Bernard Scott



Hi Mayhem,

Please find enclosed a photo of a "Bathurst" class minesweeper which I have recently built.
It's steam powered with a Wilesco D48 marine engine. Its constructed from ply for the hull and balsa/ply for the superstructure. Radio is Acoms 2 channel 27Mhz.

Is it suitable for inclusion on your site? (Maybe just to show how not to build a boat)
"Not so, you should see some of my attempts!" Anyway, how many of us have scratch built a steam boat much less a warship!!!! - Mayhem)

 

Finding myself with time on my hands and getting bored with playing 'Minesweeper' I decided to revive my old hobby of model making, something I haven't done for about twenty years.

Since my first (and last) aircraft crashed 30 seconds after leaving the ground and having no interest in cars I decided to build another boat. Having built electric and glow engine boats in the past I decided on steam power for this one.

Sourcing engine, boiler, ship, etc was the first step. Kits designed for steam power are few (The Model Dockyard was one source) but are either smaller than I wanted or more expensive than I was willing to pay. While searching ebay for an engine and boiler I came across plans for "Bathurst" and paid the princely sum of 3.oo for them. These plans comprise a side view, a plan view and some quite detailed building instructions. The plans are 1/96th scale and since I wanted something larger I scanned and reprinted them at double size.
Engine and boiler were even harder to source. Stuart Turner, Cheddar Steam Models, Model Steam Engines and John Hemmens all supply some lovely engines and boilers but all are well over my meagre budget. Eventually I found a company called Forest Classics who deal with a German manufacturer called Wilesco, they had a suitable engine and boiler for my ship (model no. D48) at an affordable price, less than 200.00. This is a self-starting engine with forward/reverse & speed control and twin double-acting cylinders giving four power strokes per revolution.

The plans suggested using all balsa for construction and electric power - I had to make changes, I didn't think balsa would be strong enough considering size and weight of engine and boiler so I substituted 3/8ths marine ply for the main hull parts; flat base, decks and bulkheads, and 1/16th ply for side skins.
The plan showed three access holes in the deck, one at the stern for rudder, one in the middle for motor and one under the bridge for radio, batteries, etc, only the rudder hole didn't need enlarging. The motor hole had to be wider to allow fitting of the engine but access for the boiler needed to be considerably larger than the plan. Only a single bulkhead was shown in the plan so for increased strength I added two more, one at the rear of the engine access and one halfway from centre to bow so I now had four seperate compartments which proved to be very worth while.

With the basic frame of the hull constructed (without side skins) I began to think about the problems of using steam in an enclosed ship.

First thought was what to do with the steam exhaust, then what about water and steam leaks from the engine itself and finally what to do with combustion gasses coming from the gas powered boiler.

Taking these problems in order I built a small 'condenser' unit from some copper pipe. This is simply a 22mm end cap, a 22-15mm reducer, a 15-10mm reducer and a short length of 10mm pipe all soldered together. I drilled a couple of holes in the side and solder two short lengths of 1/8th diameter pipe into it, one pipe takes the exhaust, the other drains off condensate.
Next came a tray for the engine to sit in, some thin copper plate which I had lying around came in handy, cut and soldered together it makes a simple sump for the engine. Another piece of 1/8th pipe soldered into it allowed me to connect the condenser to it so all the water would end up in the sump.
The copper plate came in handy again for making a cowl to sit over the boiler. Although this may not be strictly necessary I made it anyway. Complete with a short length of 22mm pipe it guarantees that most combustion gasses go up the funnel. With the condenser sitting under it as well, steam exhaust is directed up through the funnel as well.

Now, what do I do with all that water sloshing around in the sump under the engine - a bilge pump was required.
Should I have it running full time? - no the pump doesn't like running dry so it'll have to be switched. I considered fitting a microswitch close to the tiller arm to be activated with full left rudder but decided that would interfere with my sailing. My next plan was for a float switch to operate the pump - it should have worked but didn't! A micro-switch, a piece of cork, a few scraps of balsa and some glue and I had a float switch. Testing proved it was u/s, there isn't enough depth to the sump tray so back to the drawing board. Enter my brother-in-law, "An electronic switch is what you need here," he said. Two weeks later he came back with a device which works perfectly.

Then I thought of another problem with the boiler - I'd dealt with the combustion gasses but what about air; inside a sealed hull the burner would be starved of oxygen. I thought about using the ventilators but since construction of hollow vents is beyond my capabilities and they would probably be insufficient to deliver enough air I turned to the bridge house itself. Since this sits directly over the boiler I decided that making modifications to it was the best option. The bridge is supposed to be on two levels, the lower level is a sealed box while the upper level is open to the rear. Instead of drawing the three doors onto the lower section I cut them out and also left an inch wide gap at the front of the upper section floor.
The bridge house is supposed to cover the forward access hole but with the hole enlarged to allow fitting of the boiler more mods were necessary. The only solution was to create a new forward deck from 1/16th ply. I did this in four pieces, front and two side sections glued to the existing deck and one section left removable to cover the access hole. The bridge house, funnel, vent and gun fit onto this removable section.

Next job was to plan fitting the radio gear. Within a potentially wet environment I had to protect the electronics. Putting them in a sealed container in the section forward of the boiler seamed to be the best solution but that would mean routing control rods past the boiler and engine. A better solution was to fit everything in the stern section. The access hole to the rudder is large enough to allow me to make a platform for the servos and receiver and, since its well away from the steam, a water tight box wouldn't be necessary. The aerial fits into a plastic tube glued to the underside of the rear deck. I built a platform to carry the bilge pump and its control circuit and fitted this at the rear of the engine section, it proved to a very convenient location for the receiver battery pack as well.

With all of these problems resolved I did a 'dry run' of fitting everything inside the hull prior to fitting the side skins. I had to reassure myself that I would be able to fit the engine, boiler and radio gear through the access holes. Apart from it being a little bit fiddly, especially with the engine and its sump tray, everything went in as planned.

When the hull was complete with its side skins I decided to add a coat of resin to all it's interior surfaces to protect them from steam and water should anything untoward happen with the boiler, engine or piping.

All of the superstructure is made from 3mm balsa except for the minesweeping winch which is 1/16th ply bent over 3/8th ply sides. Railings are brass wire soldered up on a little jig that took ten minutes to make and saved hours of time and burnt fingers. The funnel is a length of plastic drain pipe. Minesweeping floats were carved from 1/2 inch dowel, davits are copper tube. Vents, ladders, searchlight, bitts and fairleads bought from Ashton Models. Three vents were extended for height with 10mm copper pipe glued together with a short piece of dowel.

Length is 47 inch, beam 8 inch, height of foredeck 6 1/2 inch, height to top of foremast 19 1/2 inch.
During design and construction I have had to make many changes to the plan so it is no longer a 'true' scale model.

For a flat-bottomed boat it is surprisingly stable (at least in the bath). It requires 2 Kg of ballast to trim, 1/2 Kg at the stern and 1 1/2 at the bow. Although I haven't weighed it, I guess it to be about 10Kg including ballast.
In all it's taken me about three months to produce this model and has cost about 350.00 for materials and equipment, the engine and boiler taking about a half of this amount.

Photo details:
Engine: At the left you can see the electronic switch to control the bilge pump and the red control rod for the engine. Hidden beneath this platform is the receiver battery pack. The blue pipe on the right is the steam supply to the engine (this pipe is supplied with the engine).

Boiler: (Shown without the cowl) At the left is the top of the condenser unit and a hole through the bulkhead giving visual access to the boiler level sight glass. On the right (the red part) is the holder for the gas tank (supplied with the engine)

Radio: The receiver is hidden under the deck at the right, the black wire at the top is the aerial going into the tube. Discerning viewers may just be able to make out the lead ballast hidden under the servos.

A final note:
Anyone who is familiar with this class of vessel will no doubt note certain omissions. Most notable would be lifeboats (it's like the Titanic - unsinkable), windlass and anchors, a gun or two, some depth charges and launchers, etc. I may or may not add these things later (providing I can find a supplier for reasonably priced and correct scale parts).
 

I've created my own web site now with everything about Bathurst on it.
There's the stuff I sent you last week plus some details of her maiden
voyage with pics and a video clip (two versions .rm and .wmv)

I've just ordered plans for my next project, St Columba, a Sealink car
ferry. I'll be doing a full report of the build with plenty of pics
and putting them on my site, again you can take anything you want from
there.

Best wishes,
Bernard.

http://homepage.ntlworld.com/b.s.scott/index.html

Best wishes,
Bernard Scott