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Old 01-25-2013, 10:28 PM   #61
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Art wrote;

"What I’m not clear on is the rudder’s water course actions in reverse due to boxed-in flat rear-end on rudder that no longer “cuts sharply” to enable direction-assistance water pressure juxtapositions while backing-up with no water flow from prop thrust."

About the only thing that matters in reverse is size and that dosn't matter much either. Even w a big rudder like mine one must go pretty fast in reverse to get much steerage. Then on Willy I've got to be careful, holding on to the helm to keep the rudder from being pinned hard over and if that happens suddenly damage could likely result. So I don't think it basically matters in reverse Art.
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Old 01-25-2013, 11:08 PM   #62
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The real trick isn't putting your boat into your slip every weekend...it's putting it where the dockmaster tells you to, no matter time of day, weather or any other distraction every day of the week in a different place for months on end.

Then and only then are you getting the hang of your boat.
Now, we're down to it. We have no permanent marina home. Wherever we are we are temporary. When we are cruising sometimes we run a long day. If we decide to pull into a marina any slip that is left are probably the worst as far as accessibility. Even in adverse conditions the boat has to go it. It certainly makes it interesting. The picture is at Jekyll Harbor Marina. The strong currents run parallel to shore. This is the only tie up available when we arrived. Anyone familiar with it will know that this is inside along the walk. Lou was not feeling well. so we needed a tie up. You can see how the current has the boat pinned against the dock.

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Old 01-25-2013, 11:49 PM   #63
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"What I’m not clear on is the rudder’s water course actions in reverse due to boxed-in flat rear-end on rudder that no longer “cuts sharply” to enable direction-assistance water pressure juxtapositions while backing-up with no water flow from prop thrust."

About the only thing that matters in reverse is size and that dosn't matter much either. Even w a big rudder like mine one must go pretty fast in reverse to get much steerage. Then on Willy I've got to be careful, holding on to the helm to keep the rudder from being pinned hard over and if that happens suddenly damage could likely result. So I don't think it basically matters in reverse Art.[/QUOTE]

Eric

The matter of bigger rudder size is important due to the larger sq inch available the more availability to experience high and low water pressures on rudder sides depending in the rudder angle position.

Keeping rudder straight pretty much equalizes water pressure on both sides, in either forward or reverse. Turning rudder on an angle changes the high/low water pressure against it, depending on amount of rudder angle in accordance with direction of turn and if moving forward with prop thrust or reverse without prop thrust. So... it seems to me that the flat rear edge on rudder pictured would interfere with water pressures on rudder sides while in reverse. Flat rear edge moving into water increases water turbulence on rudder sides, sharp rear edge minimizes it... therefore increasing the % difference and usable sq inch of water pressure as compared to each side. I’ve never seen a successful airplane wing designed with a boxed flat edge on its forward edge or rear edge.

After all a rudder is basically a verticle wing acting as its own complete foil while boat moves forward or reverse.
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Old 01-26-2013, 12:04 AM   #64
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Hey Art ........

How fast do you back your boat?

Yes MS I've gotten into some interesting spots that way too. And the learning curve is steep indeed.
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Old 01-26-2013, 01:01 AM   #65
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Hey Art ........

How fast do you back your boat?

Yes MS I've gotten into some interesting spots that way too. And the learning curve is steep indeed.
Eric

I back-up a boat as slowly or quickly as each situation demands. Faster a boat backs-up the more control from rudder turn angle due to more water pass by action. In tight quarters I prefer moving slowly in reverse as compared to quick moves... if possible. Square/boxed rear edge on rudder pictured seems it would conflict with reverse direction water pass by action creating turbulences and therefore reducing the acuity of high/low water pressures on rudder sides. This particular rudder design topic is strongly related to single screw boats, not twins. Twin screws via keeping rudders straight and well used throttles/shifts positions can handle most close quarter forward, reverse, turning circular needs. Rudder angles in combo with proper throttle and shift positions can move a twin screw straight to port or starboard.
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Old 01-26-2013, 07:56 AM   #66
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Try to find an environmental force (wind or current) that is in your favor when docking.
Assess the situation before you approach (proactive rather than reactive). Your boats unique characteristics will help determine your preferred method of mooring. Sometimes waiting an hour or two will mean the difference in direction or velocity of the current. Even in areas that don't change direction, the velocity will change. The point is, that the prudent mariner will use ALL the elements that they can stack in their favor.
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Old 01-26-2013, 09:03 AM   #67
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I have the rudder with the squared off ended I had serious concern about reverse directional control when building. My understanding is the foil shape on the positive pressure and negative side of the rudder are higher related to shape in forward and reverse flow. The new rudder was 6 inches smaller then the old. The forward turn radius was reduce by 50%. The boat is 42ft and can make turn in it own length just by turn the rudder over hard. I have to spin a 180 in a tight area to dock before the rudder I would have shift to reverse 5 or 6 times to make the turn now just once if all goes as planned. With single screw boats my experience is you have to go scary fast in reverse or have a over sizes bow thruster. I will use the scary 3 knots of reverse speed but nothing expensive needs to be around and It can not be very tight. The rudder was cheaper then the oversized bow thruster I had about 300 dollars in the new rudder. the price on the hydraulic bow thruster was 10000.
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Old 01-26-2013, 01:08 PM   #68
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And there it is.

In earlier post I responded to a query about docking simulators and if anyone used them or found one they liked. I responded that we did but did not elaborate on the type.

But we do indeed have a docking simulator that we bought a number of years ago and it's terrific. Much better than the Chapman's thing or the simulators that are available today on the web. We still "practice" with it today. The one we have is still available but you have to hunt them down--- they cannot be purchased new.

It was made by a small marine company in Singapore called, of all things, American Marine. It is 36 feet long, weighs 30,000 pounds, and has everything a real boat would have--- two engines, a wheel, two rudders, etc.

As far as we're concerned it is the best docking simulator ever made and we have become extremely proficient at docking our boat using it.

There are similar devices available under a variety of names. Some have two engines, some have one. But all of them do an absolutely stirling job of teaching one how to dock a boat in virtually every situation you are likely to ever encounter.

We strongly advise getting one of these--- the brand name doesn't really matter--- and then practicing with it as often as possible. You'll be amazed at how quickly you pick up the techniques. Once you learn them it's a snap to transfer your skills to your own boat.
Now THAT is an excellent post on many levels!
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Old 01-26-2013, 02:31 PM   #69
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The boat is 42ft and can make turn in it own length just by turn the rudder over hard. I have to spin a 180 in a tight area to dock before the rudder I would have shift to reverse 5 or 6 times to make the turn now just once if all goes as planned.
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The rudder was cheaper then the oversized bow thruster I had about 300 dollars in the new rudder. the price on the hydraulic bow thruster was 10000.
Compelling reasons for researching this design further.
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Old 01-26-2013, 04:49 PM   #70
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Now, we're down to it. We have no permanent marina home. Wherever we are we are temporary. When we are cruising sometimes we run a long day. If we decide to pull into a marina any slip that is left are probably the worst as far as accessibility. Even in adverse conditions the boat has to go it. It certainly makes it interesting. The picture is at Jekyll Harbor Marina. The strong currents run parallel to shore. This is the only tie up available when we arrived. Anyone familiar with it will know that this is inside along the walk. Lou was not feeling well. so we needed a tie up. You can see how the current has the boat pinned against the dock.

WOW!!!!!....you have done it..giant smile....I am green with envy....Is this your home in the picture? I havent a clue where your at but if you get out to california or oregon I'll buy ya a beer, or what ever.

So Moonstruck has struck....ah whata life....
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Old 01-26-2013, 05:36 PM   #71
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WOW!!!!!....you have done it..giant smile....I am green with envy....Is this your home in the picture? I havent a clue where your at but if you get out to california or oregon I'll buy ya a beer, or what ever.

So Moonstruck has struck....ah whata life....
Thanks that was travelling from South Carolina to South Florida. The only deep water is right along the ends of the finger piers. It is at the marina on Jekyll Island, Georgia. Currents run very fast. In a few hours the current will reverse. That would have been a little easier docking situation, but I needed to get tied up. That's what I get for coming in late with no reservations.
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Old 01-26-2013, 05:44 PM   #72
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"What I’m not clear on is the rudder’s water course actions in reverse due to boxed-in flat rear-end on rudder that no longer “cuts sharply” to enable direction-assistance water pressure juxtapositions while backing-up with no water flow from prop thrust."

About the only thing that matters in reverse is size and that dosn't matter much either. Even w a big rudder like mine one must go pretty fast in reverse to get much steerage. Then on Willy I've got to be careful, holding on to the helm to keep the rudder from being pinned hard over and if that happens suddenly damage could likely result. So I don't think it basically matters in reverse Art.
Eric

The matter of bigger rudder size is important due to the larger sq inch available the more availability to experience high and low water pressures on rudder sides depending in the rudder angle position.

Keeping rudder straight pretty much equalizes water pressure on both sides, in either forward or reverse. Turning rudder on an angle changes the high/low water pressure against it, depending on amount of rudder angle in accordance with direction of turn and if moving forward with prop thrust or reverse without prop thrust. So... it seems to me that the flat rear edge on rudder pictured would interfere with water pressures on rudder sides while in reverse. Flat rear edge moving into water increases water turbulence on rudder sides, sharp rear edge minimizes it... therefore increasing the % difference and usable sq inch of water pressure as compared to each side. I’ve never seen a successful airplane wing designed with a boxed flat edge on its forward edge or rear edge.

After all a rudder is basically a verticle wing acting as its own complete foil while boat moves forward or reverse. [/QUOTE]


whoa....Its Saturday and me mind is not able to understand. I'm cooking and when i do high gravity brew flows and my concentration is on FOOD. So your saying that in reverse with a single you have less control?.....I think someone else mentioned that with twins the effects of rudder are less in reverse.
Ok, so I'm slow today. What your saying is always go forward and never look back, just hit the throttle and......

Kidding aside you are right, I think. The trick is to use the absolute minimum power you can to maintain steerage under current wind seas conditions and big small rudder makes little difference compared other drag factors in reverse?

Is that correct?
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Old 01-26-2013, 06:57 PM   #73
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Thanks that was travelling from South Carolina to South Florida. The only deep water is right along the ends of the finger piers. It is at the marina on Jekyll Island, Georgia. Currents run very fast. In a few hours the current will reverse. That would have been a little easier docking situation, but I needed to get tied up. That's what I get for coming in late with no reservations.
boating just about anywhere can be a challenge. I think i would have looked for a spot to anchor for the night just off the channel and not risked the fast currents at the peir in failing light.
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Old 01-26-2013, 09:32 PM   #74
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boating just about anywhere can be a challenge. I think i would have looked for a spot to anchor for the night just off the channel and not risked the fast currents at the peir in failing light.
The point was that he WAS good enough to get into a safe spot despite demanding circumstances...being good is about being able to do that...not doing it once or twice a week into a docile, home slip without crunching and thinking that's good.

Being that good means he had a safe haven pretty much guaranteed without having to poke around in unfamiliar waters, in failing light and strong currents hoping to find a decent anchorage with decent holding...all while tired after a long day. Not the best scenario....
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Old 01-26-2013, 10:49 PM   #75
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The point was that he WAS good enough to get into a safe spot despite demanding circumstances...being good is about being able to do that...not doing it once or twice a week into a docile, home slip without crunching and thinking that's good.

Being that good means he had a safe haven pretty much guaranteed without having to poke around in unfamiliar waters, in failing light and strong currents hoping to find a decent anchorage with decent holding...all while tired after a long day. Not the best scenario....
I know what he said, i just made the observation that it being a strange area, currents, not much deep water, and failing light i would have considered finding a spot off the channel and dropped the hook then waited untill morning to attempt docking. On my Alaskan i had built last year i had helm controlled adjustable lights built into the bow just for such occasions. In Delta waters with strong currents that change with the flick of a switch not to mention tides it can get a bit sticky docking at night. Flick of a switch referrs to the pumps at Brentwood which can reverse the flow of the Sacramento and San Joaquin rivers making for some interesting situations. The pumps provide water to an area that extends almost to the mexican border over 500 miles south. If it wasn't for them southern California would be a desert and California would not be the 8th largest economy in the world. They stop and start the pumps according to fish spawn needs and demand.
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