Spifurl was the name Fountaine Pajot
used last year for an asymmetric spinnaker
that they had developed together with Incidences. It uses a Facnor FX2500 furler
which has an endless loop. The Facnor furling
system has a dyneema
forestay which rotates. The spinnaker is attached with a small dyneema
loop at bottom and top to two roller bearings which are mounted on the ends of the forestay.
There is a line of around one metre between the middle of the front side of the spinnaker to the middle of the dyneema line. When you furl, first this one metre line is first rolled around the dyneema forestay, then the whole spinnaker is rolled around the forestay from the middle.
Kev and Jo had as far as I know the first instance of this system, we have the second. Don't know how many followed.
Advantages: Easy and quick to roll and unroll as long as the sail is behind the mainsail
Easy for jybing singlehanded just by furling
Disadvantages: The dyneema loops on top and bottom wear very quickly. After about 10 days of uses the bottom one tore when crossing from the UK to Netherlands
, with the spi flying from the halyard
. So you have to inspect and replace these lines regularly. I am in discussion with the Dutch importer of Facnor whether Facnor already has a solution for this. Already ahlf a year....
Other disadvantages: You should not sail with the spi unused and furled but mounted, you really have to stow it away. There is the risk that the sail unfurls at an awkward moment.
Compared to a gennaker: I do not know which I would prefer. The sail is a bit rounder I guess, so less good for smaller angles. Normally you can sail to a minimum apparent wind
of 70 degrees, 110 TWA. On very flat water
you can get to 60 degrees AWA / 100 degrees TWA.
With a TWA of 120 degrees performance is best. We have reached to speed of 16.5 knots surfing down, and sustained at 14 knots. Best hour distance 10 miles with 1 knot
against us. Wind varying 18-25 knots.
Depending on waves and how close you are to 120 TWA, and correct trim,your boat speed is between 60 and 75 % of the true wind speed. Normal is 65-70 %.
The sail is more critical in wind angles maybe then a gennaker.
I think the sail area is 50-60 m2. Halyard
has a block only just above the jib
halyard mast entry.
You can sail well in butterfly. We have been tacking with wind at e.g. 160 degrees TWA: changing between 180 and 130-140 degrees TWA gives better speed than sustained at 160 degrees. TWA's of 160 degrees are very awkward: the spifurl does not caitch enough wind, collapses, boat speed is low. Not suitable for butterflying.
Tacking with wind from straight behind is not useful: you have to go to 140-130 degrees TWA to get good speed increase, but this increases the distance too much.
We had one day where we sailed with wind from straight behind. Speed was a frustrating 6 knots, we had to sail a long distance. The wind then turned to 120 TWA, and speed increased to 10 knots!
Incidences made our sail in the wrong colours. During the week of delivery
they made a new one in the right colours. So they have a sail lying around. Maybe nice to bargain?
catamarans have a spinnaker which is one a rail which goes from one bow to the other via a bowsprit. I wonder how this would work for TWA's from 140-180 degrees. Allows you to catch more wind, less wind shadow from the mainsail
. I have been thinking about mounting the spifurl to one bow, just to try it.
Greetings to all,