Guides
Questions people actually ask, answered properly. Every claim here is sourced, every source is named, and where we couldn't verify something we say so instead of rounding it up. If the honest answer is inconvenient — an expiry date, a license you need, a rating a product doesn't carry — that part stays in.
Can I use a climbing rope for tree work?
No. ANSI Z133-2017 requires an arborist climbing line of at least 1/2 inch (12.7 mm) with a minimum breaking strength of 5,400 pounds and working elongation no greater than 7 percent. A dynamic rock climbing rope is thinner, stretchier and built for a different job. Its sheath and stretch also make it a poor host for a friction hitch.
Read the guide →Is a tree climbing saddle the same as a fall arrest harness?
No. Most arborist saddles carry EN 358 for work positioning and EN 813 as a sit harness, and neither is a fall arrest standard. Fall arrest is EN 361, which requires attachment points marked with a capital A. Teufelberger's treeMOTION evo instructions say plainly that it "must not be used to arrest a fall."
Read the guide →How does an avalanche beacon work?
An avalanche beacon is a 457 kHz radio that transmits a pulsed signal in send mode and receives it in search mode. A searching unit compares signal strength across two or three antennas to show direction and a distance number. That number tracks signal strength, not measured meters.
Read the guide →What do the numbers on a carabiner mean?
A carabiner carries three kN figures: major axis with the gate shut, minor axis, and major axis with the gate open. All three are breaking strengths measured by a slow pull in a lab, not working loads. The letter beside the standard number says which class of connector it was certified as.
Read the guide →What do chainsaw trouser class numbers mean?
A chainsaw trouser class is a chain speed the garment was tested against, not a protection level in any general sense. Under EN ISO 11393, Class 0 is 16 m/s, Class 1 is 20 m/s, Class 2 is 24 m/s and Class 3 is 28 m/s. Nothing here is cut-proof; the fabric jams the saw.
Read the guide →Do you need a chartplotter if you have a phone?
Not always. A phone running a chart app is a capable navigator, and for a small open boat in familiar water it can be the primary. A chartplotter earns its place through integration: it is the display for radar, AIS, sonar and autopilot on the NMEA 2000 network, and it runs off ship's power.
Read the guide →What is the difference between a climbing helmet and a work helmet?
A work helmet is built for something falling on a stationary head; a climbing helmet is built for a moving head hitting rock, or for the wearer falling. EN 397 requires a chinstrap that releases at 150–250 N so a snagged helmet can't strangle you. EN 12492 requires one that holds past 500 N.
Read the guide →Will these crampons fit my boots?
Crampons attach to welts, not to letters. A C1 strap-on fits most stiff-soled boots, a C2 hybrid needs a heel welt, and a C3 automatic needs a toe welt as well. The B0–B3 and C1–C3 lettering is a trade convention, not a standard — check the boot for welts.
Read the guide →Should I climb on a friction hitch or a mechanical device?
Neither is safer by default. A friction hitch is a technique: its grip depends on the cord, the host rope, the wraps and your tending, and no manufacturer certifies that combination. A mechanical device is a certified product with a published rope diameter window and an approved system you have to stay inside.
Read the guide →Should you buy a handheld or a fixed-mount marine VHF?
Buy the fixed-mount first. VHF is line-of-sight, so antenna height decides range more than transmit power does, and a masthead antenna is something no handheld matches. Then buy a handheld as the second radio — it keeps working after the boat's electrical system doesn't. The power tiers — 1, 6 and 25 watts — matter less than buyers assume.
Read the guide →How do you wash a climbing or rescue rope?
Wash it in cool water with a soap the maker allows, then air-dry it out of the sun and away from heat. Never a dryer, never bleach or solvents. Petzl, Edelrid, Mammut and Teufelberger all cap washing at 30°C; Sterling says a hot machine cycle is fine. Check the instructions printed for your own rope, because they govern.
Read the guide →What is the difference between LiFePO4 and lithium-ion batteries?
LiFePO4 is a lithium-ion battery — one chemistry inside that family, not an alternative to it. Against nickel-based cells like NMC it trades energy density for cycle life and thermal stability: heavier for the same watt-hours, but rated for thousands more cycles. The catch is charging temperature, which most makers limit far more tightly than discharge.
Read the guide →Do you need AIS on a boat, and what is the difference between receive and transmit?
US federal law requires AIS carriage on specified commercial vessels, not on recreational boats. A receive-only unit shows you commercial traffic. A transceiver also transmits your position, which is the half that changes what the other vessel does — and it needs an MMSI. Class B SOTDMA transmits at 5 watts; basic Class B at 2.
Read the guide →Do you need radar on a small boat, and what does the range figure actually mean?
Radar earns its place on a small boat for two jobs: fog and night, and seeing what AIS cannot — unlit boats, buoys, squalls, land. The advertised range describes the transmitter, not what you will see. Radar is line-of-sight, so a low antenna sees a low target at a fraction of that figure.
Read the guide →What is the difference between an MPPT and a PWM charge controller?
A PWM controller connects the panel almost directly to the battery, so the panel works at battery voltage and everything above it is never harvested. An MPPT converts those extra volts into extra amps. The gain therefore isn't fixed: Victron's own worked example shows 19 percent at 25°C cell temperature and nil at 75°C.
Read the guide →What size portable power station do you actually need?
Two numbers, not one. Watt-hours tell you how much energy is stored; watts tell you how much can leave at once. Add up each device's watts times the hours you'll run it for the watt-hour figure, then check the continuous watt rating covers everything running at the same time. Both have to clear.
Read the guide →Do you need a pure sine wave inverter?
Probably, and the makers who sell both waveforms say so. Modified sine runs resistive loads — heaters, incandescent bulbs, simple chargers — perfectly well. Anything with a motor, a clock, a dimmer or a speed control is where it goes wrong. Samlex and Renogy both recommend pure sine outright. The price gap between the two, though, has not closed.
Read the guide →What rope diameter should you use?
Buy the diameter your hardware is certified for. Every descender, ascender, backup device and belay plate publishes its own rope diameter range, and the usable rope is the overlap between all of them — not the widest one. For most rope access work that overlap lands between 10 and 11.5 mm.
Read the guide →What does MBS mean on a rope, and what can you actually hang off it?
MBS is minimum breaking strength — the lowest force at which a new, unknotted, straight-pulled sample is permitted to fail in a lab. It's a certification threshold, not a load rating. Knots, bends, wear and dynamic loading all sit between that number and your system, and none of them are in it.
Read the guide →When should you retire a climbing or rescue rope?
There's no single date. Retire immediately if the core shows through the sheath, if the rope has met chemicals, if friction has glazed or melted it, or after a severe fall. Otherwise makers cap textile life around ten years — but Sterling cuts that to one year under heavy use, and no US regulator sets a rope expiry at all.
Read the guide →How many solar panels do you need to charge a battery?
Multiply panel watts by your location's peak sun hours to get watt-hours per day, then take 20 to 30 percent off for real losses. Divide your battery's watt-hours by what's left. A panel's rating is measured with the cell held at 25 °C, and output falls as the panel heats up.
Read the guide →What is the difference between SRT and DdRT in tree climbing?
Moving rope system (MRS) is the old DdRT: the rope runs over a union, both legs move, and you lift about half your body weight but pull twice the rope. Stationary rope system (SRS) is the old SRT: the rope is anchored and you move along it, at full weight and 1:1.
Read the guide →What is the difference between static and dynamic rope?
Dynamic rope (EN 892) stretches to absorb a fall — Petzl's CONTACT 9.8 publishes 35% dynamic elongation. Low-stretch rope (EN 1891) does not: Beal's Industrie 10.5 publishes 2.9% static elongation. Use dynamic wherever a leader can fall above the anchor; use low-stretch for rope access, hauling, rappelling and rescue rigging.
Read the guide →What is DSC on a marine VHF, and why does an MMSI matter?
DSC — Digital Selective Calling — sends a digital distress alert on VHF channel 70 at the press of one button. The alert carries two things: your MMSI, a nine-digit vessel identity, and your position. Without a programmed MMSI the alert is anonymous. Without a GPS feed it has no position.
Read the guide →What is a via ferrata set and why does it expire?
A via ferrata set is a shock-absorbing lanyard certified to EN 958: two arms, two type K carabiners, and one energy absorber sized for users between 40 and 120 kg. It expires twice over — instantly after any fall that loads the absorber, and again when the maker's textile service life runs out.
Read the guide →Can you bring a knife on a plane?
Not in a carry-on. TSA bans all knives from US carry-on bags except plastic knives and rounded butter knives. Any knife can fly in a checked bag if it's sheathed or securely wrapped. Scissors under 4 inches from the pivot are the carve-out — and the checkpoint officer always has the final say.
Read the guide →What angle should you sharpen a knife to?
Match the factory edge unless it keeps failing you. Real published angles: Benchmade grinds 30–35° inclusive, Spyderco's Sharpmaker sets 15° or 20° per side, Morakniv's Scandi blades run 23–27° total, Kershaw says 18–22° without saying which convention. Always check whether a figure is per side or inclusive: 20° per side and 20° inclusive are radically different edges.
Read the guide →What do knife steel names actually mean?
A knife steel name identifies a published recipe — how much carbon, chromium, and other elements the mill melts in. It doesn't tell you the heat treatment, which decides how that recipe actually performs. Every steel trades between edge retention, toughness, and corrosion resistance; the name tells you which trade was chosen, not how well it was executed.
Read the guide →Should you buy a serrated or plain edge knife?
Buy a plain edge unless you regularly cut rope, webbing or straps. A plain edge push-cuts cleanly and is easy to sharpen. Serrations grab fibrous material — Spyderco and Kershaw both claim serrated edges stay sharp longer, and Kershaw concedes they take special tools to resharpen. No standards body publishes a serrated-versus-plain cutting benchmark; every performance claim is a manufacturer's.
Read the guide →Will a stainless steel knife rust?
Yes, it can. Stainless means more chromium — roughly 12 to 13 percent or better — which slows rust, not a blade that can't corrode. Benchmade says even its highest-grade stainless steels can pit with saltwater or humidity. Salt is the main enemy. A few nitrogen steels, like Spyderco's H-1, genuinely don't rust.
Read the guide →What does a 5,000 lb anchor point actually mean?
It means the anchorage must be capable of supporting at least 5,000 pounds for each worker attached. But that is only half the rule: OSHA allows an alternative of a system designed, installed and used under the supervision of a qualified person with a safety factor of at least two. The 5,000 lb figure is the option you take when nobody has engineered the anchor — and it applies to the anchorage, not to the connector you bolt to it.
Read the guide →What do 8x42 and 10x42 mean on binoculars, and which should you buy?
The first number is magnification, the second is the diameter of the front lens in millimeters. Divide the second by the first and you get the exit pupil in millimeters, which is what governs low-light performance — 5.3 mm for an 8x42 against 4.2 mm for a 10x42. For general use buy the 8x42: it is steadier in the hand, has a wider field of view, and most people see more detail through it despite the lower magnification.
Read the guide →Why doesn't a boat compass point north?
Because two different errors sit between the compass and true north. Variation is the angle between magnetic north and true north at your location, and comes off the chart. Deviation is the deflection caused by your own vessel's iron, magnets and electrical gear — and unlike variation it changes as the boat changes heading. The sum of the two is compass error. Deviation is measured by swinging the compass and recorded on a deviation card.
Read the guide →Do you still need a compass if you have GPS?
Yes. Carry both, because each fails in a way the other does not. GPS accuracy depends on factors outside anyone's control including sky blockage, and battery performance degrades in cold. A magnetic compass needs no power but cannot be trusted near the magnetic poles, where NOAA defines blackout zones in which compasses should not be relied on for navigation. The National Park Service lists map, compass and GPS together as one of the Ten Essentials.
Read the guide →Do you need a rescue plan for working at height?
Yes. OSHA requires it. In construction, 29 CFR 1926.502(d)(20) requires the employer to provide for prompt rescue of employees in the event of a fall or assure they can rescue themselves. General industry is stricter still — 1910.140(c)(21) requires prompt rescue with no self-rescue alternative in that sentence. Relying on the emergency services to arrive is not a compliant plan, and manufacturers say so in their own documentation.
Read the guide →When does a fall-protection harness need to be retired?
Immediately after any fall or shock load, and whenever inspection finds damage. Beyond that there is no single answer: OSHA sets no expiry date, and manufacturers disagree. Petzl, CAMP, Skylotec, ISC and CMC all publish a ten-year limit for textile products; FallTech states it has no preset service life at all. Check the retirement rule printed in your own harness's instructions, because it is the one that governs.
Read the guide →Should a headlamp use rechargeable or disposable batteries?
Rechargeable for regular use — cheaper over time, and usually brighter, because a lithium-ion cell delivers higher current than three AAAs. For deep cold and for anything stored unused, primary lithium AA or AAA cells are the better answer: they are rated to minus 40 degrees Celsius where alkaline stops at about minus 18, they weigh a third less, and they will not corrode the lamp. Alkaline's real problem is not runtime, it is leakage.
Read the guide →How many lumens do you actually need in a headlamp?
For camp tasks, reading and walking a known trail, 150 to 250 lumens is enough. For route-finding, technical ground or night running, 400 lumens and up earns its weight. But the headline number is measured under a standard that most buyers misread: the advertised maximum brightness and the advertised maximum runtime are almost never the same mode, and lumens do not predict how far the beam reaches.
Read the guide →Should you buy a headlamp or a handheld flashlight?
Buy a headlamp for any task you perform with your hands — camp work, repairs, climbing, night running. Buy a handheld when you need to see something far away, because reach comes from a large reflector and a headlamp cannot have one. A 250-lumen Streamlight handheld reaches 447 meters while a 2,200-lumen Fenix headlamp reaches 229. Most people who work in the dark end up owning both.
Read the guide →What do IP ratings mean on a flashlight or headlamp?
The first digit is protection against solids and dust, on a scale of 0 to 6. The second is protection against water, on a scale of 0 to 9. An X means that digit was not tested, not that it scored zero. Two traps matter: a higher second digit does not automatically include the lower ones, so IPX7 immersion does not cover IPX6 water jets unless the product is dual-coded; and IPX8 depth and duration are agreed by the manufacturer, not fixed by the standard.
Read the guide →What is a leading-edge SRL and when do you need one?
A leading-edge SRL is a self-retracting lifeline tested for use where the line can bear on an edge during a fall, and for anchoring at or below the worker's dorsal D-ring. You need one whenever the lifeline could run across a sharp or abrasive edge — most often when the anchor is at foot level rather than overhead. A standard SRL in that position can have its line severed or its energy absorber prevented from deploying.
Read the guide →What actually makes binoculars expensive?
Four things, roughly in order: coatings, the glass itself, the prism system, and manufacturing tolerance. Fully multi-coated means every glass surface has multiple anti-reflective layers and is the meaningful bar — coated, fully coated and multi-coated all mean less. ED or fluoride glass reduces color fringing. And a roof prism must be made to roughly 300 times the angular precision of a porro prism, which is why a good compact binocular costs what it does.
Read the guide →Do EPIRBs and PLBs require a subscription?
No. A 406 MHz EPIRB or PLB transmits to Cospas-Sarsat, an intergovernmental search-and-rescue satellite system, and carries no subscription or airtime fee. Satellite messengers such as Garmin inReach are a different product and do require a paid plan. Beacons must still be registered — free, and the step most owners skip.
Read the guide →Should you buy a foam or an inflatable life jacket?
Buy foam for children, non-swimmers, and anything fast or rough — personal watercraft, tubing, towed sports and whitewater. Buy an inflatable for adults who would otherwise leave a bulky vest in the locker, since the jacket that gets worn beats the better one that doesn't. Inflatables are serviceable devices and need rearming after use.
Read the guide →Do you need a carbon monoxide detector on a boat?
Yes. Any boat with an enclosed cabin or sleeping space should carry a marine-rated carbon monoxide alarm. CO is colorless and odorless, its early symptoms are indistinguishable from a long day on the water, and it can reach you from your own generator, your own exhaust drawn back aboard, or the boat rafted up beside you.
Read the guide →Do marine flares expire, and how do you dispose of them?
Yes. Pyrotechnic marine distress signals carry an expiry date stamped on each unit, and expired signals do not satisfy the US carriage requirement. Disposal is genuinely unresolved: they are pyrotechnics, they cannot go in household trash, and firing them off is a false distress alert and illegal. Routes vary by locality — ask marine patrol, the fire department or your hazardous-waste program.
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