2004 130 Sport: Relocating Battery

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Foulweather Jack
Posts: 19
Joined: Tue Apr 19, 2016 3:56 pm

2004 130 Sport: Relocating Battery

Postby Foulweather Jack » Sun Jun 25, 2017 12:31 pm

I'm considering relocating the battery on my 2004 130 Sport from its current location on the starboard side to the port side underneath the forward seat in order to reduce the tendency for the boat to list to starboard at rest. The boat, which has bottom paint, is kept in the water year round at my dock on a saltwater river and has a tendency to accumulate water on the starboard side which turns into an unholy mess of slime and filth. The water tends to pool around the cockpit drain hole on the starboard side which is supposed to be "self bailing" but really isn't.

The boat has a Yamaha F25 four-stroke-power-cycle engine, which, according to the manual, weighs 191-lbs. The information plate on the side of the hull states the maximum outboard motor weight is 204-lbs.

My thinking is that relocating the battery to the port side may reduce or eliminate this tendency to list to starboard.

Thinking this through, I see two possible concerns:

I cannot find a wood location diagram for the 2004 130 Sport anywhere online, and I am concerned that if I drill holes into the deck underneath the front seat there may not be enough structural support (if there is no wood backing underneath the deck) to support the brackets that hold the battery mounting straps.

If I increase the distance of the battery from the engine, the battery cables will of necessity be longer and thus may encounter more resistance, possibly reducing the efficiency of the battery in turning the starter motor. I know only enough about electronics to be dangerous, but I do remember that it is always better to have shorter battery cables than longer cables.

jimh
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Location: Michigan, Lower Peninsula
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Re: 2004 130 Sport: Relocating Battery

Postby jimh » Sun Jun 25, 2017 3:52 pm

It is quite normal for Boston Whaler boats at rest to have a static trim that is slightly to starboard. This is usually intentional because the cockpit sump is located to starboard. Water that accumulates in the sump is exhausted overboard by an electrical pump, or permitted to drain to the sea by leaving the drain open at the bottom of the sump. If the sump is left closed and the electrical pump left in the OFF position, then water will accumulate in the sump and can overflow the sump if enough water is collected.

If the starboard side of the boat is not low enough to get water in the cockpit to drain overboard, the solution would seem to be to make the starboard side even lower, rather than higher. Making the starboard side lower would help get water out via the drain. I don't understand the notion that getting the static trim of the boat be on a precisely even keel is going to eliminate the accumulation of water in the cockpit.

For help in obtaining a embedded wood locating diagram, contact Chuck Bennett at Boston Whaler customer service. If there is a diagram available, it would be from the factory. Like you, I could not find such a diagram at the usual resource provided by Boston Whaler, https://www.bostonwhaler.com/boat-ownership/resources/

Your concern about moving the battery and placing it in a location with proper reinforcement is very appropriate. Not only should there be embedded reinforcement for the hold-down strap Footman's Loop, but the general area on which the battery will rest should be reinforced to bear the weight of the battery.

For advice about the proper size of the primary power cables connecting the Yamaha F25 engine to the boat cranking battery, consult the Yamaha installation guidelines. Increasing the length of an electrical conductor in a circuit involving 12-Volt power distribution must be carefully considered. Voltage drop in the cable can rob a significant amount of the electrical energy by dissipating the electrical power in the cable resistance. Generally, any increase in the conductor length inherently causes an increase in resistance, and thus will require an increase in the conductor size in order to maintain the original resistance.

For more advice on electrical power distribution, please start a new thread in SMALL BOAT ELECTRICAL, the forum whose topics are focused on boat electrical topics. Describe the present conductors: their length, their electrical wire size in American Wire Gauge (AWG) rating. Then described the planned extended length. I can offer more advice in that forum. If the size (in AWG) and length of a conductor is know, then its resistance can be calculated. Once the resistance of the present cable is known, a longer cable can be made to have the same resistance by just increasing the conductor to an appropriately larger size.

ollie366
Posts: 15
Joined: Fri Jan 22, 2016 7:55 pm

Re: 2004 130 Sport: Relocating Battery

Postby ollie366 » Sun Jun 25, 2017 9:36 pm

I have a 2002 with a Suzuki 30-HP engine. I relocated the battery to the port side under the stern seat. The Suzuki engine had long battery cables, sufficiently long so I didn't need to modify them. [I] enclosed the cables in a corrugated plastic cover from the engine to the seat.

I also added a terminal strip under the starboard side of the stern seat for the various electrical needs--lights, pump, and electronics. I ran a double insulated cable from the battery to the terminal strip, with a waterproof fuse at the battery. The water in the boat drains nicely through the through-hull just below the helmsman's seat. And the boat sits with virtually no list while at the dock.

Foulweather Jack
Posts: 19
Joined: Tue Apr 19, 2016 3:56 pm

Re: 2004 130 Sport: Relocating Battery

Postby Foulweather Jack » Wed Jun 28, 2017 12:32 pm

Thanks for the replies and the advice. I've finished relocating the battery under the port side of the forward seat but have not had a chance to put the boat in the water yet. It's good to know that your boat drains better with the battery weight re-distributed.

Relocating the battery required an extra 6-feet of [2-AWG] copper battery cable, but all of the electronics appear to function well so the extra loss must not be too bad.

jimh
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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: 2004 130 Sport: Relocating Battery

Postby jimh » Wed Jun 28, 2017 2:18 pm

Voltage drop in a conductor is proportional to current. The current during engine cranking will be about 100-times more than the current to power small electronics. You will discover if the re-done battery cables with extensions have sufficiently low resistance and thus low voltage drop only during engine cranking.