‘Does anything ever go completely to plan at sea?’ – Nikki Henderson

Again in December I reminded myself what ‘too shut for consolation’ seems like. After 18 days at sea, my crew and I completed an Atlantic crossing and parked up in Rodney Bay, St Lucia, with round 5lt of usable diesel left – barely a few hours run time for our 60hp Volvo.

You may have a look at that and contemplate it an instance of outstanding seamanship and exact gas administration – an ideal plan. Barely a drop within the tanks greater than wanted!

Or you could decide it a reckless ‘near-miss’. Only one surprising variable reminiscent of a messy sea state or soiled gas, and we’d have been caught, windless and embarrassingly fuel-less, in sight of land.

Whether or not you decide it good or dangerous; two issues maintain quick. 1) Minimize it nice and get away with it and you’ve got an incredible story within the bar. 2) Dig deeper, and there’ll be classes to study.

So, was it luck? Or a masterful plan that got here collectively?

A month earlier, I joined buddies of mine on their new residence: a 45ft catamaran. The boat was model new. They’d sailed her straight out of the manufacturing facility to the Canaries. By the point I joined them they’d a number of thousand miles underneath their belt, and the very brief record of guarantee points meant a crossing earlier than Christmas was viable. Excellent news!

We ready collectively for nearly per week, at which level an excellent climate window awaited us. As is my routine on becoming a member of a ship, I gathered information.

On the gas particularly: the crew had been monitoring rpm and engine hours from new. From all the time operating the engines in gear at 2,000rpm, after which cross referencing their logged engine hours with the diesel they added to the tanks on their first refill in Tenerife, they knew the engine was burning 3.8lt/1gal per hour, which matched the gas consumption curve as per Volvo’s handbook.

So, we made an informed assumption that the graph might be used to precisely predict gas consumption for decrease rpms and assumed a 2.2lt/hr burn at 1,800rpm.

At 2,000rpm the boat made 6.2 knots in a flat sea; at 1,800rpm it was 5.4 knots. The facility era was equally considerably extra environment friendly at decrease rpm. On a cloudy day at sea, the ability draw on the batteries required 5 hours of operating the engines at 1,800rpm to carry the batteries again as much as 100%.

Based on the producer’s handbook the boat had two diesel tanks of 250lt every and 90% of the gas in every tank was usable in apply. So, we had 450lt of usable gas. We then added 4 20lt jerry cans as an emergency reserve – which might provide us 125 miles vary at 2,000rpm or 160 miles at 1,800rpm.

Assuming a 28-day crossing through which day by day was cloudy, we’d want 308lt [28x5x2.2] for charging, and would have 142lt remaining [450-308] for motoring. That will imply 40 hours, or simply over 200 miles of vary.

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As every day of the crossing progressed, we recalculated these figures to have in mind our real-time progress, the discount of charging time wanted on account of photo voltaic era, and the long run climate forecast.However regardless of our meticulous planning and monitoring we encountered a number of surprises. Does something ever go fully to plan at sea?

Throughout a bilge inspection on day 14, we found a stamp on every of the gas tanks exhibiting their capability was 230lt and never the 250lt said within the boat handbook. Lesson: examine the tanks match the handbook.

On the penultimate day, our starboard engine stopped as we’d run its tank ‘dry’. So regardless of the handbook stating that 90% of the gas is usable, in actuality it was 84%. Lesson: discover out what the real-time ‘backside’ of the tank is earlier than you face a wind gap on day 17 of an Atlantic crossing.

We’d been operating our two engines in sync, to keep away from one having too many extra hours than the opposite. So, when one tank reached backside, the opposite wasn’t far off and there was no scope to alter technique. Lesson: keep away from stressing all of the techniques on the similar charge.

The jerry cans saved the day. We hadn’t anticipated to make use of them in any respect. Lesson: the additional weight of the odd jerry can of gas can save an entire load of stress.

So to sum up, assumptions and ambiguity are a sailor’s worst nightmare. Check all the things, by no means guess. And have a back-up plan.

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