FOND DU LAC, Wis. (AP) -

Boat engine builder Mercury Marine is investing $20 million in two expansion projects in Wisconsin.

The company is adding on to two plants in Fond du Lac. The Reporter Media reports construction has already started and is expected to be done by December.

Mercury Marine is adding 20,000 square feet at one plant to house horizontal machining equipment and 18,000 square feet at a casting facility to house high-pressure die-cast machines. Some equipment will be installed this year, with more coming in the following two years.

Mercury Marine President Mark Schwabero says it's seeing stronger demand as the boating industry slowly rebounds.