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Gasoline Venting


Just as automobile technology is changing to match new environmental standards, so must our boats. Evolving awareness of open gasoline vents expelling raw hydrocarbons into the atmosphere has prompted re-engineering solutions. Some, such as the portable jerrycans with spring-loaded openings that we use for gasoline equipment at home, seem to spill as much as they used to vent. But some of the current engineering entering the world of boats mimics the vehicle rules and, thus, will start to seem familiar.

While new standards do not apply to existing gasoline boats with single direct vents, anyone buying a newer boat is going to find new features. The first familiar item is the gasoline fill cap, which clicks or gives some other indication that it is fully engaged and sealed, ensuring that any changes in tank pressure can’t vent hydrocarbons into the atmosphere.


Tank pressure increases with rising temperatures as volatile solvents are released; pressure decreases with high demand from the engine as fuel is consumed and air fills the empty space. One way around this is to use a bladder tank, but nearly all recreational tanks are a fixed size. One of the best methods to stabilize tank pressure is a second venting system with a carbon canister that blocks the escape of vapor when the tank is above atmospheric pressure.

The canister acts as a catalyst, consuming volatile solvents rather than allowing them to release. It will not work if it is flooded with gasoline, so there are safeguards (just as with our vehicles) to ensure proper fill levels. The canister also cannot get wet or flood with water, which means more safeguards.

None of these eco-friendly evolutions will affect your boat’s operation, but it will be a little “greener” as vapors stay in the tank.

This article originally appeared in the April 2018 issue.



Repairing Composites

When a single-skin fiberglass boat has a hole or severe gouge, the damaged fibers have to be replaced with laminates that match as closely as possible the construction of the original.

Illustration of Typical OEM alternator setup

High-Output Alternators

Most engine manufacturers deliver the  electrical system so that the installer just has to hook up a cranking conductor and engine block ground cable.

Alternator Pulley Side View Illustration

Alternator Upgrades

If the size of a boat’s battery bank is  increased or the type of battery is changed, the engine alternator might have to be upgraded to a higher-amp model.


Vacuum Bagging

When building or repairing a substantial laminate, it helps to have pressure to compress the air from a stack or hold the core in place until a cure is reached. Frequently when doing hull and deck repairs, we have to work upside down, and applying pressure is difficult.


Sizing Batteries

Amp-hours on board are measured just like kilowatt-hours in your home. How much current we consume and for how long are the factors that determine the overall capacity needed in a boat’s house bank of batteries. Starting batteries are easy to size since


Charger Wiring

The size of battery-charging equipment has grown to keep pace with larger and more sophisticated batteries.

Drawing of Fuel Gage System

Troubleshooting Gauges

At the engine instrument panel, there are usually alarms for low oil pressure and high coolant temperature, often with monitoring gauges. Although there are new technologies, most gauge transmitters (typically called senders) work on an electrical principle of varying resistance.


A Perfect Day Aboard A Perfect Schooner

Gazing out over the ocean, I take a deep breath. A low fog bank hovers just beyond Nova Scotia’s Mahone Bay islands — a tangible if not impenetrable barrier between the land and the blue sea beyond.