A suite of samples of English oak stored in marine environments for durations of up to 4 centuries was studied using THM-GC-MS. As a result of these measurements, we offer an interpretation of the successful use of PEG to conserve the chemical state of the Mary Rose wood after burial. Additionally, the use of PEG has preserved the core sample in a state of chemical degradation which is not observed in the other maritime oak samples, which we attribute to bacterial activity. Our data also establishes a baseline for assessing whether a ship has been biologically degraded. However, the majority of the samples are very similar to recently collected oak, suggesting that complete immersion of English Oak in seawater reduces chemical degradation.