Recently, a visitor to the Virtual Boatyard wrote:
"hello I have a 24 sportcraft that I would like to convert from a single I/O to a double I/O with maybe more hp. what kind of problems might I encounter in this endevour? "
Just off the top of my head, I can think of several issues to be concerned with.
1. Weight and balance. The additional weight in the stern will affect the fore and aft trim of the boat, with the stern digging in deeper until the boat planes.
2. Transom strength and stiffness. You will be filling in one big hole and cutting two others and the transom will likely require strengthening.
3. Motor mounts. Affitional stringers and motor mount will need to be installed to accept two I/Os in place of the single, adding more weight.
4. Fuel capacity. Your range will be reduced due to having twice as many engines installed. So you might get more performace for a shorter distance unless additional fuel tanks are installed.
5. It will be a whole lot of work so be sure the result will justify the time and expense involved.