The Gearbox Saga

As our regular readers will know, Valent suffered a gearbox failure whilst anchoring in Deshaies, Guadeloupe on the 9th March. Not so much Death in Paradise as Adrift in Paradise. The failure occurred with no discernible change in noise, just we ceased to be able to go forwards or backwards. A quick investigation showed that the control cable was intact and the gearbox had oil, so the problem became more serious. Something was wrong inside the gearbox. To refresh your memory, a tow into the anchorage, followed by a series of manoeuvres under sail, and then another tow from the anchorage in Antigua saw Valent safely into Jolly Harbour, alongside the boatyard wall, and work could begin.

First thought was that the oil pump might have failed. The pump was removed and it was quickly apparent that this was not the case. Nothing as simple as that. Unfortunately this now meant that the old gearbox needed to be removed from Valent to enable it to be opened up and the cause of failure determined. The gearbox on Valent is a substantial piece of kit and weighs in excess of 50kg. At this point we feared that in order to remove the gearbox we would need to pull the shaft back and that would mean being lifted out of the water. Apart from the cost of the lift, we would not be allowed to stay on board Valent whilst she was out of the water and our fridge/freezer would not be available. All that lovely French food in the freezer would either be gone or we would need to find a freezer elsewhere. And the cost of accommodation in Jolly Harbour over Easter was eyewatering. After a bit more investigation we realised that Valent had an Aquadrive coupling between the gearbox and shaft. This coupling could be removed without affecting the shaft or stern gland (the key part of stopping the boat filling up with water – a bit like taking a bung out). Removing the Aquadrive luckily gave us just enough room to disengage the gearbox from the engine and the space to manoeuvre it out of the engine room. It was a 3 man job and required serious agility in some cases.

Having removed the gearbox it was taken to the workshop and investigation began. It became apparent that it was not a simple issue. The fault turned out to be a sheared keyway. The key is a solid piece of metal that provides the fixing between the shaft and gearbox. This had cleanly sheared in half, hence when the gearbox spun there was no force or engagement on the shaft, hence no propulsion. You can clearly see the 2 halves of the key in the pictures below (middle and right). Now started the saga of finding the solution.

The sheared key is at the 10 o’clock position on the right picture and top centre on the middle picture.

After a few hours of searching online I had found both UK and USA suppliers of spare parts for our gearbox (Twin Disc). Unfortunately none of these suppliers had the parts in stock and the best lead time was 12 weeks on certain parts. We then tried to find a new gearbox, but the only 2 we could find of the correct size had the wrong ratio (means that the shaft/engine will not spin in alignment). While we were debating which of the new gearboxes was the least bad solution we started investigating the option of machining replacement parts on Antigua. We found a workshop that could do the job, but we would still need to find some piston rings/seal rings (think tight fitting rubber bands that fit on the shaft to provide a seal). These are a specific size. No one had these bands without a 93 day lead time. Then I found a supplier in Greece who was selling a Twin Disc service kit that included all of the required seals. At the same time as I found the Greek supplier, the Nanni distributor in the UK (AR Peachment) contacted me to say that Nanni had found an identical gearbox to ours languishing in their warehouse. It had never been used, but had been on the shelf for a long time (maybe 20 years). I decided to progress both solutions, you never know what might go wrong, but the favoured solution was the new gearbox.

The next challenge was logistics. Firstly we had to overcome the reluctance to ship the new gearbox direct to us in Antigua from Bordeaux. At one point it looked as though we would need to ship it to a UK address, then onto an agent in Antigua at the other end of the island. Eventually common sense prevailed and our gearbox started its journey from the Nanni warehouse in Bordeaux. After a brief stop in Paris it got stuck in Leipzig. The DHL website implied that there was a paperwork issue. However this turned out to just be a glitch due to the Easter holidays. The gearbox continued its journey and arrived a week later in Antigua, and thanks to some good work from our agent it was delivered to us the following afternoon.

In the meantime our seals has started their journey from Greece. Fedex would not quote direct to Antigua due to a lack of ZIP code/Post Code. No such problem from DHL. They too came via Leipzig, Cincinnati and Puerto Rico. The seals arrived the day after the gearbox, 5 rubber bands in a large cardboard box!

Next step was to examine the new gearbox. The guys here decided that the red colour was a primer coat, and matched the Nanni engine blue and repainted the new gearbox. After a weekend of drying Monday 8th April was the big day. Again 3 people were required, and the new gearbox was carefully lowered and manoeuvred into place. It meshed in beautifully, everything lined up and now we just had to reconnect everything and tighten it all up. On Wednesday the gearbox was in, engine rebuilt and we started her up. Everything sounded good. We went forwards and backwards.

On Thursday we took Valent out for a longer shake down. Having successfully slipped the berth, we did some turns near the berth and then headed out for an hour or so of motoring. All seemed good. The engine sounds a bit louder/throatier at high revs, but all seems to run well. At slow ahead it is significantly quieter, very smooth.

The issues remaining are all related to the other jobs that we originally came to Antigua to resolve: a non-working alternator (which they could not start to work on until we had a working engine) and a faulty log/boat instruments. We have fitted a new transducer (twice) (measures speed & depth) and ITC-5 (twice) (converts the transducer output to a visual figure). The first new transducer was so ‘Smart’ that it tripped the boat’s navigation system. It was diagnosed as a factory fault and a refund issued. Then we found that the ITC-5 was not working as well as it should, and the first new one had also failed! Some bits are getting fixed, but annoyingly something is wrong and is now traced to separate wiring faults with both the alternator and boat instruments. We are hopeful that Monday 15th April will bring a solution and maybe, just maybe we can leave Antigua and go somewhere new for Suzy’s birthday.