Hi YunYao,
TIREM & LongleyRice propagation model the behavior of electromagnetic radiation from a point of transmission as it travels over irregular terrain. Kindly elaborate on the question to clarify what you mean by 'maritime simulations'.
Although, You should note that the Longley-Rice propagation model documentation doesn't indicate any restrictions linked to maritime environments. Hence, I'd suggest you to share the issues that you are encountering in your workflow.
If you are also interested in analysing the reflectivity of sea surfaces, investigating the effect of sea state, frequency, polarization, and grazing angle, etc. I'd recommend exploring the below documentation page:
