Skip to main content

Maintaining Belt Tension

One day I discovered the romantically named Belt Tension Jack. Suddenly belt tensioning not only lost all its emotional tension, it even acquired a certain elegance.

I don’t know about you, but for the longest time I always had problems getting my diesel’s alternator drive belt tensioned correctly. For starters, the engine is mounted backward, so to check the belt tension I first have to empty the cockpit locker, then climb into it and contort myself until I can get my arms and head under the cockpit sole and in the right position to reach the belt and pulleys. Fortunately, the belt always seems to need adjusting, so it’s never a wasted effort.

Beyond that, what really annoyed me was that after the usual rigmarole of loosening the pivot bolt and the pinch bolt on the adjusting arm, and then levering the pulleys apart with a long screwdriver until the tension felt right, then tightening the bolts again, the belt was always a little looser than I wanted. Inevitably, the screwdriver would slip or I’d misjudge the tension, or both. There was just no getting around the fact that it was one of those jobs you really need three hands for, and the result of having only two was an engine coated in that fine black dust that comes off poorly adjusted drive belts—not to mention frequent trips down to the dungeon to do it all over again.

Then one day I discovered the romantically named Belt Tension Jack. Suddenly belt tensioning not only lost all its emotional tension, it even acquired a certain elegance.

This clever tool has one purpose and one purpose only: to push two pulleys apart, thereby applying tension to the relevant belt. Juggle it between the pulleys you want to separate, and then crank on the hexagonal body with a wrench to extend a threaded rod with a curved horn on its end until the belt is properly tensioned. After that you can nip up the nut on the pivot bolt and tighten the pinch bolt on the adjusting arm at your leisure, humming a merry tune as you go. Brilliant! There’s nothing like using the right tool for the job, especially a tool you had no idea existed.

This is one of those little things that turns an unpleasant chore into a simple and quick maintenance task. You can buy these nifty tools from MSC Direct for around $20.

Belt Love

• A belt that’s too tight can cause wear on pulley bearings, and one that’s too loose can affect alternator output

• As a rule of thumb, if the belt deflects no more than half an inch when firmly poked with a finger, tension is about right

• Belts are not expensive and should be replaced annually along with engine oil and fuel filters. Keep the old one as a spare

• If you’ve installed a new belt, check its adjustment after a few hours of motoring. It will have loosened and may need retensioning

• Clean that nasty black dust off your engine and alternator. It can foul up the alternator’s delicate interior works. A sponge or rag coated in WD40 works well



Crowdsourcing Age-of-Sail Weather Data

Although big, multi-million-dollar projects like the Large Hadron Collider and the human genome project with their legions of PHD’s tend to grab headlines, there’s still a part of play for the “citizen scientists” of the world. Amateur birders have long contributed to an more


Ultims to Race Solo Around the World

For years now, maxi-trimarans, both solo-sailed and fully crewed, have been racing the clock on their own around the world in an effort to set ever faster records for the world’s fastest circumnavigation under sail. Back in 2000-01 there was also a no-holds-barred more


Juneteenth on the Water

Discovering Amistad and Mystic Seaport Museum have partnered to organize their third annual Juneteenth festival, featuring concerts, speakers and a reflection on the lasting legacy of racial injustice in America. Declared a National Holiday in 2021, Juneteenth celebrates the end more


New Multihulls for 2022

Lagoon 51 In keeping with many of the more recently launched models created by French multihull builder Lagoon, the Lagoon 51 is all about comfort, “en plein air,” in particular, as the French might say. Topside, a whopping 80 percent of the boat’s flybridge is given over to more


How to Spectate on the Newport Bermuda

The biannual Newport Bermuda Race starts on Friday with the first warning signal at 1 pm. Whether you’re tracking a loved one’s progress or just spectating an event that draws pros and weekend warriors alike, there are plenty of ways to stay up to watch. The starting line will more


US Sailing Strikes Gold in Hyères

After being skunked or nearly skunked at multiple Olympiads, could the US Sailing Team (USST) now under the direction of Olympic veteran Paul Cayard, be finally turning it around? If its performance at the 53rd French Olympic Week regatta in Hyères, France, where the team posted more


New York City’s Newest Fleet

120 children enrolled in Brooklyn Boatworks’ STEM and life skills-focused program launched their hand-built optimist prams on June 14 from Pier 2 in Brooklyn Bridge Park. The launch is the culmination of years of student work, with boats in process before the pandemic caused the more


Charter: Off the Beaten Path

So, you like to charter in the Caribbean with its warm waters, swaying palm trees, steady trade winds and strong rum drinks. What’s not to love? It can be easy, though, to get stuck in a rut when chartering year after year in the same place. Sure, the British Virgin Islands are more