A new ASME code boiler for a Steam Launch

[Lopez Mike]

I'm headed for a sheet metal shop. I need to know some numbers.

Diameter of the flue and width of the strip and how many turns per foot. Also how thick is the sheet metal?

My flues are 1". I'm guessing I should make the strips a loose enough fit so I can get them out when there is some soot buildup. If they are too loose will they rattle when the boat rolls around?

[DetroiTug]

Mike, Mine are made from 14ga hot roll. They should fit close to the inner diameter, but not too tight, leave .03-.05 clearance. Some of mine are tight, some loose, never heard them rattling at all. The water probably deadens any noise. And too that are twisted, so they are in a natural bind. Also the amount of twist is like 1 in 2 feet. Not sure about the optimum twist rate, but that is what I have in mine and it works.

Per Fred's advice which was good as usual, I stopped the strips off at the normal water level to keep from overheating the exposed upper tubes. They start at the bottom of the tube and go up to the normal water level. They are suspended in the tubes with a tacked 1/8" rod up to the top and then a simple 1/8" T-bar tacked across the top to suspend them at correct position. If you burn some really green wood, just twirl the turbulators while working them up and down and they scrape everything out. Definitely a good thing to have a VFT.

-Ron

[cyberbadger]

So I read everything posted. But no one directly answered my question.

LundMachineWorks has offered me (at no extra cost to me), to make up to 2 ashpan/draft doors in a width and angular orientation that I want because that assembly has not been made yet and is separate from the pressure vessel.

I want to take him up on that offer to have 2. If I eventually don't need both I can just leave the one shut.

As far as the height DetroiTug suggested at a minumum 4" height. They are both going to be 4" height

As far as the width, LundMachineWorks was a little wary of going as wide as 18" for structural integrity reasons. Lopez Mike commented that he thinks that would be fine going that wide. Lopez Mike - I'm not saying you are wrong, but if the person making my boiler maker doesn't think it's a good idea I tend to go with his judgement. (I'm paying so I have some say )

So again the question I pose.....

2 square ashpan/draft doors, 4" height.

Let's say the limits are 4"-12" wide.

What angular offset and widths would you recommend if you were in my position?

-CB

[Lopez Mike]

Probably fine with one 4 x 12 door.

You've got 97 sq. inches of tube area. with 48 sq. inches of draft opening that is a 50% ratio. I seem to remember earlier in this thread something about the minimum ratio being smaller than that.

And a door that size will let you get in there and grub around cleaning up.

[cyberbadger]

Mike,

Probably fine with one 4 x 12 door.

I appreciate your input, and I'm not trying to be a stickler. But I was trying to be pretty clear on the last post.

I will be taking up the offer to get 2 (TWO) ashpan/draft doors.

So given the constraints I have set ....

So again the question I pose.....
What angular offset and widths would you recommend if you were in my position?

For example, 2 12" draft door 180 degrees apart? That was my initial stab after talking to Jeff Lund, but then I called him back and asked if I could have a week. I did that because I was worried that maybe the ashes could be blown across the deck if the there was a strong wind/etc.

Another example, 1 4-8" and 1 12" offset by 90 degrees. (One for ash removal, one for draft control)

I really want your input on this, given the constraints I'm setting. I can always just have one shut permanently if turns out not to be useful.

If your "vote" by posting on this thread makes sense to me - I will tell Jeff Lund to do it that way. Either way I'll let you folks know what I end up choosing.

I'm not trying to build the perfect steam launch. I'm trying to do it my way and tinker and enjoy the journey.

-CB

[DetroiTug]

We're being asked for a reasoned reply or opinion on something that doesn't make sense to us, or me anyways. Why have two doors?

I don't see any advantage to it. Remember, all of the boiler controls need to be on the engineer's side. So following that requirement, both doors need to be on your intended side of operation. Remember the engine is likely going to be directly behind the boiler, so can't have one there. The most acceptable orientation is going to be right next to one another facing the engineer. And the doors opening away from one another.

I can state with certainty, the first time ashes are being taken out and the shovel bumps that center jampost on the way out and ashes go everywhere including the bilge, you're going to wish it was one big wide door - about 4" X 12"

-Ron

[johngriffiths]

I agree with Ron, use a single ash pan door hole with a door that can be closed in stages to control draft and which allows you to get a decent sized shovel in to lift the ash out. A rake can then be used to clear the corners. Its a good idea to either let some condensate drip into the ash pan (if it of sump form) or to have a water cooled floor to the pan. This saves burning the boat hull, which has happened. I direct some of the cooling water from the condenser through the ash pan water space before it goes to the outfall.

John

[fredrosse]

My vote, a 12 x 4 opening facing the engineer, say 45 degrees aft of Starboard, and a 4 x 4 set 90 degrees to that, say 45 degrees aft of port. This assumes the engineer sits on the Starboard side of the boat, just aft of the boiler. The 4 x 4 may usually be always shut if cross winds are a problem, but may be useful for some application.

[cyberbadger]

I can state with certainty, the first time ashes are being taken out and the shovel bumps that center jampost on the way out and ashes go everywhere including the bilge, you're going to wish it was one big wide door - about 4" X 12"

Ron - I can tell you I'm definitely going to have 1 of the 2 being 12" wide or perhaps wider, simply for ash removal if nothing else.

Also I don't know the term "center jampost" - what does that mean?

As far as why have two? because it's free. I can experiment with it if I want to. Crazy idea - Have a long pipe going up to a wind vane with a horn on it so that any wind can be caught and directed as a forced draft into the firebox. Use your imagination.

-CB

[mtnman]

I can state with certainty, the first time ashes are being taken out and the shovel bumps that center jampost on the way out and ashes go everywhere including the bilge, you're going to wish it was one big wide door - about 4" X 12"

Ron - I can tell you I'm definitely going to have 1 of the 2 being 12" wide or perhaps wider, simply for ash removal if nothing else.

Also I don't know the term "center jampost" - what does that mean?

As far as why have two? because it's free. I can experiment with it if I want to. Crazy idea - Have a long pipe going up to a wind vane with a horn on it so that any wind can be caught and directed as a forced draft into the firebox. Use your imagination.

-CB

Imagination is for artist. Facts and test are what steam engineers use. Crazy ideas mixed with steam will get you hurt.