Using Modern Techniques to Control Historical Troubles
Temperature, humidity and ventilation are the keys to the conservation of the inner hull of a historical wooden ship. Get them right and keep them right then condensation is unlikely to become an issue within the hull to harm any untreated or unprotected timbers. It was when looking at the various means on how to control temperature and humidity that I became aware of the mind-set of some companies (not all) who manufacture or supply such units or systems. The mere mention of a Heritage Lottery assisted Project sent the income expectations of some into overdrive. ‘Ours is the best system on the market and it will only cost £250,000 (TL700,000) to supply and fit’, was a typical response. Get real!! The one thing that many manufacturers and suppliers did not do when I made initial enquiries was ‘get to know the customer’! Had they made the effort they would have learned that I was working to a tight budget and needed original thinking not salesmen’s chatter.
The system I opted for was simple. Portable, thermostat/humidistat fitted, manual control over-ride, heaters and dehumidifiers. These would be placed in the different compartments, a heater at one end and a dehumidifier at the other. First however a safe, tested electrical supply had to be made available in these compartments. The electrical wiring that was already fitted was tested and it was found that it too had suffered from the damp conditions on board. There was no other choice but to rewire the whole of the system, not by any old electrician but by a qualified Marine Electrical Engineer, one that fully understood the conditions that could prevail on board a historical wooden ship. Arbroath is a small fishing port not far from Dundee and has a history of building wooden fishing boats. Sure enough, a well-known and highly respected Marine Electrical Engineer had his business premises in Arbroath and he and I got down to business.
The bilge pumping arrangements on board were a mess. Of a total of 16 pump locations throughout the bottom of the ship only two operated, the rest had succumbed to corrosion and lack of care over the years. The priority decision had to be to get the bilge system fixed and in good working order. Why priority? Well, when the dehumidifiers were up and running they would convert the excess moisture in the air back to water that had to have somewhere to go. Each dehumidifier unit would have a drain hose leading into the bilge where the water could collect. This water could not be allowed to accumulate so it had to be pumped out of the bilges by the bilge pumps, therefore the bilge pumps had to work before the humidifiers were activated. Now a crew member could not have been expected to run around 24 hours a day operating the bilge pumps to keep the bilges dry, so they had to operate automatically. How better to do that than fit each with a float switch, a device linked to an on/off switch that operated when the float was raised to a predetermined level by the accumulating water, the pump would operate until the water level fell taking the float with it until the mechanism forced it to switch off. The pictures show the new bilge pumps being fitted. Where possible the actual electric pump motor was fitted to the deck immediately above the bilge in order to provide ease of maintenance and protection from the damp bilge conditions.
Ok! Now the water levels in the bilges could be controlled and in fitting the new pumps, including re-wiring the electrical system it seemed like job done! Was that it? Not likely! What the managers of the ship needed was real-time information of the conditions on board in order to keep her in a tip top shape. After discussing the matter with a number of companies it came down yet again to cost, and again silly figures were proposed by firms with high overheads. As is sometimes the case, failure to look at what is at the end of one’s nose often hides the obvious. A small company in Dundee took an interest in what was going on and came up with an affordable and ground-breaking solution. The activity of the bilge pumps could be monitored, recorded and the results made available on computer using internet technology. The same could be done for the temperature and humidity in each compartment of the ship. The equipment was commissioned, delivered and fitted. The Discovery’s Operations Manager then had the ability to read the results on his computer, sitting in his office at Discovery Point. The pictures show the equipment fitted in the control room on board (1), the remote temperature and humidity transmitters in each compartment (2) and a receive/transmit unit fitted to the deck housing to monitor the outside air temperature and humidity (3).
The great advantage of fitting such equipment was, and is, that it provides an early warning of problems and allows management to act quickly. For example, if a particular bilge pump shows unusual activity that could mean that a leak has developed in that compartment of the ship and steps can be taken to fix the problem. If a compartment shows that the humidity or temperature require to be adjusted then the manager is able to order the heater or dehumidifier’s controls to be manually adjusted to lower or increase the temperature or humidity.
The finer details of the equipment may be of interest to some, so anyone who may want to learn more can contact me by email firstname.lastname@example.org .
Next. Restoration of Discovery continues and replacements are necessary.
© Captain John J Watson OBE January 2012 Fethiye