Thank you, Rick. For the quarter ended March 31, 2014, we reported net income of $2 million, an increase of 36.5%, or slightly more than $500,000, compared to $1.4 million in the first quarter of 2013. Our diluted earnings per share for the quarter were $0.05, compared to earnings per share of $0.04 in 2013.
In the first quarter of '14, we benefited from a favorable model mix. Our average selling price increased because we sold some larger Chaparral SSX Sportboats and H2Os, and as in previous quarters, Robalo sales remained strong.
The first quarter's model mix was comprised of boats that were higher priced and more profitable. Our Chaparral unit sales declined slightly during the first quarter as compared to the prior year. Increased sales of the larger Chaparrals and Robalos also contributed to higher parts and accessories sales during the first quarter.
Rick mentioned that we sold our first Vortex jet boats during the first quarter. And we're pleased with the initial sales of this new product, but I will note that these sales did not contribute materially to our net sales or profits during the current quarter.
Gross profit in the first quarter was $8.8 million, an increase of 24.3%, compared to the first quarter of last year. Gross margin during the quarter was 18.5%, compared to 16.1% last year. The increase in gross margin was generated by our improved model mix and the operational efficiencies achieved during the quarter.
Selling, general and administrative expenses increased by 7.6% in the first quarter, compared to the prior year and were 12.7% of net sales, the same percentage of net sales in the first quarter of '13. These costs increased due to costs that vary with sales and profitability, including incentive compensation, our sales commissions and warranty expense.
The U.S. domestic net sales increased by 12.6% in the first quarter of 2014, compared to the first quarter of last year, while international sales declined by 9.7%. International sales comprised 18.4% of consolidated net sales in the first quarter of this year, a decrease compared to 22% of consolidated net sales last year. This continues a trend of declining international sales as many countries continue to experience struggling economies.
Interest income during the first quarter was $122,000, a slight decrease compared to $149,000 in the first quarter of 2013.
Marine Products income tax provision was $912,000, compared to $172,000 in the first quarter of 2013. This effective tax rate of 31.6% is significantly higher than the effective tax rate during the first quarter of '13, as it reflected a benefit from research and experimentation credits for both the first quarter of last year and the full year of 2012.
As of the end of the first quarter of 2014, this federal tax credit has expired and has not been renewed. And as far as we know, it will not be renewed. We believe that our effective tax rate for the full year of '14 will be comparable to the first quarter's rate.
Our balance sheet remains strong. And our cash and marketable securities balance increased to $49.3 million at the end of the first quarter, compared to $43.6 million at the end of the first quarter of last year. Accounts receivable and inventories at the end of the first quarter were comparable to the same time last year in spite of higher sales.
On March 31, 2014, dealer inventory and units were slightly higher than at this time last year. Also, order backlog is higher compared to the prior year, although it is slightly lower than at the end of the fourth quarter of 2013. We are comfortable with these levels of backlog and dealer inventories, although the prolonged winter weather has impacted retail sales in many parts of the country and caused dealer inventories to be slightly higher than normal.
And with that, I'll turn it back over to Rick for a few closing remarks.