Lost rudder in the pacific, outside Marshall

[B23iL23]

I was on a boat (40 footer) years ago and we had to be towed about 50 miles. What I did was take a line from one winch in the cockpit (on starboard), up to the bow, then connected to a loop of anchor chain which was taken outside the bow and pulpit, then back to another line going back to a winch on the port side.


The tow line was connected to the chain. All worked really well and no chafe. Also taking it to the main winches spread the load and I doubt the anchor winch would have done it.

Originally Posted by Don C L

You know on a side note, after reading a note in one of the articles about lost rudders and a boat (can't recall which) that got picked up in a tow but still had to be abandoned and scuttled due to the inability to maintain the tow line without it chafing through, I know the boat I was on, the TOW was by far the more troublesome part of the adventure. We just don't outfit a boat to be prepared for a tow, and I'd say that, along with other preparations, is just as important. In our case, on a smaller "maxi," we had to resort to chain going through the hawse holes. The nylon lines lasted a couple hours, and steel cables used next just started sawing through the hawse holes, The chain we finally settled on only worked because it jammed in the hawse holes. So, in essence we were relying on the strength of the bulwarks to take the strain of the tow! It worked, but we were lucky. If you plan on the tow line going over the anchor roller, ok, maybe, but will it survive (and will the line stay in the roller) with the bow pitching up and down for hours, or days? Now, if I were to plan a big trip, I'd think in terms of fittings that are strong enough and offer NO chafe on the bow in case of a tow needed, especially in rough seas where the bow will be pitching. Personally I'd be thinking of a super beefy fitting down at the waterline on the bow. And in our case we were being towed at about 9-10 knots IIRC, and that was slow for the ship towing us, they shut down one of their engines during the tow.
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on edit: found it:
https://www.yachtingmonthly.com/sail...steering-30065
toward the end
BTW I think what "Heya" did in that article makes the most sense of the options.

[Paul L]

Originally Posted by AmericanVagrant

When I lost my rudder coming down Baja earlier in the year the Hydrovane really saved my ass. Paid for itself many times over, not just keeping the boat afloat, but allowing me to sail many hundreds of miles the rest of the way to La Paz which also saved tons of money over getting repaired in Cabo San Lucas.

Practically speaking, there were really not many changes following rudder failure, as the Hydrovane was already in charge of steering 99% of the time. I guess the only difference was that we used the emergency tiller on the Hydrovane rather than the helm when motoring into port.

Rudder failure south of Ensenada! | American Vagrant

Interesting writeup. How do you think the Hydrovane would have steered if you had lost the rudder, rather the just the use of the rudder.
Was the root cause just the age of the strap and one too many hard slams? How old?

[mikedefieslife]

Any catamaran owners here lost their rudders? It would be interesting see what jury rig systems they came up with.

I know when I had a steering issue on my cat, one rudder wasn't enough to cope with the 25-30 knt winds and large-ish seas on the starboard quarter. Motoring on the other hand was perfectly fine.

[AmericanVagrant]

Originally Posted by Paul L

Interesting writeup. How do you think the Hydrovane would have steered if you had lost the rudder, rather the just the use of the rudder.
Was the root cause just the age of the strap and one too many hard slams? How old?

I would say there were likely two issues at play, the first being that the bushings were a bit worn causing just enough deflection to wear out the welds over time.

I believe the second issue - and this is a very humble opinion - would be that it was simply under-engineered. The straps were butt welded to the shaft with only around 3 inches of weld bead on either side of the stock.

During the repair I had the welder add decent size gusseting plates to each side of the stock, which essentially doubled the weld area. Hopefully this will suffice in curing the problem. Thus far it has taken me another 3000+ miles to French Polynesia, where the vessel resides now (on the hard in Hiva Oa).

To be honest, I believe that the Hydrovane would have had an easier time controlling the vessel if the rudder was gone completely. As it was loose, the rudder got wedged against the shaft in a deflected position a couple times while in very calm winds/seas (within Sea of Cortez). The only fix was to dive down and pull it back to center by hand.

[Paul L]

Thanks. And the age of straps?

Originally Posted by AmericanVagrant

I would say there were likely two issues at play, the first being that the bushings were a bit worn causing just enough deflection to wear out the welds over time.

I believe the second issue - and this is a very humble opinion - would be that it was simply under-engineered. The straps were butt welded to the shaft with only around 3 inches of weld bead on either side of the stock.

During the repair I had the welder add decent size gusseting plates to each side of the stock, which essentially doubled the weld area. Hopefully this will suffice in curing the problem. Thus far it has taken me another 3000+ miles to French Polynesia, where the vessel resides now (on the hard in Hiva Oa).

To be honest, I believe that the Hydrovane would have had an easier time controlling the vessel if the rudder was gone completely. As it was loose, the rudder got wedged against the shaft in a deflected position a couple times while in very calm winds/seas (within Sea of Cortez). The only fix was to dive down and pull it back to center by hand.

[SnakeEyes]

Originally Posted by Checkswrecks

SnakeEyes -
No, it did not just fall off. The photo below shows the straight line of final attachment at the near side and a build-up of a tannish color material on the far side. Note that rather than being a general corrosion of the entire area, the tannish color material is linear with the fracture, indicating that this took a period of time to progress to failure. Also notable is that the build-up was inside the shaft which would be really hard to inspect for.

Without actually having hands-on, this looks similar to cases with corrosion weakening of the parent material and then a load which flexes the shaft away from the weakened location. What induced this likely corrosion in that exact spot where maximum stress would be is what I'd want to look into further for cause.

The question was if they hit anything, making it fall off. No they did not so yes it actually just fall off.

Now if you are a metalurgic expert that can conclude the reason for why it fall off from just a blury youtube frame than good for you. I never did personate myself to be one, I just answered a simple question.

[Metal Boat]

Forgive my ignorance but I relate this type of rudder to an all flying tailplane on an aircraft. All the stresses are concentrated about the point where the rudder meets the hull and once it breaks you experience total loss of control. I much prefer a conventional tailplane with a fixed surface and a moving elevator which is akin to a skeg and rudder setup which will spread the load through multiple hinging points. Also if the shaft snaps you will still have the skeg to maintain yaw stabilty. When the guy got towed the yacht yawed all over the place, willing to bet that would have been sharply reduced if he still had a skeg. If an all flying tailplane in an aircraft lets go it is certain death but with a conventional tailplane you can use trim to efffect an emergency landing if you have a cable break.


Also this failure is known on this type of yacht. If this was an aircraft the fleet would have been grounded. It seems to me that yachting can be just as dangerous as flying the only difference is that on a yacht it takes a lot longer to die.

[Paul L]

Originally Posted by Metal Boat

Forgive my ignorance but I relate this type of rudder to an all flying tailplane on an aircraft. All the stresses are concentrated about the point where the rudder meets the hull and once it breaks you experience total loss of control. I much prefer a conventional tailplane with a fixed surface and a moving elevator which is akin to a skeg and rudder setup which will spread the load through multiple hinging points. Also if the shaft snaps you will still have the skeg to maintain yaw stabilty. When the guy got towed the yacht yawed all over the place, willing to bet that would have been sharply reduced if he still had a skeg. If an all flying tailplane in an aircraft lets go it is certain death but with a conventional tailplane you can use trim to efffect an emergency landing if you have a cable break.


Also this failure is known on this type of yacht. If this was an aircraft the fleet would have been grounded. It seems to me that yachting can be just as dangerous as flying the only difference is that on a yacht it takes a lot longer to die.

You are assuming tbat the shaft and rudder strength when implemented with a skeg will be similar as to when built as a balanced spade rudder properly implemented. History hasn't shown that. Skeg rudders rely on the skeg in most implementation - which are notoriously tough to fabricate properly. Turns out you can under build or fail to maintain a spade, skeg or barn door rudder, or for that matter a transom hung rudder.

[AmericanVagrant]

Originally Posted by Paul L

Thanks. And the age of straps?

As far as I am aware, it is original - the boat was built in 1970 so coming up on 49 years old at this point

[Paul L]

Originally Posted by AmericanVagrant

As far as I am aware, it is original - the boat was built in 1970 so coming up on 49 years old at this point

Clearly they need to be on your 48 year maintanance cycle😓

[sv mintaka]

Don't remember where I read it but there was a sailboat whose rudder broke 300 miles from Hawaii. They used a bucket on a rope to steer and it worked well.

[Metal Boat]

Originally Posted by Paul L

You are assuming tbat the shaft and rudder strength when implemented with a skeg will be similar as to when built as a balanced spade rudder properly implemented.

I am assuming the engineer who designed this rudder in particular underestimated his leverage moments and cyclic fatigue calculations. The rudder failed from cyclic fatigue stress right at the point of forces meeting the hull, probably both twisting and lateral.


A rudder on a properly engineered and built skeg will experience twisting forces on the shaft but the lateral forces can be transferred through multiple hinge points, greatly reducing lateral fatigue.


Also I will take a properly built skeg (full keel ideal) in front of the rudder for collision protection every time. But I am very conservative and prepared to sacrifice some speed.

[cyan]

Originally Posted by Metal Boat

I am assuming the engineer who designed this rudder in particular underestimated his leverage moments and cyclic fatigue calculations. The rudder failed from cyclic fatigue stress right at the point of forces meeting the hull, probably both twisting and lateral.

These are all very interesting observations.
The broken rudder shaft on Hilma looks like a very thin metal tube filled with resin, with a very small diameter. No engineer worth his salt needs to run calculations before calling this design into question.
However, the specifications for this model that I have found online refer to solid stainless. I’m guessing my search was faulty, or else this was an unfortunate replacement rudder that was undisclosed to the buyers?
Curious, now.

[Paul L]

Originally Posted by Metal Boat

I am assuming the engineer who designed this rudder in particular underestimated his leverage moments and cyclic fatigue calculations. The rudder failed from cyclic fatigue stress right at the point of forces meeting the hull, probably both twisting and lateral.

Perhaps, or maybe there was crevice corrosion that significantly weakened the post and thats where it snapped. As reported by others this rudder was not struck near the time of loss. I don't want to play armchair forensic mechcanical engineer but I doubt that the failure was primarily caused by cyclcal loads.

A rudder on a properly engineered and built skeg will experience twisting forces on the shaft but the lateral forces can be transferred through multiple hinge points, greatly reducing lateral fatigue.


Also I will take a properly built skeg (full keel ideal) in front of the rudder for collision protection every time. But I am very conservative and prepared to sacrifice some speed.

You've got a lot of faith in properly engineered and properly built. How will you test the 'properly built' skeg in your 30 year old potential purchase?

[Metal Boat]

Originally Posted by Paul L

You've got a lot of faith in properly engineered and properly built. How will you test the 'properly built' skeg in your 30 year old potential purchase?

Two ways, the same way an aircraft is tested.

In real life

1. Appproach the still living designer and ask him how many were built (more the bettter) and if any of them lost a skeg ( I seem to remember somewhere in the thread that this type had experienced multiple failures). Then take the yacht out and give it a good flogging in controlled conditions, eg no family. Then observe.

Theoretically,

2. Ask the designer for his structural calculations and apply forces to designed load limit and measure the structures deformation. (obviously this is extreme and could damage the structure but this is done for all production aircraft types)

A good production yacht should have this test done to destruction limit on a prototype.

I spent my whole career building and maintaining structures, Ive got a basic idea of whats going on here....