![]() ![]() It’s located farther away, on rubber mounts that isolate its vibration from the boat. An outboard boat engine has many design advantages that keep sound levels low in the boat cockpit. Which means the jet is more than 10 times “louder” than the outboard. The dbA scale is logarithmic, so a change of 10 dbA is a change by a factor of 10. At cruising speed the outboard is 6 decibels (dbA) quieter than the sterndrive and 11 dbA quieter than the jet. This is another easy win for the outboard. Outboard vs Sterndrive vs Jet Drive In this comparison, we think styling is really the only reason to choose the sterndrive-powered boat. That happens to be about 35 mph, so we compare the other two boats at a similar speed in the water. It likes to have more pressure under its hull to feel planted in the water. At speeds below 7,000 rpm, the jet-powered Glastron felt like it was wallowing just a little. For this comparison, rather than select each boat’s best possible cruising speed, we picked a “pleasing” cruise speed, because in the real world you are not going to want to wobble along just on plane. Note that each of these boat engines has a different operating range - wide-open throttle is 5,000 rpm for the sterndrive, 6,000 rpm for the outboard and 8,000 rpm for the jet - so each also has a different cruising rpm. Also, while the jet’s appendage drag is less, since no gear case is being dragged through the water, this may result in increased wetted surface of the hull, since it offers no ability to trim the boat. We don’t have a good explanation for this beyond the fact that the sterndrive boat weighs 600 pounds more than the outboard, and the jet drive system is less efficient than the outboard’s propeller. At cruising speed the outboard manages 5.0 mpg, 25 percent better than the sterndrive and 52 percent better than the jet. That the outboard proved most efficient is obvious - with just 150 hp it can match or exceed the performance of engines making more than 200 hp, as our performance charts show. Outboard vs Sterndrive vs Jet Drive The jet drive Glastron can easily navigate shallow water and carves turns with ease. We were told the jet hull has much less deadrise forward and less lift aft. There’s a huge weight difference between the two powertrains, and the thrust angle makes the boat handle differently. It’s important to note that the running surface of the jet-powered GTS 187 is specific - Glastron did not simply drop the jet drive into the sterndrive hull and call it a day. The jet ran 43.5 mph, handicapped despite its power advantage by its lack of trim, which on the outboard and sterndrive let us raise the bow and reduce drag. Top speeds for the outboard and sterndrive boat engines were very close, at about 49 mph. This weight difference will affect every aspect of performance and economy. There’s a spread of 610 pounds between the outboard, our lightest version of the boat, and sterndrive, the heaviest version, with the jet weighing 60 pounds more than the 2,120-pound outboard-powered boat. We used Rec Boat’s tech-center scales to weigh the test boats. However, it has very quick steering and is extremely agile. Outboard vs Sterndrive vs Jet Drive The jet drive Glastron can be a little trickier to dock or load on a trailer due to the absence of a rudder on the jet pump. We encountered the expected compromises with each powertrain, but there were a few surprises too. We compared performance, dimensions, features and cost to see if one power option would prove superior. Glastron provided an outboard-powered GTS 180, a sterndrive-powered GTS 185, and a jet-powered GTS 187 for trial on the same day at its test facility in Cadillac, Michigan. Glastron recently achieved a trifecta of sorts, becoming the first boatbuilder to offer the same 18-foot bowrider with each power option, which presents us with a golden opportunity - the chance to finally mount a real head-to-head comparison of outboard, sterndrive and jet propulsion. Outboard, sterndrive or jet drive: These are the available boat engine choices in today’s runabout market. Boat Engine Comparison: Outboard vs Sterndrive vs Jet Drive When Glastron said it was making a runabout available with three different power types we jumped at the chance to pit: outboard versus sterndrive versus jet drive. ![]()
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