Preheating combustion air does the following: * increases flame temperature; this may reduce smoke as well. * increases boiler efficiency about 1% for every 40F increase in combustion air temperature if the heat is scavenged from the exhaust. Combustion air preheating is used basically on all large ...

... A V-belt is quiet and easily slacked with an idler wheel. Or I could arrange some sort of mechanism whereby opening the fire door closes a damper in the duct from the fan to the ash pan. Or both. ... My stack blower uses quite a bit of water and some more sustainable way to get a few more r.p.m...

Still a work in progress though, I need to sort out a governor for it as it can only deal with steady loads at the moment, i.e. lighting and battery charging. I'd definitely use a battery to help regulate the output of your generator as the output voltage is likely to shoot up if the load decreases...

I wouldn't get too worried. Otter's prop has been 'hanging low' w/o even a preceding skeg for the almost 30 years she's been steaming. Yes, I've grounded the prop on a rock a time or two, but nothing really bad that a bit of light filing didn't clean up. I do stand and slow down when steaming in sha...

I think that valve mechanism is designed to control fuel flow while maintaining a relatively constant jet velocity, and providing a needle type orifice that can be cleared by cycling the valve. The construction isn't clear, but I'd guess the vertical needle has a slot that is engaged by a fork threa...

To make boiler nipples removable, use neverseize. There's one w/ PFTE specifically called out for steam piping. Teflon tape works as well, but the goop is better. RectorSeal #5 is similar - I've had no troubles removing boiler nipples after 10 years. To prevent corrosion, paint fittings with moistur...

If you're interested in more of a period piece, there are various articles on the net about making slow speed generators for wind turbine use. These could support direct drive from our steam engines; some skill w/ electronics would be needed to properly regulate the output, but this could look very ...

If you have a rigid canopy, solar panels make a lot of sense if your climate isn't too sunless. A couple of 100w panels and you're set. Large boats fit alternators, but I've seen those only on 35-40 footers. Most small boats just pack enough battery to last a weekend. Rainbow, our 26' ex-Navy whaleb...

It's certainly possible, of course. However, the cost of the fuel (unless you've got a pretty big boat) is a tiny part of the expenses of maintaining a boat, and it's not trivial getting pellet fuels to burn at the desired rate, esp. w/o forced draft. Rats would pose a problem - a ship's cat might b...

When I wound the 1/2" (~13 mm) tubing for Otter's boiler, I filled the tubes w/ sand. For very small tubes, you might want to consider Cerro bend or other very low melting point (below 100 C) metal alloys to prevent tube collapse.

- Bart