Maritime emissions have also been the subject of significant attention, including those associated with personal water craft (PWC) such as jet skis and recreational boats with outboard motors.

Measures put in place between 1998 and 2006 by the U.S. Environmental Protection Agency to limit the engine emissions of these craft were progressively restrictive. In 2008, the European Union published a consolidated guide to member states, summarizing various EU directives which have tackled the issue.

The main target of legislators was to restrict the use of conventional two-cycle or two-stroke engine technology, which was particularly problematic on the emissions front. The issue historically had been that these engines were particularly wasteful, their design allowing a high percentage of the fuel consumed to pass into the exhaust pipe unburned. This problem was compounded by a total loss lubrication system. The oil, whether premixed with the fuel or pumped into the engine from a separate tank, similarly passed out of the engine partially burnt via the exhaust pipe.

For a long while, Honda had been the only game in town for four-stroke outboards and PWC. The two-stroke was preferred by most other large producers, on account of its simplicity and a superior power-to-weight ratio providing better performance. The design of the lubrication systems of the four-stroke also required careful consideration to: a) avoid oil starvation and consequent engine damage, for example, when a PWC is capsized; and b) avoid spillage, say, when an outboard is detached and stored on its side.

The emerging regulations gave rise to significant competition in the four-stroke space, while diehard two-stroke manufacturers were forced to perfect the application of electronic direct fuel injection so as to lower fuel and oil consumption and hence emissions.

The U.S. National Marine Manufacturers Association operates the only internationally recognized certification and approvals program for the lubricants of these engines, publishing lists of approved oil products according to the following specifications:

TC-W3 for two-stroke cycle gasoline outboard engines;

NMMA FC-W for four-stroke cycle gasoline outboard engines;

NMMA FC-W Catalyst Compatible for four-stroke cycle gasoline outboard engines with exhaust after-treatment.

One might have imagined that the moving target in terms of engine technologies could have caused a proliferation in NMMA oil requirements. However, on this subject, NMMA Vice President of Engineering Standards Tom Marhevko explains:

TC-W3 is a mature specification, resulting from historic fine-tuning along the way. None of the test requirements for two-stroke oils were changed directly as a result of the EPA regulations. As [original equipment manufacturers] introduced four-stroke engines to meet the EPA regulations, the NMMA responded by developing the FC-W specification.

OEMs continued to modify the four-stroke design by adding catalysts, so we changed some of the parameters – introducing a phosphorus limit of 0.06 to 0.08 percent – so as to minimize any poisoning of the catalyst. We didnt make any changes in the FC-W oil requirements because of the emissions regs, other than to protect the catalyst.

Noting numerous revisions since its 1999 introduction, the TC-W3 document available from the NMMA website confirms Marhevkos point about the evolution of two-stroke oil certification. In contrast, the four-stroke programs are more recent initiatives, dating from 2004 for FC-W and 2010 for FC-W Catalyst Compatible; arguably, they are a response in themselves to the market dynamics and the emerging emissions challenge.

A further contrast between the two and four-stroke NMMA specifications lies in the number of engine tests specified. TC-W3 incorporates six separate tests, including three for piston deposits covering a range of engine power ratings, two for lubricity and one for pre-ignition. Conversely, FC-W and FC-W Catalyst Compatible call for just one fired test: the General Performance Engine Test, which uses a 115-horsepower Yamaha outboard motor to asses various wear and engine cleanliness parameters in a 100-hour test.

The 4-cycle oils have passenger car motor oil heritage, Marhevko said. NMMA certification starts with an affidavit confirming a performance level of API SG or better for FC-W and API SM or better for FC-W Catalyst Compatible oils. We added on to that type of heritage – using the GPET and a new rust test – for marine applications, as opposed to the two-cycle oils that didnt have passenger car applications to use as a starting point.

So despite the environmental challenges, is it all calm seas in the boating world as far as lubricants are concerned? Not quite. The environmental agenda is giving rise to other concerns, notably around the increased ethanol content of gasoline and associated changes to fuel additives.

Ethanol is much more corrosive compared to gasoline, and this can be a particular problem for boating engines that might be inoperative – and therefore not lubricated – for six months of the year. Various additives are also emerging on the market to counter corrosive and other side effects of ethanol.

The NMMA hosted an industry meeting about this, Marhevko noted. There is a lot of concern from the OEMs and the oil manufacturers about what fuel additives do to the engine and their interaction with the oils. The U.S. has gone from E10 to allowing E15 in our pumps and even E85 [gasoline with 10, 15 and 85 percent ethanol, respectively]. We just dont know what these new ethanol fuel additives will do when you put them in an outboard, particularly a two-stroke. Were looking at bringing all the fuel additive manufacturers and the testers and the OEMs together to look at this whole aspect.

So even if the emissions story didnt turn out to be a boating blockbuster, it sounds as though the sequel may yet have a few twists and turns to play out.