The Challenge:
The operators of the museum ship M S Norgoma (Sault Ste. Marie,Ontario) as heritage site and tourist attraction were looking for audio devices:
- to tell the story of the vessel (its role & significance),
- to guide the visitor through the vessel and
- to interpret the features of the vessel.
Portable hand held audio devices were considered, but it was felt that stationary stations had several advantages:
- no handling, do not need to be given out or retrieved
- much simpler to operate
- do not have batteries to charge
- can be heard by more than one person
- more durable & maintenance free
- not easy "to walk away with"
- give a sense of participation in vessel operation
Tour Format: the following approach was developed.
Narration is given by 7 independent audio stations located at strategic locations on the vessel. Each station introduces portions of the vessels story, describes the features of the vessel on the deck on which it is located and provides direction to the next station. Each narration starts with sounds appropriate to the station - fading to the background as the narration commences, ie., restaurant, kitchen, wheelhouse, engine room, hall chatter, waves, gulls & ships horns etc. A volunteer with access to the radio station recording equipment & sound effect library prepared the narrative. Narration is available in English and French.
When a visitor arrives at the vessel the attendant describes the "special feature", referring to a sample audio station and provides instructions and a handout on the operation of the stations and the tour route throughout the vessel (See attached samples of attendant introduction & handout).
Tour Station Concept:
The audio stations are modeled after official "special purpose" channel marker
buoys used to guide vessel on local small craft routes.
6" x 10' PVC sewer pipe & caps was selected for the outer "tube". The material is durable & easy to cut with woodworking tools. Manufacturers information was removed with steel wool & light sandpaper & a fiberglass boat restorer cleaner/wax applied as a finish.
Station 0 is a "dud" for instruction purpose.
Each operating station is activated by a simple push button at the centre of the top and a toggle switch at the back offers a choice of narration in English or French.
Each station is self sufficient but requires a connection to a 110v electrical outlet. The outer tube containing the controls & speaker lifts off the base to allow adjusting the volume with the unit in the location where it will operate. The audio unit is mounted on the inner tube. The height of the audio unit is for convenient access to the unit controls. 4 "x 10' PVC pipes & caps were used for the inner tubes
The audio units are CFS III's from ASC-Ackerman Computer Sciences, Saratoga, Fl. www.asccontrol.com. They use standard WAV files stored on individual 512 meg Flash Cards. They put out 25 watts per channel with CD quality. The audio units & 3" car speakers will not be bothered by the winter conditions in the Norgoma. Sound quality from the speakers is fine for voice & sound effects.
Wiring is contained between the inner & outer tubes. Wires to the speaker & switches are long enough to allow the outer tube to stand alone.
Wires for the power exit the tubes through a notches in the outer tube base & outer tube itself.
Fabrication
Shop drawings show the details & the important dimensions for fabrication.
The first drawing details layouts for cutting & drilling & the graphics. Fabrication required drilling & countersunk holes for the many 1 & 3/4" OH #8 stainless steel screws used to assemble the components. Graphics were precut self adhering vinyl supplied by a sign shop.
Details of the inner tube & mount for audio unit
Location of speaker compartment is in the outer tube.The lower chamber in the inner tube is filled with sand to add stability to the unit.
Speaker Mount
Mounting the circular speakers inside the circular tubes required a special "transition piece" made from 3" ABS pipe caps.
The speaker, transition price & grill are mounted by 2 bolts through the outer tube. The grill consists of a polyester speaker cloth backed up with a curved metal grill salvaged from a dollar shop waste paper basket.
Wiring
Set up of the audio unit followed the extensive instructions supplied by the manufacturer.
Parts Fabrication The units require several duplicate parts needing accurate, and difficult cuts.
Four jigs were developed to hold the parts firmly & guide precise cutting.
The first jig holds the outer tube for accurate layout & drilling. A bolt in the back of the tube holds it securely to the base of the jig. It is shown below holding the test mock up of the speaker chamber.
The second jig is for cutting the various "rounds" with the band saw. Blanks are rough cut & drilled with a shallow bolt hole at the centre of the blank.
The jig for the final cut is clamped to edge of the saw table and has a bolt that can moved to various pivot points for different cut radii. The blank is placed over the bolt & rotated for a precise cut.
The speaker transition piece requires 2 jigs to guide its shaping. One is for cutting with the band saw to match the inside of the outer tube. Another is to hold the piece for cutting out the opening for sound from the speaker.
The third jig has 2 bolts to hold the 3" ABS cap to the vertical surface of the swivelling clamp. Two holes are drilled in the cap for the bolts & a third small center hole guides later cutting with the hole saw.
The clamp swings the cap on a pivot at the radii required for the inside of the outer tube.
The fourth jig holds the cap horizontally for cutting out the speaker opening with a hole saw in a drill press.Two holes for the clamping bolts match the holes in jig #3.
Station No. 7 is outdoors & requires an outdoor speaker, mounted separately - the electronics are kept indoors – the station only contains its control switches.
The 4" outdoor speaker is mounted directly to the cabin of the vessel.
2 toggle switches operate the unit an Off-On(inst) and a On-On. Switch boots provide waterproofing. Wiring is connected through a cabin mounted terminal, security is provided by a chain & lock.
The colour coded spade terminal provides easy disconnect & connect for annual storage.
Visitor Tour Guide A handout introduces the vessel and guides the visitor on the tour around the vessel . Hopefully the handout is kept and becomes free advertising.
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