Hi Tim,
You certainly have a mystery boat there!
I only know of two yachts called SeaHawk that were produced in Europe.
That featured on this site was a one-off for its various builders. None were major players producing a range of yachts. Certainly, there was no "SeaHawk 28" produced by any of them.
The other SeaHawk I know of was produced by Westerly who were a major manufacturer of a large range of boats. However, it was a 34/35 footer, so doesn't sound like the boat you have. See:
http://www.yachtsnet.co.uk/archives/westerly-seahawk/westerly-seahawk.htmYou are welcome to post a few photos here, but you may be better off posting on the forum at:
http://www.ybw.com/forums/index.phpI find the folk there very knowledgeable and most helpful.