bassemir wrote:Q1: where is the bilge [sump] pump located?
Q2: why is there a bilge [sump] pump switch to begin with?
I will give you the long answer so you learn a bit more about the construction of a Boston Whaler boat.
A Boston Whaler boat does not have a bilge space as found in most boats. The Boston Whaler boat is constructed with a double bottom hull called the Unibond Hull. The space between outer and inner hulls, which in a normal boat would be the bilge space, in a Unibond Hull boat is filled with foam. There is no open space in the "bilge" for water to collect and slosh around.
The inner hull is called the HULL LINER. The design of the hull liner includes some intentional depressed areas or SUMP area where water is designed to collect. These sump area are usually near the transom. They are often on the Starboard side of the boat, where the engine cranking battery will typically be located as well. The reason for this is the boat at rest (static trim) will then take a slight lean to Starboard, which will help the tendency for any water to flow off the cockpit deck and into the sump on the Starboard side.
Typically any sump area on a Unibond hull boat will have a drain in the lowest point of the sump, through the hull bottom, to the sea.
The owner's manual gives the operator advice on which of these sump drains should be closed shut (by insertion of a circular drain plug) in normal operation, and which sump areas can have their drains left open when the boat is not in use.
The extent to which seawater will flow into a sump area from the sea if the drain is left open depends on the particular boat and how much weight is being carried, particularly weight on the transom.
Of course, if the boat is not in the water when not in use, there is no hesitancy or reason to keep the sump drains closed. If the boat is to be left in the water an not attended, keeping a sump drain open can be very useful,
as long as the level of water with the boat at rest does not rise to overflow the sump compartment. To determine how your particular Boston Whaler boat and its engine and other gear left aboard when the boat is unattended and in the water will rest with regard to the water height that will flow into the sump in that situation, you just need to make a test. Tie the boat at a dock. Get all the people off the boat. Remove the plug from the stern sump. Step off the boat. Observe how high the water rises in the stern sump.
If the water overflows the sump and begins to flood the cockpit, then your particular boat at rest should not leave the stern sump drain open.
If the water flowing into the sump from the sea only rises slightly and remains contained in the sump, then your particular boat is able to be left unattended with the stern sump drain open.
AN ELECTRICAL SUMP PUMP or "bilge pump"When the stern sump area on a Boston Whaler boat has its drain to the sea plugged, there may be an electrically operated pump installed in the sump. The pump is designed to lift water from the sump bottom level, up and out of the sump, and then overboard to flow downward into the sea. That the exhaust of the sump pump rises far enough that the water lifted then drains directly to the sea is very important; the water exhaust from the pump should NOT drain into any other compartment, like the engine splash well.
VARIATION IN ELECTRICAL SUMP PUMP OPERATIONTraditionally an electrically operated sump pump was controlled in two ways:
- the pump is energized when the operator moves the switch controlling the pump to the ON position from the normal OFF position of the switch; in some cases this position is a momentary switch action. (In electrical switch terminology, the notation MOMENTARY means the switch must be held in this position, otherwise it returns to the OFF position when released.) Or,
- the pump is energized by a hidden switch called the FLOAT SWITCH, which is usually located in the sump along with the pump, and detects the presence of water in the sump above a certain level; this is the FLOAT SWITCH ON THRESHOLD. Note that the level for the PUMP ON actuation MUST be higher than the level that the pump can create when it exhausts as much water from the sump as it can; if this were not true then the pump would run continually, trying to lift water out because of the float switch was calling for the pump to run, but the pump cannot reduce the water level below the float switch OFF threshold. This position is usually marked AUTO, and is commonly seen on pump control switches which have three positions: ON-OFF-AUTO.
If you are able to read and understand an electrical schematic diagram, you can find such a diagram and further comments about sump pump control wiring in
an article in the REFERENCE section of the website titled Cockpit Sump PumpWith modern technology, a newer type sump pump has been developed, which allows use of the pump without needed an external float switch to control the pump. These newer pumps periodically turn on the pump motor at present intervals, and then monitor the amount of electrical current that results. If the pump impeller is turning in air, the electrical current will be very low as there is almost no resistance on the impeller to turn. If the pump impeller is turning in water, the electrical current will be much higher, as the water exerts resistance to turn onto the impeller. In this manner the pump can deduce if there is water in the sump or not. Pumps controlled in this manner usually have only a two position switch with OFF and ON designations.
HELPING YOU WITH ELECTRICAL OPERATION OF THE PUMPThe first step in offering advice to you about the electrical sump pump requires that you locate the pump on your boat. Inspect the aft cockpit sump areas and look for a pump. If you find a pump, then report that in your next post and more advice can be given.
Also, describe the switch that controls the pump:
Q3: how many positions does the switch have?
Q4: what the the labels on the switch?
Q5: is the ON position a MOMENTARY ACTION?