Having crewed on one for a number of years I would say that the Shipman is a good boat of it's type. There is a constructional weakness in the attachment of the forestay, which relies on the nut on a built in stud in the stem. The second bolt will shear off if the forward one goes. We made up a steel bracket to curve round under the stem to strengthen this.
The fixing of the inner forestay is also suspect as it was fitted with small washers under the deck. Due to the inner molding it is difficult to replace these by a plate but it is needed, if it hasn't been done.
I had a Shipman 28 for five years and enjoyed it very much. An early one, prod nbr 30, with a lot of baby sicknes. The quality improved after a reconstruction of the yard. You can see the change as the later, and better ones, have numbers 4000 and up. Later Albin took over the production, and they are of very good quality.You need to reef rather early, but on the other hand you are overtaking almost all yachts in light winds. In Sweden (where I live) many owners have added extra led pigs to make it stiffer (around 100-150 kgs). She is a very nice yacht to sail, also single handed, apart from her nice looks. Things to look for at older yachts: the stem chainplate (as mentioned in an earlier mail), the engine bed (if it still attached to the hull), the coach roof at the mastfoot (on some older ones the beam under the roof is brooken). You should add a "baby stay" from the chainplate of the inner forstay to the bottom of the hull, to avoid lifting the deck in heavy winds. Many early Shipmans have a Baby stay already from when they were built. You will love the Shipman, she is a wonderful yacht to sail, as all of Olle Enderleins constructions. Hope you understand my "Swenglish".