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Tiller/rudder thang agin

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John Russell
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USA
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Initially Posted - 03/14/2008 : 21:50:04

I started to reply in Quilombo's thread but decided that I didn't really want to hi-jack any more than it's already been hijacked. Besides, I had a new thought regarding that tiller/wheel thing.

I have to agree with Mike (Stampeder) I lock my motor amidships and come into my slip with rudder alone. I, too, have a tiller. I think it has lot to do with being able to turn the rudder past 45 degrees at very slow speeds but, hey, I'm no engineer and not nearly as experienced at Randy and others.

Here's where the new(to me) thought came in. As I begin to turn into my slip, my rudder is between 90 and 45 degrees to the transom. Therefore, it is 45 - 90 degrees to the direction of travel. But, as the turn progresses the angle as compared to the direction of travel for the stern significantly decreases. With the rudder at 45 degrees to the transom, and about halfway through the turn, the rudder is essentially "amidships" with respect to the turning radius. So, obviously, it loses any ability to more acutely turn the vessel. That's when the advantage of the tiller comes into play. While normally underway, turning the rudder that far over (essentially paralel to the transom) would act as a break since it would be at 90 degrees to the direction of travel through the water. But, as Frank pointed out, the boat is pivoting on the keel and the direction of travel for the stern is at whatever angle the rudder is at. That's because the rudder is always working to present its leading edge to the direction of travel. So, once the turn has commenced, the rudder, while at 90 degrees to the transom is still only at 45 degree or so to the direction of travel. Therefore, it does not lose its effectiveness as a steering device and simply become a brake. Therefore, I think that a tiller provides a more responsive helm (than does a wheel) in slow speed, close quarter maneuvering and now, I think I understand why.

Thanks, Frank.

Make any sense? Man, I wish I could draw pictures on this thing.

John Russell
1999 C250 SR/WK #410
Bay Village, Ohio
Sailing Lake Erie
Don't Postpone Joy!

Edited by - on

dlucier
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Virgin Islands (United Kingdom)
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Response Posted - 03/15/2008 : 10:11:06

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by John Russell
 Make any sense?<hr height="1" noshade id="quote"></blockquote id="quote">

John, it makes perfect sense.

I once asked a question about the C250 concerning the rudder movement in the picture below and I was told, "yes,...If I disconnect the link, there is still no more rotation of the rudder."

When pivoting in my rather tight marina, with my transom almost parallel to the direction of movement, my rudder is sometimes positioned almost parallel to the transom. I can only imagine how much more difficult it would be if my rudder's movement was as limited as the rudder in the picture above.

Another point regarding slow speed manueverability, many people are under the misconception that the rudder is useless under a certain speed, but actually this is not the case. With the use of sculling, one can still turn the boat or increase forward momentum while manuevering, which is why sculling is specifically banned in sailboat racing, but in order to do so, one must have the ability to quickly jerk the rudder side to side like a fish tail. During certain times of the year when floating masses of seaweed appear, I scull while still tied up to the dock to push the seaweed well clear of the stern.

Edited by - on

dlucier
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Response Posted - 03/15/2008 : 10:36:15

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Nautiduck
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Response Posted - 03/15/2008 : 11:04:11

I don't bang into the dock or other people's boats. The vast majority of boats out there do not have tillers, do not scull, and are not banging into everything.

A rudder works like a sail using differences in pressure on the leading and trailing sides to create the movement. The amount of movement and control is relative to the speed of the water passing the rudder. At slower speeds there is less movement, less pressure difference and less control via the rudder. Inboard boats have an advantage in that they can juice the throttle and send a current of water to the rudder this creating pressure. When the prop is alongside and aft of the rudder, like on our boats, this is not effective.

At slow speeds steerage is still there but is diminished. Throw in a current or wind pushing in the wrong direction and the steerage may very well be inadequate to maneuver effectively.

I use a combination of rudder and outboard steering to get into my slip. The use of each varies but as the boat gets very slow the OB becomes more important to me. We each have different situations and likely have reached different methods to safely maneuver our craft.

Edited by - Nautiduck on 03/15/2008 11:16:13

John Russell
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Response Posted - 03/15/2008 : 12:28:40

I agree Randy. My thoughts are only to explain this bit of enlightenment I had late last night while waiting for the teenager to come home. Others have said in many previous threads that the rudder acts only as a brake when past 45 degrees to the transom and that just had not been my experience while docking my boat. Until last night, I couldn't explain (to myself or others) why that wasn't the case. I'm not interested in the "tiller is better than the wheel" discussion because I just don't believe that. I agree that it's a "Ford vs. Chevy" kind of thing. The tiller and the wheel are different and this just helps me understand one of the differences.

Edited by - on

dlucier
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Response Posted - 03/15/2008 : 12:33:36

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Nautiduck
 I don't bang into the dock or other people's boats.<hr height="1" noshade id="quote"></blockquote id="quote">

That's great for you, but it has been my observation over the years that, more often than not, most docking mishaps, including some of my own doing, have been compounded by too much outboard use. Maybe I'm a bit more skiddish since at my marina we share a well, with nothing between you and your neighbor, and the docks themselves, which are fixed and made of concrete and steel, have zero give.

At a marina with floating docks made of soft wood or plastic with plenty of give, a small docking oops may only hurt one's pride, but that same little oops at my marina could result in the mast coming down. This is why I take the old adage, "Never approach a dock faster than you want to hit it", quite literally.

I often tell novice sailors at my marina something Derek once said,...

"Approach the dock as if you were a butterfly with sore feet landing on the lawn" - Derek Crawford

If that isn't the perfect analogy, I don't know what is.

Edited by - on

Nautiduck
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Response Posted - 03/15/2008 : 13:04:34

Don, we also share a slip and it is tight. Our docks float and we have a rubber liner plus round buoy floats to protect the dock side. I don't envy your situation with that dock so high!

When we put the boat in this April I will mess around more with rudder control at low speed. It certainly would be easier than kneeling by the outboard. We wheelies like to stand! I completely agree that slow is the way to go when docking.

One of the difficulties we face is that our slip is often 90 degrees to the prevailing wind. Coupled with the high freeboard of the C250 makes things interesting at times. The wind wants to push us into the neighbor's boat. I actually steer at the dock. The buoys keep us from hitting and then the spring line secures us.

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Dave Bristle
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Djibouti
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Response Posted - 03/15/2008 : 15:30:58

John: While I've been a principle proponent of not pushing the rudder past 45 degrees, I think you're right--with two qualifications...

1. After the boat begins to turn so that the stern is moving in an arc, the rudder can be pushed further over without "stalling" (becoming a brake). However, the mistake I've seen is pushing it hard over immediately, before the boat starts to pivot--especially when backing (where the rudder likes to push itself over). I was on a boat where the guy, backing out of his slip, almost backed into the boats behind him that way.

2. If you turn the engine with the rudder, the engine will immediately push or pull the stern over, at which point the hard-over rudder can help the boat to virtually pivot on its keel.

3. I do think you'll find, if you watch carefully, that with no engine involved, the boat turns more sharply if you hold the rudder short of 90 degrees than at 90 degrees. To turn without the engine, you have to have some way on, even as the boat pivots, and the rudder is more effective at say 60 than at 90. Then again, if you want to slow down, alternating between 90 to starboard and 90 to port will do the job--another think the wheel aficionados can't do!

Edited by - Dave Bristle on 03/15/2008 15:39:43

dlucier
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Response Posted - 03/15/2008 : 15:51:00

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave Bristle
 John: While I've been a principle proponent of not pushing the rudder past 45 degrees, I think you're right--with two qualifications...

1. After the boat...

2. If you turn the engine

3. I do think you'll find,..<hr height="1" noshade id="quote"></blockquote id="quote">

My math says that's three qualifications.

Edited by - on

John Russell
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Response Posted - 03/15/2008 : 15:59:45

Yeah, Don, but the important part is that DAVE AGREES WITH ME!

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dlucier
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Response Posted - 03/15/2008 : 16:04:11

Another instance when your rudder may need to be over 45 degrees is when you are heaving to.

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Nautiduck
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Response Posted - 03/15/2008 : 19:12:06

Mea Culpa!

I hereby renounce my previous postings on this topic. After spending some time at the boat today and reminiscing about last season I realize that I do dock using the rudder alone. Once the spring line is set I use the OB to move the bow and stern to accommodate the setting of the dock lines.

My bad.

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John Russell
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Response Posted - 03/15/2008 : 19:53:37

Absolvo Te!

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Arlyn Stewart
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Response Posted - 03/16/2008 : 09:49:13

There are actually two forces at work with a rudder, airplane wing, etc.

There is both a lift factor and a force vectoring factor. At rudder lock, a rudder has a high angle of attack though as pointed out that angle of attack is not as much as one might initially think considering the arc of the stern of the boat as has been pointed out in this thread.

At high angles of attack... the lift factor has stalled leaving only the vector factor. Both factors and especially the lift factor require boat speed. A high angle of attack produces great amounts of drag which does kill speed as well as an increasing vector force.

How one plays these factors and many more when docking contributes to success or failure when docking. The ability of a tiller to respond quicker and produce more throw can only be argued to provide more rather than less options and therefore would be a plus. I'd have no problem with an argument that a tiller offers some docking pluses over a wheel.

Comparing outboard thrusting to rudder control is not apples to apples because rudder control depends upon the center board or keel. A water ballast boat with board up reduces the ability of a rudder and requires the force vectoring of the outboard for docking controls. As well, there are a lot of unique qualities of all boats that must be factored when docking abilities are assessed. The 250 is light, it has minimal rocker, it has hard chines, it offers a lot of windage, all factors that play into the mix.

On my maiden with my 250... I was astonished at the leeway the boat has to a breeze. Loading onto a trailer with a cross wind was a challenge. I discovered quickly that the way to deal with it was to forget about trying to come straight into the trailer from any significant distance away... estimating the leeway to arrive at the trailer bunks would be next to impossible. Far better was to approach the cross wind trailer by heading directly into the wind and making a 90 deg turn onto the trailer. There can be no dallying as the cross wind will drift the boat. The boat has to make a smooth sharp turn onto the trailer and stick the bunks... or in the case of a slip, it has to make a clean entry and then get secured quickly.

To make those 90 degree turns without the board down is impossible without motor thrusting.

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