TCE Rate. The average TCE rate for our fleet was $27,895 per day for the nine months ended September 30, 2022, an increase of $16,742 per day from $11,153 per day for the nine months ended September 30, 2021. The increase in average TCE rate was the result of higher spot rates for the nine months ended September 30, 2022 as compared to the nine months ended September 30, 2021. TCE rates represent net revenues (or revenue less voyage expenses) divided by revenue days. Net revenue utilized to calculate TCE is determined on a discharge to discharge basis, which is different from how we record revenue under U.S. GAAP.
Vessel Operating Expenses. Vessel operating expenses were $45.8 million for the nine months ended September 30, 2022, an increase of $0.8 million from $45.0 million for the nine months ended September 30, 2021. Vessel operating expenses, by their nature, are prone to fluctuations between periods. Average fleet operating expenses per day, including technical management fees, were $6,792 per vessel for the nine months ended September 30, 2022, as compared to $6,370 per vessel for the nine months ended September 30, 2021. This increase was a result of higher costs due to additional crew changes, as well as an overall increase in costs due to inflation, together with lower operating days due to the sale of three vessels during the nine months ended September 30, 2022 as compared to the nine months ended September 30, 2021.
Charter Hire Costs. Total charter hire expenses were $9.0 million for the nine months ended September 30, 2022, an increase of $6.4 million from $2.6 million for the nine months ended September 30, 2021. This increase was a result of our having five vessels chartered in as at September 30, 2022 compared with two vessels chartered-in as at September 30, 2021. Total charter-hire expenses were comprised of an operating expense component of $4.7 million and a vessel lease expense component of $4.3 million for the nine months ended September 30, 2022.
Depreciation. Depreciation expense for the nine months ended September 30, 2022 was $22.0 million, a decrease of $1.7 million from $23.7 million for the nine months ended September 30, 2021. This decrease is a result of the sale of one vessel in June 2022, and two additional vessels in July 2022. All three vessels were classified as held for sale up until their respective disposal dates. We ceased depreciating these three vessels, when they were classified as held for sale, during the first quarter of 2022.
Amortization of Deferred Drydock Expenditures. Amortization of deferred drydock expenditures for the nine months ended September 30, 2022 was $3.2 million, a decrease of $0.7 million from $3.9 million for the nine months ended September 30, 2021. The deferred costs of drydockings for a given vessel are amortized on a straight-line basis to the next scheduled drydocking of the vessel.
General and Administrative Expenses: Corporate. Corporate-related general and administrative expenses for the nine months ended September 30, 2022 were $14.6 million, an increase of $1.9 million from $12.7 million for the nine months ended September 30, 2021. The increase in costs was primarily due to one-off costs during the nine months ended September 30, 2022, that aren’t expected to reoccur, compared to the nine months ended September 30, 2021.
General and Administrative Expenses: Commercial and Chartering. Commercial and chartering expenses for the nine months ended September 30, 2022 were $2.9 million, an increase of $0.7 million from $2.2 million for the nine months ended September 30, 2021. The increase in costs was primarily due to an increase in travel-related costs during the nine months ended September 30, 2022, compared to the nine months ended September 30, 2021.
Unrealized Gain on Derivatives: Unrealized gain on derivatives was $4.3 million for the nine months ended September 30, 2022, an increase of $4.2 million from $0.1 million for the nine months ended September 30, 2021. The increase is due to the accelerated reclassification of $2.1 million from other comprehensive income into earnings. As further discussed in Note 5 (“Interest Rate Swaps”) to our interim condensed consolidated financial statements included in this Report on Form 6-K, the reclassification was triggered by the refinancing of our debt agreements and paying down our revolving credit facility, which caused the forecasted transactions that the interest rate swaps were designated to hedge against no longer being probable to occur The unrealized gain on derivatives was also impacted by the increase in the value of the interest rate swaps, that have not been designated as hedging instruments, because of rising interest rates during the nine months ended September 30, 2022, which are recognized directly into earnings.