Bilge Pumps and Emergencies
(Courtesy of Cleghorn Waring
)
In the unlikely but possible situation of a hull leak
by collision damage or a failed seacock how many 2 gallon(10litre)
buckets a minute can you fill down below and empty over the side?
| Water flow through a circular hole |
|
|
|
| Depth of hole below waterline |
300mm(12") |
500mm(18") |
1000mm(36") |
| Hole diameter |
flow rate |
litres perhr |
(gallons per min) |
| 13mm(1/2") |
1000(3.7) |
1250(4.6) |
1750(6.4)
|
| 25mm(1") |
2700(10) |
3400(12.5) |
4900(18)
|
| 50mm(2") |
11000(40) |
14000(50) |
20000(75)
|
1000 litres per hour is equivalent to 2 x 10litre buckets per minute!
Manual pumps do not depend on battery, engine
or generator power. Fit the largest you can reasonably accommodate
Install it where you can still attend, if necessary , to other emergency
tasks while operating the pump
Engine driven pumps will keep working as long
as the engine keeps going. Most engines have ample power to drive a
robust pump and clutch unit that will self prime quickly and reliably at
any engine speed.
Electric pumps will work as long as the power is there. An electric pump should not be your last resort.
A submersible pump can shift a lot of water
quickly but is not designed to run for hour after hour. You may be lucky
but they are not designed for this use.
When operating also keep an eye on flow rates interrupted by debris accumulation in the strainer.
Regular inspection and maintenance + replacement spares to hand and how to install offer peace of mind.