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Old 01-23-2016, 04:09 PM   #21
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Absolutely, I will add as much as I can to the front of the rudder to keep it balanced.
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Old 01-23-2016, 06:43 PM   #22
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I replaced the rudder in my charter boat (Bruno & Stillman) which was very inadequate. Consulted with several authorities (self proclaimed) and came up with the ratio of 25 to 30% of what is behind added in front for a rectangular shaped rudder. Mine is 28% and works effortlessly with mechanical steering (not hydraulic).

One of the points that was made to me about the leading portion was when hard over, the greater the length of the leading edge, the higher the percentage of water coming off the prop hits the rudder. Theoretically, if there is no leading edge, only half the water from the prop is hitting the rudder.

When adding more to the leading edge, remember to consider prop clearance for pulling the prop. Otherwise you may have to disconnect the linkage to turn the rudder enough to pull the prop.

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Ted
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Old 01-23-2016, 08:33 PM   #23
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Rudder Modifications

Before you go about redesigning and replacing the rudder, satisfy yourself that the problem isn't something like insufficient hydraulic fluid and/or hydraulic ram problems.

We had a similar problem with a vessel we chartered in 2012. I thought the rudder was too small or some such thing but in hindsight I wondered if it was a problem with the hydraulic system as it's response was too slow. I guess I'll never know.

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Old 01-23-2016, 08:57 PM   #24
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I wonder how many people who have modified their rudders have any real before and after data with a good before baseline to prove the modification was of any real benefit.
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Old 01-23-2016, 09:28 PM   #25
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Ever see one of these?
The US Navy thinks highly of them, this one is under a 50' Utility boat.
It is a reverse thrust rudder, it has a linkage to the main rudder and turns with it. Although it looks small, it is effective, as the cylinder has much more surface area than is apparent.
While you still have to "back and fill", the reverse burst is much more effective than without the device.
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Old 01-23-2016, 09:58 PM   #26
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I wonder how many people who have modified their rudders have any real before and after data with a good before baseline to prove the modification was of any real benefit.
Not sure what data you're looking for.

In my case, the rudder had almost no leading edge and was about 2/3 of the square inches of surface area of the new one. Without the leading edge it was difficult to turn as speed exceeded 6 knots. Backing was horrible (new rudder can't quite overcome all the prop walk, but pretty good). Do to the small surface area and no leading edge, you had to throw a lot of water at the rudder to kick the stern over. New rudder can back and fill with almost no throttle (bigger diameter prop also). The only trade off with the new rudder is that at 15+ knots, do to surface area, the rudder is a tad to sensitive ( takes very little movement to change course). This isn't a problem for the autopilot; I just need to be more precise.

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Old 01-23-2016, 10:09 PM   #27
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To the OP. Just read Gerr's book.
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Old 01-23-2016, 10:28 PM   #28
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I wonder how many people who have modified their rudders have any real before and after data with a good before baseline to prove the modification was of any real benefit.
I have good data. However, it is described in sailing terms so not really applicable here.

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Old 01-24-2016, 12:12 AM   #29
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Rudder Modifications

If you look back through my post you can see what I did. I can make a near zero radius turn if I want with my single screw boat. Just google funangler rudder and that will lead to most of the post. There is also a video of the boat in action on YouTube.
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Old 01-24-2016, 07:35 AM   #30
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Can't tell from the picture but rudders in front of the props are flanking rudders...very common of tug/utility craft.


Can be set up many different ways to spring into action...not always a direct connection.
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Old 01-24-2016, 08:06 AM   #31
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Greetings,
Re: Post #25. Is there a propeller missing on the end of that shaft or am I missing something?
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Old 01-24-2016, 08:24 AM   #32
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Not sure what data you're looking for.
I was just saying that because someone feels a modification has made an improvement, doesn't always mean it's so. Especially if the modification was made by the seat of ones pants.

And I'm not speaking to any one person here directly. Just making an observation.
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Old 01-24-2016, 08:36 AM   #33
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If you look back through my post you can see what I did. I can make a near zero radius turn if I want with my single screw boat. Just google funangler rudder and that will lead to most of the post. There is also a video of the boat in action on YouTube.
Now thats impressive. I can spin twins on a 180 easily, but thats the first time I have ever seen a single screw do it. Any chance of a couple pics on the steering cylinder attachments at full turn?
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Old 01-24-2016, 08:48 AM   #34
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I wonder how many people who have modified their rudders have any real before and after data with a good before baseline to prove the modification was of any real benefit.

I did. Given the same set of circumstances again, I would wait until I am sure it wasn't just a new boat owner that didn't know the handling characteristics of the new boat.

I have the same problem now. We now have out first twin screw and I am FIGHTING the urge to install a bow thruster until I figure out how to really handle her in different conditions.
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Old 01-24-2016, 08:59 AM   #35
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Tom....don't fight too hard....


To me the better reason for a thruster on a twin screw boat is when you lose one, some boats are dang near uncontrollable on one screw.


Sure the braggarts will say...'No problem...it can be done"...well so can a lot of things "be done", but why struggle and take the chance.


Getiing used to twin screw is just practice and unlearning some old habits to a point. My own 10 year old son and many other kids who have never even drove a car learn a twin screw pretty quick and pretty good. That's not a slam if it's taking you a bit...it's that "seeing through different eyes" that may be taking the problem. You will get it and twins will make some tough docking situations seem like why aren't all boats twins (that's for the argumentative, which is better types).
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Old 01-24-2016, 12:20 PM   #36
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I have about 38 degrees and to get any more I would need a bigger steering ram, I think I am going to add material to both sides of the Rudder, that should give me a few more degrees, and might even help in reverse.
Steve
I am not an advocate of more than the std 70 degree rudder swing altho several here have good reports. To increase rudder swing, you don't need a longer ram. You need a shorter rudder arm. Just move the hole towards the rudder stock slightly and you increase your angle. 38 degrees should be enough tho. How is adding to the rudder (anywhere) going to give you more angle??
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Old 01-24-2016, 12:51 PM   #37
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Thanks Brooksie.
While I've recomended increasing rudder deflection numerous times in the past the following comes to mind.

I have 90 degrees of rudder deflection and it never occured to me that my larger than normal ram cylinder had anything to do w the 90 degree deflection. Well the more deflection you have the less torque will be applied to the rudder shaft? I have a very large ram and helm pump for a 30' boat also w a very big rudder. Not to mention three turns L to L. Knowing that I may not now be as eager to recomend it to boaters w normal sized steering systems. I also have noticed in 7' quartering stern seas that my system handles the large rudder forces fine. So at this point I need to say that a steering system w a faster rudder (large deflection) will need the whole system powerful enough and robust enough to handle the increased loads and I have no idea if the average system can do it gracefully. I installed the oversized steering system for other reasons and it came in very handy when I increased the swing to 90 degrees. So if one goes to the wide swinging rudder w decreased mechanical advantage (as I did) the whole system needs to be strong enough to handle the increased forces.
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Old 01-24-2016, 03:08 PM   #38
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Thanks Brooksie.
While I've recomended increasing rudder deflection numerous times in the past the following comes to mind.

I have 90 degrees of rudder deflection and it never occured to me that my larger than normal ram cylinder had anything to do w the 90 degree deflection. Well the more deflection you have the less torque will be applied to the rudder shaft? I have a very large ram and helm pump for a 30' boat also w a very big rudder. Not to mention three turns L to L. Knowing that I may not now be as eager to recomend it to boaters w normal sized steering systems. I also have noticed in 7' quartering stern seas that my system handles the large rudder forces fine. So at this point I need to say that a steering system w a faster rudder (large deflection) will need the whole system powerful enough and robust enough to handle the increased loads and I have no idea if the average system can do it gracefully. I installed the oversized steering system for other reasons and it came in very handy when I increased the swing to 90 degrees. So if one goes to the wide swinging rudder w decreased mechanical advantage (as I did) the whole system needs to be strong enough to handle the increased forces.
Good point.
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Old 01-24-2016, 04:02 PM   #39
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When I fit the boat out preparing to move to Alaska I installed a new engine, rebuilt trans and lots of other stuff. The Capalano hydraulic steering was one of the up grades.

But Willard put the two holes in the rudder horn so the original push-pull cable steering must have been strong enough as I have not made my rudder larger.

When I had another Willard 30 skipper aboard I turned around (180) in a fairly narrow fairway and he got very nervious. Thought he was going to throw into reverse w/o my permission. He was reaching for the levers. We cleared the stern of the big seiner w room to spare.

One of the reasons I went to hydraulic steering was for a lighter steering effort. It turned out considerably heavier and I think it's due to the two large hydraulic units and the larger seals. Seal friction is the cause IMO.
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Old 01-24-2016, 04:34 PM   #40
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Greetings,
Mr. TB. "Slight" thread drift...Having been aboard your previous vessel and seen the modifications/upgrades and excellent quality of your work (and Bess's), I would think you will never suffer an engine loss short of an unforeseen catastrophic failure thus negating the need for a bow thruster in the situation suggested by Mr. ps (post #35) although anything is possible. Save your pennies for that craft beer hobby you enjoy...Practice, practice, practice...um, sorry, I mean practice maneuvering...
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