November/December is a difficult time of year to run North up the South African coast owing to the prevailing South Easterly wind. A new Magnum 36, destined for a client in Port Elizabeth had completed her sea trials in Cape Town towards the end of November and was expected in Port Elizabeth harbour, for a final hand over on Sunday 5 December.
The weather window just wasn’t there. Planning for a trip like this requires a 48 hr period of reasonable weather conditions, wind speeds of up to 25 knots being acceptable. Head winds and seas are generally avoided in trip planning stages, as these contribute to excessive fuel consumption, and unnecessary wear and tear on the equipment.
The new vessel, the second Magnum 36 to launch this year, “Challenger”, fitted with Yamahas latest V 8 outboard engines, is however robust, and comfortable at sea, and therefore a gap in the South East / South West gales had to be found.
The difficulty, is to find a time period, that is long enough to get out of Cape Town waters between the big South Easters, and to be able to run as far as Cape Aghulus where it is safe to shelter from the South West gales, which at this time of year, usually follow a big South East blow. Once at Cape Aghulus it is safe to wait for the South Westerlies to abate, and then to follow them up the coast before the onset of the next South Easter.
For trip planning we use various weather forecasting models that are available. With the practical knowledge of our staff, gained from experience over years at sea, the predicted conditions are interpereted to suit the delivery plan, ie speed, load, fuel consumption and range. For this delivery the weather models, Buoy weather, Passage weather, and Wind Guru were consulted.
It looked as if the trip could be completed without stopping, and departure from Hout Bay, was planned for Thursday, anticipating arrival in Port Elizabeth on Friday. However as Thursday dawned the South Easter was still blowing at 50 knots at Cape Point, and the long range forecasts had changed dramatically, resulting in a rescheduled departure.
The next South East blow for the Cape Town area was forecast for the weekend, and all indications were that it would last for a week. This meant that the boat had to get out of Cape Town as soon as the wind died and before the next blow, if it were to get to Port Elizabeth for the scheduled hand over. Normally one can expect two days of calm weather between blows, but at this time of year normal is not always normal, and plans have to take into account the possibility of stop overs, or even an aborted trip and the consequent return to base. Fuel loads and food and water requirements have to be adjusted accordingly.
The delivery got underway at 0500 hrs on Friday morning, with the sea and about 20 knots of wind on the stern.
The new Magnum 36, carrying 2500 litres of fuel for the 450 mile voyage, 5 lit /mile being the anticipated fuel useage, ran particularly well in the moderate sea conditions and an early average speed of 20 knots was maintained toward Cape Aghulus.
Unfortunately the weather conditions were soon to deteriorate and the Passage Weather forecast changed dramatically for the worse.Wind speeds of 40 knots were forecast along the coast from Stilbaai, up to, and beyond Port Elizabeth.The next South Easter for Cape Town had come forward to Saturday, the net result being the decision to pull in to Struis baai, to allow the South West gale to die down.Buoy Weather, like Passage Weather, also indicated the change in conditions, which had occurred as a result of the formation of a cut off low pressure system off the Southern Cape Coast.
Owing to the rougher than expected sea conditions, the fuel economy was borderline for a possible refuelling stop at Knysna, or Cape St Francis, and the next leg of the trip would dictate this.
The wind blew hard all night at Knysna and a steady 50 knots was recorded on the yachts moored in the lagoon ,from midday until midnight on Friday. The stop at Stilbaai had been a wise move made by the crew. However as Challenger was a new boat, on her maiden delivery voyage, no fishing tackle had been packed aboard, and the crew unfortunately had to spend a quiet time, whilst anchored off one of the best fishing spots on our coast line.
Early Saturday and the wind had died down considerably with forecast conditions between Struisbaai and Port Elizabeth favourable for the next 24 hr period.
On approach to Knysna, the fuel levels clearly indicated that a refueling stop would not be necessary, and as the condition of the bar, at the Knysna heads was favourable, Challenger put in to Knysna to take on some hot food, and an emergency fuel top up of just over 100 litres. At this stage the fuel consumption was 4.34 litres /mile, well under the anticipated 5 litres /mile used for the trip plan. The sea was moderate and at 3800 rpm the speed over ground was 24 knots.
When Challenger left Knysna after the short 20 minute stop, a Magnum 23 followed her out to get some photos of her running at sea.Well this is where you realize that there is a difference between, a big boat, and a not so big boat.It was just not possible to keep pace at the 24 knot cruising speed in the prevailing sea conditions, and the Magnum 23 returned to the calm of the lagoon after only a few meters at sea.Shortly after this the ground swell in the Heads effectively closed the bar for the next 24 hrs.The short stop had been very well timed.
The Magnum 36 arrived in Port Elizabeth harbour at nine o clock on the same evening, having used a total of 1950 litres of fuel, for the 440 n mile voyage. This translates to a fuel useage of 4,43 litres /mile which is exceptionally economical for a vessel of this size and weight. For sake of interest a Magnum 32 operates at 4 litres /mile, at 18 to 20 knots, using four stroke Yamaha outboards.
Two Oceans Marine Manufacturing now has real time, sea performance data, for this exciting new vessel, and are very pleased with her overall performance and particularly her comfort,fuel ecenomy and sea keeping abilities.
