Spinn Report

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In October 2002 the South African Mosquito Association undertook the development of an asymmetric spinnaker for the Mosquito Catamaran. 

We got considerable info off the web from the Australian Mosquito Association, as well as the International Tornado web site and the Hobie Tiger for rig setup.

Geoff Meek was once again called on to do the spinnaker design while Kevin Webb set about establishing the pole length, fixing points and bridles, as well as designing and installing a spinnaker launch chute.

The original spinnaker was way too big at 17.2 sq/m, but was soon cut down to size and has now been thoroughly tested. The final cut is as follows:

Luff                6500mm

Leech           5880mm

Foot              3080mm 

The total sail area is 12.96 sq/m. 

Pole length    3000mm

Spinnaker hound    1000mm  above the mast hound (or 1000mm from tip of mast)

The spinnaker has been tested in winds up to 25 knots and we have observed the following:

Light winds: - 3 to 8 knots. The boat can be sailed on a beam reach with Main and jib in tight (traveler in the centre) and the foot of the spinnaker will almost be taught. I felt a fair bit of lee helm but nothing uncontrollable. Later on it was quite comforting as soon as we were overpowered the boat bears away with ease and settles down immediately. The boat speed is almost doubled on this leg and has left the other skippers feeling  demoralized. My crew and I sat on the weather side and in 8knots the crew will trapeze.

Medium winds: - 8 -15 knots. I could no longer beam reach and found us going lower in order to stay upright. The crew will trapeze and I found quite a bit of lee helm. As soon as we felt overpowered I allowed the boat to bear away which immediately reduced the lee helm and stabilized the boat. The apparent wind is awesome as we found ourselves sheeted in almost to the centre while sailing on a broad reach. The spinnaker lifts the bows and at no time did I feel that the boat would dig in. The speed is thrilling and the downwind leg is reduced considerably in length because you sail so deep. Imagine the look on the faces of the other boats as you pass them sailing deeper and on trapeze while they sit inboard and have to sail longer angles.

Strong winds: - 15 - 25 knots. It was with some trepidation that we raised the spinnaker for the first time in 20 knots of wind. Reaching is out of the question but the runs are awesome. Main sheeted in tight and traveler 3/4 way out - the boat is easy to keep under control as long as you remember not to bear up in a puff, but rather bear away. Both skipper and crew were hiking as I felt more in control and felt the speed was more than enough for the deep angle we were achieving. I discarded the main sheet and played with the traveler sheet, which I occasionally dumped when we were overpowered. We dumped the spinnaker and bore away a few times rather than risking a capsize. In 25 knots I found us having to almost run to keep control, which caused us to nose dive several times. I watched the mast each time we buried the bows, but it looked stable and I am quite confident that it will stand up to the strain.

What I did find is that it is imperative that you keep your Main sheeted in at all times, and only dump the traveler and never the main - ask 'Backstay" van der Merwe what happens when you ignore this rule!

The spinnaker chute works extremely well and I found it easy to raise and lower the spinnaker with no jamming or dropping the bag in the water and can be used on any tack.

 

It is the intention of the South African Mosquito Association to standardize the Spinnaker setup and will be proposing a Mk III Mosquito in the near future.