How we tested them
Some past tests have focused on how snubbers perform under increasing static loads, but we wanted to see how they would react to a snatch load. To measure this, we installed a strongpoint in the PBO garage roof, to which we attached a load cell. We then connected the load cell to a conditioning amplifier to provide a stable supply voltage and amplify the tiny output voltage to a level easily measurable by our Velleman WFS210 softwarebased oscilloscope.
We tested each snubber by rigging it into a length of 14mm three-strand nylon rope attached to the load cell. For the Easterner snubber we used 12mm line, as we were unable to source it in the correct size. We tied an 11.2kg mass to the end of the line (Ben Meakins’ diving weight belt), and adjusted it to measure 1.2m from the load cell to the mass. We then dropped the mass from a point level with the load cell. A rough calculation suggests that the mass is travelling at around 9.4 knots at the end of its travel. A 2,500kg boat would need to be moving at around 0.6 knots to have similar energy – easily possible from waves or wash. To capture the initial absorption and subsequent bounces we set the oscilloscope to trigger on a rising voltage, capturing around three seconds of data from that point.
In addition, we also set up each snubber on a length of line between a winch and a strongpoint affixed to a 6in square oak post, using a 500kg dynamometer to measure 20kg steps up to 200kg, unless the snubber was still extending – in which case we continued the test to a maximum of 300kg. At each point we measured the extended length of the snubber.