The Steamboating Forum

Hi Everyone.

I'm fairly new to steam but have been pottering around in timber boats since I was a kid.
My present project is the restoration of my 110yo steam yacht Avalon.
She is 40ft x 8ft x 3ft draught.
On top of all the other work to be done I'm returning her to steam.
To this end I have a very nice 4x4 inch twin double simple engine.
Based on a very conservative PLAN 33,000 calcs it should deliver 15-18hp without too much stress.
She was previously powered by a 20hp diesel that I never ran over half speed.

My next big task is securing a boiler to run it.
I've had a look at some similar engines in other boats and it looks like a heating area of around 50ft and capable of delivering around 500pph would give me some room to move.
At some point I plan to install a condenser but will initially just settle to have live steam.

I have a bit of room for a boiler but my preference would be for a vertical, although I could place a 4-5ft horizontal in her.

I have recently been offered a copper tubed LPG fired Odfelt that looks promising, but am waiting on the technical specifications for it.

Has anyone on here had experience with an Odfelt boiler, or any other suggestions as to boiler type?

I've looked at a couple of US based do it yourself plans but they were all too small, only having a heating surface of around 25ft.

Cheers

Wes

Keep in mind with the PLAN formula that you need to consider not the boiler pressure, but the brake mean effective pressure. Engines like this were rated at 60-65 psi BMEP for 150 psi inlet pressure If those 4x4 cylinders have conventional slide or piston valves, you're going to use a lot of steam. My references indicate between 30 and 40 lbs steam/hp-hr for something like this. I'd look for a boiler rather larger than 50 sq. ft - something like 80 sq. ft. would not be excessive. How much does that boat weigh? What prop diameter can you fit? 15 hp from a double simple will need a _lot_ of fuel; somewhere between 5 and 10 gph, I think.

- Bart

Hallo Wes,

some calculations:
4x4 twin at 250 rpm with 10 bar / 145 psi and 55% cutoff will give a steam consumption of 170 kg/hr / 375 lbs/hr,
Output should be 11.6 SHP (32.2 lbs/HP,hr), non condensing.

A vertical boiler should have 0,3 m² / 3,1 ft² grate area and a heating surface of 8,45 m² / 91 ft².

Fuel consuption should be:
hardwood - 36,2 kg/hr / 80 lbs/hr
coal - 19,3 kg/hr / 43 lbs/hr
fuel oil - 13,8 kg/hr / 30 lbs/hr

You should really think about a horizontal boiler, a clyde boiler (dry back scotch) would be ideal.
- very low center of gravity
- completely watercooled furnace (important in a wooden boat)
- better efficiency (less fuel consumtion)
It would have a length of appr. 5.5 ft for 6,5 m² / 70 ft²
(horizontal boilers need less heating surface in comparison with vertical)

One remark: have you measured the engine (bore/stroke)?
I've found that very often the inch measurements are only an approximation.

regards
Scotty

I'm running the same engine config, only smaller at 3+3X4 and the internal volume of each cylinder is 28 sq-in. Running a 42 square foot VFT boiler, and it's really too small for wood firing, but it pushes the boat at hull speed at 60 psi with good seasoned wood. I can't imagine that engine at 150 psi on a sustainable supply of steam. It would be way too much for my boat.

Your 4+4X4 has an internal cylinder volume of each cylinder, at roughly 50 sq-in. I should have a VFT of 55- 60 square feet of heating surface, I'm guessing your requirement at around 70 - 90 square feet of heating surface. Oil or gas firing you can go with less. Oil firing, you may get by with as little as 60.

Regarding the Ofeldt. I wouldn't put one in a steamboat to be wood-fired. They make steam really fast, but they also require continual tending. They have a very small internal volume (relative to the heating surface which makes them great steam generators) depending on the design - as little as a gallon of water which can be gone in a few minutes. They need automatic controls.

-Ron

Thanks for your thoughts guys.

The boat would weigh around 5-6t.
I could fit a horizontal boiler that came in around 5ft.
I do like the idea of a Scotch boiler but I suspect I'd struggle to find one out here, and at what cost

She also has room for a fairly large holding tank, I've one at holds 500L that I plan to restore and hide under her saloon table.

The Odfelt I had offered to me runs on gas, not wood, I should hopefully hear back on its specifications in a couple of days.
I'm told it was designed to run a 12hp Vosper for use in a 40ft launch.

Cheers

Wes

This forum is for Technical advise, but it may help others if we demistify it a bit...

1) BMEP?

2) 500pph - I assume that means 500 lbs of steam produced per hour?

3) 4x4 inch twin double simple engine?
Usually as I understand it, BoreXStroke. Twin and Double? Simple Engine.
Confused.

3+3X4
Confused.

I have 1902 Toledo Steam Carriage Engine.
It's a 3"x4" Twin (Two cylinders). It's Double acting of course, but most respectable reciprocating steam engines are.. It maybe a Simple because it's not expanding the steam again in other cylinders.

-CB

a few answers.

BMEP this is "brake mean effective pressure" a contrived unit not usually associated with steam. Basically from the measured Brake power (measured on a dynomometer) the usual formula is worked backwards to get a theoretical mean effective pressure.
Mean effective pressure is the AVERAGE pressure developed in the cylinder during the entire stroke.

500pph not sure not seen before.

4x4 twin double simple: this means a twin high pressure engine cylinders 4 ins bore x 4 ins stroke

3+3 x 4: The same thing but 3ins bore, this is the usual notation used by steam boaters.

All steam reciprocating engines are assumed to be double acting unless stated otherwise.

Regards
Jack

As I stated earlier I'm relatively new to this so please forgive me for any obvious or otherwise silly questions, or confusion I may create

Yes my engine is a twin cylinder double acting engine with a bore of four inches and a stroke that's the same.

My rough calculations show it is capable of delivering ample HP to power my boat, based on operating at 125psi and around 500RPM.

But what I'm still trying to determine is what size/type of boiler I should be trying to source to power it at 125psi, along with how much steam I should expect to generate per hour.

My engine room could take a boiler either around 5ft long or high, depending on the type and could have a diameter of around 3ft.

As previously stated I'm seriously looking at a second hand gas powered Odfelt, dependent on forum feedback and determining its theoretical capacity, some initial calculations indicate a heating area to the north of 50ft.

I like the idea of weight savings, along with ability to quickly generate steam - along with the fact there isn't exactly a long list of people in Tasmania, or Australia, wanting to sell me a suitable boiler

Plan B might have to be save some pennies and import something from the UK, with Plan C being to buy some plans and build something.

I'm tipping I'm not the first steamer to have this problem(s).

Cheers

Wes

Wes,

There are numerous Aussie preserved historic/modern private steam boats/launches with some very knowlegeable and experienced engineers who build/maintain them.

I've met quite a number now who have made a 'pilgramage' over to the UK to see SY Gondola and other boats over here. From what I can tell, despite the huge distances seperating them, for the most part they all know each other through at least one or two people- I would suggest doing a bit of digging and see if there is anyone local(ish) to you who could provide a bit of a guiding hand and a sounding board for your ideas.

Your project sounds great, and has the potential to be something very special, however your boat and engine are both quite large for a first time steamboater and you could be easily forgiven for underestimating certain aspects of a project of that size.

Firstly- a gas fired Odfelt boiler of a size big enough to provide steam to that engine is going to drink fuel for fun when running at a decent cruising pace. Any vertical boiler is going to be pushed to keep up with that engine, unless of a large and heavy design, which as you rightly say is really not to be desired.

Sound advice has already been provided above, and I'll reiterate- you ideally want a large capacity horizontal boiler such as a scotch return boiler, or slightly lighter design with higher evaporative properties such as a locomotive type boiler. There are plenty of qualified and experienced boilermen over your way, and finding/building a boiler suitable for your needs wouldn't be difficult. The UK Steamboat Association provides a few standard boiler designs (although I don't think any would be in the size you want). Also, Preston Steam Services have had a lovely scotch return tube boiler in stock for a while now that would suit your needs just fine- although I still think you could build a boiler new cheaper than buying one here in the UK and shipping it over there.

I would also suggest you go through the steamboat register on the website of the Steamboat Association and research boiler types and machinery on boats of the size of yours- there are quite a few in that size range here in the UK, using a variety of boiler types including watertube boilers.

Good luck with your project, I look forward to seeing it steaming very much!

Greg

Thanks Greg,
Thats sage advice on the boiler and I'm going to take it
Yes it's a big project for a first timer, I never intended for it to be so.
I have had the boat since I was at university and literally saved her from the breaker's yard.
She is 110 years old and was originally a steam launch.
Now I'm older, but no wiser, and restoring her to resemble something like she once was.
I'm more than prepared to play the long game on finding or building a boiler as I want to get it right.
I've been talking to Prestons as I know some people who regularly move freight from the UK to Tasmania.
But you are in right in saying you would think there would have to be something lying around closer to home.

I guess if it were easy someone else would have already done it.

Wes