Spring Fever – tide by tide

June (2) – overnight to Plymouth, fuel consumption

With half a dozen tidal gates on a passage from the Solent round Lands End, we managed to get through four of them in 24 hours last week. The westerlies that usually slow a cruise to Devon and Cornwall gave way to light winds from between north and east, with calm seas.

Two of us were standing ready to sail to Plymouth as soon as we had the right weather forecast, so we would be better positioned for rounding Lands End on our way to Wales and Ireland next month.

*Tony bringing the boat in from our mooring to Cowes Yacht Haven so I could do a pierhead jump – we’re too mean to pay marina day rates*

We went to Cowes on Monday afternoon, left at 5am on Tuesday and were in Plymouth Sound about the same time on Wednesday.

We logged about 130 miles, mostly doing two hours on and two hours off, because there was not much sail handling to do – we motorsailed for all but two hours. We had to plug contrary tides twice, of course, but that’s a lot easier to plan when you aren’t beating at the same time against a contrary wind.

A friend who will join us for the next leg found us a friendly berth at his club at Saltash on the Tamar, and that’s where Spring Fever is at the moment.

How much fuel do you burn?

We all know that fuel consumption per hour rises dramatically with rising engine revs. But that doesn’t give a true efficiency rating because with higher revs and speed you go further per hour, of course. What really matters is consumption per mile, which is harder to measure. There is an excellent article on this subject in the summer issue of Cruising, the Cruising Association’s magazine.

Our nearly new Beta 30 is proving helpfully economical measured per hour: purring along at only 1500 -1800 revs, fuel consumption was less than 1.5 litres an hour on the way to Plymouth. We were getting a knot or two from the sails so we averaged just over 5 knots. If we had pushed the boat at engine cruising speed of 6.5 knots we’d probably have doubled or trebled the consumption per hour.

The good news is that Cruising’s research report shows very clearly that consumption per mile also rises with engine revs, though not as fast as consumption per hour. Our 1500 to 1800 rpm looks close to the optimum engine speed. Consumption per mile rises steadily as the engine revs up beyond that. The tests were on a 50HP Beta, so are not directly comparable, but it seems unlikely our Beta 30 would be very different.

There is also some useful related data in the article on the effect of headwinds and waves on consumption per mile at different revs, which is of course to drive it up further. But other than at very low revs, the data shows that the relation between rising revs and fuel consumption per mile is maintained.

October – the shortest season ever

That’s that, for the moment: new lockdown, can’t go to the boat for an autumn mini-cruise or even to do some maintenance, so sum total of this year’s sailing is 5 days in the Solent. I try not to contemplate the cost per day.

We have however decided to leave the boat fully in commission in Chichester Marina (above) over the winter and into next season, with sails bent on and engine not winterised. This is because Spring Fever was launched only in mid-September, so gear and antifouling have not just finished a long, hard season.

July – launch date at last

So far the only boating I’ve done the entire year is rowing my little dinghy to harvest some luscious but otherwise inaccessible early blackberries hanging over the water.

This lovely little lapstrake boat, a Roger Oughtred design called a feather pram, is too fragile to want to knock it about on beaches as a yacht tender, so I keep it safe on our pond.

February – averting satellite disaster

The British government turns out to have been ahead of the game on the satellite risks I mentioned last month, with a £36 million programme just announced to prevent navigational satellite failures damaging the economy by as much as £1 billion a day. It is feared that the entire country has become over-dependent on a handful of satellite systems.

Emergency services, the energy grid, mobile phones, Satnav, broadcasting and other communications, the Stock Exchange and an array of other activities all rely heavily on the super-accurate timing provided now by navigational satellites such as GPS and similar systems. There are life-threatening risks from failure, says the government.An image of a third generation Lockheed Martin GPS satellite

The new investment is in a National Timing Centre to create a network of super-accurate atomic clocks around the UK, accessed through ground-based communications, so that the economy will no longer be over-reliant on timing from GNSS signals from the sky.

GNSS is the term that embraces the US GPS, the first system, Russia’s GLONASS satellites, Europe’s new Galileo and also a rapidly developing Chinese system.

Galileo failed completely for a while last year during its start up phase, because of operator errors, and there are now many examples of interference with GNSS systems and malicious ‘spoofing’, in which navigation instruments are fooled into thinking they are somewhere else. The heart of all navigation by satellite is accurate timing, without which positions cannot be fixed.

December – thinking about Spain

Spring Fever was taken out of the water on December 16 and put ashore at the Kingston yard in East Cowes, where we are planning to leave her until May. Idle thoughts now turn to planning next year, and to Spain.

We have given up our pontoon mooring on the River Medina for 2020 because we plan to stay away from the Solent for the whole season and it will be cheaper to take a visitor mooring for a few weeks before we leave than to pay a whole year for our own. The conversation is increasingly focussing on the wonderful hills and Rias of North-West Spain, though we do not need to take any decisions for a few months.

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