Systems & Propulsion

In the June 2018 article Air Conditioning for Sailboats, we compared several options for 12-volt air conditioning on boats, and more recently we looked at the power requirements for running our air conditioner without being tethered to shorepower, see Air Conditioning at Anchor, PS June 2019). Since that article was published, we were told about the new i-Line VSD Series of compact air conditioners from Velair-an Italian company that is part of the Ultraflex Group.

The human body runs on electricity and if you overload the nervous system with an external field, everything goes haywire. Every year several people die because they go swimming near a dock, a wiring fault creates an electric field in the water, and their muscles freeze. It is called Electric Shock Drowning (ESD).

As a subscriber, you have free access to our back-issue archive-more than 2,000 articles. Here are a few topics you might find relevant this season.

Weve followed countless debates about the best engine oil and the right time of year to change it, as well as quite a few debates about oil analysis. Just as controversial is the advice on oil filters, which ranges from a blas recommendation to use whatever fits, to an adamant insistence to use only original equipment manufacturer parts (OEM). Because the oil filter is sealed in a cartridge, unless your filter leaks oil into the bilge we never actually know if it did its job or not. Given the filters important role, this is unsettling.

Simple tank fill advice from an old fuel oil delivery guy - when filling your boat diesel tank listen to the sound coming from the tank vent, it is attached directly to your tank. The fueling sound will change when the tank fills and fuel enters the vent line. Stop then. Dont leave fuel sitting in your fill hose in the off-season.

Estimating size has always been tricky, because it depends on the insulation value of the boat, climate, and how quick you want the boat to cool down. It also depends on window covers and awnings and how much window space you have. Houses, on the other hand, tend to have similar insulation values, and the rate at which they cool is not important because people leave the AC on all summer.

The popularity of micro-electronics and LEDs has greatly increased the number of small wires on board, and whether the added eyestrain is a fair trade-off for a lighter, more energy efficient boat depends upon your perspective. Fortunately, some welcome accessories are relieving the headaches associated with joining two wires of tiny diameters-at times as small as button thread.

The loss in RF coaxial cable increases substantially and quickly, when there is water intrusion. Coax that uses foam dielectric, like RG8X and LMR type coax, is particularly prone to this problem because the water can quickly propagate along the foam dielectric used in these type coaxes.

Recreational marine VHF antennas are usually broken down into three categories: 3- and 4-foot sailboat antennas (3dB gain), 8-foot powerboat antennas (6 dB gain) and 16-plus-foot, long-stick antennas (9+ dB gain) that are popular on larger, long-range craft. Antenna gain is a ratio related to an antennas effective radiated power (ERP) instead of a fixed quantitative value.

No one really wants just practical gifts, so weve tried to locate a few items that go beyond pure utility for this holiday season.