Pitfalls of Plastic- Or Not? A Cautionary Tale

[Kerry1]

We finally had a summer weekend free to take family out for day trips. We chose to motor down the harbour just my wife and I and pick family up from a public jetty, and take them to do whatever they wanted, fishing, snorkelling or just to a nice beach for a swim, lunch on the boat whatever.

The plan was to take a family of six out on the first day and a family of four the second day of the weekend. The first three times coming into the jetty went well, and the guests boarded and disembarked without fuss. I noticed from the first, there was a proliferation of fishermen on the wharf so I duly did a "fly by" asking if they could interrupt their fishing long enough to berth and exchange passengers. Then I came around, usually up wind and came alongside, taking maybe 5 or 10 minutes which they in general were more than happy to do, even offering to take ropes, steady the boat etc.

On the final approach to the pontoon jetty (of which there is a dearth of in Whangarei Harbour, particularly in its outer reaches) I was a little unsure of myself. The wind had strengthened blowing us at an oblique angle onto the pontoon, but the tide was also at a strong ebb in an almost opposite direction. Which force is going to affect our ship the most? At first I decided it was the current so we would go for a starboard berthing. But as I slowly approached and gave my customary warning to pull fishing lines in, I realized in fact the wind had got hold of us more than the current. At just a few meters from the pontoon I asked the crew to swap fenders and lines and we'd go around and come into the jetty upwind.

That was the plan.

What actually happened was quite different. Just as my wife was forward swapping lines over to the other side, she called back that we had a fishing line over our bow.

What is a piece of nylon, a hook and a piece of lead worth anyway?

I think my next decision tells a lot about the difference between being experienced and not so much. Unfortunately I fall into the latter. My only redeeming feature is that henceforth on this score I now have some experience. I will not stop for a fishing line again.

I quickly threw the gear shift into reverse, and hoped that we could slow the boat down for long enough for this deaf and blind miscreant to pull his line in.

But it was not to be so easy.

The boat came to a stop easily enough, but of course we were now at the mercy of the wind which promptly started to bring us ever closer to the pontoon. At this stage I recall having just crept past the end of the pontoon so that our starboard quarter was not quite past the corner of the jetty. My reverse thrust had kicked the stern towards the pontoon. At this point even though I had put the gear into neutral I was surprised to see the stern approaching the pontoon at a steady pace. Was the current stronger than the wind after all? I moved the gear into forward and increased the revs to counteract this reversing movement. Much to my consternation the speed of my starboard quarter towards the pontoon also increased. Before I had time to react and take in what had happened- whump we hit the jetty with the rubber edge of the sugar scoop stern with quite a smack, I saw the rubber crumple and distort and hoped like hell the hull/deck join was solid.

At this point I decided against using the gear/throttle lever for anything. The gearbox was still in reverse, but being a single lever for gear shift and throttle, while I couldn't get into forward gear, I could indeed give it more throttle in reverse, even while from appearances I had the lever in forward position, the throttle aspect of it was working fine- to my disadvantage actually. If I had more time, which at this point I didn't, I would have been clearer in my understanding, but other matters were quickly pressing for attention.

At least one other question had been answered. In fact the wind was just slightly more in control of our boat than the ebbing tide. Because at this point we were totally at their mercy, with our craft drifting slowly onto the shallows and rocks just past the jetty. By this time the crew were wildly throwing lines to people onto the pontoon to regain some control, as clearly the skipper, God bless him, had apparently lost the plot. Everyone, it seemed at this point, was determined to take control, and there were commands going in all directions, and one and all saw themselves as the authority on everything. Every rope we threw fell just short of the many outstretched hands craning out from the pontoon.

In an act of desperation and contrary to all nautical protocols, I- like the master of the Concordia- abandoned ship. I took to the water with my own lifesaving strand of line while my son-in law made it fast to the port quarter. Now I'm not a great swimmer and certainly no match for an 8 ton vessel with the wind up her bum. While I didn't make it to the pontoon with my line, I took the next best course and finally managed to stand on the rocks leading to the jetty and held on for dear life as my pride and joy largely decided for herself what course she should take. While I stopped the forward progress I watched the bow come round and a gentle thump as she grounded or at least came alongside rocks-I couldn't tell- on a strongly receding tide.

That's when my evil imagination got into hyperdrive and real panic started to set in. Well actually I was probably somewhat there already. A member of the public kindly jumped in to help me with the line. Well actually he landed right on top of my bare feet which were gripping tightly to oyster covered rocks. I let out an involuntary scream and then thanked him for his help.

Leaving him to man it out, I realized the others had finally got another line to the pontoon, and was somewhat surprised to see my daughter was on the pontoon encouraging others to haul as hard as they could to bring the bow back towards the deeper water, but the angle the boat had taken was making it impossible at that point. In the kerfuffle she had at jumped onto the jetty as I was trying to make sense of the odd behaviour of my engine controls.

Now free of holding that line for grim death, I had time to think- what now? I made my way back to the boat and hauled myself into the dinghy which was quite nonchalantly tugging on her tether oblivious to the perils at hand. I barked at my wife to get me the oars stowed on deck, and made a vain attempt to pull the bow round under oar power. But to no avail. It didn't help at all that one of the oars kept popping out of the plastic rowlock holder when under any sort of pressure. I had done so much rowing with that rubber ducky that I had worn the ridge out that held the rowlock in place.

Think again....

It took longer but I went back to the stern and hauled myself aboard to get our 3hp outboard engine off the pushpit railings and mounted it on the dinghy. While the engine was warming up I hauled the dinghy round to the starboard bow and fastened lines from the dinghy davit brackets welded to the RIB hull fore and aft and put it into gear. As we slowly brought her round by this time the corner of the pontoon was about midships and with help from the forward lines and the dinghy we pivoted "Silent Charm" until she came alongside the outer edge of the pontoon where we had intended to be from the start- and we collectively breathed a sigh of relief and took stock. Obviously we hadn't grounded but had come alongside rocks. There was no swell, just wind and current, the sea was flat.

I say breathed a sigh of relief, but that's not quite true. While it may well have been for everyone else I took it in my head to get angry about the guy that didn't pull his fishing line in. The next thing I found myself standing on the deck looking down at all the people who had been helping us on the pontoon and giving a fine speech about irresponsible people with their fishing lines. "This is a public jetty, not just for fishing blah blah..." One of them, apparently the wife of the man who had jumped on my foot to take the strain, took special offence at my speech and started berating me for not being thankful that her husband had "risked his life to save my stupid boat". The jetty quickly emptied and we were more or less left alone to ponder our next moves. I have vivid recollections of this mans wife walking backwards vociferously exclaiming what sort of person I was while all the while raising her hand with one middle finger extended. Even my daughter apologized for my ungracious behaviour.

By this time, a skipper from a launch anchored close by who was a diesel mechanic had come aboard for some diagnostics. This may sound ungracious as well but I couldn't help wondering where he was when I needed a pull off the rocks. I was sure they were observing the whole drama as it unfolded from the comfort of their deckchairs. I guess we all like entertainment whichever way it comes. I could smell the rum even as he gave his candid opinions and then he departed saying that the rum was calling. Okaaaay....

Now the part you've all been waiting for. Well probably just one or two of you hardy souls who have chosen to endure my novella.

What went wrong?

When we bought our Bavaria 38 we were warned to do the gear change quietly and smoothly. As the broker took us out for a sail he inadvertently demonstrated what he called a "flying change" as he graunched the gear a little too quickly in the marina as we were leaving. There is no clutch on a saildrive, at least not in our Volvo Penta 120S. So the linkage just meshes two gears together at a necessary idling engine speed. There is always a little clunk as this happens and off you go, there is no clutch system softening that sudden change in loads. With our mechanic friend I had opened the inspection hatch in the side of the pedestal and found that one of the control cables had come away from the gear lever attachment point. I had lost the ability to change gear but not the ability to rev the engine. Only the gear shift cable had come adrift, so that when I tried to counteract the reverse motion of the boat I had in fact made it worse- contrary to appearance- I gave more impetus with more throttle on, thinking it had gone into forward gear. Having had a subsequent look at other morse controls I see that most of them have metal clamps to hold the outer cables to the control lever base so that the inner moving core of the cable can do it's work effectively. Once the outer cable has come adrift the whole thing moves negating the effect of the gear lever.

In our case the outer cable sleeve has a plastic fitting held to the alloy base plate bracket by a single stainless screw which pivots to allow movement in an arc. The plastic is in the form of an open ended trough in which the outer cable sits covered by a clip on stainless steel cover which prevents the cable sleeve jumping out. There is a plastic sleeve stopper which sits in a groove in the outer cable and a groove made in the plastic fitting preventing forwards and rearward movement as the gear shift is engaged.

When I examined this piece carefully where the plastic trough broke I was astounded to see the part was deliberately moulded to weaken the trough at the critical area where the cable clip sat in the moulded grooves in the trough.

Which set me to thinking. Why?

My only conclusion that could mitigate my concern at such a design "flaw" is that this piece is made to act in the same way a fuse does in an electric circuit. In this case a very fine piece of wire is designed to take the whole load of the electric circuit, but only just, so that at any moment of a circuit overload this fine fuse wire burns out inside a protective ceramic environment in order to protect all the rest of the circuit.

I can only imagine this thing is designed to break if a heavy handed operator changed gear too quickly and thus potentially avoid a far costlier calamity such as a blown gear box. Am I correct? You be the judge. I hate to imagine if this incident had taken place under much worse conditions.

I enclose photographs and diagrams to show the weakness, and the actual broken part.

[NCGunDude]

That's quite the tale, Captain! Your design assessment is quite plausible. Either way, you know the cause, and unlikely to make the same mistake in dire straights, again.

It's amazing how wind, tide, rocks, and oyster shells can get out of hand, so quickly. I quite literally felt your pain at it's telling! A little rum, however, goes a long way to rinsing out new wounds, and reminiscing about old ones. Here's to your new wounds becoming old ones, cheers!

[Kerry1]

Yes, as always the buck stops with the master, and ultimately the responsibility is mine, but other people have responsibilities for their actions as well, and the purpose of my speech was simply reminding them of that, but tinged with anger, and just after their efforts to rescue us, I guess it's never going to be an opportune moment to castigate anyone. I just hope the next time they see someone who hasn't pulled their line in that they might have a mind to get them on to it. But as for us, we will just keep trucking, fishing lines or not.

I am left wondering if I did use more force than usual or whether that plastic was (after 14 years) just fatigued. Perhaps anyone with the same and similar aged engine control system might contemplate putting new ones in.

Cheers

[Tillsbury]

I'm not sure I understand the problem with the fitting. I'm guessing you're talking about a standard Volvo Penta throttle/gear linkage, right? The plastic part you're showing shouldn't be taking any force at all really -- the fittings are secured by the two bolts (one in place in your photo, and one missing but should be going through the second hole visible). Or do you have some other arrangement in there?

[Kerry1]

Originally Posted by Tillsbury

I'm not sure I understand the problem with the fitting. I'm guessing you're talking about a standard Volvo Penta throttle/gear linkage, right? The plastic part you're showing shouldn't be taking any force at all really -- the fittings are secured by the two bolts (one in place in your photo, and one missing but should be going through the second hole visible). Or do you have some other arrangement in there?

The force it takes is whatever resistance is in the cable and whatever it takes to move the throttle spring at the injector pump. or in the case of the gearbox, whatever it takes to move it into/out of gear. Of course- if the cable is kinked, damaged, corroded, or just lacking lubrication, then it will take more effort all of which gets focused at the weakest link which is right at that plastic part and the half moon retainer. The force is no doubt magnified if the gear change is fast or rough.

The second hole visible is, as I understand it, an alternative place for the single retaining bolt, I imagine for a different length cable. All of the attachment points on the whole mechanism have dual position options for both the inner cable termination and for outer sleeve retention. There can only be one retaining bolt for the outer sleeve because that plastic part must rotate with the cable outer, in an arc to follow the position of the cable core end as the arm swings, either to give more throttle or as the other arm swings through an arc to change gear. The place in the plastic piece which appears to be made to accommodate the second bolt, is really there to accommodate the rubber grommet where the outer cable reduces to a stainless tube. I have written a post on how to replace these parts or do an inspection:Replacing Engine Gear Control Parts On A Bavaria 38

I hope this helps.

[Tillsbury]

Ok, that's a very different fitting from the one I have. Mine is a top-mounted semaphone which inexplicably has one side made from plain steel (the rest is cast aluminium) The top had been cracked, allowing water in and that had rusted away the steel plate. I managed to find an old stock Teleflex one (identical to the Volvo Penta one but missing the little Volvo Penta sticker), and swapped it in. Although the termination mountings for the control cables are plastic and similar, they don't have the section shown in your example, and each one is held on by more than one bolt. Sorry for the confusion.

Having said that, your reminder that one should always deliberately take the throttle to the centre, then carefully to reverse, then increase thrust is a good one. Make sure you're always in the gear that you're going to want to use, even if the engine is only idling.

And, of course, only approaching something fixed to the ground at a speed you're happy to hit it :-)