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

Still waiting for a better air pump so thought I'd try whacking 2 pumps on and upping the voltage from 2 to 2.5V Works a lot better but smoke still a bit slow. If I blow gently into the air tube I get massive clouds of smoke (hence the need for a better pump) Sorry about the crappy vid,- camera lens has a cloudy spot and not so good inside.
JB

Trying air injection to break up the water flow. The air pumps I ordered finally arrived a week late but are too small to be of much use. I need a much bigger and faster volume of air to achieve what I want, which is for the water to almost be sprayed out in a mist. Might need to mod the water outlet by fitting fine tubes or stoppers around the inner smoke tube to build up a bit of back pressure, which might be another alternative
Unfortunately, as I've said before, you can't scale water, due partly to surface tension etc (why it either drips or runs out of a small pipe), so to make it fine you have to pressurize/vaporise it at the point of exit (ie garden sprayer) which is the hard part on a small scale. Lots of fun trying to perfect it though, and it keeps me out of trouble, and keeps the brain working - (although it's just asked for a pay rise due to all the work it's been doing lately!😂)

Tip,- if you run both videos at once you can see the difference between this and the last vid. It also breaks the smoke up.
JB

Using the e-cig element in the alloy box again but with the old smoker pump bored out and converted to a single outlet in line with the piston. Even makes a cool sound out the exhaust side!. Still waiting for my air pumps so just playing around in the mean time. Also trying glycerin and water 50/50 instead of baby oil. The pump doesn't shift much air ( slightly more blowing than sucking, - sort of pulsing back and forward) but if I blow down a tube I get clouds of smoke, I'll see what the air pumps do. Still only running on 2v.
JB

This version of a smoker box uses an E-Cig element in an alloy electronics enclosure.I gave the lid and box a 7mm haircut on the mill to reduce the size, (now 50x50x26, - was 50x50x33) but it could still be 1/2 the width. haven't found a smaller alloy box yet but might come across one, (only really needs to be 35mmx35mmx25mm The element is mounted on a bracket screwed to the bottom of the box (the box being the resevoir and neg) and against the outlet tube, and the pos wire runs through the side (in silicone tube) to the element.

The box is packed with cotton wool which is surrounding the element and soaked in smoke fluid (in this case baby oil) but leaving a passage through the center for air flow. I'm waiting for a couple of air pumps to arrive but I've used the old smoker unit pump again to demo the smoke and pulsing, (makes good smoke rings too)😊

The element is capable of taking 4.5v, but I'm only using 2v for the test and it smokes quite well. The pump is running on 7v but can be varied from around 3v - 8v. The large tubes are to allow for later exhaust fitting (water or dry stack). Once I get the air pumps I'll be running this one with the water again. I've done this (like Grahams version to be able to easily replace the element as the Heng Long smokers, while working ok (but noisy) have non replaceable elements, so if you kill one, it's off to file 13 at the end of the bench😉😁

The pump actually works quite well and if you mount it on sponge rubber it is reasonably quiet and could still be useful in a boat with a bit of interior room.

Found a way of pulsing the water using the pump of a dead smoker (Hen Long smoker that is) In this test I used a pump to prime the smoker pump (smoker pump on 2s) and the rest is just syphoning through the pump to the smoker. You can vary the amount of 'spitting' from the exhaust by running the pump at low voltage or maybe using a peristaltic pump with a small flow.

I did not connect the fan powered smoker unit as I ran out of silicone tube, but the result should be the same as the last vid but with 'spitting' water. Using the smoker pump for water is not perfect as it would need sealing properly, and it's cumbersome, but you will get the idea. I have ordered a couple of small air pumps, so might have another crack when they come. I'll use them at the exhaust to disrupt the water flow if they are powerful enough, rather than use the smoker pump.

Changed the piping around and modified the outer tube so the smoke tube now comes straight in the back, and goes almost to the end of the outer tube. The water now comes into the outer tube and flows round the smoke tube and out, stopping any suck back to the smoke pump.

Finally managed to get this to come out the right way up on You Tube (didn't like MP4,- came out upside down). Running the 2 boats from an HK 6ch 2.4 radio (slight crash and jostling by the Maiami at the start) . You'll get sick of it in a few minutes and fall asleep but I've put it up anyhow😁 If this doesn't make you seasick, nothing will!😊 Hit a Koi carp (Chinese sub) at 3.01!

Get the kids into sailing ! - RC model land yacht project suitable for schools.

See also :-

My scratch-built 1/72 scale Type 1936A (mob) destroyer, photographed by a good friend at Albert Park lake in Melbourne.
It has rotating turrets linked to the gun directors and rotating torpedo tubes, the front 6" guns elevate and there is also a ship's horn.

New video on Stevenage MBC YouTube channel. Fast electric ‘mini starship’ shows paces round the lake.

I started the SMBC Youtube channel a couple of months ago... here's the latest video, with on-board cameras...