Kevin,

I bought a four-position switch to replace my four-position/four-terminal switch on my Mercury Marine 5.0 MPI’s boat wiring. 

The problem is the new switch has arrived and has six wires. The extra two say 5 and 6 position are for the battery and ignition – as shown in the attached picture.

Should I ignore these and cut the wires off or should I connect them to 1 and 4? 

Do I need a different switch?

Dan

Hi Dan,

This switch will work fine.

Ignore positions 5 and 6. They are internally connected to 1 and 4. You can either cut them off or tape them up.

Kevin

Hi Kevin,

I work in the telecom industry, where we always isolate AC equipment from DC equipment ensuring that each has the required earth path.

I need to locate a regulation in BS7671 or elsewhere that indicates if a distance is required between the two separate systems as there is obviously a different earth potential between the two systems and a person touching the AC equipment and the DC equipment at the same time could in theory receive that difference in potential as an electric shock.

Regards

Mark

Hi Mark,

I am posting a copy of ABYC E-11, which is the marine electrical boat wiring standard for the industry.

On boats, it is required to connect the AC Ground to the DC ground to give a low resistance path to ground in the event of an AC fault to a DC device. Without this connection, the AC path to ground would be through the water which creates an extreme hazard.

Hope this helps,

Kevin

Kevin,

My family and I are planning on a multi-year sailing trip. I have an Perkin-Sabre M65 engine in my 44′ sailboat. I want to upgrade the existing alternator with a high output Balmar alternator. I am interested in one that works with an external regulator and has the highest amp rating without jeapardizing the water pump bearings. Probably one of the 70-Series 3.15” Dual Foot alternators?

I am also interested in a second alternator.The Perkins-Sabre rep advised:

“The challenge with running a high output alternator in place of the stock 65 A is that you are limited to about 90 A on a single belt. If you require a high output at a lower rpm the belt tension is critical which is extremely hard on the water pump bearings. I have a friend that went through 3 water pumps in one cruising season. The bullet proof way to run large cruising alternators is to run them off the front end, inline with the crank shaft using a coupling and a jack shaft with 2 bearings. This way the engine has no side load on the crank shaft.

The second best would be to have some pulleys made to a specified size for proper alternator speed and side mount the alternators, 1 on each side. This would allow you to drive with double belts as well. Alternators can be a bit of a science project. In a perfect installation the alternator mounting brackets would bolt to the engine allowing everything to operate on the same plane. This does throw you into one more consideration if you choose heavy large frame alternators……front motor mounts. The extra weight may sag the mounts causing alignment problems. The other way is just like the second ,only mounting the alternators to the stringers, one on each side and hope for the best counting on the belts to take up any shock.
There are no brackets available. Anything you do will be custom if you go above 90 A………maybe 100A if you don’t try to pull full output at low rpms.”

I have found no reference to any alternator that operates inline. Can you help me?

Jim

Hi Jim

I have little experience with customer alternator installations.

I would recommend checking with Scott Fracter. Last year, Scott generously allowed us to publish his “Adding a second alternator” article, which is a comprehensive overview of the whole process. He is truly an expert in this area.

If Scott doesn’t have the parts you need, he may be able to make them, or send you in the right direction.

Enjoy your trip.

Please send photos,

Kevin

Dear Kevin,

I am currently beginning my first boat wiring project, a total rewire of a small Owens cruiser from the late ’60s.

Here’s my problem:

The old wiring runs behind the original paneling and headliner. I could try dismantling everything to remove and replace the wires, but am concerned about damaging any of the woodwork. It’s old. It’s gorgeous. It would be a bitch to replace.

I don’t mind leaving the old wiring in place and just running a new harness, but that still leaves the problem of installing the new wires without causing any damage.

Any ideas?

RP

Dear Ron,

Your problem was common with boat restoration projects – until the introduction of Harness in a Can.

Harness in a Can lets you spray pro-quality boat wiring into even the most hard to reach areas. Simply point, spray, and apply power. What could be easier?

And, it’s not just easy, it’s ABYC approved! Harness in a Can sprays out a harness with correct wire color and sizing – and with all of the connections that you need to get the job done fast.

If you order now, you will also receive a cap snaffler – absolutely free. Cap snafflers snaffle caps off any size jug, bottle or jar…and they really really work.

Call now to order. The toll free number is 877-277-3665. Operators are standing by. That’s 877-APR-FOOL.

Kevin.