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 Post subject: Trouble with EPO rudders
PostPosted: Sun Nov 13, 2011 11:17 pm 
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Location: Tucson, Arizona
I finally put a set of EPO rudders on my H20 and the results were disappointing. I tried them for the first time at the Fleet 514 Piñata Regatta last month. We only did one day of racing with the rudders. The first day of the regatta we didn't race in order to tune the boat. The only problem that was noticed was the EPO rudders aren't as wide as the stock rudders and vibrated in the rudder casting. I fixed that by shimming the bottom of the rudder casting with some electrical tape. The rake was adjusted so that the leading edge of the rudders was firmly held against the bottom of the rudder casting and the upper arm set flush on the rudder casting.

I took pains to drill the EPO rudders. I used the drill template, a wooden jig and the stock rudders as a guide for marking the holes and a friend with a drill press helped me drill the holes.

Initially when the wind was light (5-10knots) the boat helm was neutral and as the wind got stronger weather helm increased but was never considered excessive.

Race day the wind was strong (15-20knots). The problems started bearing off at A mark to head back down to the C gate. I was crewing for my Dad and his recollection was that "on a broad reach with plenty of power the boat accelerated and the rudders began to hum louder and louder. Then abruptly the rudders lost effectiveness and the boat would bear off slow down and the rudders would regain authority"

The first two times this happened I didn't believe him and I complained about the sudden heading changes. We were double trapped as we came around A mark and a sudden heading change was going to make me lose my footing. The third time this happened, again, at A mark my Dad lost his footing swung forward and knocked me off my feet. Needless to say it was quite the circus getting sorted out and afterwards I accepted that fact that something was wrong with the rudders. For the fourth and final race of the day we deliberately slowed down rounding A mark and the boat stayed under control.

Previously, we've never had trouble losing control of the boat rounding A mark with the stock rudders.

I don't trust the EPO rudders. I don't understand why they were cavitating :?: causing the boat to go out of control. The trailing edges of the rudders look good.

Has anyone else had a similar experience with the EPO rudders?

Is it possible to get another set of stock rudders?


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PostPosted: Mon Nov 14, 2011 10:15 am 
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Location: Jersey Shore
I sailed/raced a H20 pretty extensively in the mid-90's/early 2000's. My recollection is that the 20 always seemed to have issues with the rudders while sailing downwind. They had a nasty habit of ventilating during high-speed reaches which would cause them to stall and you'd lose control of the boat brifly until the flow became re-attached (usually by giving the rudders a few sharp wiggles). It was real important not to over-steer and also try to use the sails to help with turning as much as possible. The mainsail is very powerful and can easily overpower the rudders (this would definitely be the case during an A-mark rounding where the main will want to continue going upwind if you don't dump it during the turn). The EPO rudder profile probably has even less surface area than the original 20 rudders, so I think this could be making the problem even worse - a very powerful boat with relatively small rudders.

My experience with the new EPO2 rudders is pretty limited. However, I tried them on my racing H18, and didn't like the feel. The helm was much less consistent than the original EPOs (probably because they are a little thinner). So now I use them on my beach boat where we don't push it as hard as when racing and overall helm feel isn't as critical. Pretty much all of the 16 racers use and like them, although the 16, 18, and 20 are very different boats, so what works on one, may not work on the other.

sm


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PostPosted: Mon Nov 14, 2011 12:12 pm 
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Has to be a rake issue. You may have them set too neutral (too far forward). Try raking them aft a little. You should have a slight weather helm on a reach / downwind run. Your's sound as though they go leeward-helm as you turn down.

Most reports here in the forums have been favorable to the EPO on the H20.

Quote:
Phil Collins has won at least two H20 National Championships with EPOs

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PostPosted: Mon Nov 14, 2011 7:57 pm 
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Location: Tucson, Arizona
What should I try for an initial rudder rake setting?

The plastic Allen screws at the base of the rudder castings that set the rudder rake stick out 1/8". Should I set them at 3/16", 1/4" or more? Thanks,


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PostPosted: Tue Nov 15, 2011 9:38 am 
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Now that you have sailed them and they work, but may need slight adjustments, it will be trial and error from here. Sail again. Check the helm on a reach / downwind. If they truly are going lee... you have to determine if it is just one of the two rudders or both. Sail each tack with the weather side rudder up. That should help narrow it down. Then adjust the rudder(s) aft a bit. And sail again.

There is no rake "setting" as helm can be affected by mast rake differences, sailing styles, conditions. Rudder drilling, blade differences... all can have an effect.

In any case, you should be able to lay the tiller down when sailing off the wind. The boat should round up, at least slightly. Lee helm is dangerous and difficult to control. Neutral helm can be a problem too, I find the helm is easier to control if it always has a slight pull on the tiller, on all headings.

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PostPosted: Sun Nov 20, 2011 6:38 pm 
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Location: Tucson, Arizona
Any recommendations for shimming the bottom of the rudder casting near the rake adjustment screw for EPO rudders?

Currently I'm using electrical tape but I'd like to use something more permanent.

I need one of the plastic screws that set the rudder rake at the bottom of the rudder casting. On one of the rudder castings, it was frozen and I had to drill it out. Can I get a set from Hobie Cat?


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PostPosted: Sun Nov 20, 2011 7:57 pm 
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Last year, I was working through the same issues with rudders that you are. One of my rudder rake screws was frozen. At the recommendation of someone on this forum, I cut both screws off and epoxied a piece of neophrene in the lower castings where the screws were to keep the front of the blades from chaffing against the castings. On the blades, I used the paper template as a reference and positioned the bottom holes about a half hole width forward of the where the template would have had me drill them. With a bolt through the lower hole and casting, I held the rudder with the rake I wanted and positioned the upper casting where it needed to be in relation to the rudder rake adjustment screw in the upper casting. It was set in the middle. Do this with the rudder in the locked postion and push the plate in the upper casting against the cam to unsure the blades will lock when you are done. I made sure the angle of the tiller arm was such that the upper and lower castings were in alignment. A helper with a light colored Sharpee marked the blade through the upper casting hole. I drilled the holes with a drill press using a level to ensure that the blades were level from top to bottom and from front to back. I used clamps and improvised various shims and supports to hold them level on the press. Matt Bounds' article in one of the recent Hotlines was a huge help. If you mess up, it's not a big deal to fill the holes with Marine-Tex (one of the few applications for this stuff on a Hobie) and drill again. I believe Matt even writes about the proper way to do that so you don't get air bubbles in your filled holes. Once you start putting the pieces together and walk through the process before you drill the upper hole, it will make more sense. Good luck.

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PostPosted: Mon May 07, 2012 2:35 am 
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Location: Kaneohe, Hawaii
AJ,
Make sure your rudders are aligned and not toed in or out. This will cause some of your problem. I agree the EPO2's are not a rudder designed for this boat. I'll keep rebuilding my stock ones.
I sail in surf and ocean swells, the EPO2's are so short fore and aft that you can't drive the boat on a wave. The bottom of a Hobie 20 is not a planning hull it's more pointed which is typical of the design of the 90's and you need more rudder to drive the boat because she will track. If you want high aspect rudders get yourself a Tiger or WildCat the bottoms are flat and they spin on a dime.
That's my not so humble opinion and I've been sailing a 20 for 18 years now.


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