The Solent Class and 48’6″ Oakley Lifeboats all have 24v electrical systems for the operating systems on the engines, navigational, communications and lighting systems when new. Two very powerful CAV alternators being mounted remotely, driven by shafts and toothed belts, one ahead of each engine, generate the electrical power which is supplied via a pair of heavy duty rectifier/regulator units to two separate, fully switchable battery banks under the wheelhouse. Originally each battery bank comprised of four 6v heavy traction batteries mounted in series to achieve 24v. Currently I have a pair of heavy duty 12v batteries mounted in series for each battery bank, I may return to 6v traction batteries when a replacement is needed, hopefully that is not for some time yet though!
The Gardner engines are started by large 24v CAV starter motors which almost sing when operated, beautiful pieces of equipment. If there is ever a problem with the starter motors, there is a manual starting system with twin handles turning a chain which then turns the crank pulley, that’s two people turning the handles while a third releases the engine decompressor levers at the opportune moment . . . Luckily the CAV starter motors and CAV starter buttons are very reliable in service!
All original electrical equipment on the boat in RNLI service was 24v, that included navigation equipment, intercom / radios, ventilation, safety, lighting and the very important hot water kettle.
These days we still have 24v for most of the boat’s electrical systems but some of the current navigational equipment is 12v and a separate power source is utilised for this from the battery banks.
In addition however we have a useful Lister/Peter diesel powered 240v 10KVA generator that as well as providing 240v for sockets, lighting and some domestic appliances will also provide 24v via an Inverter/Charger to run the 24v equipment and charge the 24v main batteries and a back up battery bank. This provides us with a convenient extra electrical system and of course provides an additional 24v back up should the main system have any problems at sea, a great safety feature .
Ventilation – The Solent Class have a total of six, 24v operated Airmax fans that ventilate the Engine Room, Fore – Cabin and After – Cabin. The Engine Room has three fans pumping fresh air via ducting to the rear of each gearbox reduction unit and battery bank, the third duct blowing at the base of the port engine. There is one vent outlet above the starboard engine for hot air venting if necessary but it must be remembered that the engines total a swept volume of 29,000cc between them so are already extracting a huge volume of air from the engine room with each revolution, the fans are very powerful so that the air flow demanded by the engines is matched even when the engine room doors are shut, which they should be at sea. On ” James And Mariska Joicey’ one of our Airmax fans had been taken for repairs by the previous owners and cannot be traced currently, so currently we’ve fitted a modern but less powerful bilge blower pump to feed air he port aft ducting as a temporary measure and are actively trying to find a replacement Airmax fan as a priority. We just missed a pair on eBay 2 years ago and despite having an active search set up, to date frustratingly, during which we have written in desperation to the original manufacturer but they’ve closed down it seems and to date no more have been found!
Our good friend and fellow historic Solent Class Lifeboat owner Derek John Briggs has secured a pair of genuine ex Solent Class aft cabin ventilator boxes c/w capsize valves, these will be stripped, cleaned and powder coated before fitting to J&MJ, we now need an extra Airmax fan of course!
The fore-cabin has one smaller Airmax fan drawing in fresh air form the starboard side which circulates in the cabin before exciting via an outlet in the heads (toilet) on the port side. As the forward compartment that was originally closed off and filled with buoyancy foam has been opened up and made into a double bed on ON1008, I’m currently experimenting with extended ducting from the fan to the forward part of the cabin, if the airflow isn’t deemed to be high enough then a second 24v fan will be fitted inline in the ducting.
