For some modellers there is no option but to have a funnel belching smoke as the model steams away from the side of the lake. If you are considering fitting such an effect then make sure, as with an engine sound, that this is appropriate for the type of model, e.g. modern large diesels will give a cloud of dirty smoke on start-up, but then run without any visible exhaust, while other vessels have exhausts situated below the waterline.
Smoke or steam simulators work on two different principles. The first type e.g. Marks Model Bits’ 'Foggy' has an internal nebuliser and runs on water. The nebuliser creates a mist of water vapour which is then forced up a short plastic funnel by a small computer fan. This is quite a bulky unit and requires a 24v power supply to run (or a 12v/24v voltage converter). A more sophisticated version is available which has a small speed controller to increase the speed of the fan and thus the volume of smoke as the throttle is increased. The newer Steam Master unit does essentially the same thing, but works on any supply from 6v to 20v. It’s also smaller, but produces greater volumes of steam; has four different, programmable smoke outputs and is nearly twice as expensive.
The other type of smoke unit actually does produce real smoke, usually from a commercially-available hydrocarbon-based distillate. This oil is retained in a metal reservoir which also has a wick inside it. This soaks up oil and is ignited by a heating element to produce the smoke. This exits the funnel, either with or without help from a fan, as per the Foggy system. Hunter Systems’ unit works on 12v, but has no fan assist, while the daddy of them all has to be the Harbor Models unit. This 12v 'squirrel cage' blower-assisted unit is expensive, but mightily impressive and there is a video on their website.
The other pros and cons I have heard, are that the water-based units are ineffective in hot or humid countries, while the oil burners can leave a sooty residue all over the model. Oh, and you won’t get black smoke from either type, at least not safely, Photo 20
& Photo 21