Built for Chay Blyth to win the 1978 Round Britain Race this 53 foot trimaran design was further developed as VSD 1.  After Chay won the race he entered other races but was not successful feeling that GBIV was too delicate in heavy weather because she was built very lightly.  His crew Rob James wrote a book called "Multihulls Offshore" which tells the story. Sold GBIV was later lost by capsize laying ahull in a storm although the crew were rescued the yacht was destroyed. However, it must be said she was a success because  she did exactly what she was designed to do by winning the 1978 RBR. Rob James was implicitly critical of Derek in his book suggesting that the boat was too lightly built and that Derek was casual in his attitude; he cited that Derek lined the hulls up by eye before final glassing together and that a stay broke a chainplate and similar things. Others subsequently involved with this boat reported that she was fragile and best in moderate and light weather. There is no doubt that Derek pushed boundaries with many of his boats. With Trumpeter for example in 1970 critics thought she was too lightly built however with modifications that Derek's experiments and lessons with design and construction development showed could improve her she is still sailing the Oceans 55 years later. GBIV is no longer with us. She was built very lightly but she achieved what her design and commissioning required. Development of the same design further in VSD 1 and 2 also showed that the basic design was good.