Should you buy a two-stroke, four stroke, or electric dinghy outboard?
There are good reasons to look at all of them to make an informed decision. It often comes down to how much smoke/pollution you are willing to put up with, how much you want to spend for the engine, and how fast you want to go.
Two-Stroke Dinghy Engines
Two-stroke engines require oil added to the fuel to operate. On small engines the oil is added to the fuel when the tank is filled, while larger engines have a separate oil tank which allows the oil to be injected during the firing cycle. Two-stroke engines are less expensive to buy, easier to maintain, have an overall simpler design and in general, go faster that four-strokes. You need to balance those pros against the need to mix oil with the fuel, more noise when running, and more smoke on starting. In addition, if you screw up adding too much oil to the fuel you can gum up the spark plug and make it much harder to start.
Two-stroke engines are banned from some waterways so check your local authority before purchasing.
Four-Stroke Dinghy Engines
Four-stroke engines tend to run more quietly and smoothly than do two-strokes. They pollute less and meet current pollution standards. In addition, oil is already in the engine crankcase eliminating the need to add oil to the fuel. However, four-stroke engines tend to be heavier and more complex than do two-strokes. Weight is a consideration if you plan to lift your outboard onto the deck or a transom bracket when not in use. Also, establishing a proper maintenance routine on fluid levels, filters and connections will help the longevity of a four-stroke engine.
Electric Dinghy Motors
Until the advent of the Torqueedo electric motor, most electric motors tended to be trolling motors for slow fishing. Torqueedo has made it possible to have a moderately powerful outboard that can move your dinghy at speeds near to those of a non-electric outboard. This ecologically friendly motor is lighter and quieter than gas powered and is often specified in bodies of water where engine pollution has become a problem.
An integrated GPS receiver monitors your range, speed over the ground and battery capacity providing you alerts when there is less than 30% charge remaining. To recharge connect the integrated lithium battery to a charger connected to the mains. Another option is to purchase a 45W solar charger to recharge the engine while it is not being used. There are several models and options to choose from to best suit your needs.
If having gasoline on board is a concern, consider the Lehr propane powered engine. They have four models ranging from a basic 2.5 h.p. to a 15 h.p. with electric start. The size propane tank depends on the range you wish to achieve and the size of the engine. The LP 2.5 and LP 5.0 will even run off a 16.4oz. camping bottle for emergency use.
A big advantage of a propane engine is that the tanks can be filled anywhere that LPG is sold. Plus, there is no clogging or “varnish” in the carburetor if you leave the engine for six months or longer.
Here are other considerations you should keep in mind:
• Will you be lifting your outboard on and off the tender? If so consider a lightweight two-stroke with the best power-to-weight ratio.
• How will you lift the outboard on and off the dinghy? Many outboards have become instant anchors between the boat and the dinghy when one person has tried to lift it onboard. The best way is to use a halyard, a davit, or the lower end of the main sheet (Make sure the topping lift is attached!) to lift the outboard.
• Will you be using the outboard daily, weekly, or monthly? Using the outboard daily means that you will usually leave it mounted on the dinghy transom. Using the outboard monthly may mean that it sits on its storage bracket until you are ready to use it. In this case a four-stroke, electric or propane might start more easily, but the four-stroke will be heavier and harder to lift on and off. However, if you are going to leave it for more than a week or two on the bracket, you should add Stabil or Startron Enzyme Fuel treatment to the fuel to ensure easy starting later
• Where will you store the outboard? Storing it upright helps to make it easier to start. Putting it horizontally into a locker, can get oil into the cylinder head and make it difficult to start.
Choosing an engine, then, is not simply a matter of putting on the largest motor the dinghy or tender will carry, but is more a choice of how much weight you want to move around and how fast you want to go, balanced by the amount of pollution you are willing to accept.