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Boat System by Greg Seman

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Greg Seman is no stranger to the pages of the Crutchfield Custom Car Center. Check out the boss system he installed in his 2000 Cadillac Escalade. When Greg's brother listened to the Cadillac's system, he demanded that Greg work the same magic for his ski boat. Greg loves a challenge, and was only too happy to take on the job!


Greg Seman's Cadillac Escalade, with his brother's 2003 Ski Nautique in tow.

The boat already had a stock system installed — four 6-1/2" speakers and a Clarion marine CD receiver. Greg's brother wanted a system that would give him the great bass and clarity he heard in the Escalade, even when the boat was revving it up out on the water. Greg realized right away that to give him the performance he was looking for the boat needed subwoofers, high-quality speakers, and a big step-up in power.

Greg's brother already had a set of subwoofers, a pair of 10" JL Audio W0s in a sealed custom box. The boat's front compartment was big enough to hold the sub box, so that was an easy match. To power the subs, Greg chose a Kenwood KAC-7251 2-channel amp. The amp pushes 150 watts to each channel, for a total of 300 watts of bass bumpin' satisfaction. A very neat feature of the KAC-7251 is the wired remote-mount bass control. With the remote control mounted, the amount of bass can be easily boosted or attenuated.


The remote bass knob, on the left below the console.

Greg's ideal setup for the mids and highs would have been to install component speakers, but his brother wanted the new speakers to fit in the existing speaker openings, so Greg chose Infinity Kappa 62.5i coaxials instead. Greg was happy with the compromise. As he says: "I chose the Kappas (because) they had external crossovers that would provide near component quality sound." Greg had to do a bit of disassembly to get to the speaker locations, but once there, the Kappas fit perfectly into the factory cutouts. Plus, the grilles matched up nicely with the boat's interior. Although the Kappas aren't marine speakers, the durable C.M.M.D. woofers and tweeters and rubber surrounds ensure that they'll hold up well to moderate exposure to the elements.


The boat's port side (left side for you landlubbers) with the panels and stock speakers removed.


The new port-side speaker — now an Infinity Kappa — installed in the factory location and looking shipshape!

To drive the Kappas to their full potential, Greg knew he needed serious power. Enter the Kenwood KAC-8401 4-channel amp. With 60 watts of clean RMS power per channel, it was a nice match for the Kappa speakers. To ensure optimal signal transfer, Greg replaced the stock speaker wire with StreetWires Ultra Cable 14-gauge speaker wire. The twisted pair construction of the Ultra Cable helps reject noise, and the tough outer coating of the wire makes it durable, as well as easy to pull when doing the install.

As we've seen, the sub box fit into a front compartment, and the speakers slipped into the stock locations. Where to mount the amps? Greg's clever solution was to mount the amps on the sub box — they could then stay in the front compartment along with the sub box.


A closeup picture of the amp mounting, taken during the installation.


The sub box, with amps attached, fits into the boat's forward compartment.


The spotter seat, on the left, covers the forward compartment.

To send the signal to the amps, Greg chose StreetWires ZeroNoise RCA patch cables. Greg chose to go with preamp-level outputs since they provide a cleaner signal than speaker-level connections. Greg's installation was made easier by the Kenwood KAC-8401's set of preamp outputs. The front and rear preamp outputs of the Clarion receiver were connected to the preamp inputs of the KAC-8401, and then a set of RCA cables connected the KAC-8401's preamp outputs to the preamp inputs of the KAC-7251. This eliminated the need to use a Y-splitter on the preamp cables coming from the receiver's preamp outputs, and kept the signal path clean and direct.

To feed 12-volt power to the amps, Greg ran a single 4-gauge cable from the battery to a StreetWires power distribution block mounted on the sub box. From there, 8-gauge cables take power separately to each amp. Greg chose StreetWires battery terminal fittings for a clean install on the battery. To ground the amp, Greg reversed the process — 8-gauge cables from each amp go to a power distribution block, also box-mounted, and from there to a single 4-gauge grounding cable. The entire power chain is well planned and executed.


The power and ground blocks, mounted on top of the sub box.

Greg's install has given his brother a boat that sounds great, with a clean, stock look. Great work, Greg, and enjoy yourself on the water!

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