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Old 11-09-2013, 10:28   #106
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Re: ANOTHER Hunter rudder!

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Originally Posted by hellosailor View Post
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>
My thoughts re lead brittleness were in response to Mainsail's post #10 where he showed a lead keel with a chunk broken out of the leading edge. Nothing to do with keel bolts.

But on that subject, seems to me that use of one of the super duplex stainless steel alloys in keel bolts would be a good upgrade. Considerably higher strength, freedom from crevice or stress cycle corrosion... what's not to like? Well, higher material costs, but really, the increment relative to the total cost of a boat is insignificant and they would likely outlast any other component of the boat! I know that the chap who built our boat used 2205 for the keel bolts and spade rudder post in his new boat and while more costly than 316, didn't break his budget. 2205 isn't super duplex but is considerably better than 316. If I were specifying a new construction I'd sure be looking at these options.

Cheers,

Jim
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Old 11-09-2013, 10:44   #107
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Re: ANOTHER Hunter rudder!

I recall once seeing 4 different hunters on the hard at Swan Point marina. All 4 had rudder failures....

I have never understood why they persist in making the shafts hollow.....
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Old 11-09-2013, 10:56   #108
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Re: ANOTHER Hunter rudder!

Most problems at the rudder stock could be caused by top cracks at the joint, torsional loads cause the rudder to make a great force over the shaft and sometimes water get traped by the crack allowing the ss to get crevice corrosion, if not a saturated rudder with water, the perfect combination to get all the SS inside of the rudder corroded, thats the weak point of foam rudders, there is no real beef inside to avoid flexing and twisting, relying in the flat bars welded to the shaft in many cases..Making a good rudder is expensive...
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Old 11-09-2013, 10:56   #109
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Re: ANOTHER Hunter rudder!

End plate effect is something the designers are very aware of. Even the keel is effected by end plate effect so they try to make that area as thin as possible where it meets the hull. Its not something that the cruising crowd need worry about but in the latest and greatest racers its something that has to be considered. Having said that a spade rudder is still the most effective rudder there is to steer a boat. In practice it may not be the best for crossing oceans on many cheaper boats and I personally prefer a partial skeg but I can't argue that my rudder is as effective as a spade because it isn't.
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Old 11-09-2013, 10:59   #110
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Re: ANOTHER Hunter rudder!

Yeah , but Swans and Oysters are fited with spade rudders, even HR`S and other hig top yachts, if you take a look at a Swan rudder stock you be surpised by the size and diameter, overkill...
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Old 11-09-2013, 11:31   #111
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Re: ANOTHER Hunter rudder!

We have been cruising our 1982 Hunter 36 for about a year now. I replaced the rudder before we left last year. Foss Foam (Florida) built it, and I am a satisfied customer.

Our rudder was bent during Hurricane Ike, in Baytown. It was slipped at Bayland Marina, where the pilings were too short (floating docks) for the amount of surge that happened during the storm. Boats, still tied up to their slips were floated off the pilings, and shoved onto the shore.

After haulout, we discovered the bent post, so ordered a new rudder. We did sail with the old one for three years, so not sure that can actually be called a failure. At least the tube and supports inside the hull remained intact and undamaged. I think I'd prefer the bent post. Something has to give, in my mind.

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Our rudder post is hollow, and filled (with foam?). And yes, there was the instructions about painting with a light color.

I am not sure why they fill the post. Strength being the reason seems unlikely, but maybe? Could it be to keep moisture out of the inside of the tube? Also, looking at my pictures, there is a very small area that can actually bend.

So far, so good with the new rudder. We do try our best not to run aground, but have once on Texas, and twice on the Florida ICW (same spot, but took three tries to get past this one known problem area. Not too bad having gone from Texas-George Town, Bahamas-Georgia.

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Old 11-09-2013, 11:51   #112
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Quote:
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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.
I read somewhere the aerodynamic wing tips (e.g. Boeing 737) are designed to put more tension on the wing to stiffen it. The vertical tip is designed so it pulls on the wing in flight making the structure more rigid. This allows a lighter wing which saves fuel. Not sure what that has to do with rudders.
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Old 11-09-2013, 11:55   #113
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Re: ANOTHER Hunter rudder!

As I understand it, inboard rudders that center right up against bottom of hull are less likely to ventilate/cavitate, and hence tougher to stall.

I believe that is the issue with outboard rudders. great because accessible and located aft for best leverage, but when turned too aggressively more likely to suck air down the low pressure side of the blade and cavitate. I remember the unpleasant feeling of the rudder slowly losing grip in Lasers and 505s when closereaching at 15 knots and overpowered.


In my current (slower) boat, the rudder is keel attached, and fits flush up under the bottom of the boat. I have had the winches and coamings awash with 45+ deg heel in puffs (racing, overpowered on purpose), and still not had the rudder stall out...
of course this is overly simple- there are many other variables. That said wider sterned boats with centerline rudders stall more easily because rudder lifts out of water when heeled and ventilates...
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Old 11-09-2013, 12:04   #114
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Re: ANOTHER Hunter rudder!

Malbert 73 has it properly figured out.
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Old 11-09-2013, 16:11   #115
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Re: ANOTHER Hunter rudder!

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Jim-
Antimony in the keel wouldn't really matter, since the question was the keel bolts snapping like glass--not the keel tearing apart.
Dead soft lead is around 6 brinell. I've tested some antimonyal hard lead alloys at over 35 brinell. The alloy can make a big difference. I'd need to do some destructive testing to see if 35 brinell is enough to snap a 304 or 18-8 ss bolt.
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Old 11-09-2013, 17:35   #116
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Re: ANOTHER Hunter rudder!

Curved wing tips are to increase end plate effect. During flight the low pressure air on the top of the wing tries to meet the high pressure air on the bottom near the end of the wing and it creates wing tip vortices . These vortices increase drag and reduce lift. This means the wing does not lift as much and goes slower in flight. Curved up or down tips reduce this effect and allow the wing to fly faster and lift more. The higher the aspect is on the wing design the more effect it has.
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Old 11-09-2013, 18:17   #117
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Re: ANOTHER Hunter rudder!

[QUOTE=hellosailor;1336572]Raku-
Foss Foam also does business under the name "Newrudders.com" and if you look at their web page on NewRudders.com Rudder Care you will see their statement that their rudders must be painted white, not dark, or else the heat will damage them:

"We recommend that white paints be used. ...
We do not recommend the use of dark color bottom paint for your rudder, as they generate heat whenever your boat is out of the water and in the sun. Since your rudder is made of cellular material this heat can cause dimensional changes and cosmetic damage. If the rudder is painted a dark color it should be shielded from the sun with a white wrapping whenever the boat is out of the water. YOUR RUDDER WARRANTY EXCLUDES DAMAGE CAUSED BY HEAT. "

OK? You don't have to believe me, you can read it directly from them. Now, did anyone tell you that about your rudder? Have you ever heard that rudders can't be painted with the same dark bottom paint as the rest of a boat?
[FONT=Arial][/FONT
Sure, I believe their warning, for their product. I just
find it most peculiar compared to the rest of the rudders in the world. Invulnerable closed cell foam...that can melt on a hot summer day. Hmmm...
[/QUOTE


I believe you but did not realize you were talking about out of the water. Probably has something with the special foam they use. I have no beef with Foss Foam. They were ezxtremely helpful as well as fast for me. No one bats 1000.
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Old 11-09-2013, 19:30   #118
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Re: ANOTHER Hunter rudder!

If Hunters are fited with foss foam rudders that mean hunters are painted white at the antifouling?? from the factory? are new owners aware of this isue with dark colors?
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Old 11-09-2013, 19:53   #119
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Re: ANOTHER Hunter rudder!

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Originally Posted by Rakuflames View Post

Foss Foam was terrific the two times I dealt with them. Both times they had the rudders done under schedule, and they were extremely helpful. I'm sorry if you had a different experience but I have no reason to think that your experience is the norm.
After running through this thread a bit today, I sent an email to Al at Foss Foam. I asked about the reason for having foam in the rudder post. As I have mentioned, I'm a happy customer, but curious. I got this reply back from him this evening -

Thanks for your e-mail. I'm glad to hear that your rudder is performing well. The reason we foam fill the shafts it to prevent moisture from going down inside the tube. Before we started foaming the shafts there was an issue with water going down the shaft and freezing and busting out the side of the rudder during freezing weather. Since we don't know where a boat may wind up we foam fill all shafts. That is a great question!
Thank you,



Bob "Al" Walker
Foss Foam Products of Florida, Inc.

www.newrudders.com
PH 352-529-1104
Fax 352-529-1106


I think a same-day reply to a customer's question is pretty awesome, and says a lot for the company.

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Old 11-09-2013, 20:40   #120
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Re: ANOTHER Hunter rudder!

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Originally Posted by neilpride View Post
Yeah , but Swans and Oysters are fited with spade rudders, even HR`S and other hig top yachts, if you take a look at a Swan rudder stock you be surpised by the size and diameter, overkill...
Oysters are all fitted with a full skeg hung rudder except for one new model Which I believe is the 88 footer which has dual spade rudders.
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