Ask the Expert Archives - BoatHowTo

Marine Diesel Engines: Flexible Shaft Couplings and the Grounding Question

Nigel Calder — Wed, 15 Apr 2026 04:44:39 +0000

This is a question that comes up more often than you might expect, and it touches on two things that matter enormously on a boat: corrosion protection and electrical grounding. The question is a simple one on the surface — if I install a synthetic flexible coupling between my transmission and my propeller shaft, have […]

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Is Your Galvanic Isolator Actually Fail Safe? Here’s What You Need to Check

Nigel Calder — Wed, 15 Apr 2026 04:44:33 +0000

One of the questions I get asked fairly often concerns galvanic isolators — those small but important devices that sit in the safety grounding connection between your boat and the shore power system. Specifically, people want to know whether their galvanic isolator is fail safe. It is a question worth taking seriously, because the answer […]

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Understanding Marine Corrosion Protection: Are Your Zinc Anodes Working Correctly?

Nigel Calder — Wed, 15 Apr 2026 04:44:28 +0000

A question that comes up with surprising regularity among sailors is whether their sacrificial anodes are doing their job correctly — and whether the rate at which those anodes are being consumed is normal. It is a question worth taking seriously, because the answer tells you a great deal about what is actually happening beneath […]

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Why Positive Side Switching Is Required on Boats — And Why the Automotive Comparison Doesn’t Hold

Nigel Calder — Wed, 15 Apr 2026 04:44:21 +0000

A question came in recently that I suspect many people have wondered about, particularly those who have spent time working on cars before turning their attention to boats. In the automotive world, some manufacturers place switches on the negative side of a circuit — after the load — as a way of reducing arcing and […]

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Marine Diesel Engines: Why Aluminium Anodes on an Aluminium Sail Drive?

Nigel Calder — Wed, 15 Apr 2026 04:44:14 +0000

It is one of those questions that sounds almost contradictory the first time you hear it. Why would you protect an aluminium sail drive leg with an aluminium anode? Isn't the whole point of a sacrificial anode that it corrodes instead of your boat? The answer comes down to metallurgy, galvanic chemistry, and a few […]

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Understanding Marine Electrics: How to Recover Lost Capacity in a Sulfated Battery

Nigel Calder — Sat, 08 Apr 2023 20:36:23 +0000

If you have a lead-acid battery that seems to be discharging faster than it used to and recharging faster than it used to, it may be sulfated. In fact, it probably is sulfated! This is a common issue with batteries that are not regularly fully recharged, which is also a common situation with boat batteries. […]

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Understanding Marine Electrics: The Challenges of Using Fuel Cells on Boats

Nigel Calder — Sat, 08 Apr 2023 14:10:10 +0000

With the growing interest in renewable energy and new ways to store energy, fuel cells seem like an interesting option. However, having been on the fringes of three well-funded marine fuel cell projects that never made it to commercial viability, I know only too well the challenges to optimizing fuel cell installations in boats.Hydrogen Storage […]

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Understanding Marine Electrics: Converting a 230V SHORE POWER system to 120V

Nigel Calder — Sat, 08 Apr 2023 14:03:03 +0000

In the USA, when you plug into an outlet in your house or on a boat you are plugging into a 120-volt circuit. In Europe, when you do the same thing, you are plugging into a 230-volt circuit.Equal Power, Different AmpsLet’s say we are plugging in a microwave with a power rating of 1000 watts […]

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Understanding Marine Electrics: Corrosion Issues with Thru-hulls and Seacocks

Nigel Calder — Sat, 08 Apr 2023 13:52:16 +0000

Let’s talk corrosion! There are two types, galvanic and stray current. They are very different and should never be confused.Galvanic CorrosionGalvanic corrosion occurs as a result of properties inherent in metals. When immersed in a conductive liquid (an electrolyte, for example saltwater) all metals have a ‘natural’ voltage. If you place two different metals in […]

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Understanding Marine Electrics: Maximizing Battery Life on Your Boat

Nigel Calder — Sat, 08 Apr 2023 13:45:31 +0000

Do the quality lead-acid batteries on your boat last at least five years and preferably ten? Very few do. Most boatowners have come to assume changing batteries every two or three years is normal whereas this is, in fact, an indication of expensive improper systems design and battery maintenance.Cranking BatteriesA battery that is solely reserved […]

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