Rudder Mod

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wilfbradbury
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Rudder Mod

Has anyone tried to modify the rudder on the Mk2 , to increase the surface area? I find our boat could use a little more rudder control to prevent "round up" and improve low speed control.
Hull number 1437 1995.

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LCBrandt
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Wilf,

Describe the situations in which you experience the 'round up', please. What waters, seas, winds, sail that you have up, etc. How long have you had your boat? What is your standard 'policy' for reefing? Do you reef the main first or the jib? At what wind speeds?

Also, please click the User CP link in the upper left corner of this page and set up a signature (using my signature below as a model) so that we know more about you and your boat. What rig (tall or standard) and what keel (fin or shoal)? Thanks.

Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
 

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Nimue
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Correct me if I'm wrong, but the Mk II already has an enlarged rudder relative to the mark 1?

If you go too big with the rudder, the loads on all the parts go upwards. I was on a boat a couple winters ago that lost it's rudder (while doing about 13 knots) and I would have to say that a moderate sized rudder is far superior to none at all.

Jason V
Vancouver, BC, Canada

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deising
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Larry's questions are all good.

I can tell you from racing on other people's boats that if you fail to adjust for excessive weather helm, you can wind up with the rudder at too high an angle. At that point, if a gust starts the boat rounding up, the helmsman tries to apply even more rudder, and the rudder will likely 'stall' hydrodynamically (meaning it can't produce the proper sideways force it needs to steer the boat). There is no question that a fast round-up will occur at that point.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

wilfbradbury
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Larry
I,m not too computer literate, so I was unable to find that CP link u referred to.
Our boat is a 1995 mk2 standard rig, shoal draft. We use a 135 geny and a maxiroach main. I have moved the mast top forward as much as the roller reef adjustment will allow to reduce the weather helm with some success.
We normaly start reducing sail (forsail) when the wind hits 15k. We also reduce the main at the same time. I have a 3 blade sail prop which gives a little more turbulence through the rudder.
We sail in the southern Georgian Bay area (part of Lake Huron). We have 3 other mk2 Cat 36's and one has a larger rudder. He claims it works much better. One of our club members has a 34. He modified the rudder by adding roughly 5 in to the trailing edge and he claims it is a hugh improvement. The 5 in added was in the middle and it tapers in at the top and bottom.
I have sailed for about 35 years and have owned this boat for about 8 yrs.

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plaineolde
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I had an '88 C30 prior to my current 36. The 36 was a huge improvement over the C30 with regard to rudder stalling. Where the 30 would stall and round up fairly readily when heeled over, the 36 has only had an uncontrolled roundup a few times in 13 years. In the situations where this happened, I'd rate the roundup as being a safety 'feature' as otherwise, I'd have been heeled dangerously by the sudden/unexpected gust:eek:. It's my understanding that most 'consumer' non-racing boats are designed with a certain amount of weather helm for just that reason.

Note that my 3 favorite words are 'small craft advisory'; so I enjoy sailing with a couple reefs in the main and most of the jib rolled up (or just the jib). There are times I'd prefer a bit less weather helm, but it's also probably a good warning that perhaps I'm pushing things a bit too hard ;) But I've always felt that the C36 rudder was much better sized than the C30, though the C30's beam to length ratio probably had something to do with the the amount of weather helm it has.

Not saying you're wrong, just my experience.

Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay

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deising
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I agree with Gary's first paragraph. A little weather helm also puts the rudder at a good angle to create lift in the same direction as the keel to reduce leeway.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

wilfbradbury
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Interesting.
We had a Cat 30 before this boat, but it was a full keel. For some reason I find this 36 rounds up rather easier. We do get some very gusty days which of course makes us more subseptible to getting caught with ones guard down.
I thought I read some thread about a modified rudder for the 36 mk 2 but perhaps it was between the mk1 and the mk2!.
Wilf

BudStreet
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We found out the exciting way last year that the boat wants a reef in the main first. Sailing with full main and reduced genny caused weather helm and uncontrollable rounding up in 22-25 knot wind (on a day when 15 was forecast). Now we go out with first reef in the main if wind is forecast at 15 because as often as not we get way more than that. There is no rake in the mast from what I can determine.

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bcam
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[QUOTE=bstreet;7354]We found out the exciting way last year that the boat wants a reef in the main first. Sailing with full main and reduced genny caused weather helm and uncontrollable rounding up in 22-25 knot wind (on a day when 15 was forecast). Now we go out with first reef in the main if wind is forecast at 15 because as often as not we get way more than that. There is no rake in the mast from what I can determine.[/QUOTE]

I have the same rig and keel as Wilf. The boat is sensitive to the main trim and a reef is the first way to reduce weather helm.

As far as the rudder is concerned. There is a deeper rudder (as found on my friend Walchenbach's boat, Mata Hari). However it only works with a deep keel because it would extend below the keel. Not a good thing!

Bruce Campbell
Evergreen Dreams #1409

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LCBrandt
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Bud's exactly right. If you're flying a 135 Genny, you should be able to begin reefing with winds greater than 15 (and maybe at 20), first with a single reef in the main. Don't reef the genoa until you have the second slab in the main. The real power of our boats in these conditions comes from the jenny. The fastest I've ever seen my boat on a reach was 8.1 kts on an accurate knotmeter with one reef in the main and the 135 genny full out.

Of course, boat balance is essential for control AND speed. Too much sail up and not only do you have excess heel, and therefore poor control, but you are wasting power. With appropriate reefing the boat will stand up and be considerably faster than if you have a rail under. I say on our boat, tongue in cheek, "When the skipper gets scared it's time to be reefed." Of course I'm talking about excess heel. A lot of people think that a boat is faster the more it heels...Wrong!

Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
 

wilfbradbury
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Thanks Larry
Yes I agree with your comments.
I'll try and get a picture of the C36 at our club that has the modified rudder.
Unfortunately the current owner of that boat bought it from the PO and is not aware of the rudder mod on his boat. Since our boats are currently under numerous feet of snow it will be spring before I get a pic!
Merry Christmas to all
Wilf

wilfbradbury
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Well I think I have found the answer to the rudder issue. Apparently early Mk2 wing keel have the original rudder which was cut off on the bottom to accomodate the shallow draft wing keel, thus reducing the rudder area! Two later MK2's in our club have the modified rudder I was referring to in my previous thread. Three of us are in the process of modifing our rudders to match the size of the later production MK2's. Once in the water I'll post a report as to the results.
Cheeers Wilf

wilfbradbury
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I seem to have continued problems with this system. Everytime I log in I have to start over again and log in despite clicking the "remember me " box.

Anyway I have rebuilt the rudder on our Cat 36 to match the profile of the later hull numbers and sofar the difference in handling is amazing. Two of us did the Mod after copyng the profile on a later production hull number. It was not difficult and since we have just launched the boat from winter storage I have only had a chance to motor. Under power the helm no longer pulls port as it did before we changed the rudder.
Once it quits raining here I'll have a cha:)nce to see how it affects the sailing and will report.
Here's hope for a good summer in Georgian Bay.
Cheers Wilf

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LCBrandt
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I *think* that the way the bulletin board system recognizes you when you come back is via a cookie. If your antivirus software scans daily and is programmed to delete cookies you'll probably have to sign in each time.

Disclaimer: I am not a computer guru so my impression on this may be wildly erroneous.

Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
 

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deising
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I visit the Forum everyday and I get about 2 weeks before I have to log in again with my credentials. I believe there is a time expiration on it.

Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/

BudStreet
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I checked the cookies the site leaves and there are only 4 that I can find. Two of them are Google Analytics cookies, the other two I think track activity on the bulletin board (bblastactivity and bblastvisit). Those two don't contain a recognizable date just a number which could be a date representation. So I'm not sure it is a cookie. It may be tracked by the site itself. I get I think about a month between log ins but never really recorded it.

You also may have your web browser set to not store passwords and so it can't log you in automatically.

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