Bilge Pump Hose Placement Questions

[BillOfCapeCod]

My wife and I purchased a Cape Dory 28 last summer, after having been out of sailing for 30 years. So we don't mind the most basic advice.

We enjoyed our first season, doing a bit of open water sailing between Long Island and Cape Cod, which the boat took to nicely. However, its clear our boat, as well as her new crew, need some work if we are to be more sea worthy.

I have some questions about the placement of the automatic bilge pump hose. First let me try to describe our current setup: The pump is in lowest part of the bilge, just forward of the main hatch steps. From the pump, the hose (plastic with reinforcing ribs outside, smooth inside) runs 18” straight up to enter the engine compartment. From there, it travels 50” at about a 70 degree angle, where it enters the forward bottom of the starboard lazaret. It then moves up the inboard side of the lazaret 48” at a 45 degree angle, where it is tied to the engine exhaust hose. It then moves down 30” at 45 degree angle to the lazaret sole, across the lazaret sole to the outboard side and then up, with a nasty, tape covered 80 degree angle bend, to the thru-hull fitting. Altogether about 12 ft of hose from pump to fitting; however, the fitting is only about 2.5 ft higher than the pump.

Assuming we use the current thru-hull fitting and want an arrangement that keeps the hose off the lazaret sole, (where it lays about with various bumpers, line and chain, boat hooks, etc), and also allows the hose to enter the fitting at a more reasonable angle:

Question 1: In general, what is the effect of length of smooth hose vs. height of rise; so, for example, how much length of smooth hose rising at an angle to 2 ft produces the same pump work load as a perpendicular rise of 3 ft?

Question 2: Is it better to have the hose quickly raise to just above the level of the thru-hull fitting in the forward part of the lazaret and then gradually move aft and down to the fitting; or, should it gradually rise toward the fitting over the length of the lazaret?

Question 3: Given the thru-hull fitting is located at the far aft end of the lazaret on the boat’s starboard side, only 3” forward of the stern and 9” above the at rest water line, can I do anything to the hose, short of a siphon valve I would prefer to avoid, to reduce the chances of sea water flowing, perhaps siphoned, into the bilge. (Someone suggested the line be run higher up, under the top of the lazaret and back before going lower to the thru-hull fitting, and perhaps add a loop to the hose.

Discussion: It seems to me there are two conflicting objectives: the first to maximize the amount of water that can be pumped; and second, to passively prevent water from easily reentering the boat. Also, I have this vague notion that the less hose length lifting the water to maximum height the better, with the longer length moving aft and gradually downward toward the fitting. Perhaps with a loop at the top well forward, combined with a gradual downward run aft, to reduce back flooding and ease the strain on the pump. Of course what is gradually flowing out downward aft could turn to flowing in, downward forward by a substantial following sea if the pump if were not running.

After writing this, I am thinking that perhaps a new thru-hull fitting, more forward near the pump and higher up the hull is really the proper answer. Our previous boat, I now recall, had her thru-hull fittings for both the automatic and manual bilge pumps located higher up the hull, just above each pump. Hmmmm, maybe they were onto something. It does seem a bit bizarre to have the thru-hull fitting so far aft of the pump. Clearly Carl Alberg knew what he was doing when he designed our boat, which handles wonderfully, but I am not sure he had much to do with the fitting placement. I am missing something obvious here?

Sincerely,
BillOfCapeCod

[gc1111]

Why not a siphon breaker fitting? I bet that under power your outlet is under water. If so, run the pump while you are running under power, shut it off and time how long before the floor boards start floating.

Anti siphon valves are absolutely standard stuff, work well and require little maintanence. I highly recommend one.

[BillOfCapeCod]

Having read other posts about this before writing my own, I got the impression there were mixed conclusions about anti-siphon check valves.

But knowing really nothing about this, I am open to suggestions and will consider this further, thank you.

[gc1111]

I have been on (someone elses) boat that had the problem I described. We were in the Atlantic off Long Island and got a Coast Guard escort into port because of it. Going below at night and finding water over the floor boards is an UNSETTLING experience. And a simple anti-siphon valve can prevent it.

[JHJensen]

Originally Posted by BillOfCapeCod

Having read other posts about this before writing my own, I got the impression there were mixed conclusions about anti-siphon check valves.

Bill,

I would suggest you obtain Nigal Calder's book (third edition)if you don't have it.

The biggest problem with anti-siphon breaks (vented loops) is usually when they clog due to salt build up. On critical systems like bilge pumps and engine raw water exhaust injection, I am partial to the Grocco bronze types. In my experience they seem to have fewer problems with salt build up and are easy to maintain, though the price may seem steep for bronze over plastic.

Check valves are not acceptable in this application.

As the previous poster noted you really do need a vented loop. You can also have the same problem if you have alot of folks visiting in the cockpit while sailing or under power. The stern will sit lower.

If you are like me and like really dry bilges I would suggest adding a smaller postive displacement diaphram type pump to get the last bit of water out that your submersable pump will not handle.

Here are several links you might find useful for reference.
BoatUS BoatTECH Guides: Plumbing and a nice article on how they workhttp://www.myboatsgear.com/featured_product/vented%20loops.asp

In reference to your initial post on this subject you are on the right path and thinking about what you are doing, for which I compliment you! Times have changed and so have ideas on system design/location etc. Also standards and regulations have changed as well. One of my mentors drilled in to me,"everything on a boat is perishable!"Since you have a more mature vessel, many items/systems may be at or near the end of their life cycle. As you upgrade or add new systems make sure your installations are consistant with current practice, standards (ABYC)and regulations(required!) Your insurance company will thank you and your surveys down the road will have fewer must do items. You will also maintain your vessel's value and enhance her systems function. Your vessel (Cape Dory) happens to be one of my favorite vessels to refit!

Take your time and good luck to you!

John

ABYC Master Technician
ABYC Certified in Standards, Corrosion, Diesel, and Sytems

[motion300]

Why are check valves not accepable? I thought they were a standard fitting?

[bubb2]

Any Gunk sucked up by the pump will pass to and pack up in the check valve to the point of rendering the bilge pump useless. Check valves in in the bilge discharge line are not just a bad idea they are a really bad idea! Are you confusing Check valves with anti-siphon valves/breaks?

[motion300]

bubb 2 No I do mean check valve I have not looked at it that way I have a automatic pump that turns on when only about a cup of water in present. without the check valve it pumps the well out then the water runs back down the hose and the cycle starts again

[bubb2]

That can happen and does, it's called pump cycling. But to put a check valve in that discharge line is trading one problem for a potently a much bigger problem! The best way to correct this, it is to raise the pump up in the bilge. Thereby any water that drains back won't be enough to kick the pump on. Sometimes you just can't get every last drop out of a bilge.

[JHJensen]

Originally Posted by motion300

Why are check valves not accepable? I thought they were a standard fitting?

When is standard.........standard on a boat?

Motion,
You ask a great question. As Mike (bubb2) points out check valves stick and submersable pumps may not develop enough head pressure to force a stuck check valve open. I have a whole box of them I have removed over the last 20 plus years if you need one for a proper application !

You would be better served by using a postive displacement pump to drain a sump. A postive displacement pump by it's nature (like a head pump) does not allow reverse flow.

Use a submersable pump when you have to move lots of water fast but pay attention to your system design.

Here is some info from ABYC Standard H-22: ELECTRIC BILGE PUMP SYSTEMS 7/05 which should help you to understand. I have highlighted some of the more important parts in bold or colors.
Based on ABYC's assessment of the existing technology, and the problems associated with achieving the goals of this standard,
ABYC recommends compliance with this standard for all boats, associated equipment, and systems manufactured after July 31,
2006.
Note: This is not the entire standard and other standards and regulations may also apply.

22.7.3 On boats with an enclosed accommodation
compartment, an alarm shall be installed indicating that
bilge water is approaching the maximum bilge water level.
22.8 LOCATION AND INSTALLATION
22.8.1 Bilge pumps shall be mounted in accordance with
the pump manufacturer instructions, and in an accessible
location to permit servicing and cleaning of the intake
and/or screening.
22.8.2 The bilge pump inlet shall be located so that
excess bilge water can be removed from the bilge at static
floating position, and at maximum conditions created by
the boat’s motion, heel, and trim.
22.8.3 Pump intakes shall be protected to prevent
ingestion of debris likely to cause pump failure.
22.8.4 Intake hose or tubing, if used, shall not collapse
under maximum pump suction.
22.8.5 Pump discharge systems shall be as nonrestrictive
as practicable.
NOTE: As installed, pump discharge capacity may be
reduced by such factors as
a. length of discharge piping, and/or
b. number and radius of bends, and/or
c. roughness of the interior surfaces of piping and
fittings, and/or
d. reduction in cross-sectional area of discharge system
components such as check valves and thru-hulls.
22.8.6 The discharge location shall be above the
maximum heeled waterline, or
22.8.7 the discharge may be located below the
maximum heeled waterline if the discharge line is provided
with both of the following:
22.8.7.1 a seacock installed in accordance with the
requirements of ABYC H-27, Seacocks, Thru-Hull
Connections, and Drain Plugs, and
[B]22.8.7.2 a vented loop or other means to prevent
siphoning into the boat. A check valve shall not be used for
this purpose.[/B]
22.8.8 If the discharges of several pumps are manifolded
to discharge through a single thru-hull fitting, the system
shall be designed so that the operation of one pump will not
back feed another pump, and the simultaneous operation of
each pump will not diminish the pumping capacity of the
system. A check valve shall not be used in the discharge
manifold system.
22.8.9 A check valve may be used only when necessary
to prevent an automatic bilge pump from cycling on and off
due to back flow from the discharge line.
22.8.10 Hose connections shall be secured with a noncorrosive
type of clamp, or be mechanically fastened with
permanently-attached end fittings, such as swaged sleeve.
Threaded inserts shall be attached with corrosion resistant
metallic clamps.
22.8.11 Motors of non-submersible bilge pumps shall be
located above the maximum anticipated bilge water level.
22.8.12 Bilge pumps with automatic controls shall be
provided with a readily accessible manual switch to
activate the pump.
22.8.13 Manual switches for bilge pumps shall be readily
accessible. See ABYC E-11, AC and DC Electrical
Systems On Boats.
22.8.14 Pumps with automatic controls shall be provided
with a visual indication that power is being supplied to the
pump.

Above should give one a basic understanding of the considerations involved.

There are some end fittings (screens etc) for submerging in the bilge/sump which have check valves in them for when there is a long pipe/hose run to the pump to to stop back flow mentioned... but they are on the suction side.... not the discharge side.

Hope this helps,

John

ABYC Master Technician
ABYC Certified in Standards, Corrosion, Diesel, and Systems