Another Hunter Rudder!

[fgd3]

Originally Posted by neilpride

Thin wall filled with foam sugest me Builder saving costs at the owner risk...

I have no quarrel with that statement.

Fabbian

[neilpride]

Well i have no idea why someone can choose a hollow stock filled with foam, but thinking well i figurate could be to make the whole thing sacrificial , in case of collision or grounding bye bye rudder and keep the hull intact, a weak hull or weak rudder post with a solid or stronger stock can put the whole structure at risk...

[bobconnie]

Seems to me that if yall want to keep runnin your boats aground, yall should trade for full keel boats with some old fashion rudder fitings !! Of course this is coming from someone with only 5 1/2 ft draft, and we live in the Mud Country!! But ya either need a different style of keel-rudder, or ya need to figure out how to keep from runnin aground! Don't get me wrong, everyone runs aground sometime!! but as ya go along ya sorta get out of the habit!! Also might help to learn to use a kedge anchor to get ya off! might save ya some parts!!

[transmitterdan]

Originally Posted by bobconnie

Seems to me that if yall want to keep runnin your boats aground, yall should trade for full keel boats with some old fashion rudder fitings !! Of course this is coming from someone with only 5 1/2 ft draft, and we live in the Mud Country!! But ya either need a different style of keel-rudder, or ya need to figure out how to keep from runnin aground! Don't get me wrong, everyone runs aground sometime!! but as ya go along ya sorta get out of the habit!! Also might help to learn to use a kedge anchor to get ya off! might save ya some parts!!

Many rudder failures happen after running ground but many others happen in deep water. Frankly I don't much care about damage from running aground. Even though running aground is going to happen to all of us we should not sit around complaining after the fact about damage. If you are going to complain about it then you should have thought of that when evaluating the purchase and/or deciding where to sail.

But rudders snapping off in deep water is another thing. Granted that some times there is a "theory" about possible submerged object or whale or whatever. But it happens that rudders just fold over or snap off. Usually the crew reports a "loud bang" and suddenly no steering but often no mention of the boat lurching or a shudder. Rudder failure is such a problem in racing today that US Sailing is recommending that even category 2 races should require emergency steering that is equal or more more robust than the primary. Quoting from the 2013 Islands Race report recommendations:

"emergency steering shall be constructed to the same or greater strength standard as required for the yacht’s primary steering and that can be deployed in any weather condition.". (http://media.ussailing.org/AssetFact...id=21870#page9)

They no longer want backup steering to be "we know how to steer with just sails or two buckets hung off the stern". They want a real backup rudder and the means to steer it. To me that speaks volumes about this problem. I don't have access to the data they have but clearly these people are tired of convening to draw up a report on another death or injury due to a snapped off rudder.

How many cruisers have a backup steering system that is more robust than the primary and are able to deploy it in any weather? I would venture to say less than 1% have that. So we need to make sure the primary steering is very robust and inspect it often enough. The winds are changing on this subject. It is no longer acceptable to just say "well don't run aground".

[jkangas]

We lost the rudder on our 466 in June. Yes we hit bottom before we lost it. It was one of the composite rudder posts. Had Foss Foam build a new rudder for us. They were great to work with. New rudder has a very heavy stainless post...

[robert sailor]

Hi Fabbian,
I think the transom rudder is a very good design that is very easy to work on especially on cruising boats but it stalls easier than a spade because it doesn't have the end plate effect that a spade rudder has. Its also not a balanced design or at least not as well balanced as a spade and there for the forces can be much higher.

[boatsail]

Originally Posted by Rakuflames

No one said the rudder has an "issue." I asked a question. I did not make a statement.

Rakuflames
Registered User


Join Date: Aug 2011
Location: Tampa Bay area
Boat: Hunter 31'
Posts: 5,255
Re: ANOTHER Hunter rudder!
Quote:
Originally Posted by boatsail View Post
Car runs into brick curb striking right front wheel, wheel breaks, must be cheap wheel because it broke.....

***NO****

wheels are not meant to run into brick curb.

To say the wheel has issue because it broke when doing somehting other than sitting driving is ridiculous!
No one said the rudder has an "issue." I asked a question. I did not make a statement.
__________________
See my blog for newer sailors at:
Boldly Go Sailing

I was not quoting you. There were several people who posted before you regarding "hunter" rudders. The fact that the thread states "ANOTHER Hunter rudder!" really has nothing to do with hunters, but more to do with rudders doing something they were not intended to do. My intention might have been mistaken. My intention was that it has nothing to do with hunters, so any hunter bashing, I thought was unwaranted.

[neilpride]

If you go to Hunter Owner forums , in the search tab , rudder !! clicking next and next make my dizzy..

[psneeld]

Originally Posted by robert sailor

Hi Fabbian,
I think the transom rudder is a very good design that is very easy to work on especially on cruising boats but it stalls easier than a spade because it doesn't have the end plate effect that a spade rudder has. Its also not a balanced design or at least not as well balanced as a spade and there for the forces can be much higher.

Love to know what "end plate effect" is and why any rudder can't be as balanced as a spade.

Unless there's something I'm missing, the lateral forces on the further back mounted rudders should be less as less turning force is necessary all things equal...just the helm forces change with balance.

[MARC D]

How a rudder is balanced depends on proportion of area in front of shaft rudder to area aft of shaft.

Not sure about ''end plate effect'' Maybe the bottom of the boat over the rudder?

[robert sailor]

You can learn about end plate effect and how it effects any foil or wing by doing a little research, long and short of it is that a spade rudder does not stall as easy. The forces I was referring to are helm forces.
PS The next time you fly in a larger jet aircraft look out at the wing tips and you'll see the tips of the wings are curved up. When you look at a crop sprayer you'll see the wing tips curved down...these are both attempts to increase the end plate effect, which improve lift and increase speed and aileron authority and in the case of the crop duster gives a nice clean spray line.

[robert sailor]

And yes Mark D you are correct it is the bottom of the boat over the rudder

[lifeofreilly57]

I work in an engineering environment and one thing I've learned is that an initial design is just a guess, no matter how much theory and how many numbers were run to arrive at the design at hand. Any new design is just an educated guess, based on theoretical postulations, the actual reality is in the application and how that design performs in the real world. When it fails or succeeds it is now the new standard on which the theory is based.
In the older boats the designers didn't really have enough history on materials applications to design part close to the theoretical application limit and therefore tended to over design assemblies. In newer designs cost and weight is a factor so parts, including rudders get designed to the theoretical load bearing needs of the application, of course that's when the limits of those designs run up against reality and the designers have to go back and change the standards.
No amount of number crunching can ever predict all the different loads, corrosion issues, life cycling and abuse these assemblies will see in the average life of a boat, it would be impossible to quantify, at least within constraints of the budget most companies have, so we become the crash test dummies and limits will be found, hopefully without any loss of life. As much as I trust my boat I also check out all the important assemblies on it on a regular basis, especially before heading offshore, even then it's impossible to see hidden damage or corrosion, it's not always evident to an eyeball inspection. Prudent maintenance is just as important a safety practice as all the safety equipment aboard.
In my line of work (not marine related) I've seen some of the most well designed, robust assemblies fail spectacularly, usually from something no one could have predicted, that's when the learning curve really takes off. As much as the designers know there is much more that they don't. Admitting that and learning from it seems to be the hardest part.
Boats are a huge compilation of design compromises, otherwise, no one but the wealthiest could afford them, it's up to the end user to decide which compromises they can live with, so look at the boat you want to cruise with and decide what's important to you.
If the boat manufacturer doesn't look into the causes of failures that are above the normal rate they will continue to make the same mistakes. Some of the failures here seem to be related to damage from misuse but others don't seem to fit that scenario, those are the ones that seem to need further scrutiny.

[psneeld]

Originally Posted by robert sailor

You can learn about end plate effect and how it effects any foil or wing by doing a little research, long and short of it is that a spade rudder does not stall as easy. The forces I was referring to are helm forces.
PS The next time you fly in a larger jet aircraft look out at the wing tips and you'll see the tips of the wings are curved up. When you look at a crop sprayer you'll see the wing tips curved down...these are both attempts to increase the end plate effect, which improve lift and increase speed and aileron authority and in the case of the crop duster gives a nice clean spray line.

As a pilot I do understand aerodynamics a little...I just don't buy that it's all that much of an effect at 6-8 knots and that the rest of the boat design (production boats) is altered that much to produce the effect to any great degree (like the space between the rudder and hull)....how many rudders have plates on the bottom?

I'm not so sure that the flow is down the rudder, not up it so again I'm not sure the bottom of the boat helps in that theory...

[hellosailor]

Fabian, the foam filling would add so little to the rudder strength that it might simply have been done to ensure water could not condense in there and rot the tube out from the inside. Or, to ensure more buoyancy allowing the rudder to be dropped and refitted in the water. Unless the foam was as dense as concrete, odds are it was there as a filler, not a structural component.

Jim-
Antimony in the keel wouldn't really matter, since the question was the keel bolts snapping like glass--not the keel tearing apart. When you see a stainless bolt snap like glass, that's usually crevice corrosion caused by immersion in stagnant water. One forum member had posted pictures of his rudder stock sheared that way a couple (4?5?) of years ago. All it takes is one owner who doesn't keep a dry bilge, then the bolts start to go. Add the right (wrong) mineral balance, you'll find a lot of web hits on "crevice corrosion" in stainless that is deprived of oxygen. It looks perfectly good, unless you have eagle eyes and do a dye test. And then it snaps.

Neil-
Your bronze rudder post is the exception proving the rule. What make is your boat, I want one.<G>