Log In
Register
Home
Topic RSS
Offline
Some of you may remember that Mariposa lost her rudder in 2009 and I have have a new rudder and rudder post made . The fella from Santa Anna that built the new rudder recommended and did build a rudder that was somewhat bigger than the old one. He was right..steering is much improved over the smaller factory built that came with the boat, which as luck would have it..was built by the same guy who just built our replacement.
Where our problem comes in, is that since this rudder has been installed, the wheel is very hard to turn either direction. We have had the boat in two yards with no success. The problem is made worse by the fact that when the boat is on the hard, the rudder and helm spin back and forth with no resistance at all. But as soon as the boat goes back in the water instantly the helm is very difficult to turn. For example, for those of you who can remember this far back..it is like the power steering on the car goes out and you are left with standard steering. The cables run freely and there is no binding in the cables or pulleys.
The first pic is the original rudder and the second picture is the new larger rudder.
Any help anyone can offer as to why the helm is so stiff would be appreciated.
Offline
The very first thing that comes to mind is that the new rudder is lighter than water and wants to float. This would put pressure upwards.. is the very top of the rudder rubbing and binding on the boat or something else in the bearings etc... When out of the water gravity would make all the weight come down on the bearings rather than up on them. Other than this I couldn't imagine what might be causing it.
It should be a little harder to turn because of the larger surface area but I wouldn't think it should be very hard to turn.
Offline
I have thought of this and have put in a clamp around the rudder shaft just below the upper most fitting in the boat. (In the aft lazerette where the emergency tiller fits in) When I put it in I measured clearance between the clamp and fitting and there was no change. I am considering putting some kind of bushing in where the rudder post enters the hull but I did put in a delrin washer there. I was expecting increased pressure due to extra size and you can feel it but that is not the whole problem.
Offline
That was all I had.
Does the stiffness change depending on speed of the boat through the water? Give us a comparison of sitting still at anchor or dock and turning the wheel vs 1 knot vs 3 knots vs 6 knots etc..
Offline
No joy there Scott...it is a little more difficult at speed but it is so hard to turn anyway, you can hardly notice the difference. It is so hard to turn at anytime that trying to steer from the inside station which is a 26" wheel is next to impossible.
Offline
I would suggest taking some weights.. dive weights etc.. and adding them to the rudder in 10 or 20 lbs increments while sitting at the dock or at anchor and test the feel of the rudder at each increment. Just put them on a belt and hang it over the projecting top of the rudder blade in the water. Regardless of whether the rudder is moving up or down or not, if it has positive buoyancy in the water then it is exerting tension upwards that might be causing something to bind. I have racked my brain trying to think of the difference between in the water vs out of the water and the only two things I can come up with is surface area resistance to pivoting in the water and the relative weight of the rudder itself on its bearings depending on in or out of the water.
If adding weight fixes it then you could get some flat round hemispherical lead weights made that you could bolt onto the rudder to compensate. Its a real easy empirical test at least. If it doesn't make a difference then I am going to go out on the clueless plank and jump off the boat. 
Offline
That will be an easy test..and I will try it but I am about to go on a trip for a bit and will try that when I get back. Thanks Scott for the ideas and I will let you know about walking the plank!
Offline
rofl walking the plank is easy.. its the long jump with the short stop with the sharks that is the issue.
Offline
I assume I'm not the only one that thought of this. By enlarging the rudder, you have increased the surface area by X without enlarging the steering quadrant to compensate for the increased drag the new rudder will encounter. Since the steering quadrant is really just a lever, without making it larger too, you're trying to turn more mass with the same working effort. To continue the car steering analogy, now that the power steering is out, you installed bigger tires. Maybe my thoughts will help you find the true solution. Good luck!
Thanks
Mike
Offline
I thought of that to but he says that the difference in force from sitting in the slip vs sailing isn't any different. It should take a lot more force to turn the rudder moving at 6 or 7 knots than sitting still if that was the issue. At least I would think so. There is a lot of mechanical advantage in the stock DE steering system. On our boat there is little to no feedback at all. His description sounds more like binding than heavy resistance to water. Sitting at the dock if you gently turned the wheel even with the larger blade it should turn pretty easy as your not trying to force it through the water quickly. I wouldn't think you would feel a lot of resistance in that situation.
Interesting problem... I would love to get hands on with it and troubleshoot it just for curiosity's sake.
Offline
May, or may not be of help here, but I noticed that the factory rudder ( mine at least) has a hole in the top of it, just behind the post.
I had read somewhere that the rudder would float... making it lighter than water like Scott zeroed in on.
But from my observations, mine held a considerable amount of water. Might be that the balance point is very slight.
I also had the joy of the SS rudder post being frozen solid to the Aluminum packing gland. After 3 years, it still is. To overcome this issue on a temporary basis while I transported her to the work yard, I simply removed the clamps on the hose, and gave it a shot of lithium grease. Worked surprisingly well, and didn't ship any water while under power.
Sounds to me like Scott is zeroed in on it. Buoyancy of the rudder is really the only thing I can think of that changes when in the drink. Might do some experimentation with the stuffing box for the rudder. I've got what appears to be a 1/4 thick washer on top, looks like Delrin to me. There is one on the bottom as well, although it's pretty much deteriorated. I'm going to whip up a couple out of Delrin when I change the packing gland.
I'm curious as to what you discover.
S/V The Last Farewell,
Currently laying Panchos Marina
Marathon, Florida
Offline
SoloBob..the yard that did the work would never have earned the good work certificate from me. They figured, wrongly, that the job was going to be done by insurance, so bugger the costs..they took the packing gland out and replaced it with a dripless seal. I mean if you think about it...with all those high speed direction changes and rotations that they rudder post has to go thru...I am surprised that you didn't just melt your rudder post from high speed friction. Lol. I was not impressed with that expediture at all.
All this talk of bouyancy..does anyone out there know a way to figure out just how much bouyancy this thing has?
Boat Nectar I have tried to turn it with the Emergency Tiller..taking the quadrant out of the equation..totally disconnecting it and unfortunately it made no difference..except the wheel spun like a damn!
Offline
Scott Carle..I knows I have been slow getting back to you..but I think you hit the nail on the head. Today I got a diover to come to the boat and we draped about 80 - 100 lbs of chain over the top of the rudder and it greatly improved the ability to spin the helm. So now the dilemma is what to do about it..I mean how am I going to add that much weight to the rudder. I sent an email to the rudder manufacturer to see if they have any suggestions. Anyone out the know how to add more than 100 lbs to a rudder?
Offline
Shouldn't be that hard to threw bolt or clamp some weight to the sides of the rudder. If out of the water you could even drill a couple holes through the rudder and clamp some lead to either side of it. :). Fill the holes with epoxy and then drill through so you don't create a water ingress point . I have the feeling that the majority of our rudders after all these years are wet inside though.
I would consider bolting a 100 lbs to the rudder the easy if sub optimal solution though. On my boat I would hate to put that much more weight back there in addition to all the junk in the cockpit lockers, dingy and dingy davits and solar panel. Optimal method would be a real pain though. That would require a new redesigned rudder. I wouldn't imagine that take the rudder below neutral in weight in the water would help much. Do you think that the rudder really has a 100 lbs positive buoyancy?
Honestly it's a bit strange... On Valkyr our rudder has always been easy to turn whether sitting in the slip or overpowered to the point of rounding up. Valkyr is a 79? DE38. What year is yours? could be a design change or the rudder has been replaced in the past and wasn't built the same. Maybe?
The only thing handling wise we have never been happy with that involves the rudder is backing up.
Offline
Scott..Remember, this is a new rudder post and a new rudder that is at least 100% bigger or put another way..twice as big as the original was. I am impressed with the way it performs..forward and backward, but this buoyancy issue. I talked to the manufacturer and they said that it is likely binding on the hull, so just drop it out and they will rework it. It was good of them to make the offer, but last time it cost me $16,000 to drop and re-install the rudder post. To test their theory, I piled weight on top of the rudder post in the cockpit. 120 - 150 and then 200lbs..made no difference. I don't think it is strictly buoyancy that is the problem. You have the same rudder that I am supposed to have. Now double the size and consider the angle of the rudder post...I am sure that the rudder is forcing the post into the side of the log. The chains effectively not only gave the rudder the weight but pulled down to compensate for the angle.
Bob
Most Users Ever Online: 120
Currently Online:
20 Guest(s)
Currently Browsing this Page:
1 Guest(s)
Top Posters:
Jonathan Oasis: 174
bobmcd625: 165
CAE: 150
mgav451: 143
Rick: 94
svbodhran: 84
Member Stats:
Guest Posters: 7
Members: 364
Moderators: 1
Admins: 1
Forum Stats:
Groups: 3
Forums: 13
Topics: 744
Posts: 3833
Newest Members:
Spirare, BradHartliep, Duncan, MistyDawn, realitysailing, Kwally@sbmnModerators: Patrick Twohig: 134
Administrators: Scott Carle: 1480
