Boating Straight

AllanY wrote:

The leading edge balances the rudder and the other effect is to give better steerage when reversing

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Actually in addition to physical balance, the whole idea behind a pivoted rudder is that the portion of the rudder forward of the pivot point, the part that actually moves out in the opposite direction of the turn, is*to reduce the pressure or force*needed to turn the rudder.* The water hitting this smaller forward*portion of rudder provides a force that helps turn the rudder in the direction of the turn.* So less force is needed at the helm, or less force is required by the hydraulic system.

Now rudders that are hinged directly to the end of the keel don't have this feature.* The*whole surface of the rudder*has to be moved out against the force of*the water flowing past it.

But if the rudder is a balanced*pivoted rudder (or a spade rudder on a twin) there is, I suspect, a formula or two that governs the ratio of surface area ahead of the pivot point to the surface area aft of it.*

Too*much surface area forward and the steering can actually be overcome by the force*trying to pivot the rudder and you (or the hydraulic system) will have to "hold it back" from going too far over.* Too little surface area aft of the pivot point and you'll have to add more steering pressure to move the rudder over.* The correct ratio will yield a neutral steering effort with the rudder being easy to put over without having to add much*force to move it or any force to*hold it back.

Obviously the forces will change with the boat's speed but if you get that ratio*wrong, you or your steering system will be doing more work than necessary at cruise speeds.* Or the boat may start hunting as the rudder is moved around by unbalanced forces.

The steering on our GB with its two pivoted spade rudders is absolutely neutral.* It requires no change in effort to move them near their center of travel as it does at the ends of their travel when underway.* And if you put the rudders over into a turn, even a fairly sharp turn, and let go of the wheel, the wheel just sits there.* This is with cable-chain steering.* The mechanical steering ratio tends to resist backfed forces, so that's some of it.* But the point is that the design of the rudders was carefully calculated to minimize the force needed at the wheel.

I believe it is much more than an "eyeball" art to design the right rudder for any given boat.

-- Edited by Marin on Wednesday 25th of August 2010 06:20:29 PM

Absolutely right Marin, and many times after following similar discussions re the issues which can arise with hydraulic steering, I am often pleased that my vessel, like yours, has chain & rod/cable steering. However, to Gonzo, I would strongly urge the proper purging process be followed as described by Walt, even if it needs an expert to do it, so there is absolutely no air in the system before having anyone attack his rudder again, is case it is air in the hydraulics, and not the rudder balance.* If there is no improvement after that, then it has to be a rudder balance issue, as long as there is not excessive play (ie wear), in the rudder bearings.* A good wiggle of the rudder from below when out of the water (before hacking into it) should reveal if that is an issue.


-- Edited by Peter B on Thursday 26th of August 2010 05:53:48 AM

Installation instructions for my Wagner 700 series hydraulic steering recommends that it be plumbed*entirely*with*copper tubing (vs hose)*to a short flex hose at the cylinder to prevent instability in the steering system. That's how sensitive they are.

The point of the leading edge addition was a late adjustment. The yard where the work was done suggested we add the same ratio to the fore as aft to prevent extra stress on the bearing/bushing/stuffing box. We originally wanted to make the additions smaller, but like I said, the steel stock the welder had that was the same-ish thickness was no smaller than 1". So 4" was added aft.

Gonzo,Looks to me like you should cut off most or all the leading edge addition. You say it's steel.
When the boat's out just burn it off w OA cutting torch.
Another thought from my guest from Washington State (BYC) is to disconnect the ram rod end and push and pull the rudder horn thereby checking for lateral movement that would allow the rudder to move without a corresponding movement of the helm.


Anode,
I was told this also when I expressed my displeasure about the friction of the hyd steering. I bought the "Capilano" helm pump (much larger unit than my boat required) thinking that a large pump and large dia tubing would make for very light steering * * .....NOT so. Then they told me I needed copper tubing but I've talked to numerous others that say copper tubing is a maint nightmare. I think the reason the hyd steering has high friction is that all the seals exert significant pressure on the cylinder and rods. My larger components have larger area and bigger seals and hence more friction. If I had bought a system w small components my steering would have much lighter feel. By the way I didn't use marine hyd hose. I used large dia industrial hose * *...the kind found on equipment like back hoes and excavators. Shot myself in the foot but when I'm out on the outer coast in the nasty those big beefy steering components are a comforting thought.

Then they told me I needed copper tubing but I've talked to numerous others that say copper tubing is a maint nightmare

How so? I have the original 1983 copper tubing in my Albin. It looks good (where I can see it) and everything works fine. I have maybe 2 feet of hyd hose* from the uniflow valve to the cylinder, and I plumbed in the new autopilot pump with hydraulic hose (old non working pump was hard plumbed).

Chip,

That is what we have. Copper tube with a short length of hose at the ram.

Rob
37' Sedan

I too have copper lines with just the last connection to the cylinder a hydraulic hose.
The boat is 33 yrs old.*** I did some repairs about 12 years ago but not to the copper itself, but rather to the poorly done flares.** They are now all double flares and leak free.

One of the helm pumps is showing signs of a leak so that repair may be upcoming soon.*

The Wagner book strongly suggested the copper to eliminate expansion of the hoses.

Yeah,
Hydrive here in Australian reccomend the same, HP copper pipe all the way except at ends to ram and Octupuss pump short flex hose.
I installed mine 15 years ago and no probs.
A little leakage at the pump but easily tightened.

Benn

Hey y'all,

Sorry to dig up another old thread of mine, but I wanted to touch on this subject again as we are getting ready to pull Skinny Dippin' out for some routine work. I'd like, once again, to ask your opinion based on the pics I am posting. (I found them just the other day. Figured it might help you see my issue.)

I am now back on the side of doing nothing, even though I have just changed sides after seeing the pics. My memory thought the rudder was closer than it appears to be in the pics. Add to the fact that I don't know any other boat but this one. I spoke with someone with way more experience than I and he said, all single-screws wander around. He did qualify it by saying that it is more of a problem with the CHB trawlers because of their smaller rudder, but unless you can make it, and the screw, MUCH bigger, it's going to happen. I won't be able to go dead straight without any helm input very often.

One thing he said to try was to remove the zincs and see if that helps... I will try that in the future. I will also try what others mentioned here and bleed the hydro steering system. Perhaps explore slightly heavier oil in it.

*NOTE* The additions are not quite as thick as the original rudder. 1/16th smaller, or so.

Anyway... chack out the pics... See if I should just leave it alone or cut off the addition(s).

Thanks,
Tom-

In my experience copper tubing is fine as long as it is hard mounted with a flex at both ends. (Some sort of flexable hose.)
Sort of like an earthquake flex hose on the gas line mounted to houses in earthquake pron areas.
got to have something to counter the vibrations so it won't vibrate loose.

SD*

-- Edited by skipperdude on Tuesday 26th of October 2010 04:02:48 PM

I don't think you replied in the correct thread SD>

jleonard wrote:

Then they told me I needed copper tubing but I've talked to numerous others that say copper tubing is a maint nightmare

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I thought I was on the right page.

SD

*

GonzoF1 wrote:

Hey y'all,

Sorry to dig up another old thread of mine, but I wanted to touch on this subject again as we are getting ready to pull Skinny Dippin' out for some routine work. I'd like, once again, to ask your opinion based on the pics I am posting. (I found them just the other day. Figured it might help you see my issue.)

I am now back on the side of doing nothing, even though I have just changed sides after seeing the pics. My memory thought the rudder was closer than it appears to be in the pics. Add to the fact that I don't know any other boat but this one. I spoke with someone with way more experience than I and he said, all single-screws wander around. He did qualify it by saying that it is more of a problem with the CHB trawlers because of their smaller rudder, but unless you can make it, and the screw, MUCH bigger, it's going to happen. I won't be able to go dead straight without any helm input very often.

One thing he said to try was to remove the zincs and see if that helps... I will try that in the future. I will also try what others mentioned here and bleed the hydro steering system. Perhaps explore slightly heavier oil in it.

*NOTE* The additions are not quite as thick as the original rudder. 1/16th smaller, or so.

Anyway... chack out the pics... See if I should just leave it alone or cut off the addition(s).

Thanks,
Tom-

Click to expand...

Oh... You're right, just not to the "new" question. My mistake.

*

So GonzoF1---- what if anything did you decide to do about your rudder?

I think I am going to leave it alone for now. Chatted with a delivery captain today. He said every single-screw boat he's ever delivered, needs constant input to go straight. That said, he also said that I may have made it worse with the extensions, BUT that the handling I gained at slow speed and in reverse, surely offsets it.

Still, if you have any opinions based on the photos, don't hesitate to express it. I know how reserved you can be sometimes.

The only thing I would say is that I think the delivery skipper you talked to is off the mark. We charterd a single-engine GB36 before buying our own boat and it tracked just fine. It had an autopilot but we never used it--- we always steered by hand as we do on our boat. The effects of waves and currents aside, that single-screw GB tracked perfectly. No wandering tendency at all.

Carey on this forum has a single-engine custom lobsterboat and I've never heard him comment on any steering "wander" on his boat. I believe he has hydraulic steering, the GB we chartered had cable-chain steering.

Last summer we talked to a number of lobstermen on Prince Edward Island and while we never talked about steering specifically I did ask them about the handling of their boats when they were empty and loaded, in the rough seas they get, and so on. None of them talked about a need to stay on top of it due to inherent steering wander.

And I've never heard anyone on the GB forum--- and there are a lot of single-engine owners there from GB32s on up to GB42s--- talk about any wandering tendency whatsoever in their boats.

So based on all that I'm not sure I'd put too much credibility in that delivery guy's "constant input to go straight" statement. In wind, waves, currents, sure, all boats will need steering corrections. But if he's saying that all single engine boats wander even in dead calm conditions, I don't go along with that one.

But if your boat's handling is something you can live with and you like the improvement to it's low-speed maneuvering, then do as you're doing.

Well, perhaps I should qualify that because GB's (and other quality trawlers) have MUCH larger rudders. We were on the hard next to a Eagle and it had a rudder easily twice the size of ours. We have a cheap CHB (Senator), I think the guy was generalizing some, however, my mistake was really changing it before I knew all the facts or given myself enough time to get used to the stock rudder. I still have a few things to check before I start hacking off what I have already committed to.

Have you ever heard of the zincs causing issues like this?

Hiya,
** Can't comment on rudder size/design but I very much doubt your zincs have much effect on what you percieve as "wandering".* Leave the zincs on.* Could it be that you are running bow heavy?* THAT will definatly affect straight line performance and contribute to loose tracking.

GonzoF1 wrote:Have you ever heard of the zincs causing issues like this?

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No, but I haven't heard of a lot of things I would be surprised if the zincs would cause the rudder to move back and forth unless there's only a zinc on one side.* But my knowledge of hydrodynamics is minimal at best and is confined to pretty basic stuff like how floatplane floats work.* So I'd ask a pro about the zinc thing.* And I think RTF is right--- don't take them off at this point.

A larger rudder can make for a more rapid response to steering input but I'm not sure that size alone is the significant factor in rudder "wander."* I think it's much more to do with design and balance.

*


-- Edited by Marin on Tuesday 26th of October 2010 06:24:03 PM

I recall reading about an "articulated rudder", where the rudder was in two parts (fore and aft) and it worked well at all speeds.

Perhaps a web search will turn up more information and perhaps this would solve the problem.

You shouldn't have "wander" in your steering system at all.
screw boats don't wander!
Either your wander is in the system or its environmental effects on the hull itself(wind/current).

Your boat has high freeboard and a large cabin, if the effects are caused by wind, they would be more pronounced than say a lobster boat such as Careys'. Lobster boats by design are made to "Stay on the gear", meaning that when working a trawl they have to maintain a course while
hauling trawls (more than 1 pot on a groundline). Notice that they all have a relatively deep forefoot, long keel and minimal above deck windage. They don't add articulated rudders and
other goodies to maintain their mission. There is nothing wrong with articulated rudders-but adding them to a pleasure boat for "improved handling" is just plain nonsense.

Find out from a competent source if your steering system has issues, and deal with them if it does.
Your boat will never maneuver as well as a lobster boat but who cares? You want predictable,reliable steering within the parameters of your hull design.

Passagemaker Mag. had an article on a trawler with an articulated rudder, I believe Sept 2007. Additional underwater linkeages from the "flap" to the hull were used, not for me.
Steve W.

I would guess its slop somewhere.

Too much lead on a rudder makes for unstable turns.

Feed in a couple of deg for a slight turn and it tightens and turns more sharply as you go.

If you can create a mild turn , and the boat continues in that radius , the lead is fine.

I would have someone put a large wrench on the top of the rudder , and as you steam slowly, and see if they can wobble the rudder against the steering gear.

Hyd , look for air or a shot steering cylinder .

Cables , just keep looking , an you will see something stick and release , or have slop.
Wih little or no lead a barn door takes GOOD effort at all times, but a balanced rudder will require far less force , showing up play.

I think FF is right on. Been think'in slop has almost got to be the problem for at least a week.
Doug Dupuis,
I saw a picture of a Fales 32 on a brokers page and the Fales had a rudder considerably larger than my Willard. Could that be a stock Fales rudder?
Here is my rudder for reference.

I really don't think it's a problem with the rudder moving when it shouldn't be. I mean, I guess it COULD be, but I can make small adjustments with the rudder and feel them. The problem comes in correction of drift away from "setting the helm" to keep us going straight ahead, then, after a few small adjustments, she'll start to go slightly off course (be it from wind, current or whatever) and a small adjustment to port (just a few degrees on the wheel) to try and correct may go too far, but then it takes a full turn to starboard to correct it back. At that point, the back and forth begins all over again until I can again settle her back down to a somewhat straight course. It's a zigzag pattern that I have some concerns with a) in tight quarters b) when people are following me and I look like a dill-weed

The wheel is very easy to turn to starboard and there is a bit of resistance when turning to port. I have to assume that it's because of the prop wash for my anti-clockwise screw. Hydraulic steering system.

Now, that being said, we had a marina party this weekend and the previous owner was around. I did have a chat with him and he said that it is something he dealt with too. On one hand, it did help me come to term with it. I have been thinking that the change was due to the extensions I put on... Apparently not. So I won't be cutting them off as previously planned.

On the other hand, the question still remains as to what exactly is going on. I will take a crack at bleeding the system, but I think it's just "the way those boats are" and I just need to get used to it. I at least know I didn't cause it and won't be chasing my tail to undo it only to find it didn't fix the issue.

I don't think your problem is in the water (rudder). It sounds like an air problem to me. If it drifts off to port for a second or two, a full turn of the helm to starboard should not be needed to correct.What kind of system is it?

Beats me... Books are down at the boat

It does not sound like its the rudder leading edge or the rudder it self as you said it has gotten worse since you bought the boat?* Since you messed with the rudder had it gotten worse?* How do you know the rudder is straight?* Rudder indicator?* When we first got the boat it tended to drift to starboard. *To make the boat go straight the rudder had to be turn slightly, so I just reset the rudder indicator so it shows the rudder is straight.* Now it tracks straight solid according to the rudder indicator?* *****


*
So if your rudder post square post so you can get something on it to move back and forth.* Do you have an emergency tiller that looks like a big tire wrench thing to use to see if there is any play?* Many trawler have them!* We have a manual emergency tiller that fits over the top of the square rudder post.*


*
Is there play in the helm or is the helm solid?* If a three line system they are easy to bleed by turning the helm hard over back and forth to the stops and hold, which pouring fluid in the to helm to keep full.* If a two line system then have to actual undo a fitting at the piston, turning back and forth and adding fluid, which is more messier, but there is not that much fluid in the lines. Some pistons have a bleeder valve. Emergency Tape really works well even when the line is slippery and holds under pressure.* Great stuff to have around for temporary fix.*


*
Our hydraulic line developed a leak as it was run under the batteries and over the years, battery acid dripped on it.* Used plain domestic water pressure fit connection to fix.****


*

Wow.. Lots-O-Questions:

Has (it) gotten worse since you bought the boat? Since you messed with the rudder had it gotten worse? --- I wasn't sure until I talked to the PO. Apparently, it was like this prior to adding the extensions. My big mistake was adding the extensions only after owning the boat for a few months. I didn't have enough experience to make that call, nor did I look elsewhere for a problem. However, I now don't think it's the problem. I haven't checked the hydro steering system yet, but I don't think it's that either. My belief is that the single-screw CHB trawlers in general do this, but I don't know for sure until I hear from more of them. I just don't think there are that many of them here. I'm in a marina with 400 sailboats and only one other single-screw trawler with regular visiting owners. That's part of the reason we are relocating to Carolina Beach... MORE POWERBOATS... but that is a story for another thread.

How do you know the rudder is straight? Rudder indicator? --- We do have a rudder indicator. And while underway it DOES read about 10 degrees (or is it 20... DANG... I can't remember) steering to port, that is expected with an anti-clockwise screw wanting to walk the stern to port and steer the bow to starboard. Resetting the gauge won't fix anything except make it lie to me about the actual position of the rudder.

Do you have an emergency tiller that looks like a big tire wrench thing to use to see if there is any play? --- Yes. Not a bad idea to use it to look for play. It will surely give me more lever-arm that a pair of Channel-Lock pliers. Although, it looks nothing like a tire iron. It looks like a giant tiller

Is there play in the helm or is the helm solid? --- It seems solid. Well, solid turning it to port, but it's far easier to turn starboard. Again, propwash is causing this I think.