I doubt Pearson made any boats with core below the waterlines, there may be an exception. Some like the 32 have core above the waterline. You can detect the presence of core material by the change in thickness of the laminate..the laminate will bulge (grow thicker) where the core begins. You can see this most easily by looking at the underside of any deck...you'll see a thick ridge running around the deck abouth 2-3 inches in from the toerail...that is the core area. The same is true in a hull...assuming you can see the inside of the hull...if you look down form the toerail, you can detect core by the change in thinckness.
I'm not interested in engaging in a religious war, but I respectfully disagree with CP as to whether to avoid cored hulls - it is my advice to do so, as any boat comes with sets of risks what can become expensive repairs - why introduce the most expensive risk possibile...the recoring of a wet hull...if you have other choices?
You can see extensive commentary on hull coreing at Boat Hulls - Cores and Structural Issues: Online Articles by David Pascoe, Marine Surveyor
Your choices, you decide.