MOST rudders are woefully; under designed, AND under built. I've had plenty of engineering... including Naval, as well as about 4 decades on the
water, working on & rebuilding boats etc., etc. And years ago I began to do a bit of studying on Multihulls. Well, one of the better designers flatly states that he designs his rudders with a 1.5-2 factor of
safety for when the rudder were turned 45 degrees & the vessel is doing 25 knots.
Given all that I've learned about boat design, construction, &
repair. I wouldn't call his design standards to be overbuilt at all. And yet most of his designs get HAMMERED on by their owners, some of whom
race them mercilessly in places like the N. Atlantic. Regardless of time of year. But to the best of my knowledge, not one of his boats have suffered ANY kind of structural failure.
The forces on a rudder can FAR exceed the weight of the vessel, if it is being pushed hard, and or they're caught in a storm. Given that, frankly, it's a surprise that we haven't seen a lot more failures (in both vessels, & rudders) than we have. And realistically, the only reason we haven't is that when things begin to get truly nasty, it's the crew which folds first, for the most part.
If even a fraction of the vessels out there were pushed by crew with the tenacity of professional ocean racers, every time there was a storm, it make the '79 Fastnet look like a 4yr old's Birthday Party. The boats would fold up as if they were made of paper machie.
One should literally be able to pick up a mid-sized pleasure vessel by it's rudder & shake it around, with at worst, moderate damage to it or the vessel. And in the yachting realm, only the most serious of
racing vessels might be able to pass this test. Witness the VOR or ORMA boats, & the literal
hurricane force conditions which they sail through day in, day out, for literally years at a time (between practice, testing, & races).
When I toy with the idea of getting a new (to me) boat. After going through the fairly standard pre-purchase checklist in my
head. The next items of business which run through my mind are what
parts of the boat need replacing, & or beefing up structurally. And assuming that I plan to do more than just day sail, replacing
steering components, beginning with the rudder, are pretty much at the top of the list.
Then there's standing rigging, &
sails, which under most owners sees next to zero maintance. And if a boat's previous owners are too
cheap to have shelled out $2.5k to replace a 25 yr old
mainsail, you can only imagine the true condition of the standing rigging, or what lurks at the bottom of an engine's
oil pan.
It's a sad truth, but the reality is that literally everything on a boat which the
wind, sun, sea, &
salt can touch on a boat are semi-disposable items. Meaning that they need replacing with regularity. Yet aside from those who race seriously, or are preparing a vessel for a long distance & term oceanic voyage, who out there takes the time, & spends the $ to properly look after a vessel's care & feeding?
As to autopilots & some of the questions posed. In particular, the surprise at belowdecks AP's tearing themselves off of their mountings. Most of us have steered a boat with some stiff
weather helm using a tiller for a few hours. Well, the AP's have at best 2' long tillers, as compared to the 4-5'ers in the
cockpit. And they're asked to drive in much more demanding conditions, without the ability to see a good path through the worst sets of waves. Or to see when & where a gust is coming from, & compensate in advance. So it's kina of unsurprising that the result is akin to if we were to toss them into the ring with the terminator for a few days.
Much like
wind vanes, boats need to be setup properly for conditions if we are to expect AP's to survive. However, unlike vanes, who's
power input goes up as the wind rises, AP's max out at a certain level, mechanically. So again they're handicapped.
And as to ones of the hydraulic sort, yes, they can, or rather they could be setup to not beat themselves to death when conditions are bad. It's quite simple to do. However, when they did get to the point where their relief valves popped... and in the midst of heavy winds & seas, the boat subsequently crashed abruptly, not many folks would be happy. Despite the fact that all that's needed to
monitor how hard they're working is a temperature gauge, & a hydraulic fluid pressure gauge mounted at the nav station. And that by viewing said gauges, the watch
captain could make changes in sail combination, course steered, or decide it's time to kick out the
drogue... prior to 5k worth of pilot self destructing, & leaving them to hand steer for the rest of the storm.
Sorry for the rant, but you guys asked why, & what was possible. And the thing is, is that in reality, a vessel to be seriously used needs a maintance schedule pretty much akin to one for light aircraft if it's to be reliable, & perform optimally.
The difference being that if you skip some, or a lot, of significant care items on a boat, it doesn't fall out of the sky.
I mean how often do you hear of a military vessel loosing their rudder, or steerage? And do you think that those components which make up said systems have a detailed maintaince & testing checklist which is adhered to?
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