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Author Topic:   2005 305 CONQUEST Forward Bilge and Shower Sump Wiring
3boys posted 05-16-2015 08:18 PM ET (US)   Profile for 3boys   Send Email to 3boys  
Hi all. The forward bilge [pump on a 2005 Boston Whaler 305 CONQUEST boat] stopped working (due to corroded wires). I decided to replace both the bilge and shower sump [pumps] and their float switches. The wiring was broken to the point that I cannot tell what was wired to what. For the bilge [pump], it appears I have two brown wires and one black wire, which I assume are the manual power (brown), auto power (brown), and ground (black). For the sump, it appears that I have a brown and black only. I suspect both float switches may have been wired to one of the brown wires at the bilge pump, but this cannot be confirmed.

[Seeks a source for] the wiring diagram for connecting these two pumps and switches.

Also, as I purchased the boat used a few years ago and have never used the shower, I'm not certain what switch turns on the shower sump. Is the circuit always ON in auto mode?

Any and all advice would be appreciated. Thanks--Chris

jimh posted 05-17-2015 07:01 AM ET (US)     Profile for jimh  Send Email to jimh     
Visit the website


On the left side, select the year (2005) and model (CONQUEST) for your Boston Whaler boat. On the right, select the individual model (305). A list of drawings will be presented in the right side panel. Choose the drawing you want to view.

For the 2005 CONQUEST 305, all the drawings are contained in a large PDF file:

Download the PDF file to your local terminal, and open the PDF document in a good viewer application. On page 34 of 92, you will find the electrical wiring schematic diagram for the 2005 Boston Whaler 305 CONQUEST. If you are familiar with electrical wiring schematic drawings, you should have no problem locating the details of the electrical wiring to the two sump pumps.

The schematic diagram for the 2005 Boston Whaler 305 CONQUEST has a border with numbers (boriszontally) and letters (vertically) to help locate regions of the drawing, which is large and complex.

The circuit for the SHOWER SUMP originates in region 7F on the drawing. The SHOWER SUMP PUMP is shown in region 2F on the drawing.

The circuit for the FWD BILGE PUMP originates in region 7F on the drawing. The FWD BILGE PUMP is shown in region 2E on the drawing.

The size of the conductor in American Wire Gauge units and the color of the insulation is shown for each conductor, and an identifier number is given. The identifier number may be affixed to the wire in some manner, usually a wire label tag. For example, the conductor bringing 12-Volt power to the float switch for the FWD BILGE PUMP FLOAT SWITCH is identified as

300A-12 RED/BRN

This is interpreted as follows: the wire identifier is 300A; wire size is 12-AWG; insulation color is RED with a BROWN Stripe.

This information should give you a great deal of guidance in undertaking this electrical repair project.

jimh posted 05-17-2015 07:07 AM ET (US)     Profile for jimh  Send Email to jimh     
If the wire insulation colors are difficult to identify, try using detergent to clean the wire insulation to remove any marine gunk or other residue on the wires.

Look for any sign of the wire number tags.

If visual identification of the individual wires is no longer possible, you can identify the individual wires by using a continuity checker. Remove power from the circuits. With all the wiring disconnected at the pump end of the circuit, you should be able to identify the power lead, the power common or return circuit, and the switch leads using a continuity checker.

jimh posted 05-17-2015 07:12 AM ET (US)     Profile for jimh  Send Email to jimh     
According to the schematic diagram from the factory (see above), on the 2005 Boston Whaler 305 CONQUEST the circuit to the SHOWER SUMP PUMP is not operated by any switch or circuit breaker. It comes from a 5-Ampere fuse identified as SHOWER SUMP, which is likely part of the MAIN DC BREAKER PANEL. As long as the fuse has not blown and the boat's primary power distribution switches are in the ON position, the circuit to the SHOWER SUMP PUMP should have power.
jimh posted 05-17-2015 09:20 AM ET (US)     Profile for jimh  Send Email to jimh     
Note carefully that the wire colors shown in the electrical diagram are for the wiring installed by Boston Whaler in the 2005 305 CONQUEST. The circuits are carried to the devices, and connected to the devices. The color of the wiring of the devices themselves is not designated in the schematic diagram. For example, a particular electrical pump device may have two conductors, and the color of their insulation is not necessarily a match with the color of the wiring in the boat. A pump might have a black conductor and a brown conductor. A float switch might have a white conductor or a black conductor. These conductors are likely connected (by splices) to the boat wiring.

When re-fitting new pumps and float switches, I recommend you look for the location in the circuit where the boat wiring was joined to the device wiring, and use that point as the location to connect your new replacement devices. Don't cut off long conductors from the new devices and splice them into old conductors that remain from the original devices you will be removing.

3boys posted 05-17-2015 10:14 PM ET (US)     Profile for 3boys  Send Email to 3boys     
Hey Jim,

Wow, thanks so much for all the info - really appreciate it! This is certainly what I was looking for and will definitely help - although I'm wishing I had studied Electrical Engineering at University rather than Chemical Engineering...

3boys posted 05-19-2015 09:36 PM ET (US)     Profile for 3boys  Send Email to 3boys     
Hi Jim,

Thanks again for your kind assistance - the wiring schematic was really helpful! I'm pleased to report that the forward bilge is now working. Unfortunately, the shower sump is not although I'm certain that it's wired correctly. I suspect it could be the Carling 15A breaker on the main panel. I've ordered a replacement from Amazon and will keep you posted.

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