn 
cools the fresh water circulating through 
the main engine. The bilge pump which 
is similar in every respect to the sea water 
circulating pump is fitted in series with 
the sea water pump while the fresh water 
pump is of different construction. The 
drive for the fresh water pump is taken 
from the main engine drive shaft through 
gears which change rhe direction of pump. 
The pump operates at 1000 r. p. m. The 
pump is coupled to two other centrifugal 
pumps with flexible coupling shown m 
drawing (Fig. 'B'). 
Fig. 'C' shows modified centrifugaX 
pump fitted on to the main engine. The 
main modification is the replacement of 
water seals with !" gland packing which 
can quite easily be tightened without dis-
FISHERY TECHNOLOGY 
V'anjan: 1\[odification to ilie lhlge and sea meier Pumps fiited in 17.5 wwtre type h·arvlers 
mantlirg the whole unit. in the original 
pump the bearings were housed in 
the pump casing exposing the same to 
sea water corrosion, but in the modified 
version the bearings are fixed on exten-
sions to pump body far removed from 
contact with sea water. 
RESULTS AND DISCUSSION 
Since all the three pumps are fitted 
in line, alignment had to be maintained 
correctly. A slight misalignment (inspite 
of the dowel pins used for maintaining 
the correct alignment) would damage the 
water seals, shaft and the impeHer. On 
numerous occasicms (as evident from re-
cords) it was seen that the average loss 
of fishing days for break down of these 
pumps were high due to water seals at 
either end of both of the pumps leaking. 
Due to leakages flow of circulating water 
VoL XI No. 1 1974 
'·
1
1;1Vi··l 1 ~1?5 22.A 1 
II ~ 
through the main engine as also loss of 
bilge suction was being experienced. The 
stainless steel shaft of the pumps were 
showing distortion resulting in the impe-
ller fouling with the pump casing. To 
refit or reuse the mechanical carbon 
seals, springs as also baH races in the 
pump, it was necessary to completely re-
move the pump from the main engine 
mounting. H was also noticed that the 
coupling flange bolts were broken on many 
occasions and the flexible rubber coupling 
was found to be damaged. 
As the modified pumps have an in-
creased length due to additional space 
taken by the ball race bridge support and 
gland packing, certain modification had to 
be carried out in regard to securing the 
pumps to the main engine without major 
alterations. This was accomplished · by 
providing new brackets and drilling and 
65 
'R:anjan: Modification to tfie 5ilge and sea water pumps fitted in 17.5 m<'tre jingfia type traw~ers 
tapping new holes in the cylinder block. 
The original tap holes were plugged and 
revetted over. The sea water lines as weU 
as the bilge lines both inlet and dis-
charge require modification due to the 
fact that there has been longitudinal dis-
placement of the pumps to· the extend of 
approximately 50 mm. There was no need 
to replace the pipes but some were heated 
and bent to suit the new position of the 
pump flanges. As the bilge pumps run 
dry when the bilges are not connected, 
it was necessary to have the pipe conne-
ction between the delivery of the sea 
circulating pump and suction side of the 
bilge so as to prevent the bilge running 
dry thereby burning packing and over-
heating the shaft. The discharge of both 
the pumps are more than the original as the 
clearance between the impeller and pump 
body has been maintained to the minimum. 
66 
Modifications carried out to the pump 
did not result in any increase in the 
cost. Additional expense to the extent of 
Rs. 200/- per boat has to be incurred 
for fixing the pump to the engine. 
AcKNOWLEDGEMENT 
The author is thankful to Shri S. 
Miskeith, former Superintending Engineer, 
Deep Sea Fishing Organisation, Bombay 
for his kind permission to publish the 
paper and also to Shri Pradip Tagore, 
Deputy Director, for his encouragement in 
completing this work. The author is also 
thankful to all the staff concerned who 
have helped in the preparation of this 
paper. 
FISHERY TECHNOLOGY 


Modification to the bilge and sea water pumps fitted in 17.5 metre Jingha type trawlers

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Modification to the bilge and sea water pumps fitted in 17.5 metre Jingha type trawlers

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