Empathy List Archives

passagemaking@lists.trawlering.com

Passagemaking Under Power List

Bilge Pumps

Peter Sheppard

Mon, Feb 18, 2008 9:23 AM

Quite a lot of discussion and research has taken place on the Nordhavn 55
weblog about bilge pumps.
I have come to the conclusion so far that bilge pumps will only buy you some
time while you get to the core of the problem and that is stopping the
source of the flooding. I'm advised that most problems will get down to
hoses coming off a thru hull giving away, and we have valves to close off.
If the actual skin fitting gives way which I can't imagine likely, but we
should all have conical plugs to hammer in, as well as many other devices
available in my damage control kit
If we have a breach caused by hitting something serious like a sharp bommie,
and low down below the water line, we are in big strife because flooding
tables show that bilge pumps are going to struggle big time, and a hole 1'
below the water line will in no time become 3' or 4' down in no time,
increasing dramatically the ingress pressure.
I am having a collision mat made, and the design will be that it will have
enough lines secured to stop it peeling off the hull when underway. This
will probably take some real life testing to perfect the design. Anyone that
has been down this track maybe can offer some advice.
I am also purchasing a portable gas (or diesel) fire fighting pump that can
be selectively deployed to either of the four compartments that make up the
bilges, and to support the current 3 pumps (2 electric and 1 manual). Limber
holes are not designed to compete with an aggresive breach.
In Australia they have an umbrella type device that can be poked through the
breach, and opened up giving a seal to reduce ingress, but I am yet to find
who makes these, so any info from the list would also be gratefully
received.
I'm certainly not paranoid about this issue because I don't plan to hit
anything, but the wilderness areas I'm going to soon is devoid of help, and
I must prepare for the unknown/unlikely/and statistically remote occurence.
Peter Sheppard

Quite a lot of discussion and research has taken place on the Nordhavn 55 weblog about bilge pumps. I have come to the conclusion so far that bilge pumps will only buy you some time while you get to the core of the problem and that is stopping the source of the flooding. I'm advised that most problems will get down to hoses coming off a thru hull giving away, and we have valves to close off. If the actual skin fitting gives way which I can't imagine likely, but we should all have conical plugs to hammer in, as well as many other devices available in my damage control kit If we have a breach caused by hitting something serious like a sharp bommie, and low down below the water line, we are in big strife because flooding tables show that bilge pumps are going to struggle big time, and a hole 1' below the water line will in no time become 3' or 4' down in no time, increasing dramatically the ingress pressure. I am having a collision mat made, and the design will be that it will have enough lines secured to stop it peeling off the hull when underway. This will probably take some real life testing to perfect the design. Anyone that has been down this track maybe can offer some advice. I am also purchasing a portable gas (or diesel) fire fighting pump that can be selectively deployed to either of the four compartments that make up the bilges, and to support the current 3 pumps (2 electric and 1 manual). Limber holes are not designed to compete with an aggresive breach. In Australia they have an umbrella type device that can be poked through the breach, and opened up giving a seal to reduce ingress, but I am yet to find who makes these, so any info from the list would also be gratefully received. I'm certainly not paranoid about this issue because I don't plan to hit anything, but the wilderness areas I'm going to soon is devoid of help, and I must prepare for the unknown/unlikely/and statistically remote occurence. Peter Sheppard

Ron Rogers

Mon, Feb 18, 2008 4:01 PM

Another distinguishing feature of these types of pumps whether or not they
are self-priming. Self-priming pumps cost more, but are worth every penny.
Having used a non self-priming trash pump, I can assure you it's a pain even
in daylight without stressful circumstances.

I believe that a Pacer trash pump's pressure is adequate for onboard
fire-fighting.

BTW, on larger Nordhavns they specify a diaphragm bilge pump of great
capacity. I believe that it's normally found on commercial vessels.

Ron Rogers

----- Original Message -----
From: "Peter Sheppard" petershepp@gmail.com

| I am also purchasing a portable gas (or diesel) fire fighting pump that
can
| be selectively deployed to either of the four compartments that make up
the
| bilges, and to support the current 3 pumps (2 electric and 1 manual).
Limber
| holes are not designed to compete with an aggresive breach.

I guess that you've made a conscious decision to go with a fire-fighting pump instead of a trash pump. The latter pushing more water at lower pressure. The trash pump, however, can accommodate literally some trash from the bilge while the fire pump cannot. Another distinguishing feature of these types of pumps whether or not they are self-priming. Self-priming pumps cost more, but are worth every penny. Having used a non self-priming trash pump, I can assure you it's a pain even in daylight without stressful circumstances. I believe that a Pacer trash pump's pressure is adequate for onboard fire-fighting. BTW, on larger Nordhavns they specify a diaphragm bilge pump of great capacity. I believe that it's normally found on commercial vessels. Ron Rogers ----- Original Message ----- From: "Peter Sheppard" <petershepp@gmail.com> | I am also purchasing a portable gas (or diesel) fire fighting pump that can | be selectively deployed to either of the four compartments that make up the | bilges, and to support the current 3 pumps (2 electric and 1 manual). Limber | holes are not designed to compete with an aggresive breach.