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 Post subject: Re: EPO3 rudders
PostPosted: Tue Jul 09, 2013 5:28 pm 
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Start by using your existing hole locations as a guide. The lower casting hole has to move forward on the rudder to account for the rubber pad on the rudder (casting impact resistance).

Then use the information in the instructions for rudder rake: http://www.hobiecat.com/forums/viewtopic.php?f=18&t=467

Quote:
RUDDER RAKE -

Rudder rake (forward or aft in the lower casting) changes the helm feel. Weather helm (pull on the tiller) is caused by the rudder being aft of neutral. Lee helm is caused by the rudder rake being too far forward. Best adjustment is to have slight weather helm on all sailing angles. This allows you to hold the tiller against a slight pull for stable sailing angles. The boat should round up slowly if you drop the tiller. Lee helm is dangerous and can cause you to loose control of the boat. Neutral helm can be difficult as the tiller is pulling and or pushing against you on different sailing angles and can cause you to have erratic steering.

On older boats, rudder rake is adjusted by re-drilling the rudder blade. Either the upper casting hole or possibly both. Newer boats use the upper casting plate (see adjustment under "CAMS" above) and set screw in the lower casting for rake adjustments. There is a basic rudder rake setting to compare to. You can also use a drilling template http://www.hobiecat.com/support/tech/rudder.html

For proper rake adjustment you may need to try several settings. Helm feel will change with different mast rake, sailing angles and sail settings...

Start off with the rudders in the locked down position. Measure down the blade 12" from the bottom of the lower casting. Mark the rudder with a line 2" long perpendicular to the 12" point (fore and aft on the blade). Using a very thin piece of line, starting at the top of the rudder pin, align the "line" with the rudder pin top to bottom (on the pins center line / axis) and check where the line intersects the mark on the rudder. Mark the point where your rudder pin axis crosses the mark you made 12" down the blade. Measure in from the front of the rudder. A larger measurement means that the rudder is raked forward more. More forward rake is less weather helm. Optimally, you should have 1 5/8" to 1 3/4" for a measurement. To achieve the 1 3/4" number, you might have to re-drill the front hole on the rudder or file away at the front of the rudder where it hits the casting. To much forward rake can cause lee helm and THAT is WORSE and even dangerous. The boats sail better and are safer if the boat rounds up slowly when the tiller is released.

You can use the above technique to measure and re-drill a blade. Mount the blade on the lower casting. Make all of the above measurements and set (and hold) the rudder in the desired rudder rake position. Lock the upper casting onto the rudder and lower casting. Push the upper assembly up into the cam to seat it tightly (that holds the rudder in the raked position once the rudder system is fully set up). Align the tiller arm angle (vertical position) with the rudder assembly on the opposite side of the boat. You can mark the bolt hole position or drill right through using the casting as a drill guide. You must hold the upper arm in position while drilling this way. I angle the drill slightly forward rather than straight through. This forces the upper casting forward more as the drill reaches the opposite side of the casting after going through the rudder blade. If the hole is too far aft, the rudder will slip aft a bit when under sailing loads.

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 Post subject: Re: EPO3 rudders
PostPosted: Sat Jul 27, 2013 5:40 am 
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Joined: Mon Mar 22, 2010 1:33 pm
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This drilling is probably easier for people who have done a few of these and it becomes old hat. I misdrilled the top hole of my first one, but was able to salvage it. Second one I just used the good holes of the first. Don't forget to use a level to make sure you are going through the blade at 90degrees.

I went from standard blades to these and it's night and day. Great upgrade but lots of work and heartburn without a drilling template.


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 Post subject: Re: EPO3 rudders
PostPosted: Wed Apr 15, 2015 12:25 pm 
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We've been contemplating EPO3s but have to know what we can expect. I've been through all the notes here and things sound positive but experience is telling me different. I've never stalled my original EPO (1??) on either a 16 or my 18. It was an experience outside of anything I have heard, until we had a boat with the EPO2s (2013 H16) on it. They were drilled at the factory and we've had a lot of cavitation issues that renders them nonfunctional. We have to stop and regain flow to get out of it. This is a story I was beginning to hear from other folks. It was "Oh ya, you have to travel down" or something else, lots of damage control. At the Worlds I have on a GoPro video the rudders just quit right after a start with a near total loss of any control. Problem was these were EPO3s. I'm thinking of dumping the 2s and going back to the original EPOs we have around the house.

Is there something wrong with our sailing that is getting into this situation?? Something like over sheeting before we reached top end or something like that?? The Australian experience told me it is better to use "old" rudder technology that does not fail versus going faster but crashing more often. Help??

Jerry


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 Post subject: Re: EPO3 rudders
PostPosted: Wed Apr 15, 2015 1:03 pm 
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Never heard a negative comment on EPO3 until now. I suspect it was racing conditions in a big fleet jitters. Trying to pinch and over sheeting. Maybe the higher winds and not being far enough aft on the boat.

The blade is VERY close to the EPO2. Mostly a refined trailing edge a trued foil shape.

We have not "Factory Drilled" rudders in many, many years. To many variations in castings and boat models.

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 Post subject: Re: EPO3 rudders
PostPosted: Wed Apr 15, 2015 7:28 pm 
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yes Matt the 16 came with the EPO2s so I assume they were drilled at the factory. The boat was sailed a weekend or two just a couple of days and medium winds, still happens and I'm not getting it.


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 Post subject: Re: EPO3 rudders
PostPosted: Thu Apr 16, 2015 8:52 am 
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Joined: Mon May 09, 2005 10:25 am
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Location: Jersey Shore
I had a set of early production EPO II rudders and my experience using them on my H18 was similar to yours. The rudders would simply not balance out correctly - they would stall and the helm was whacky (they would develop lee helm from out of nowhere). Comparing them to the original EPO blades, they were noticeably thinner and I think that contributed to the problem. I was told by one of the top racers in our area that the later generation blades had been improved, but I just went back to the good ole' original EPOs.

I have original EPOs on all three of my boats, and I'm still very happy with the performance - very consistent handling. The only time I've ever stalled out an original EPO is when it either 1) gets covered in weeds, or 2) sailing my H17 upwind in medium wind trapped out off the front of the wing. If that happens, I know I'm standing too far forward and need to move back to get more rudder in the water.

sm


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 Post subject: Re: EPO3 rudders
PostPosted: Thu Apr 16, 2015 9:02 am 
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mmiller wrote:
We have not "Factory Drilled" rudders in many, many years. To many variations in castings and boat models.


When sold as a replacement part or accessory.

I'd say you may have too light a helm... lee helm can easily allow over steering and cause rudders to stall.

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 Post subject: Re: EPO3 rudders
PostPosted: Thu Apr 16, 2015 9:34 am 
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I believe I understand what Matt is saying and yes sheeting to hard and too soon (going from 1st gear to 3rd too fast) is a contributor. With the factory drill holes, we are getting a what I'm told is a lot of weather helm. The have the boat at a relative rake of 17 or so. Most all the adjustment is out so re-drilling is the next option. I really don't want to do that as when we do Worlds or charter another "stock" boat we will have the same problem. Does Greg have any of these issues??


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 Post subject: Re: EPO3 rudders
PostPosted: Thu Apr 16, 2015 11:57 am 
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Location: San Diego
No problems at all with the 2 years now of sailing the H16 with the EPO3 on my personal (totally stock) boat or at the H16 Worlds with the EPO3 rudders.

I also have some experience with the EPO2 on a couple of previous boats. The only negative I can say about the EPO2 was sometimes in a lot of breeze sailing downwind (one rudder down) when I had to drive off in a puff the rudder would cavitate not allowing me to turn down. When this would happen I would have to move weight toward the back of the boat and sheet out which would reattach the rudder and off you go.

With the EPO3 I've never once had the rudder cavitate as described above or in any other way.

As for having any rudder stall going upwind, this is not a cause of the rudder itself, any rudder will cavitate going upwind when you're pinching and over sheeted. I've had this happen on the Tiger, H18, Wild Cat and yes the H16.

If you're having a lot of weather helm try experimenting with your settings, mast rake, down haul, mainsheet tension, etc. Those are more likely to cause weather helm than factory supplied / drilled rudders.

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 Post subject: Re: EPO3 rudders
PostPosted: Thu Apr 16, 2015 8:22 pm 
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Joined: Wed Jan 16, 2013 5:52 am
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Location: Perth - Western Australia
I have an ex-worlds 2014 boat with the red EPO 3 rudders and they do not stall unless i sheet in too hard after a tack while trying to drive too high. Usually I just have to ease the sheet, straighten the rudders to re-attached flow and then sheet back on.

Rake on my mast is set on the 5th hole from the bottom if that helps


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 Post subject: Re: EPO3 rudders
PostPosted: Fri Apr 17, 2015 6:52 am 
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gthomas wrote:
No problems at all with the 2 years now of sailing the H16 with the EPO3 on my personal (totally stock) boat or at the H16 Worlds with the EPO3 rudders.

I also have some experience with the EPO2 on a couple of previous boats. The only negative I can say about the EPO2 was sometimes in a lot of breeze sailing downwind (one rudder down) when I had to drive off in a puff the rudder would cavitate not allowing me to turn down. When this would happen I would have to move weight toward the back of the boat and sheet out which would reattach the rudder and off you go.

With the EPO3 I've never once had the rudder cavitate as described above or in any other way.

As for having any rudder stall going upwind, this is not a cause of the rudder itself, any rudder will cavitate going upwind when you're pinching and over sheeted. I've had this happen on the Tiger, H18, Wild Cat and yes the H16.

If you're having a lot of weather helm try experimenting with your settings, mast rake, down haul, mainsheet tension, etc. Those are more likely to cause weather helm than factory supplied / drilled rudders.


I checked several EPO2 rudders with a profile gauge, and while most of the ones I have looked at are pretty good, I did find a few which had noticeable differences in profile from one side to the other. The EPO 1 rudders I have looked at showed much less variation. The only set of EPO3 rudders I have had a profile gauge up against were nearly perfect.

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