Sinking alongside
John Rogers has a close call when his shaft seal stops working and starts letting in water
A close call with a leaking shaft seal
While reading the article ‘Stay Safe on the Water’ in the winter 2020 RYA Magazine, I felt a chill go down my spine when I read ‘sinking’. I commented to my wife, Diana, this could so easily have been us!
The article I was reading analysed the reasons for RNLI callouts between 2017 and 2019 and of the 17,000 callouts over half were to recreational boaters.
They divided the causes into five categories and the first four were quite self-explicit and not unexpected: machinery failure, equipment failure, stranding or grounding, and human error. It was the fifth category of ‘sinking’ which alarmed me: during that period there were 200 callouts to sinking vessels.
The common causes given were: prop shaft coupling, stuffing box, deepsea seal, exhaust, and skin fittings. The RNLI’s advice is to check these regularly but they tend to be in the most inaccessible areas of the boat and hard to deal with when there’s a problem – as we found out to our cost last August.
Di and I were enjoying a leisurely cruise in our Southerly 100 Lyra in the lovely summer weather despite the strong onshore wind generated by the hot inland temperatures.
Most of our sailing was done in the early morning before the wind strengthened and we made a good passage taking the ebb tide from Brightlingsea to Walton Backwaters. Once through Hamford Water we lifted the keel and dropped anchor in Landermere Creek in the lee of Skipper’s Island, one of our favourite anchorages.
We enjoyed a quiet evening and comfortable night in these beautiful surroundings with their interesting wildlife, but it was too windy to take out the dinghy to explore. We therefore decided next morning to contact Titchmarsh Marina for a berth giving us the opportunity for a shower and a wedding anniversary meal at the Harbour Lights restaurant. We were given a berth number and it was agreed that we’d arrive around 1300.
As we weighed anchor at 1200, a DSC emergency made our VHF radio ‘screech’ to a point where communication was impossible, so in haste we turned it off and then forgot to turn it on again, something we were to regret later.
As we headed out of the shelter of the creek, we became aware of the full strength of the north-east wind and noticed the numerous yachts that had been anchored in Hamford Water the previous evening had sought shelter elsewhere, many in the lee of Stone Point and Walton Channel.
As we arrived at the entrance of Titchmarsh Marina the wind strength increased further, and we prepared for a challenging berthing in the strong crosswind! Our concerns were compounded when we found our allocated berth was still occupied by the incumbent resident who’d decided not to venture out in the windy conditions!
Fortunately, the bowthruster saved the day as we managed to power round and look for an alternative berth. At this point a helpful resident seeing our predicament informed us that the berth next to him was free, so we turned and cautiously made our approach starboard side to! With the help of four others to take our lines, judicious use of the bowthruster and the wheel hard to port with bursts of engine power we managed to get alongside.
Relieved to be safely berthed, we asked ourselves why we’d not been advised by the marina of the change in berth? At that point we realised the VHF radio was still turned off so it was our mistake and we learned later that the marina had been desperately trying to contact us!
Before we headed off for a shower, Di suggested I wash the Blackwater’s mud from the foredeck. I took a bucket and sponge from the cockpit locker and once the foredeck looked respectable, stowed it back in its correct place.
Running water
It was then, with my head down in the locker out of the whistling wind, that I noticed the unmistakable and chilling sound of water gushing into Lyra. I asked Di, who was in the cabin, if she’d heard any water ingress and she said that she may have heard something, but it was difficult to determine over the sound of the wind and clattering rigging!
Together we hastily lifted an inspection cover on the cabin floor and peered into the bilge; sure enough there was nearly a foot of water – which is a significant amount in a Southerly’s flat bilge. What’s more we could hear water still gushing in and it was almost up to the electrics of the keel hydraulics.
I removed the engine cover and tried to lean over the engine to find the source of the leak but, having been recently used, it was far too hot to lay on. Then at breakneck speed I cleared the inflatable and other gear from the quarter berth to give me access to the back of the engine.
To my horror there was a massive ingress of water around the stern gland. Water was spraying in all directions and I really had no idea what to do. All I knew was that I had to act fast to stop us sinking to the bottom of Titchmarsh Marina!
Knowing little about the workings of these PSS (Packless Sealing System) stern glands, I noticed two Jubilee clips and assumed one had become loose. I grabbed the correct sized socket and at full stretch managed to give a few turns, but to my dismay they seemed tight and the water was still pouring in. I then waggled the water feed pipe which lubricates the gland, to ensure it hadn’t
broken off. To my amazement the water flow suddenly reduced to a small trickle! This was a massive relief; I had no idea of what I’d done but I had saved Lyra from sinking, something that would have been certain had we not noticed the problem and gone for a shower!
This all happened so fast that we had no time to seek help or pump the bilges but hereby hangs another lesson! As with most GRP boats there is so little water in the bilge that the pump is rarely used to properly test it. This was true in our case for when we tried to pump out the huge volume of water in the bilge the pump proved to be ineffective. We also have no electric pump (unlike most owners of wooden boats), so we were lucky that the water had not reached vital electric components causing expensive repairs!
Luckily, we were loaned a very effective hand bilge pump and, after an hour and a half pumping, we managed to reduce the bilge water to a minimal level. To be on the safe side, the marina kindly provided us with an electric salvage pump to leave in the bilge overnight, just in case!
On Monday morning an engineer from French Marine came aboard and re-set the preload on the PSS gland to give it more pressure against the large stainless collar on the prop shaft. He said it was an excellent installation but worryingly he couldn’t really explain why it had failed, beyond saying it somehow lost its preload! However, he stressed to my concerned wife that we’d be OK to sail back to Maldon – we didn’t want a recurrence of the problem off the Naze!
Looking for answers
Technically PSS glands replace the traditional grease packed stern gland with a smooth rubber gaiter which is pressed against a stainless collar on the shaft to give a perfect seal. They are used reliably in all types of craft and my engineer, who has fitted hundreds, has never known one to fail.
On our return to Maldon the engineer, who’d fitted the gland only two years before, was so concerned that he ran some stationary tests while Lyra was lying in her berth. He asked me to mimic the engine actions I used when mooring up in the marina by giving bursts of high revs with the helm fully to port to kick the stern against the pontoon.
I was instructed to alternate the helm between port and starboard giving full bursts of engine power on each full lock while the engineer kept a close eye on the PSS gland.
I only use this effective action occasionally when there is a difficult berthing. During this action the 14in propeller, powered by a 34hp Beta, creates an enormous prop wash across the rudder to kick the stern in. This in turn puts a high torque on the prop shaft and makes it flex, especially when the rudder is on full lock. During this manoeuvre, the engineer noticed a spray of water from the gland interface which was more pronounced when the helm was to port rather than starboard. It seemed something was compromising the ability of the gland to make a perfect interface when the helm was turned fully to port.
Assessing the problem, the engineer decided to cut the cable tie which was supporting the water feed pipe, thinking it may be too close to the gland. This appeared to be preventing the PSS gland from compensating for any slight flexing of the prop shaft particularly when the helm was to port. Miraculously by allowing the feed pipe more freedom to move, the problem was solved and there were no more leaks.