Episode 3 Rust (Part 1)

The most galling thing about a trailer sailer is that the trailer, as the name suggests, makes up about half of it.

Keeping a trailer sailer without a trailer is like keeping a bottle of wine without the bottle. Theoretically, it could be done ("would you like that in a bag, sir?") but, at some point, the practicalities of the situation will force a more conventional outcome upon you.

And, its not as if the trailer is designed in any way to be pleasurable. It has all the grace of an electricity pylon and habitually produces copious amounts of that kind of rusty-grease-mud that perpetually turns up on the one's hands and clothes and gleaming boat parts and car-seat covers. It is the embarrassing uncle that has to turn up for every family Christmas dinner, the tax bill on every pay packet, the manic Monday morning after every balmy Sunday.

Boat trailers, it turns out, are not hard to find if, and this qualification needs to be stressed, you have a motor boat. Snobs and purists (the ranks of which I secretly wish to join) refer to them as "stink boats". Less derogatory language might refer to the motor as an "iron sail". For the sake of world peace, I'll simply refer to them as "other" boats and adopt the politically correctness of the habitual conflict avoider (the ranks of which I have already joined). In any case, the shape of the hull (that part of the boat that gets wet) in these "other" boats is significantly different from sailing boats, and that affects trailer design dramatically. "Other" boats have a planing hull that is typically stamped out of aluminium or steel sheet to form flat-ish surfaces on the boat's underside. Such a hull has as much respect for the water that it is designed to bash through as a hammer has for a nail-head. Because of the planar lines of the planing hull, these boats can be driven directly back onto their trailers with little more that a straight line of rollers or bunks to support them thereon. The boiler-plate hull construction and angle-bracket straight lines makes these "other" boats much quicker to unload and load on their trailers, let alone on the water, and it is the cheapness of their construction, I suppose, that makes them so popular. Looking in used trailer boat yards, like John Crawford Marine, one can estimate that "other" boats outnumber the sailing boats by about ten to one. Commercial realities being what they are, trailer makers now only manufacture trailers for "other" boats and never (or hardly ever) for trailer sailers.

The hulls of sailing boats are the subject of much fascination among sailers, leading designers to all sorts of intricate science and other witchcraft. Fundamentally, though, sailing hulls are not designed for the convenience of being driven up onto trailers with a flat set of rollers and bunks, but are designed to minimise the force needed to ease the boat through the water. Here, we could talk about bow-waves and quarter-waves, tumblehomes and keels, but like all aspects of boat design, everything is really a compromise between the ideal and the practical. For instance, an ideal racing hull is rounded in cross section, rather like the under-quarters of a canoe. The problem with these hulls in trailer sailers is that when loaded onto the trailer, the whole weight of the boat has to sit on tilting rollers. These rollers, in turn press directly onto the surface of the hull, rather than onto some mediating member. Now, because glass reinforced plastic (GRP) hulls tend to creep (deform slowly over time under load), they will get dinted by the pressure of the rollers. To counter this effect, the loads on the rollers are alleviated by providing a cradle on the trailer to support the heavy keel directly, provided it is routinely dropped onto the cradle after use.

In the case of my Austral 20, the boat does not have a nicely rounded cross section, but a skeg keel that forms the rear end of the keel case. This provides a nice flat surface on which the boat can sit, and allows it to sit on an easily-manufactured straight row of rollers arranged down the spine of the trailer. Launching and retrieving is simplified because all you have to do to retrieve the boat is to line up the keel on the rollers and winch it in.

Austral 20 skeg keel on roller bed on trailer. This photo was taken in February 2015 before the trailer rusted further, and needed substantial repairs in September 2015.

These are important facts about trailer sailers that novices, like me, overlook. It becomes even more important when the trailer, like mine, reveals its penchant for producing rust.

This was pointed out to me by a friend after a pleasurable sail, who noticed that the central strut that should have joined A to B was, in fact, cantilevered off A with the joint to B comprising a small volume of rust and a large volume of air. On closer examination, it appeared to have been constructed from fence-post tube and bubble-gum welds. Being a tubular section, the water had got in and had done its dirty work in undetected and uninterrupted seclusion.

At first, I was tempted to accuse the person who had issued the roadworthy certificate of all sorts of wrongdoing. But the certificate was, by then, several months old and the roadworthy certificate does not guarantee any sort of durability. Technically, I believe, all that the roadworthy certificate does is certify that you can drive the trailer onto the road at the instant it is issued without risk of being fined by the Police, who are more interested in lights, brakes and tyres in any case. What happens in the following days, or even seconds is not the certifier's business. So, the prospects for pursuing the owner for selling me a heap of rust-in-the-making appeared poor, and I resigned myself to the costs of repairs.
Austral 20 tilt trailer. manufactured by Kessner, showing signs of rust. More rust was hidden underneath.

I then went about researching trailers. What was the cost of a new one? Between $5K and $10K, depending on how tricky it was to shape the various rollers and bunks to the hull. That's almost as much as the cost of a used trailer and boat, and justifies my earlier comment that the trailer is about half of the trailer sailer in terms of dollar value, if not in frustrated wonderings about where the next thousand will be needed. Further, no one seemed interested in manufacturing tilt trailers, like mine. Tilt trailers have a hinge pin forward of the wheels that allows the rear to tilt down into the water and makes launching much easier and less wet than having to float the boat off the trailer. With a bit of practice, so I am told, you can keep the important things like the bearings and brakes above water, which is a not insignificant fact in terms of their continued functionality.

Having found that new trailers could cost as much as the entire package (hence my comment about them being "galling"), I then asked the wise people on-line about replacing the steel parts with something less prone to the adverse affects of seawater. Aluminium had problems with fatigue cracking and timber had problems with rot (especially in the joints). I suggested that gold might be an ideal material because of its ability to remain untarnished for archaeologically long periods of time, but my ability to source an appropriate amount of the raw material was somewhat limited. It should also be pointed out that the probability of leaving a solid gold trailer parked on the roadside, or by a boat ramp and successfully returning to it after a lengthy sail was disappointingly small. The same could be said of the less expensive approach of using stainless steel. So, I was stuck with mild steel and the problem of how to stop it rusting.

Being disposed toward the miserly, I opted against hot dip galvanising, which would have raised the cost of repairs to something like a new trailer, and employed Brisbane Axles and Trailer Components (BAT) to cut out the rusty members and replace them. My one modification to the design was to replace the central fence-post tubular strut with a "C" section that had the "C" pointing down so that it would not retain water. BAT did a splendid job, and finished it off with "cold galvanising", which involves smothering the metal with zinc sprayed from a can. You need a large number of cans, and you need to re-smother regularly. My re-smothering habits lapsed the moment I got the trailer home. The cost of the repairs was $2500, which is less than a new trailer, and I got to keep the tilt-trailer mechanism and the rest of the gubbins that were tailored to my hull.

Almost two years on, the trailer is rusting again, though not as badly as before. It is amazing how quickly these things degenerate. In my defence, the location of my parking spot is directly adjacent to the saltwater in Manly harbour, but my to do list has another problem looming. I wonder how long I can procrastinate before further repairs or clean-ups are required?

Austral 20 trailer, after repairs in tilted position. Trailer at home.
Post script: I have been informed (by a fellow customer in a nut and bolt shop) that the cost of hot-dip galvanising can be about $2:70 per kg. So, if the galvanisable part of your trailer is about 370 kg, the cost of acid-bathing and galvanising is about $1000.

No comments:

Post a Comment

Episode 45 Electrifying Sandpiper Part 1

Sandpiper came without electrics (not counting the battery-operated cabin lights). There are good reasons for this, other than keeping the p...