We covered some basics of steering systems for outboards and we will do the same in this article for sterndrives. The same principle applies except that your sterndrive has a steering system built in that is obviously a little different. What is the same is the fact that you can have a mechanical system utilizing a cable and a hydraulic system. When you look at aftermarket steering for popular sterndrives you’ll see options for internal systems and external. Basically, an internal hydraulic system replaces a cable system or popular power assist cable systems with a full hydraulic unit from the helm to the drive. For high performance purposes, an external system with full hydraulic steering is ideal. Generally, on boats that can go faster than 65 MPH, you want the safety and control an external steering system can provide. Similar to outboards, bad handling characteristics are often a cause of sloppy steering, preventing the driver from controlling the boat properly. The external ram attaches to the drive by a cap mount, heavy duty clevis joints allow movement (steering and trim) and the ram attaches directly to the transom via a mount plate for incredible rigidity. Helms come in different displacements and rams come in different lengths as well as volumes for specific uses. All kits come with fittings and SS hoses for the hydraulic fluid. 

Because sterndrives rely on a unique drive shaft and gimbal assembly, sloppy steering can wear your internals faster. With a full hydraulic steering and external ram, not only is it safer and better for performance, your drive has better support and will last longer. With external steering for single drives you have a choice of going with one ram or two. For engines with less than 500 HP, you would be fine with one ram, more than 500 HP, it would be advisable to go with two. Depending on the manufacturer, more often than not it is a better value to get a complete kit, rather than build it out by piece over time.  

Quite a few of our readers are interested in improving the performance of their existing boat or they are planning on restoring an old performance boat. The steering is often overlooked but it is critical to your boat, especially when you are repowering with a more powerful engine. Installing is not that difficult but consult a professional if you have no mechanical experience. 

The pictures of specific brands are not necessarily an endorsement of that brand. In the installation video they use "marine silicone" but I would use 3M 5200 sealant or 3M 4200. 
 

Example of an Installation