Don't add a spi or hooter to the Dart 18. They tried and the design apparently doesn't like it very much. Reasons I heard pop up here and there. The steerage goes from weatherhelm and leehelm under spi depending on how much the nose if pressed in the water and the back is lifted. Also the less than crisp steerage of the Dart 18 tends to make bearing away in the gusts, under spi, awkward and too slow.

Several sailors have tried and advice against it.

Wouter