Complex sentence: Two small boats had been swamped and lost in the enormous swell by the slipway at the landing place and the regulations associated with this change prevented both alongside landings by tenders and the lighthouse men keeping dinghies onshore.
Split into simpler sentences: Two small boats had been swamped and lost in the enormous swell by the slipway at the landing place. The regulations associated with this change prevented both alongside landings by tenders and the lighthouse men keeping dinghies onshore.