These items were discovered 10 months before the Inquiry convened. No mention was made whether Barclay, Curle and Co had in fact received and examined the hatchway, forming an opinion as to its origins. In a case glaringly absent of physical evidence, this should have been a crucial component in the final report - I don't believe an answer from Barclay, Curle and Co was forthcoming one way or the other. My impression is that the 'powers that were' obstructed the course of justice.
Mossel Bay was a last port of call before objects were swept south by the retroflecting Agulhas Current. One could argue that the lifeboat sighted further out into the southern ocean had missed being washed up onshore and was embarking on a slow drift back to the Antipodes. But all of these objects remain in the realm of speculation as to their origins.