Fitting a Small Engine on an Inflatable Boat for a Powerful Ride.
You should limit journeys in small inflatable boats to smaller distances in the calmer waters of the harbours and in winds of under force 4. If not, you will have difficulty in controlling both the boat and navigating the direction in which you are going. A solution is to fit a bracket over the tube or transom on which a small outboard engine can be mounted.
Inflatables are so easily driven that you only need an engine of 1 to 2 horsepower to make progress in reasoncale conditions, but the quality of these boats has advanced so much that most can easily take a 5-10 hp engine. One of the main issues you might experience is in engine starting, because these are almost always hand-started. The strong pull you need on the starter cord can be enough to make you lose your balance, particularly if the engine has to be started in gear making the boat move forward as soon as the engine is started.
You should be able to start the engine from a seated position. Once underway be ready to direct the boat in the right direciton. With one person steering from the back the bow will be lifted enough to deal with small waves. Luggage and travelers will have to be properly arranged to slim the boat to give a reasonably dry trip and good progress. You will also need to adjust your speed to match the conditions of the water. A bow dodger will help to give a clean dry ride.
If you think you can avoid getting wet during a serious trip in an inflatable, one trip will quickly correct your thinking. Any water in the bottom of the boat will immediately collect around your shoes as you step into the boat. It will run to the deepest part of the bottom where the majority of your weight is concentrated.
If the boat is inflated properly it will respond more like a hard hull boat and this would enhance its performance when rowing or with an engine. A soft boat will be harder to row that a fully inflated boat since the row locks will bend under the strain. This boat will also deform under with heavy cargo sitting on the tube. Often, problems with uner-inflation stem from the difficulty of inflating the boat on the deck of the yacht or when alongside, especially when the temperature may be moderately high. The pressure of a boat may be fine on land, but when it is put into the cold water it reduces the pressure inside the boat and the boat becomes flabby. Rock solid inflation of inflatables certainly helps the handling, but do remember that if they are left out in the the hot sun the pressure will rise to unacceptably high levels.
A good alternative to the gas engine is of course the electric motor which requires no hand-starting.