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   The Steamboat Association of Great Britain

Boiler Design Library

SBA Services has a library of tried and approved designs for steam raising plant for steam boats


The aim of this library is to offer steamboaters approved designs of boilers suitable for a wide range of boats.

All the drawings contained in this document are copyright SBA Services Ltd and may not be reproduced without the permission of the Company.

The role of SBA Services Ltd (SBAS) in operating the boiler design library is strictly that of Librarian. The Company may in future commission new designs if it is felt appropriate and arrange for such designs to be approved by a competent person. SBAS does not have the necessary technical competence to comment on the design or approval process.

The designs in general, are for the pressure vessel only. The cladding, fittings and pipe work of the boiler are the responsibility of the owner. However others (notably the John King water tube boilers) include a complete set of drawings for cladding and suitable fittings and are marked ** in the listings. 

Drawings are provided as printed and folded sheets, and some will include constructional details/guide (see those marked **).
Designs marked ( ^^ ) can be built without the need for a coded (certified) welder, therefore these "weldless designs" are suitable for construction by amateur engineers , without professional assistance.

Members who purchase a set of plans are strongly advised to consult a competent person or their boiler inspector before starting the construction of a launch boiler. The SBAS Construction Surveillance Service is designed to provide the required support and certification of the construction phase of a new boiler for professional or amateur constructors.

Users of these designs in countries other than the UK should check with the authorities in their own country that the design they choose is acceptable to their authorities.

If in any doubt please contact the SBAS for advice and help.

Conditions of Purchase

  1. 1. All the designs have undergone a design approval by a competent person to standards detailed in the United Kingdom 'Pressure Equipment Regulations 1999". Although it is recognised that marine boilers are an exempt category, the regulations specify current best practice. The assessment applies strictly to the documents held in the library, and any alterations to the design made by the user (even details) may render the assessment invalid. It is the responsibility of the purchaser of a library design to obtain a Competent Person’s assessment of any alterations made to that design.
  2. Notes on Manufacture and Inspection
    • 2.1 The compliant construction of a boiler within the UK is the responsibility of the boiler maker and the competent person appointed to witness satisfactory construction.
    • 2.2 The appointment of a competent person to witness satisfactory construction of the boiler is the responsibility of the boiler maker.
    • 2.3 Where the purchasers of the design are intending to construct the boiler themselves (rather than through a commercial boiler maker), it is vitally important that they agree with their boiler inspector how the condition in 2.1 above relating to the appointment of a competent person to witness satisfactory construction is to be implemented before any construction is started. If they intend their boiler to be inspected by SBAS and do not yet have a boiler inspector, they should contact the SBAS Boiler Inspection Scheme Administrator so that one may allocated to them. (see SBAS Boiler Inspection Scheme page)
    • 2.4 Any boiler to be accepted by SBAS for inspection & issue of a boiler certificate must comply with the requirements of 'The Purpose, Operation & Requirements' booklet issued by SBAS. Of particular importance is section 4.1 Preliminaries. (A copy of the booklet is available from the SBAS Boiler Inspection Scheme Administrator), (see SBAS Boiler Inspection Scheme page).
  3. Copyright subsists on the designs in the library and is owned by SBAS. Copies of the design documents are supplied to members on the condition that they are for the member’s personal and private use. It would be a breach of copyright to (inter alia) pass on the documents for use by another person; make copies of them; or use them for any commercial purpose.
  4. Purchase of a set of drawings is for the construction of one boiler.
  5. SBAS accepts no liability that the boiler will perform in accordance with any estimates shown on the drawings. Purchasers must ensure that the boiler will be suitable for their proposed application. The SBA website forum pages & the Steam Boat Register may give helpful guidance on this matter.
  6. Purchasers of designs are deemed to be in agreement to the above conditions.
  7. Payment via PayPal for the above, payment on order.
  8. Prices include VAT and postage and packing
  9. Typical delivery time 18 days.

Prices and Ordering

You can order a full set of printed drawings for a design, for £100 by clicking the link below. This will generate an order request. We will respond with a confirmation, order number and payment details.

Ordering your Boiler design drawings: Click this link and we will create an email you can complete and send. We will respond with a proforma invoice and order number.       

    SBA Services Ltd

    Library of Boiler Designs

    Note: all information and drawings in this table are indicative only.  The delivered drawings are the definitive version of the design.

    Performance and Application Notes
    Design Num Description Sample GA Drawing
    (Click Image for a larger View)
    Heating Surface

    Working Pressure

    Typical Usage
    Fire Tube Boilers

    VFT 100

    Welded Vertical Fire Tube
    Diameter: 15 inches  (38 cm)
    Height: 27.4 inches (69 cm)
    Weight: n/a
    Tube Size:  0.75"dia x 16swg x 12"
    Tube Number of Tubes:  72 (copper)
    Designer: David Beale
    Design Assessment: ABS (Europe)

    13/1.20 125psi/8.6bar

    Steam Launches up to 18ft or Stuart 5A or Beaver compound

    Installed in Polly, Momad, Melissa

    VFT 101

    Welded Vertical Fire Tube
    Diameter: 18 inches  (45.7cm) Height: 24 inches (61cms)
    Tube Size: 0.875" dia
    Tube Number of Tubes: 84

    11.4/1.06 200psi/13.6bar Elidir
    VFT 102

    Welded Vertical Fire Tube
    Diameter 20 inches  
    Height 26 inches 
    Weight: 300kg (pressure vessel)
    Tube Size: 0.875" dia 12swg
    Number of Tubes:109

    17.6/1.63 200psi/13.6bar Anna, Dyad, Grayling, Obsidian
    VFT 103

    Welded Vertical Fire Tube
    Diameter: 22 inches  (45.7cm) Height: 29.5 inches (61cms)
    Weight: n/a
    Tube Size: 1 inch dia 8swg & 12swg
    Number of Tubes: 109

    24.1/2.24 200psi/13.6bar

    Suliven, Nokomis, Niad, Araminta, Quetzal, Roundtuit, Tambora

    VFT 104

    Welded Vertical Fire Tube
    Diameter: 30.75"  (78 cm)
    Height: 30" (76 cm)
    Weight: n/a
    Tube Size: 1" diameter
    Tube Number of Tubes: 181

    60.8/5.64 180psi/12.4bar
    VFT 105

    Welded Vertical Fire Tube
    Diameter: 26 inches  (66 cm)
    Height: 32 inches (81 cm)
    Tube Size: 0.75" dia
    Tube Number of Tubes: 209

    37.0/3.52 200psi/13.78bar Bluebell, Moondance, Wide Awake
    Water Tube Boilers

    WTB 1 

    Welded??? 2-drum water-tube boiler (Lune Valley Type)
    (dimensions exclude casing)
    Width:  20" (55cm)Depth: 15.5" (39 cm)
    Height: 26" (66cm)
    Weight: n/a

    n/a 150psi/10.34bar Silkie  and Lightning (small engine)
    WTB 2 

    Welded Vertical Water Tube
    Central Drum dia: 10.75"
    Central Drum Length: 21"
    Tubes: 20 cunifer coils, 4.75" dia
    Pressure Vessel Height: 21.25"
    Width: ~20" 
    Weight: ~167kg (inc casing)

    n/a 200psi/13.7 Stuart 6A Bramble, Lady Barbara
    WTB 3-1
     ^^ **

    Three-Drum John King weldless Yarrow design
    Steam Drum: 6"dia. 604mm long
    Mud Drum: 4"dia. 604mm long
    Grate Area: 2.6 sq ft
    Weight: 180Kg (with casing & fittings)
    Tubes: 206 x 12mm OD "Cunifer"
    Height: 610mm +ashpan
    Width: ~600mm inc dog-house
    Shorter or longer versions can be made.
    Optional steam dome version, but that needs coded welder.
    Drawings of "LIFU" & "dog-house" casings are included.
    (JK water-tube Design Notes)

    32/2.97 250psi/ 17.24bar SY Befur, Lady Amanda
    WTB 3-2
    ^^ **

    Larger 3-Drum John King weldless Yarrow design
    Steam Drum: 8"dia. 28.5" (720mm) long
    Mud Drum: 4"dia. 28.5" long 
    Width: 806mm plus casing

    Grate Area: 3.9sqFt 
    Weight: n/a Tubes: 306  x 12mm OD "Cunifer"
    (JK water-tube Design Notes)


    (plus 5sqft economiser and 5sqft superheater)

    250psi/ 17.24bar
    WTB 4 

    Scott Babcock Boiler 1
    Steam Drum: 6" dia.
    Length 11.5" (29cm),
    Tube plates: 15" x 8" all steel.
    Tubes: 51 x 0.75" od 16 swg copper (optionally steel).
    Grate Area: 0.368sqft
    Weight: n/a
    Larger version with 18" steam drum available.


    or 14.9/1.34


    (larger version in Marlin)

    WTB 5  Blackstaff Type - Welded Three Drum. Can be built in two sizes with 6 or 10 coils per side.
    Steam Drum: 6" dia. Length: 12.5" or 17.5".
    Mud drums: 2.5" dia. length: 13" or 17".
    Coils: Copper 0.5" dia 18swg.
    Weight: n/a

    or 25.0/2.3

    WTB 7 

    Scott Babcock. Mk 2. 
    Steam drum 6" ID (15.24cm), Length: 18.5" (47cm).
    Tube plates: 16.5" x 11" (41.9 c 27.9 cm).
    Tubes 74 of 0.75" OD 16swg (copper or steel) Welded Headers. Grate Area 1.7sq ft

    Weight: n/a

    27.2/2.52 150psi/10.34bar
    WTB 8  Illingworth.
    Drum height: 208mm, diameter: 180mm.
    Tubes 32 of 15mm dia. Welded bosses.

    n/a 150psi/10.34bar
    WTB 9

    Woodburner. Welded.
    Length 635mm, Width 473mm, Height: 920mm. Generating Tubes: 72 x 17.5mm od
    Weight: n/a

    n/a 100psi/6.89bar
    WTB 10
    3-Drum Welded Water-Tube design 
    Steam Drum: 8" dia
    Length 30"
    D-section mud drums
    Grate Area 3.1 sqft
    Weight: 312Kg
       60/5.25  225psi/ 15.52bar  Anachronism
     WTB 11  3-Drum Welded Water-Tube design 
    Steam Drum: 10" dia
    Length 36" 
    D-section mud drums
    Grate Area 3.9 sq ft
    Weight: 337Kg
       72.5/6.75  225psi/ 15.52bar  
     2-Drum weld-less water tube design, with 6 inch steam drum.(optional welded steam dome) John King design.
    (JK water-tube Design Notes)
       28.0/2.6  250/17.24  
     WTB 13
     2-Drum weld-less water tube design, with 8 inch steam drum.(optional welded steam dome) John King design.
    (JK water-tube Design Notes)
       45/4.18  250/17.24  
     WTB 14
     Weld-less Babcock - 23 sqFt (optional welded steam dome)
    John King design.
    JK's notes on Babcock design.
       23/2.13 250/17.24  

     WTB 15

     Weld-less Babcock - 38 sqFt (optional welded steam dome)
    John King design.
    JK's notes on Babcock design.
       38/3.5  250/17.24  
    Locomotive Type

    Loco 1


    Firebox: Height: 31" (78.7cm), Width: 25.6" (65cm), Length: 22.5" (56cm). Barrel: 22.5" (57.1cm) dia, length 24" (61cm). 


    400kg/hr evaporative rate. 42.5sq/ft 180psi/12.41bar Pendlebury, Tarka
    Loco 2 Welded. 
    Firebox: Height 22" (56cm), Width 20" (51 cm), Length 19" (48cm).
    Barrel: 16" (37 cm) dia, length 18" (46cm). 
    Tubes: 25 of 1.25" 13swg and 4 x 8 swg (tube stays). (A version with inclined tubes also available - "Loco Mod 2")
    Weight: ~250kg

    136kg/hr evaporative rate 200psi/13.7bar Arlette, Annabelle, Hero, Anna Jayne, Sans Son
    Horizontal fire tube boiler

    HFT 1  Cochrane type. Welded. Diameter 18" (45.7cm), Height 24" (61.0cm), Tubes: 44 of 1.25" dia (2.3cm dia)
    19/1.76 240psi/ 16.3bar ????

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