My boat is 29 feet, but I don''t think it could do an ocean crossing unless it was all good weather. There are many capable boats such as a Pearson Triton at 28'', several of which have sailed all over.
The Pardey''s have a website at www.landlpardey.com and I think their current boat is 29 feet.
I think Robin Graham used 2 boats and the second was an Allied Luders 33 built in 1968. It is for sale in Hawaii right now listed on Yachtworld. Graham sold it in 1971.
Link to Dove http://yachtworld.com/core/listing/pl_boat_detail.jsp?currency=USD&units=Feet&checked _boats=1131046&slim=quick&