Boating by the numbers

Manufacturer anchor size charts run optimistic; experienced cruisers buy one size up from what the chart says.

The charts assume ideal holding in good bottom. Owners who actually anchor overnight, in wind, on mixed bottoms, find the honest size is the next notch up, and an anchor that is a little too big almost never causes a problem.

Source: West Marine anchor selection; ABYC H-40 ground-tackle standard. Read: Best Marine Anchors →

Anchor chain is graded and sized to boat length: 1/4 inch G4 up to 35 ft, 5/16 inch for 35 to 45 ft, 3/8 inch offshore, hot-dip galvanized 100 microns or thicker.

Grade and galvanizing thickness, not the brand on the box, decide how long the rode survives salt water. Thin galvanizing is why budget chain rusts orange in a single season.

Source: ACCO Chain grade specifications; ABYC H-40. Read: Best Anchor Chain →

An EPIRB's 406 MHz distress signal goes to the free government Cospas-Sarsat satellite network; a satellite communicator's SOS goes to a private call center on a paid subscription.

They look similar but are not the same tool. An EPIRB is a registered distress beacon that reaches search and rescue directly; a communicator is built for messaging, with SOS as a paid add-on. Offshore boats carry both.

Source: Cospas-Sarsat program; US Coast Guard. Read: Best EPIRBs & PLBs →

A satellite communicator on the Iridium network reaches the entire planet, poles included; one on Globalstar leaves real dead zones mid-ocean.

Iridium's 66-satellite constellation hands off sat to sat for global coverage. Cross open water and the network, not the handset, is the difference between a message that goes through and one that does not.

Source: Iridium network coverage. Read: Best Satellite Communicators →

An inflatable life jacket delivers about 35 lb of buoyancy versus roughly 15 to 22 lb for a foam vest, and the auto/manual hybrid models let you disarm auto-inflation for wet-entry days.

The extra buoyancy plus a slim, wearable profile is why crews actually keep an inflatable on, and wearing it is the whole point. The disarm switch matters for dinghy and kayak work, where an automatic trigger would fire on purpose.

Source: US Coast Guard PFD buoyancy ratings. Read: Best Inflatable Life Jackets →

Channel 16 is the international hail and distress channel, and a fixed 25W VHF needs a GPS feed for its DSC button to broadcast your position; a handheld puts out only about 6W.

DSC (Digital Selective Calling) is the button that sends a distress alert with your coordinates, but only if a position source is wired in. A fixed masthead-antenna radio also reaches far further than a handheld held at deck level.

Source: US Coast Guard; FCC marine VHF rules. Read: Best Marine VHF Radios →

A Class B AIS transponder that uses SOTDMA transmits at 5W and reserves its own timeslots; older CSTDMA units transmit at about 2W and yield to traffic.

AIS is how a ship's watch officer sees you by name, course, and speed. The 5W SOTDMA units are worth the premium, because being seen reliably in busy shipping water is the entire job.

Source: ITU-R M.1371 AIS standard; SRT. Read: Best AIS Transponders →

On a saltwater boat the solar connectors fail before the panels do, and counterfeit MC4s can turn UV-brittle in a matter of months, so swapping factory connectors for genuine Stäubli MC4s is a cheap, high-value upgrade.

Cheap MC4 look-alikes corrode and go brittle where the sea air gets at them, while genuine Stäubli connectors are IP68-sealed, so the panels routinely outlive the knock-off connectors that shipped attached to them. It is a few dollars of parts that heads off a common marine solar fault.

Source: Compass Marine saltwater install testing. Read: Best Marine Solar Panels →

A cheap solar charge controller can jam your VHF and AIS: radio interference (RFI) is why marine installs pay up for a filtered MPPT unit near the radios.

An MPPT controller also pulls more usable power from the array than a basic PWM unit. On a boat the quiet-electronics part matters as much as the efficiency, because a noisy controller degrades exactly the safety gear you depend on.

Source: marine electronics RFI testing (Practical Sailor). Read: Best Marine Charge Controllers →

3M 4200 is the right sealant for the large majority of a boat's bedding jobs because it holds firmly yet releases when hardware needs to come out; 5200 is effectively permanent and belongs only on structural joints like the hull-to-deck seam.

The most common expensive mistake in boat maintenance is bedding a deck fitting or through-hull in 5200, then destroying the gelcoat, or the part, trying to remove it later. Match the sealant to whether you will ever need the part off again.

Source: 3M marine adhesive technical data. Read: Best Marine Sealants →

Boat fenders are sized by diameter, roughly 1 inch of fender for every 4 to 5 feet of boat, and you err bigger, because a crushed undersized fender passes the impact straight to the gelcoat.

The rule owners get wrong is treating fenders as one-size. A fender that bottoms out against a piling is doing nothing, and going a size up is cheap insurance against a hull ding at a rough dock.

Source: West Marine fender sizing guidance. Read: Best Boat Fenders →

The best bilge pump is not the one with the highest gallons-per-hour number, it is the one whose automatic float switch stays reliable, because the switch, not the pump, is what fails, and float switches typically need replacing every two to four years.

Pumps rarely fail; the automatic float switch does, quietly, and you find out when the bilge is already full. A sealed integrated switch with a multi-year warranty beats a bigger pump sitting on a switch that sticks.

Source: Practical Sailor bilge-pump testing. Read: Best Bilge Pumps →