How To Build A Model

What Is A Fibreglass Moulding?

Drilling & Cutting GRP - Fitting Rudders & Prop Shafts

Painting A Fibreglass Hull

Ministeam Construction Tips

Building A Steam Driven Thames Launch

A Guide To Building A Steam Driven T.I.D. Tug

John Cox builds a typical Thames steam launch using Kingston Moulding’s ‘Duncan’ and powered by a Cheddar Models vertical Puffin - Marine Modelling magazine - July 1995.

Steam power has made a welcome return to the model boat world in recent years, with several manufacturers offering well-made and reliable engines. Butane gas which is clean and readily available is the usual heat source. The fact that the gas is controllable and easily stored probably contributes to the upsurge of interest. Some manufacturers are also offering suitable hulls and kits to widen the market. Many kits already on the market are also capable of being powered by steam, although originally designed for electric propulsion. Plans and articles in the model press also prompt those with the necessary engineering skills and facilities to produce their own power plants. Of course there are many model engineers who would say that steam never went away, witness the many steam presentation societies that abound in the UK.

There seems to be something in the British male make-up that provokes a love affair with anything powered by fire and water. At the very first Marine Modelling Festival at Child Beale Cheddar Models put on an attractive display of their products (a display that seems to improve with each show) Your contributor had been flirting with the idea of a steam powered model for some years so here was good starting point. John Woodroofe, their director, was unstinting with advice and patient answers to the most inane questions. The outcome was the purchase of a complete 'Puffin' engine and boiler, plus a refillable gas cylinder and other items. The whole purchase was in kit form although I believe a building service is available at extra cost. Building the engine was a simple enough operation aided by clear and concise instructions, and was covered recently in the March MM by Allan Miller. About an hour is all that is required by a novice constructor using a bit of common sense. Immediately after building, the engine was oiled, boiler filled and gas tank charged. Steam was raised in about five minutes and the engine run on the bench. The engine was then run several time over the ensuing months as a running in process.

There is nothing quite like a "fix" of hot steam oil! It may seem strange at this juncture but at the time I had no clear idea of what sort of model the unit was going to power. In any case I was very involved in model yachting and my then current scale models under construction were unsuitable for steam power. In 1994 at Sandown Park, Westbourne Model Centre were offering the recently introduced 'Kingston' moulding of "Duncan", a typical Thames steam launch. This comes complete with a moulded canopy and very good plan. It is of no particular craft but offers great potential. Although the moulding is available in several colours, white was the obvious choice. By purchasing then and there the cost of carriage would be saved. The die was cast.

Preparing to build.

The moulding itself has an overall length of 44”. It is fair to say that it is among the best I have come across. The gel coat is flawless and the lay up of even thickness throughout. It is rigid without excess weight and comes ready trimmed. No more than a light sanding is needed on the gunwale line to prepare it for fitting out. An all-up weight of 18 to 20 lbs is suggested on the plan, leaving plenty of scope for the builders imagination. The plan is drawn with a Maxwell Hemmens unit in situ but obviously the choice is up the builder. As with any project the first move is to construct a stand. (if only manufacturers would supply a plan using suitable points of the hull lines). Once the stand was completed it was lined with soft rubber to protect the hull. The hull itself was also covered with parcel tape to help protect the gel coat from the ravages of continual handling over the coming weeks. It was decided at an early stage to separate the Puffin engine from its bed plate and mount it on wooden supports and to tilt it at the same angle as the prop shaft. This would, hopefully, ease the job of the universal joint. The forward end of the saloon as shown on the plan projects 18” from the stem, this in turn positions the engine about midships necessitating a long prop shaft. We are badly served with modelling supplies locally but Mobile Marine Models who advertise in this magazine are only a 'phone call away. They will make a shaft to any size and also supply their own custom made props. These have a grub screw as well as the usual locking nut on the threads, making for a more secure fixing. A 14" shaft with a 2” brass prop was ordered and delivered within the week. While awaiting the shaft & prop a start was made on the hull proper.

First add timber.

¼” inch spruce inwales were bonded in at deck level. The stern has a very sharp radius but short sections of timber with multiple saw cuts at right angles is the accepted practice and the curvature was followed with no problems. Small clamps and clothes pegs held the timber in position while the adhesive cured. Sub decks, fore and aft, of ¾” balsa were then bonded into the inwales but left standing ½” proud. When dry they were sanded down from the centre line to gunwale, to form the deck curvature for later planking. The under surfaces were given a good coat of resin prior to fixing. Before inserting the rear sub deck, a frame work was bonded in to the hull. This takes a ply plate which in turn carries the rudder servo, RX, switch and RX nicads. A simple screw fixing allows the whole plate to be withdrawn from inside the hull.

Prop shaft and mountings.

The next move was to bond in the prop shaft and engine mount. The engine had already been mounted on ½” beech bearers running fore & aft. These in turn would be mounted with screws to bonded bearers running thwart ships. This makes for quick and simple engine removal should the need arise. Prop shaft fitting followed the time honoured method of placing masking tape on the hull and marking the shaft position. Careful drilling and filing ensures a tight fit with the minimum of bonding. The universal coupling was fitted to the shaft and a piece of 'heat shrink' slid over the coupling. This was then heated with my wife's hair dryer, the idea being that when reduced the shaft, coupling and engine would be held in line while the adhesive cured. It worked perfectly. The bearers running thwart ships were now placed into soft body filler and the engine and prop shaft aligned before the filler cured. A small amount of filler was also placed round the shaft to secure it tightly to the hull. The hull was now put aside until the filler had gone off. Once cured alignment was further checked and when satisfied glass mat and resin was used to make a permanent fixing.

External hull fittings.

A protective skeg is usually fitted to this type of craft to prevent prop damage in shallow water. This item was made from strip brass and then bolted to the bottom of the hull with 10BA. nuts and bolts. The plan supplied gives a suggested format and this was adhered to. The decks on this type of boat are a very prominent feature and deserving of a lot of attention. Mahogany planks were the chosen medium. 1/16” and 1/8" x 3” x 24” lengths were ordered from Punctilio Model Spot, (another advertiser deserving of support). I have one of the excellent Mini-Craft circular saws which cuts cleanly and accurately down to as little as 1/32". Some of the mahogany was reduced to 1/2" planks leaving plenty of timber for use in the construction of the saloon and other items that would be needed later. Prior to planking a centre line was struck from bow to stern. Plank positions were then marked either side of the line. A margin plank 5/8” wide was marked in, to follow the gunwale line. Planks were edged with black paper so that when laid a caulking line would emerge. A hatch was allowed for in the aft deck to give access to the RX on/off switch etc. Card templates were cut for the margin boards, which were laid prior to planking. The planks were laid using Dunlop 'Thixofix', an impact adhesive which allows adjustments to be made before final bonding. No problems were experienced, and after allowing a suitable drying time the planks were given their first sanding and a thin coat of polyurethane as short term protection.

Steaming the coamings.

The model calls for a raised coaming of about 5/8" depth. The fore deck portion requires a curve of 180 degrees at a 6½” radius. Steaming had to be the answer, and one of the photos shows the simple press devised, made from a piece of ‘melamine' board. The half circle was cut out on the jigsaw and then reduced by 1/16” on the inner portion which was the thickness of the plank to be used. Two planks were to be used with a simple butt joint at the apex. Pieces were steamed for 45 minutes in an ordinary domestic steamer. The press was held in the plastic pegs of the ‘Workmate' with a gap of about 3/4" into which the softened wood was coaxed. The 'Workmate' was then closed up evenly and two miniature sash cramps held the press (which looks like a large jigsaw piece) in place. Three days later a perfect half circle formed by two pieces of mahogany were removed and glued vertically to the deck, to form the coaming. fitting of the deck and coaming. Diagonal planks of 1/64” x 3/8” ply (left over from another model) were glued to the visible interior of the hull. This was a simple and effective way of hiding the fibre glass while at the same time adding a touch of authenticity to the whole model.

The saloon & canopy.

The saloon is a simple box structure of four parts, each cut from thin ply. Windows and doors were fretted out. The curvature at the top of the windows was marked out using a saucer as a template! The cabin interior was veneered to give a panelled effect while the exterior received the same treatment using 1/16” mahogany. Uprights and cross members were represented by 1/8” timbers all cut in the same way as the deck planking. I was rather pleased with the overall effect as seen in the photos and would like to think it is very similar to an original full size launch. A local model shop was the source of the door and window furniture which is intended for dolls’ houses. Clear plastic sheet was used as glazing and held in position with mitred battens. This is not a success due to a bluish tint and a very plastic appearance.

Thin glass is being considered as a replacement and I intend at a later date to furnish the saloon more extravagantly. A celeste light was fitted into the canopy above the cabin to break up at would otherwise be a rather large expanse of white I think this detail adds something to the model although by now I was getting a little concerned about top weight. In full size practice the canopy might well have been of canvas over a timber frame. The top of the fibreglass item supplied was divided up using 2mm car lining tape to give a panelled effect which was then sprayed with matt white paint. The underside was panelled with 1/64” ply and hardwood strip, hopefully similar to the work of the original Victorian or Edwardian shipwrights. Working brass lights are mounted fore and aft with the wiring concealed under the panels.

Detail fittings.

Four upright brass rods support the forward end of the canopy and two of these are used to link the canopy lights to a battery pack in the forward part of the hull. Working port and starboard navigation lights are also fitted on the fore deck. A dummy bulkhead, panelled and fitted with shelving, is a push fit under the curved coaming effectively concealing the battery and hopefully enhancing the model. One photo shows the completed saloon and canopy. Several fittings were made using mahogany and brass. The distinctive rudder is a sandwich of brass sheet for rigidity (it is a big model) with 1/16” mahogany bonded either side. Brass boiler band is riveted either side for effect. The rudder pintles fabricated from heavy brass with threaded rod silver soldered in for secure mounting, with nuts inside the hull. The two grab rails on the canopy top were milled from 1/16” mahogany as a single piece and then sawn down to give two identical items and later they were sanded to profile. The rear hatch is constructed onto solid balsa using veneer and strip to represent lift up doors. Handles and hinges are from brass rod. The 'dog kennel' in one photo with the other fittings, covers the steam valve servo and the positioning of this servo was the most thought provoking item of the whole project. The steam valve is at the highest point of the engine making it difficult to get efficient linkage without resorting to obtrusive rods and bell cranks between engine and servo. The position finally chosen makes for short, rigid control rods but still requires a bell crank. Bowden cable and aircraft model type 'snakes' were experimented with but discarded. The final servo position was very much a compromise.

Decking.

The visible decking in the open area of the launch is laid on ply cross members, bonded to the bottom of the hull. The moulded in keel leaves a shallow channel beneath these cross members. There is no decking close to the engine bearers. This allows oil and condensate (inevitable with Steam engines) to fall into the channel out of sight. Two removable gratings in the deck allows this oil/water mix to be syringed out after running. There is quite a large void under the removable cabin floor and it was decided at a late stage to use this space for a fresh water tank to feed the boiler. This facility requires a water pump driven from the engine. This is an optional extra but well worth it. Cheddar Models recommend that water should not be used direct from the pond as sediment in suspension might lead to premature engine wear. I was concerned that as the water was used, the balance would be upset. In practice this not been the case. A seat and steps were fitted in the open area, again to add detail.

Painting the model.

At this stage all exposed woodwork was given final sanding and then treated to four coats of thin polyurethane varnish, sanding between each coat. A final coat gave a thick lustre effect. White is the obvious colour choice for a hull of this type, and with a moulding of this quality it would be sacrilege to cover it up. That said, the underwater part of the hull obviously calls for something to represent anti-fouling. In the workshop was a spray canister from another project. Rover 'antique gold' may seem an odd choice but it does not attract adverse comments. The waterline was marked out to the position shown on the plan using 'Magic Tape' as I find this product works better than proprietary masking tape, which sometimes allows seepage to leave a ragged line. A dark blue boot topping was later applied by airbrush. My method here was to apply a car lining tape of the thickness required and then place ‘Magic Tape’ either side. The lining tape was then removed and the space left sprayed in. When the ‘Magic Tape’ was removed a perfect line was the result. Gilded decoration is often a part of this type of launch but I was really at a loss as to how this could be achieved. While handing in a film for development at my local chemist I caught sight of a display of earrings and there for £1.25 was a pair of Dolphins in left and right hand format. The name and decoration was achieved in one fell swoop.

Final bits and pieces.

Little was left to do except add a few commercial fittings and to connect up the rudder. This had to be left until last as its over hung position makes it vulnerable to work shop clumsiness. For simplicity two ropes forming a closed loop are taken through tubes in the aft deck to the steering servo. This gives positive control and eliminates fiddly rods and links, as seen in the photo. 'Dolphin’ had her first sail at the very successful autumn 94 Child Beale model boat weekend. My experience with steam power was at this stage limited to bench testing but Cheddar Models supply explicit instructions to make life easy. And so it proved to my immense satisfaction, in fact Cheddar Models who were in attendance thought there was too much steam leakage at the steam valve and offered to take it back to their workshops to correct it. As mentioned earlier the engine is easily removed and at the end of sailing it was handed over to return to Cheddar. There it was treated to a new control valve and returned by post in perfect health. A good service from an attentive supplier. In the final analysis what have I achieved? An attractive model certainly. It is not to scale, or to any known design. It is not to ‘stand-off’ as there is too much detail. The obvious answer lies somewhere between the two disciplines. Fellow modellers are complimentary and that is perhaps the judgement that counts. The whole project was not cheap, that is for certain, but if one excludes the engine and radio equipment ‘Dolphin’ was built for a little over £100. The engine and ancillary equipment was the major outlay, but you do get ‘quality for money’ from a Company now selling world wide. In any case I adopt the philosophy of the lucky lady who married me, ‘enjoy today, we don’t know what tomorrow will bring’.