Select to expand quoteUncleBob said..julesmoto said..troubadour said...
Use a hole saw but very carefully. If it grabs it hurts
:) Thanks. Have to see if I've got one with smallish teeth. I am envisioning a mess with wire strands hanging out everywhere :-(.
The mess is nothing compared to the black s**t that will be on your topsides if you ever use it as a fender. 
I meant as an emergency fender.
Select to expand quotejulesmoto said..Ramona said..
The nylon will give some stretch and recovery. I would be inclined to use a tyre with holes drilled around the middle of the tread area. Splice some nylon rope to it and rig it as you would a fender. Toss it in a locker and use it as a fender if required. Then if you ever have to use it in anger, attach some chain to trail off the back of the tyre and toss it off the stern or wherever.
Thanks; do you reckon 12mm nylon is adequate? Not sure how easy it will be to drill sufficiently large holes in a radial that will actually pass much water. What type of drill bit would you use to deal with the steel reinforcement? Can't get much diameter with a twist type drill bit.
40mm hole saw in a cordless drill does it effortlessly. We did a heap of tyres in the tyre wall at the local hillclimb a few weeks back. 12mm has a breaking limit of about 3,000 kilos. The old routine was to stream a SS bucket on a rope over the stern to steer. The seamanship manual says to stream teak gratings off the stern. Might be overthinking something that might not ever happen!
Select to expand quoteRamona said
40mm hole saw in a cordless drill does it effortlessly. We did a heap of tyres in the tyre wall at the local hillclimb a few weeks back.
Nothing like someone who has done it. Thank you very helpful as usual :-)
Huntress wreck found.
I get the feeling that a sturdy skeg might be the way to go. Only saying that because that is what I have.
www.abc.net.au/news/2023-01-06/sydney-to-hobart-huntress-beached-cape-barren-island/101830434
Select to expand quotejulesmoto said..2bish said..
Hi Jules, yes ... Let me know what you think of the vid.
Thank you for that.Yes it does seem impressive. Presumably folds into a relatively small package too.
Any idea what they mean by the predetermined maximum speed set by the owner at 1 minute 40 seconds? Is there some sort of adjustability.
The thing that always scares me about drouges is actually slowing the boat down enough to deploy them without ripping a winch or cleat out or snapping the rope.
Presumably the size ordered is fairly critical as well. My boat isn't that far above the limit for the smaller one but I noticed the next size up is said to be appropriate for boats a hell of a lot bigger at the upper end. Wouldn't want to get pooped regularly because it was too large.
Can't really test these things (as a sea brake) until you desperately need them so it is nice to know that they have tested them rather than relying on a home made tyre or milk crate that has never been tested in anger. The guidance as to the length and thickness of rope as well as weight of chain might be applicable to other homemade solutions.
I think there may have been some kind of adjustability in the very early models. Now that Burke manufactures them, they don't have it anymore. it stuffs into it's own bag with a velcro closure, flat package but it's still a relatively large diameter. I agree with Tarquin, if you only want it as an emegency steering device, then the smaller model and less line would suffice.
When my trailable lost its rudder we used the outboard motor to steer.
Most cruising yachts carry a small outboard for their tender.
Could be a solution (range could be a factor).
Select to expand quotegarymalmgren said..
Huntress wreck found.
I get the feeling that a sturdy skeg might be the way to go. Only saying that because that is what I have.
www.abc.net.au/news/2023-01-06/sydney-to-hobart-huntress-beached-cape-barren-island/101830434
There's skegs and skegs. Apparently a Moody sunk in the USA after the whole skeg ripped out, leaving a massive hole.
When I went sunfish hunting and snapped the spade, the rudder snapped off cleanly leaving the hull perfectly fine. Conditions weren't as perfect as Kankama recalls since at the time of impact the forward hand was watching the log which was reading over 9 knots, coming down from a 12 knot surf - that's quick for a half tonner, as shown by the fact that the rest of the halves were well astern at the time.
Designing a skeg that will take that sort of impact doesn't seem to be trivial engineering. Two Malos have suffered severe damage to the skeg, and they have a pretty good rep as a tough, well built boat; author Nigel Calder says his Malo was almost lost when the skeg partly fell off after running aground, and another Malo sank after suffering a similar issue. A Sadler 32, with skeg, sunk after rudder damage from an orca attack off Spain.
Select to expand quotegarymalmgren said..
Huntress wreck found.
I get the feeling that a sturdy skeg might be the way to go. Only saying that because that is what I have.
www.abc.net.au/news/2023-01-06/sydney-to-hobart-huntress-beached-cape-barren-island/101830434
Always amazes me how many of these abandoned boats are found on beaches as opposed to rocks.
Select to expand quotegarymalmgren said..Select to expand quote Select to expand quoteHuntress wreck found.Select to expand quote Select to expand quoteI get the feeling that a sturdy skeg might be the way to go. Only saying that because that is what I have.Select to expand quote Select to expand quoteSelect to expand quoteQuite a few references quoting a 1% failure rate for spade rudders doing ocean passages. Skeg rudders often are matched with longer keels, which do provide more collision protection for the rudder area.
A 1% failure per passage is quite a high risk. Imagine if there was a 1 in 100 risk of your car steering failing every 2000km. I have not seen any stat's on the failure rate of skeg mounted rudders.
Select to expand quoteChris 249 said.
There's skegs and skegs...
As I have posted here before my boat in the hands of a PO with a 2/3 skeg lost it's lower skeg to rudder pintle/ bearing off Bega causing the rudder to skew sideways and a massive leak necessitating an emergency pump out, rescue and tow. Upon buying the boat I chose to extend the existing 2/3 width bulkhead (which is about 2 ft in front of the skeg) so as to span the full beam creating a water tight compartment aft.
I seriously doubt that naval architects/designers (when most boats incorporated skegs 35 years ago) considered the relative strength of the skeg itself vs the surrounding hull structure so as to make them sacrificial. Anyone for a saw cut a third of the way through their skeg near the top? :-).
Speaking of the relative strength of bits and pieces on boats it is interesting that the keels of many modern catamarans are sacrificial comprising thick foam with a relatively flimsy skin relatively flimsily bolted to sturdy hull recesses.
Whilst on the subject of catamarans I also recently read that centre boards (which need to be constructed quite strongly due to the forces they are called upon to bear in large-ish vessels) have been known to slice through their centreboard casings and the bottom of the hull when grounding. Presumably the same would apply to maxis..Ouch!
In the same vein of sacrificial bits and pieces it is also interesting to note the appearance of load limiters and load measurement devices in modern rigging of fancy boats such as fancy catamarans and maxi s.
I have two rudders on my cat, so I can engage in this thread with some smugness. Also I haven't ever hit a sunfish so that makes me a better helm.
That being said, I think it would be relatively easy to design a spade rudder system that is more seaworthy. We have them on cats.
My spade rudders are on a pivoting cassette. At the moment my rudders don't even get wet unless I go sailing. They are pivoted aft like you see IMOCAs do with their windward rudder. The nice thing about them is, if you hit a sunfish and it hits the rudder, the wooden dowel holding the cassette down lets go and the rudder pops up. That is not good if you are under a kite but better than losing the rudder. Ten you go and push it back down and use another dowel.
I would even go so far as to suggest that a seaworthy backup would be an agricultural short rudder that could be inserted into the rudder tube if the main rudder broke. By pivoting the cassette installation would be all above water and when all is cleaned up, the cassette can be pivoted down. This system works especially well on twin rudder boats. I have had my rudders kicked up hundreds of times, mostly by the bottom when getting too shallow but also by fish traps and a log offshore. It just popped up and then I went aft and pushed it down as we sailed along. Go twins with cassettes.
This video shows cassette rudders - about 9 mins in is good
Select to expand quoteKankama said.. Also I haven't ever hit a sunfish so that makes me a better helm.
Oooooohhhhhh........ I've been burned.
It took a lot of skill to find and hit that sunfish once I realised that the alternative was to face the forecast bash across the Strait and up the Tassy Coast.
Select to expand quoteYara said..
A 1% failure per passage is quite a high risk. Imagine if there was a 1 in 100 risk of your car steering failing every 2000km. I have not seen any stat's on the failure rate of skeg mounted rudders.
So where does the statistic come from?
Select to expand quotegarymalmgren said..
Huntress wreck found.
I get the feeling that a sturdy skeg might be the way to go. Only saying that because that is what I have.
www.abc.net.au/news/2023-01-06/sydney-to-hobart-huntress-beached-cape-barren-island/101830434
Given the topic here and the news about Huntress, I couldn't help wondering if they tried using any kind of warps / drogue to regain some steering before abandoning the vessel?
Select to expand quotejulesmoto said..Chris 249 said.
There's skegs and skegs...
As I have posted here before my boat in the hands of a PO with a 2/3 skeg lost it's lower skeg to rudder pintle/ bearing off Bega causing the rudder to skew sideways and a massive leak necessitating an emergency pump out, rescue and tow. Upon buying the boat I chose to extend the existing 2/3 width bulkhead (which is about 2 ft in front of the skeg) so as to span the full beam creating a water tight compartment aft.
I seriously doubt that naval architects/designers (when most boats incorporated skegs 35 years ago) considered the relative strength of the skeg itself vs the surrounding hull structure so as to make them sacrificial. Anyone for a saw cut a third of the way through their skeg near the top? :-).
Speaking of the relative strength of bits and pieces on boats it is interesting that the keels of many modern catamarans are sacrificial comprising thick foam with a relatively flimsy skin relatively flimsily bolted to sturdy hull recesses.
Whilst on the subject of catamarans I also recently read that centre boards (which need to be constructed quite strongly due to the forces they are called upon to bear in large-ish vessels) have been known to slice through their centreboard casings and the bottom of the hull when grounding. Presumably the same would apply to maxis..Ouch!
In the same vein of sacrificial bits and pieces it is also interesting to note the appearance of load limiters and load measurement devices in modern rigging of fancy boats such as fancy catamarans and maxi s.
I completely agree that a coffer dam or bulkhead forward of the rudder is an excellent idea, and one that should be very common.
I'm not saying that the old skegs were sacrificial, but there's some interesting discussions around where guys like Bob Perry point out that a spade does not have to be inherently any weaker than a skeg. A spade rudder's shaft normally extends up to the cockpit floor or the deck, which gives it a good span to resolve any loads. A skeg rarely extends so high so the loads are located in a smaller area.
The Malos are a very solid, conservative boat, as are the Sadlers, so the fact that they have lost skegs indicates that it's not always lightweights or spade boats that lose rudders.
The info around seems to indicate that there is no inherent structural advantage in a skeg over a spade. Large ships have spade rudders, not skeg-hung ones. If you can built a spade rudder that will steer a destroyer, aircraft carrier or supertanker and not get knocked off then you can build a spade rudder that will steer a yacht and not get knocked off. Ship designers don't use spade rudders because they are idiots who like losing rudders.
www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjf77C8tLX8AhU7ilYBHWAHAFMQFnoECAgQAw&url=https%3A%2F%2Fkrakenyachts.com%2Fwhats-wrong-with-spade-rudders%2F%23%3A~%3Atext%3Dor%2520towing%2520lines.-%2C%27%2Cwhales%252C%2520containers%252C%2520and%2520lumber.%26text%3DOne%2520case%2520highlighted%2520in%2520detail%2Cand%2520a%25201.5m%2520swell.&usg=AOvVaw0_N1dGVsPJFxwSIhZn4MPU
Sorry for the long link, but that is where I got the statistic on failure rate. Backed up by the latest S to H failure.
The scale of a ship's rudder is vastly different from a yacht. The size relativity to the impact object makes a huge difference.
Long post
I like podcasts - 59 North are great and they had Bob Perry on. I have his books too, where he says that he saw some of his rudders supporting skegs. He reckons that new carbon stocks are stronger than old skeg rudders.
So I joined the Perry facebook group and he sometimes posts there. After a few weeks he had a rant about a client not liking his very deep spade rudders. I tried, (gently) to disagree with the idea that a modern skeg rudder would be weaker than an equivalently engineered modern spade rudder. I have built a few boats and designed a few rudders, I am nowhere near as clever as Perry but I understand basic cantilever engineering. I was polite. He didn't want to engage and got dismissive. His spade rudders are really deep. So I am not in the group anymore.
I do think sailors have a blind spot about rudders and I disagree with the Perry idea that you can build a spade rudder that is as strong as a skeg (especially from fore and aft impacts like those commonly caused by strinking bottom or objects). A modern skeg could have some rake to improve ability to ride over objects and can be made from high quality materials with a much higher second moment of area than any rudder stock. If you compare chop strand mat skegs with carbon rudders then you have a point but a equivalent modern skeg has much more area where it connects the hull than a rudder - it is simple engineering. A skeg can be slightly wider than a rudder shaft but much deeper fore and aft as well. Resistance to bending is related to the depth cubed - so any increase in dimension gives great returns on bending reduction and stress reduction too.
I think Perry's blind spot to spade rudders is reflected in many modern boats. His spades are very deep and this is problematic for those who run aground (which is everyone) and great rudders can lead to designers producing highly directionally unstable designs with easy to use low transoms. Then if the rudder breaks off then the boat is unusable.
I once was in a Laser clinic with some of Australia's best Laser sailors. The coach asked us to sail without using the rudder, no one could, even the best Laser sailors could not get a Laser to move without a rudder. My point is that designers will keep on designing Laser like yachts because they are fast and nimble, but they will probably be unusuable without the rudder. I can sail a 420 without a rudder but have to rake the centreboard aft (which you can't do in a yacht) and can only sail upwind and on a reach. Dinghy like shapes are inherently directionally unstable. So go out sailing without a rudder and if your boat is uncontrollable, then design an emergency system with permanent gudgeons somewhere and a shortened and easy to fit emergency rudder living in the bilge. The designers are enthralled with the performance of a nice deep spade, but it is the owners who have to put up with the significant ramifications of their failure. The washboard on a kite pole emergency steering system is a joke and may work on a Currwong 30 or S and S 34 but is probably useless on a modern dish shaped boat.
I must say that when I dived in and took a look under a Beneteau oceanis we hired I was both impressed and shocked at the long fine rudder and keel for that matter, it was no doubt a delight to sail but i was very wary of shoals, whales etc
Select to expand quoteKankama said..
Long post
A modern skeg could have some rake to improve ability to ride over objects
I think this is on advantage of the skeg which is often overlooked. As long as the gap on the leading edge between the bottom of the skeg and the blade is kept close then accidents with mooring risers and stray ropes can be avoided.
Select to expand quote
The info around seems to indicate that there is no inherent structural advantage in a skeg over a spade.
I think common sense would indicate that something that is supported at both ends has a structural advantage to something that extend's some distance with no support. I think common sense would also indicate that having a skeg, to offer protection to the rudder from impact, is also an advantage in the case of an collision. A skeg hung rudder "all else being equal" has to be a more robust system than a spade rudder.
However there are plenty disadvantages of having a skeg, I am learning all about them as Wapiti's rudder is skeg hung. Trying to back her into a pen is more trouble than its worth, heavy steering as no offset pivot to use water pressure to assist, extra drag just to list a few obvious ones. So yeah blade rudders are better at all the above and have their advantages but vunerability to getting knocked off is not one of their strong points. Performance vs security, make your choice, I want to go cruise remote locations so I chose security.
But really I think one of the reasons for the popularity of spade rudders among builders is cost, they are cheaper to build than a skeg, much of the modern design is as much about cost saving as it is about performance if we really get into the reasons behind why this over that, particulary in contemporary production yachts, it might be dressed up as performace but mostly its about cost. 
Select to expand quotecammd said..
But really I think one of the reasons for the popularity of spade rudders among builders is cost, they are cheaper to build than a skeg, much of the modern design is as much about cost saving as it is about performance if we really get into the reasons behind why this over that, particulary in contemporary production yachts, it might be dressed up as performace but mostly its about cost.
I absolutely agree the default position for production boats is primarily cost, not 'best'. But that's not a fault of spade rudders per se. IMO having dual rudders improve the benefits and mitigate the negatives even more compared to single spade rudders. I don't believe the hype about dual rudders increasing the possibilities of hitting stuff, it was always the keel which took the hit of any UFO's I experienced.
I could sit on the hard on my dual canted spade rudders (couldn't bring myself to do it, but it's engineered for it). I did it once inadvertently on a sandbank, it sat level, didn't dig in and floated off just fine. Was actually kind of cool!
-Dual rudders meant they were stubby which would aerate the windward rudder in anything over 20 degree heel, ie: little chance of hitting anything.
-The leeward rudder has enormous grip (canted==heel) even though it's a wee stubby thing. A 4' draft doesn't have much mass moving through the water to hit things and the grip is amazing, it's akin to being on rails.
- The stubbiness meant the rudder posts had much less shock loads. The similar distance between the upper and lower bearings with a shorter rudder meant less chance of damaging the post and bearings and making new holes in the hull.
-As you mentioned, the position of the rudders and the offset pivot can be chosen and not dictated by the keel shape and position. Which makes helming in any conditions a fingertip experience.
-Dead simple to remove and replace , I could drop a rudder out under 10 mins in the water. They don't take up that much space, I could fit a whole rudder in the rear cabin in the bookshelf.
Like everything in boats, it's horses for courses. Skeg hung rudders are damn good in some areas (eg: ice), spade rudders are damn good in others. I think we all agree one is not better than the other, they're just different.
Alubat ovni has a bit of everything. I think there is a sacrificial 'something' that will allow the bottom bit to pivot if it hits something.
Select to expand quoteDrogueOne said..
Alubat ovni has a bit of everything. I think there is a sacrificial 'something' that will allow the bottom bit to pivot if it hits something.
That's pretty interesting but the hydrodynamics of that upper section must be truly awful with that wide squared off rear end. Probably doesn't matter much because the laminar flow would have already been totally destroyed in that upper section by the skeg, prop and void.
One wonders whether perhaps a spade rudder with a bearing at the bottom of its pivot axis on a triangular plate stayed to the hull forward and to each side might have any merit? Would deflect objects and hopefully introduce only limited turbulence. Perhaps even a thin rod foreward. Works for rotating masts :).
One thing that has struck a chord with me after reading these comments is that a skeg mounted to the hull along a very short vertical portion of its upper regions may well not be anywhere near as well braced as a spade rudder with a bearing in the hull bottom spaced quite a distance from another bearing level with the cockpit floor.
Select to expand quotejulesmoto said..
One thing that has struck a chord with me after reading these comments is that a skeg mounted to the hull along a very short vertical portion of its upper regions may well not be anywhere near as well braced as a spade rudder with a bearing in the hull bottom spaced quite a distance from another bearing level with the cockpit floor.
Its the spade bit below the hull that breaks off, will be hard to steer with just a well braced rudder stock.
Select to expand quotecammd said..julesmoto said..
One thing that has struck a chord with me after reading these comments is that a skeg mounted to the hull along a very short vertical portion of its upper regions may well not be anywhere near as well braced as a spade rudder with a bearing in the hull bottom spaced quite a distance from another bearing level with the cockpit floor.
Its the spade bit below the hull that breaks off, will be hard to steer with just a well braced rudder stock.
There are two priorities here. The first priority is making sure the boat doesn't sink. I'd much rather have no holes in the boat than a snapped off rudder, that's why hull and rudder post integrity is important.
The second is re establishing steerage. Whether your emergency tiller needs the post or some transom brackets is up to the individual boat.
Not much point having a flash washboard and guy pole setup for emergency steering if you've a dirty great hole in your boat that doesn't have a watertight bulkhead or any ability to plug a sheared off rudder post.
Select to expand quoteYara said..
A 1% failure per passage is quite a high risk. Imagine if there was a 1 in 100 risk of your car steering failing every 2000km. I have not seen any stat's on the failure rate of skeg mounted rudders.
I followed your link and then went to the Sail magazine story it came from. It did NOT say anything about spade rudders having a 1% failure rate - it referred to ALL rudders having a 1% failure rate, and didn't specify what proportion were spades.
We can't take a risk that applies to ALL rudders and then claim it only applies to spade rudders to "prove" that spades are bad.
Select to expand quoteDrogueOne said..
Alubat ovni has a bit of everything. I think there is a sacrificial 'something' that will allow the bottom bit to pivot if it hits something.
Onvi's aren't as simple as they could be. There is a sacrificial stainless diaphragm in both the lifting keel and rudder hydraulics. If there is an impact the diaphragm splits andneeds to be changed and system rebled. Owners keep spare diaphragms in their spares kits. I assume they couldn't get a pressure release valve to dump fast enough to protect the boat.
Don't worry about the slot at the rear of the rudder, the bigger issue is most OVNI have a flat plate centreboard. They are not a boat designed to sailed close hauled for a significant passage.
