Author Topic: Rudder Angle  (Read 4116 times)

John Learmonth

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Rudder Angle
« on: October 11, 2014, 09:50:23 PM »
As a newcomer to the Viper and a very happy owner, with regards to the rudder angle which always seems to be pointed out when talking of the boat to others, has a vertical rudder been trialled and if so what was the results?
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Dave Nickerson

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Re: Rudder Angle
« Reply #1 on: October 14, 2014, 08:38:00 PM »
Guess this is one I should address.  John, I don't know if you voted for it, but a new Class rule just passed and goes into effect November 1 that would allow testing of new ideas while racing that would otherwise not be legal.  The idea is that a limited number of boats test something at a major regatta in a structured experiment with the approval of the Exec and Tech committees.  If successful a rule change could be proposed that would then be voted on by the owners per our constitution.  We typically address rule changes once a year and vote them before or at the annual general meeting.

So, since the ability to run a meaningful test is just becoming available, nothing has been done.

But, in a lot of ways, I think we already know what the results would be.  Some early boats had a rudder that angles forward just above the water line, effectively making the leading edge vertical (though the axis of rotation is angled).  Since these were originally supplied by the builder at the time, they are still legal on only those boats.  There are only maybe 10 or 20 in active use, one is a local friend's boat and I've sailed it.  Justin Scott sails one.  I saw one this weekend at HPDO. 

As you would expect, there is essentially no feel in the helm.  I like this, some don't.  It makes it very easy to over steer because there is no feedback. It also moves the center of lateral resistance slightly forward so the balance of the boat is different but headstay adjustments and tuning seems to be able to counteract it.  As background, I understand the rudder was made angled long ago in response to feedback from owners that they wanted more feel in the helm.

Any race course results appear to be inconclusive.  Justin sails his boat very well and has good sails.  His keel is well shaped - I've measured it.  Usually he does very well, but from sailing against him now for about 5 years I'd be hard pressed to say the rudder makes a material difference.

A new wrinkle is possibly making the axis of rotation vertical which should make the boat easier to control in conditions where a broach is possible.  The angled axis only helps create heeling forces when the tiller is pulled to windward. This has not been tested, but is doable by designing, making and adding some sort of wedge to the rudder tower and drilling a bunch of holes.

A question is whether to go through the effort to find out. 

Opinions from folks?  Is this worth digging into? 

Dave Nickerson - tech committee chair

Viper #208 - Noank, CT

John Learmonth

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Re: Rudder Angle
« Reply #2 on: October 14, 2014, 11:16:25 PM »
Thanks for the reply Dave. All points taken, I am a strong advocate of one design , although here in Australia we race sms sportsboats to experience big fleet numbers. The Viper performs well in sms but nothing beats that first over the line. I understand cost is important in making changes so not to disadvantage the guys not wanting to spend money , but if there was a definite improvement I think it would be welcome by the racing fraternity.I remember Rondar making a rudder post repair kit which could be bounded over the existing post. A similar item could be moulded with a vertical stern face but I would imagine the rudder would not suit hence more expense. I suppose its the same old story, if it isn't broke why fix it. Thanks again for a informative reply.
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Tim Carter

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Re: Rudder Angle
« Reply #3 on: October 17, 2014, 02:06:29 PM »
Another option that could be tried is making a new SS gougeon bracket with a longer top leg.  It in theory could bolt to the existion holes so no drilling and possibly a affordable path.   Existing tiller will be higher off the floor at the inboard end, may not be a problem.
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Paul Zimmerman

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Re: Rudder Angle
« Reply #4 on: October 17, 2014, 02:14:49 PM »
Something like this? Keep in mind that the tiller will be at the wrong angle using the current rudder.  Credit to Terry Phillips at Suburban Machinery

Dave Nickerson

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Re: Rudder Angle
« Reply #5 on: October 17, 2014, 03:40:33 PM »
In concept yes, but can imagine that's inexpensive.  I was envisioning a functional equivalent in glass and/or carbon that bolts or glues to the existing rudder tower.  Existing rudder plate would bolt to it.

Tiller could be straightened by a male to male angle.  Slides into the tube on the rudder, has an angle down to parallel with the cockpit floor, then a slightly shortened tiller slides onto the angled part.
Viper #208 - Noank, CT

Justin Scott

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Re: Rudder Angle
« Reply #6 on: October 17, 2014, 05:15:32 PM »
The history of the rudder is that all the original rudders had a kink like my rudder that angled it forward at the transom. Despite the kink the rudder is still not presented to the water vertically. The rudder tower is angled so that as my rudder is turns it becomes less vertical and unlike the straight rudder it is not turning on its axis so the depth of the rudder changes as well....in an unfavorable way.

The straight rudder was offered as a replacement to improve the feel on the helm.  At that time we had fixed head stay length. In hindsight it seems a pretty strange way to solve a feel issue that an inch of extra head stay could have fixed. But some of the earlier rudders were failing where the tiller attached, so I guess it was 2 birds with 1stone.

I have 3 recommendations from my experience with my fwd rudder.
1. If we are going to make changes to the Viper rudder system, don't fiddle around with trivial changes that are a hassle to implement and will not be a significant improvement. Start with a clean sheet of paper and design an entirely better rudder. The rudder shape , coming down to a sharp point was a "hot look" in 1996 but it is hugely inefficient. A new rudder shape, professionally designed, will keep the Viper as the leading edge sport boat and make it considerably easier to sail in big breeze. The other changes will have negligible effect....my rudder is no better or worse than the straight rudder. A new rudder will be a lot less than a jib.

2. Increase the max length of the head stay . I chose the current head stay length measurements. I simply added the throw of the Ronstan turnbuckle onto the previous fixed head stay length, so the min would be the length we used for aluminum masts and the max would be the Ronstan  turnbuckle fully open. No science...just a quick practical way to get a number as we wrote the first class rules. 5years of useful experience later we know the carbon mast and modern sail shapes moved the center of effort forward and all sail makers recommend sailing with max head stay length. A good rudder will need a longer head stay to maintain a nice helm. There is no reason to not have a perfect helm for everyone achieved by a couple of turns of the head stay turnbuckle .....the alternative is finding more expensive and complicated ways to balance the helm.

3. Investigate an inexpensive solution to straighten the rudder tower. This might be the least bang for the buck for existing owners. A properly designed rudder blade will solve most issues. The advantage in going the extra yard and straightening the rudder tower is that it opens the door to supplying cassette rudders to new boats which would be a nice feature for those who launch in shallow water. I have deep water so it's not a big deal for me but the dual advantage of widening the number of places a viper can be sailed and a rudder that turns on its vertical axis would probably encourage me to support the extra expense.

So 2 cents from one of the sailors with the original rudder.

Bottom line is that simply altering the angle so the existing foil doesn't make much difference.

Viper - Mambo Kings
Right Coast Refreshments Committee

Justin Scott

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Re: Rudder Angle
« Reply #7 on: October 17, 2014, 05:25:24 PM »



Any race course results appear to be inconclusive.  Justin sails his boat very well and has good sails.  His keel is well shaped - I've measured it.  Usually he does very well, but from sailing against him now for about 5 years I'd be hard pressed to say the rudder makes a material difference.


I always wondered why David used to sail behind me in races.... It turns out he was studying my rudder!!!



I guess he has found out all he needed to know because now he sails in front of me. Sigh.
Viper - Mambo Kings
Right Coast Refreshments Committee

John Learmonth

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Re: Rudder Angle
« Reply #8 on: October 20, 2014, 04:16:09 AM »
My thoughts would be either a cover to retrofit over the top of the existing rudder post or a fibreglass or carbon fibre wedge bonded on the back of the existing one, manufactured by Rondar  which wouldn't be as bulky as the pictured one. It could be done quite easy i would imagine. Another option would be a similar gudgeon as the existing one with longer top plate and revised angle however the length of it would have to have a strong gusset to stop twist,this could be an option for trialling, however the glass option would be the best for both strength and aethetics.
The tiller only would need a bend in it
« Last Edit: October 20, 2014, 10:40:00 AM by John Learmonth »
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Charlie Visser

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Re: Rudder Angle
« Reply #9 on: January 30, 2015, 04:59:16 PM »
An interesting experiment would be to trial a K6 (or VX One) class rudder on an angle adapter.
« Last Edit: January 31, 2015, 09:48:29 AM by Charlie Visser »
IceBear

John Learmonth

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Vertical rudder bracket.
« Reply #10 on: October 14, 2016, 07:06:57 PM »
I have not read anything lately on the vertical rudder. Has this simply gone away or nobody wants to discuss it. I have been racing my boat with a bracket which bolts on to the standard tower here in Bundaberg , Australia . There are only 2 Vipers in our fleet  and we both are using it. Our courses are not the standard windward leeward type but one that has to sail 3 miles out of a river mouth to the open water. We encounter a lot of tight shy running which caused many round ups. After testing the bracket we have given it the thumbs up as the boat is much more manageable, so my skipper says, and confirmed by fellow competitor Terry Riley. If we were to race in a Viper fleet the bracket could be easily removed but for our club and mixed fleet racing it will be staying on the transom. The only other mod required was a longer tiller with a bend which cost $10. I'm sure if the class accepted the change, cost would be minimal if a retrofit design could be designed by Rondar. As I have said in earlier posts, I embrace one design , but sometime improvements need to happen, look at the ultimate one design class, the Laser. It has had several rig and sail mods over the years.
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Dave Nickerson

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Re: Rudder Angle
« Reply #11 on: October 15, 2016, 07:43:05 AM »
This discussion is much more up to date in the "Class Members Discussions" section.  In our one boat, one vote structure, this is intended to help enable a discussions among the owners who vote.

Buttons is working on making sure everyone's access is up to date - he expects to be done with all that by late Tuesday 10/18.  If you are an owner and have paid your 2016 dues and don't have access by then, please let Buttons know.
Viper #208 - Noank, CT