Think I've finally sorted the mixing smoke and water for exhausts problem. Graham has already done his using the same pen / e-cig unit but with some nice electronic controls for the on off system, but not having the electronic abilities I've just gone with a more basic method. Wired up the pen and installed a filler tube (2 tubes are better - one for a breather) these are capped after filling to prevent air getting back from the pump. This system has a water pump, an air pump and the smoke unit, (all adjustable with their own voltage buck) Thanks to Martin for his pen suggestion. I was previously using large capacity elements fitted in various containers for my experiments (truckloads of smoke available) but these pens are great for tight spaces and don't draw much current.

Air, and a small amount of the cooling water are mixed by venturis just short of the exits (the air pushing the smoke and blowing the water clear of the smoke tubes). I've fitted the same system into my ST but am still waiting for the air pump from China (postal system problem there, then Chinese new year holidays with new rules apparently) Get the odd bubble at rest but with the low exhaust you can't have everything.
Latest vid with boat in the tank.

JB

A fan powered smoke unit (modified Heng Long) tried in the HSL. Not particularly good but it's output is reasonably scale(ish). As the fan (12v comp snail fan) just blows into the back of the smoke box without any positive connection, a fair bit of smoke escapes into the engine bay. The fan is hooked up to run with the cooling pump and is left on while running after the smoke (on off remote from the rotary switch) is turned off, and blows the residual smoke from the engine bay out the exhausts.

There are also the 2 small air pumps plumbed into the exhaust outlets via venturi pipe inserts, to blow the water out of the exhausts, (just on the waterline) as any water stops the smoke coming out (surface tension holds it in the pipe). Once I find a decent high volume small quiet air pump, I can do away with these and the fan, which should make things a bit better.
I've ordered some small 12v 40W printer elements to try another smoker idea, but they will be a while coming. Smoke will only be on for startup so shouldn't be too much of a problem.

I've almost become water/vaporlogged/glycerogged with all these experiments, and the other night I actually set off the smoke detectors,- house smells like a glycerine factory for hours afterwards,- but my skin's getting really smooth😂😂😂😂
JB

This is a first try at a simpler quieter smoke unit. I used the smoker box/element off the Heng Long tank/car smoker unit with a 40x40 5v fan (the fan being voltage controlled by a 5v UBEC and the lot being run by a 2s Lipo (with a y splitter for the fan UBEC and the element using JST leads. Doesn't smoke that well as I had broken then repaired the element previously, but the other one I have smokes a lot better, and has a better type of element (possibly a newer version) Some photos etc on the smoker discussion. Unit is almost silent (the noise you hear is the camera and outside noise, as the window was open)

American Scout C2 cargo ship power MACK 3-1 drive 12 volt 2 x 6 volt 3000 mah batteries. Harbor smoke unit model weighs 15 lbs.

Wahine was a car passenger ferry of the Union Steamship Co. of New Zealand, and completed by Fairfields in 1966. She was lost in a major storm in the Cook Strait in 1968 with the death of 53 people. The model is substantially scratch-built with some fittings purchased. it is driven by two Graupner Speed 500 motors powered from two 6.6V 3200mAh LiFe batteries. it is fitted with twin stern and a single bow rudders, and bow and stern thrusters as on the original. The smoke effect is provided by a Steam Master Unit.

This was a static model, that the gentleman I got it off had it for two years and when I asked why don't you put it in a box his reply was the box would be to high at 36" so I said to him is it radio control,NO static model only but can be converted,so I brought it and also showed him that if you move the tube slider on the mast it folds(one unhappy chappy),so I set about radio controlling it with a smoke unit(water) and it gets quite a bit of attention at shows because it's different,the model is based on the Queen from new Brighton 1897-1923

This is the fifth of the six sisters of the isle of Man Steam Packet Company, entered service in 1952 and scrapped in 1980. it is built on a Metcalf Models hull, and the superstructure is scratch-built from styrene. Fittings are a mix of scratch and purchased. it is powered by 2 Electronize motors with 2 ESC's by EA Electronics, has a smoke unit from Harbor Models controlled by a Viper ESC, a sound system from Model Sounds inc of Ontario, and powered by NiMH batteries. it is also fitted with a working bow rudder and lights, all controlled from a Robbe F14 Navy radio fitted with 2 twin sticks. Preferred sailing location is Lake Lisgar in Tillsonburg, Ontario.

View from aft under construction. I am planning on adding a smoke unit.

HI fellow model leers.this is my latest model.Built in 1926' for the Ffyfe(bananas) family. Originally it was run on steam,but in 1939 converted to diesel,this was kept until 1957 when all the staterooms were replaced by cargo holds . She was then made into a feeder bringing eleven thousand boxes from Rotterdam to Southampton. She was scrapped in the seventies.my model of her was from 1926 the scale is approx 1/30th her length is 48 inches including bowsprit, and has a beam of 10 inch amidships. She is totally scratch built, plank on frame, all the decks are individually planked with black card in between , wheel house and all other parts are mahogany. She runs on a decaperm geared motor @ 6 volts, and the lighting system consists of 10 accommodation lights, port and starboard , wheelhouse, and both mast headlights,the large saloon skylight is also lit up with a set of disco lights on a separate circuit. The funnel houses a heavy duty smoke unit switched on by switching unit.

Lady Wooes, by Mobile Marine of Lincoln. SemI kit. I bought the hull all the timber and drawings along with dozens of white metal fittings ages ago, started it and left it for 5 years, moved to North wales and finished it. Drive is 2 Ford Cortina fan heater motors driving a pair of 55mm Prop Shop props by tank steering, reciprocating steam engine sound board, smoke unit and full working lights all from 2 X 12 v 7 Amp batteries........a good and interesting but very frustrating build to get things right.
Sailed at Erias Park, Colwyn Bay Model Boat Club and sometimes at West Shore LLandudno.