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Hi all - cruising boat/weekend racer here - a lifelong sailor with lots of experience.  I have a 35' 'production' boat shoal draft that I'm just not happy with its sailing characteristics.  Specifically, it rounds up constantly.  Other than alway pushing on how much sail we carry, I've come to believe this is because the rudder for this shoal draft version is cut short as well as stalls out easily even at 15 kts apparent.

What does the group think about replacing this with a deeper rudder to keep steering control in an upwind blow?

Also, is there more to it than depth and width?  Would I be able to use a well chosen rudder from a different boat - say a C&C110 rudder on a Beneteau 35?

The rudder depth could go from 4'9" to 6'... would this be enough of a difference to be worthwhile?

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Could be sail trim or bagged out old sails too. What's the mast rake like too? 

What ever happened to the notion that a rudder does nothing but add drag?  I know- take it to DA-   

A little weather helm actually is faster! At about 3 to 5 degrees rudder angle, the increased drag is more than compensated for by sailing higher, so there’s your best VMG. Boats that are absolutely n

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What kind of boat and if yours is a shoal draft, what about considering a used rudder from the same boat model in full draft?

Hull form defines rudder shape needs. I’m no NA 

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1 minute ago, Zonker said:

Could be sail trim or bagged out old sails too. What's the mast rake like too? 

or position of mast butt. try moving butt forward and reduce the rake .

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Jeanneau Sun Odyssey 35.  New(ish) sails with very good shape.  Experienced sailor.  Some rake back, adjustable backstay, bocks back for flat jib, leaches twisted off, traveler down, weight out of the bow, all of that. Rudder goes over hard - at 30 degrees nearly always stalls - I try to keep it at 20 +/- but the boat often just flips through the wind. I *do* try to carry too much sail but this is a poor sailing characteristic.  

I'd love to find a rudder from a full-draft JSO35, but they were imported from France at the time and almost all were spec boats with shoal draft.  I can buy one from the factory and have it brought over.  Seems like lots of places to get rudders made, but I'm also wondering how much difference 6-9" would make as well.

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Strange! Those french boats with wide asses should be fairly well balanced and certainly not round up the way you describe.

It sounds like you know what you are doing, but again I think there is some problem. Jeanneau would not produce boats that have the described poor sailing characteristics. 

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yeah if you're seeing 20(!!) degrees of weather helm, that's way way too much. time to start going through the settings one at a time. I mean when you say you're carrying too much sail, what kind of conditions are you sailing in?

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52 minutes ago, Grande Mastere Dreade said:

jeanneau-sun-odyssey-349-layout-1.webp

not much keel..   the swing keel version doesn't look to have a longer rudder

 Jeanneau-Sun-Odyssey-349-NG2.jpg

Wrong boat, that is the Sun Odyssey 349 with twin rudders.  The 35 is a 2003 design with single rudder

24 minutes ago, AnotherSailor said:

Strange! Those french boats with wide asses should be fairly well balanced and certainly not round up the way you describe.

It sounds like you know what you are doing, but again I think there is some problem. Jeanneau would not produce boats that have the described poor sailing characteristics. 

Only if they have twin rudders.  Otherwise a wide ass exacerbates the helm.

Here is a Sailing magazine a review of the 35, which as it turns out was for the shoal draft model like the OP has: http://sailingmagazine.net/article-476-jeanneau-sun-odyssey-35.html  in it they mention the helm getting overloaded in a breeze (20+ kts), but spilling off some wind brought her under control.

 

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2 minutes ago, 12 metre said:

Wrong boat, that is the Sun Odyssey 349 with twin rudders.  The 35 is a 2003 design with single rudder

Only if they have twin rudders.  Otherwise a wide ass exacerbates the helm.

Here is a Sailing magazine a review of the 35, which as it turns out was for the shoal draft model like the OP has: http://sailingmagazine.net/article-476-jeanneau-sun-odyssey-35.html  in it they mention the helm getting overloaded in a breeze (20+ kts), but spilling off some wind brought her under control.

 

Ok, single rudder, yes then it might be a problem... 

interesting. Maybe Jeanneau was pissed at the Americans back in 2003 (for good reasons) and sent these across the Atlantic.

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Also keep in mind that these wide ass cruising boats need to be sailed with minimum heel to keep the single rudder in the water. In other words, reef early, and let the mainsheet way out in gusts (as @European Bloke already mentioned)

If you're used to more classic style boats, this behaviour can be quite disconcerting...

Also, its the reason the updated versions all have twin rudders - to keep at least one of them under water in fresher conditions

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Looks like the Sun Odyssey  35 has a very wide butt.  If you get heeled over, maybe the top of the rudder is emerging out of the water, so you get  less control.

Specs pulled up says draft of the shoal draft version is 4'9".  So the rudder should not go deeper than the bottom of the keel, you don't want to rip out the rudder if you ground.  With that wide a stern, you pretty much have to unload the rudder as much as you can by flattening the boat and easing the main.  Not sure what else you can do other than go an expensive route and put twin rudders on that wide stern.

edit:  oo alpha made the same comment as I was typing...

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2 hours ago, Renegade-27 said:

Hi all - cruising boat/weekend racer here - a lifelong sailor with lots of experience.  I have a 35' 'production' boat shoal draft that I'm just not happy with its sailing characteristics.  Specifically, it rounds up constantly.  Other than alway pushing on how much sail we carry, I've come to believe this is because the rudder for this shoal draft version is cut short as well as stalls out easily even at 15 kts apparent.

What does the group think about replacing this with a deeper rudder to keep steering control in an upwind blow?

Also, is there more to it than depth and width?  Would I be able to use a well chosen rudder from a different boat - say a C&C110 rudder on a Beneteau 35?

The rudder depth could go from 4'9" to 6'... would this be enough of a difference to be worthwhile?

Rudders are complicated. Forget taking one from another boat and using as a bolt -in  for an easy fix. Things like, rudder bearings, quadrant gear geometry, bolt patterns, wall diameter etc etc can suddenly become big  issues. I agree with other comments above. Reduce sail and do what you can to keep the boat flat.

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Are we talking 30° of wheel or 30° of rudder? 20° of rudder angle at 15kts apparent is really odd... I don't think it's an issue with the rudder unless you've got two and it's only happening on one tack.

What's your heel angle when you're getting rounded up? Is the boat moving well (5+kts) when it's happening?

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A couple of other things, sea conditions can dictate things to a degree.

Upwind in a seaway,  in stong winds you want to keep power on, so I would be more inclined to twist the main rather than dump the traveller.  Except of course in a gust, then you would want to depower so by all means dump the main at that point.

In flat water I would not fight the helm, but let her round up to feather her.  In flat water, I usually try to maintain constant pressure on the tiller and keep the inside tell tales streaming up at around 30 deg or more - was fast on my boat anyway YMMV.

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Yes, wide-ass boat.  It occurred to me that the rudder might be lifting out, but I don't see how that would be geometrically possible.  

It's 20-30 degrees rudder - - Maybe not yet at 15 kts apparent, but really fighting at 20.

OK - couple of good suggestions - couple of reminders of fundamentals.  I will be working on the discipline to use "dramatic' sail reduction (double reef) at 12-13 and seeing how that goes.

I understand to stick with the boat/boat builder if I change rudders.  I can buy a replacement rudder for the standard draft (6') version.  I'm not very worried about the rudder being deeper than the keel where I am - and I'd keep the other rudder in case the next owner wanted it.

Any thoughts if an extra 9" - 12" will make a big difference??  (i know....i know ;) )

 

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47 minutes ago, Renegade-27 said:

Yes, wide-ass boat.  It occurred to me that the rudder might be lifting out, but I don't see how that would be geometrically possible.  

It's 20-30 degrees rudder - - Maybe not yet at 15 kts apparent, but really fighting at 20.

OK - couple of good suggestions - couple of reminders of fundamentals.  I will be working on the discipline to use "dramatic' sail reduction (double reef) at 12-13 and seeing how that goes.

I understand to stick with the boat/boat builder if I change rudders.  I can buy a replacement rudder for the standard draft (6') version.  I'm not very worried about the rudder being deeper than the keel where I am - and I'd keep the other rudder in case the next owner wanted it.

Any thoughts if an extra 9" - 12" will make a big difference??  (i know....i know ;) )

 

20-30 degrees of rudder?  You sure about that (have you got a rudder angle indicator)?

The extra foot of depth will make a difference.  Might not stop the problem, but will mitigate it.  Not only will you get extra rudder down in the water, but it will move the center of hydro lift aft for the whole setup.  As long as you're good with your rudder possibly touching bottom first, heck go for another 18 inches or so down.

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34 minutes ago, European Bloke said:

If you're needing loads of rudder then the problem is not the rudder, it's what's causing you to need the rudder.

Losing it downwind and not being able to save it could be the rudder. Possibly.

This times 100.

Go back to the basics:

The rudder is a tool for converting forward force into lateral force, which manifests as force attempting to rotate the vessel about it's center of resistance.

The reason you're having to input a bunch of rotational force into the system in *one direction* (to leeward) is because something *else* is inputting rotational force in *the opposite direction*.

Could be sail balance (my bet) or the waterline itself if it mainly worsens when heeling, or something else.

I'm not a good enough sailor to say much more than that, but I bet you'd be better served by figuring out away to either move the center of effort forward or reduce heel. But I can confidently say it won't help much to just get a bigger hammer.

Remember, the lateral force applied by the rudder is *converted forward force* - so a bigger rudder will just convert more of your forward force (speed) into lateral (sideways force)*. In other words it might keep you from rounding up but it won't make you go much faster. 

*And of course, converting forward force into lateral force in a fluid inevitably creates a third, backward force known as drag.

 

So yeah, I don't think you should do that.

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12 minutes ago, Breamerly said:

This times 100.

The only reason you have to input a bunch of rotational force into the system *one direction* (in this case to leeward) is because something *else* is inputting rotational force in the opposite direction. Could be sail balance or the waterline itself if it mainly worsens when heeling, or something else.

I'm not a good enough sailor to say much more than that, but I bet you'd be better served by figuring out away to either move the center of effort forward and/or reduce heel. But I can confidently say it won't help much to just get a bigger hammer.

Remember, the lateral force applied by the rudder is *converted forward force* - so a bigger rudder in this case will just be more effective at harvesting your forward force (speed) and converting it into a lateral vector. In other words it might keep you from rounding up but it won't make you go much faster.

well kinda sorta...

With a squat shoal draft keel, if you add a bigger rudder, you'll get the center of hydro lift significantly further aft.  The boat is likely short on hydro lift being shoal keeled, so getting extra lift from the rudder will probably help quite a bit.

But- that fat stern sure don't help.  I'd bet at 20 degrees heel, there's probably a real good chunk of that rudder above the water.

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18 minutes ago, bgytr said:

20-30 degrees of rudder?  You sure about that (have you got a rudder angle indicator)?

The extra foot of depth will make a difference.  Might not stop the problem, but will mitigate it.  Not only will you get extra water down in the water, but it will move the center of lift aft for the whole setup.  As long as your good with your rudder possibly touching bottom first, heck go for another 18 inches or so down.

I would look at the balance issues first like others have said, but if OP really wants to try a new rudder, I would look at one a bit thicker with longer chord length as well as deeper.  Just going deeper helps but maybe more prone to stalling.  But a thicker longer chord pushes the CLR back a bit even more and likely be less prone to stalling.  A bit more wetted surface, but a lot less than twin rudders (which I wouldn't even consider)

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4 minutes ago, 12 metre said:

I would look at the balance issues first like others have said, but if OP really wants to try a new rudder, I would look at one a bit thicker with longer chord length as well as deeper.  Just going deeper helps but maybe more prone to stalling.  But a thicker longer chord pushes the CLR back a bit even more and likely be less prone to stalling.  A bit more wetted surface, but a lot less than twin rudders (which I wouldn't even consider)

Stall is more governed by the foil section and accuracy of the construction of the foil, especially near the leading edge. Also being deeper means getting in cleaner flow, better efficiency. That can be a negative as it will induce a bit more heeling moment though- probably best to do some real computations and figure it out, if there's money for it.

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Just now, bgytr said:

Stall is more governed by the foil section and accuracy of the construction of the foil, especially near the leading edge.

True, but t/c ratio plays a part - plus you can obtain greater lift (and drag of course)

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7 minutes ago, bgytr said:

I'd bet at 20 degrees heel, there's probably a real good chunk of that rudder above the water.

I guess I hadn't considered this as an actual realistic possibility - it would obviously throw the whole deal off.

I should clarify, by the way, that I have only the faintest fucking idea what I'm talking about with all this and really should shut up.

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8 minutes ago, 12 metre said:

True, but t/c ratio plays a part - plus you can obtain greater lift (and drag of course)

Ya- so I'd lean towards a deeper blade with perhaps a thicker section, not necessarily more chord, especially near the waterline where more chord would make for more ventilation.

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1 hour ago, European Bloke said:

If you're needing loads of rudder then the problem is not the rudder, it's what's causing you to need the rudder.

Getting a bigger rudder will help control the boat, but it will also slow the boat down if you use it to the degree indicated.

As others have noted likely better to start looking for root cause. 

One thing that hasn't been suggested - do you have a folding/feathering or fixed prop? A fixed prop will create turbulent water flow over your rudder thereby making the rudder less effective, whereas a folding/feathering prop will enhance the performance of your existing rudder by feeding it smooth laminar flow. 

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3 hours ago, alphafb552 said:

Also keep in mind that these wide ass cruising boats need to be sailed with minimum heel to keep the single rudder in the water. In other words, reef early, and let the mainsheet way out in gusts (as @European Bloke already mentioned)

If you're used to more classic style boats, this behaviour can be quite disconcerting...

Also, its the reason the updated versions all have twin rudders - to keep at least one of them under water in fresher conditions

^^^^^ This.

I had a Beneteau 27.7 which had a big stern and single rudder. Heel matters. Anything over ~ 25 degrees and there is very little rudder in the water. I carried sail area and trimmed it to keep heel below ~ 20 degrees.

I also did a lot of sailing beforehand on a Beneteau 24, which had a swing keel and single rudder. Seriously fast for a little cruising boat upwind as long as you kept it fairly flat. Lay it over and neither the rudder or keel worked well.....

There is a reason why virtually all contemporary wide sterned boats nowadays have two rudders.

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I'd concentrate on reefing the main early and dumping the traveller more agressively. If necessary, change purchase on trav to make it easier to dump and then haul upwnd as gust passes.

Another thought - it wouldn't be impossible to glass on another foot of foam and glass to the bottom of the rudder (don't need a stock because bending loads are so low at the tip) and extend the rudder yourself without changing the rest. You are increasing loads at the lower bearing doing so so keep it reasonable but there is probably no difference in bearing size between shallow and deeper rudder option.

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19 minutes ago, Zonker said:

If necessary, change purchase on trav to make it easier to dump and then haul upwnd as gust passes.

This. Or, alternatively, feather through the gusts. I still surprise myself with how much speed one can keep during a gust even with a significant gust going.

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2 minutes ago, Breamerly said:

This. Or, alternatively, feather through the gusts. I still surprise myself with how much speed one can keep during a gust even with a significant gust going.

Plus you will gain some height.

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6 hours ago, Renegade-27 said:

Yes, wide-ass boat.  It occurred to me that the rudder might be lifting out, but I don't see how that would be geometrically possible.  

It's 20-30 degrees rudder - - Maybe not yet at 15 kts apparent, but really fighting at 20.

OK - couple of good suggestions - couple of reminders of fundamentals.  I will be working on the discipline to use "dramatic' sail reduction (double reef) at 12-13 and seeing how that goes.

I understand to stick with the boat/boat builder if I change rudders.  I can buy a replacement rudder for the standard draft (6') version.  I'm not very worried about the rudder being deeper than the keel where I am - and I'd keep the other rudder in case the next owner wanted it.

Any thoughts if an extra 9" - 12" will make a big difference??  (i know....i know ;) )

 

An air Foil at 30 degrees angle of attack is not Going to be happy.  You are stalling the rudder.  Twist the main to reduce heel and move the center of effort forward.  More than 5 degrees of helm is pretty close to too much.

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10 hours ago, Renegade-27 said:

Hi all - cruising boat/weekend racer here - a lifelong sailor with lots of experience.  I have a 35' 'production' boat shoal draft that I'm just not happy with its sailing characteristics.  Specifically, it rounds up constantly.  Other than alway pushing on how much sail we carry, I've come to believe this is because the rudder for this shoal draft version is cut short as well as stalls out easily even at 15 kts apparent.

What does the group think about replacing this with a deeper rudder to keep steering control in an upwind blow?

Also, is there more to it than depth and width?  Would I be able to use a well chosen rudder from a different boat - say a C&C110 rudder on a Beneteau 35?

The rudder depth could go from 4'9" to 6'... would this be enough of a difference to be worthwhile?

9 hours ago, Renegade-27 said:

Jeanneau Sun Odyssey 35.  New(ish) sails with very good shape.  Experienced sailor.  Some rake back, adjustable backstay, bocks back for flat jib, leaches twisted off, traveler down, weight out of the bow, all of that. Rudder goes over hard - at 30 degrees nearly always stalls - I try to keep it at 20 +/- but the boat often just flips through the wind. I *do* try to carry too much sail but this is a poor sailing characteristic.  

I'd love to find a rudder from a full-draft JSO35, but they were imported from France at the time and almost all were spec boats with shoal draft.  I can buy one from the factory and have it brought over.  Seems like lots of places to get rudders made, but I'm also wondering how much difference 6-9" would make as well.

2003 is not that old of a boat. Definitely a cruiser and probably now intended to be raced hard.
My boat is an 80's design and really suffers from poor rudder design of that era, when at high speeds or reaching hard. I added 6" to the bottom and it helped a bit but a new design would be the fix.

Where are you at? PM me. I have contact on a shop with 500 rudder molds to upgrade you at a reasonable price.

 

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2 minutes ago, Amati said:

What ever happened to the notion that a rudder does nothing but add drag?  I know- take it to DA- ^_^

In the proper conditions, my rudder is fine. In fact I barely have to steer as the boat is balanced nicely. When it breezes up (18+) or power reaching (15+), the rudder has issues and ventilates or looses it's grip.

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11 minutes ago, Meat Wad said:

In the proper conditions, my rudder is fine. In fact I barely have to steer as the boat is balanced nicely. When it breezes up (18+) or power reaching (15+), the rudder has issues and ventilates or looses it's grip.

??? http://thistling.blogspot.com/2015/02/your-centerboard-and-rudder-need-you.html?m=1

wheel or tiller?  Elvstrom liked a tiller on a 12 meter- can you identify the imbalance when the pressure is on?

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22 minutes ago, Meat Wad said:

In the proper conditions, my rudder is fine. In fact I barely have to steer as the boat is balanced nicely. When it breezes up (18+) or power reaching (15+), the rudder has issues and ventilates or looses it's grip.

16 minutes ago, Amati said:

??? http://thistling.blogspot.com/2015/02/your-centerboard-and-rudder-need-you.html?m=1

wheel or tiller?  Elvstrom liked a tiller on a 12 meter- can you identify the imbalance when the pressure is on?

Yea. The thistle is a big dinghy. we are talking keel boats.

Here are tons of photos un-edited.    https://www.webbdawg.com/zap/images/

 

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Fastest heel angle is probably 10 to 15 degrees. Is the helm ok at those?  If not, then at least move the sail plan as far forward as possible. Mast partners all the way forward, then forestay shortened to stand up vertical. Maybe mast butt aft for prebend to flatten main if it needs it. 

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8 minutes ago, Meat Wad said:

Yea. The thistle is a big dinghy. we are talking keel boats.

Here are tons of photos un-edited.    https://www.webbdawg.com/zap/images/

 

My 40’er has been described as a big dinghy,  by the designer.  Saying you are talking keelboats is a dodge.  Balance is balance- talk to the designer-could be as easy as a reef in the main-

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If the rudder ventilates it might be an idea to try horizontal fence/s on rudder a third down. That might keep the bottom working and is a fairly cheap and unobtrusive procedure as opposed to lengthening the rudder or changing it. 

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Anyone who has this problem, has a very basic understanding of 'sailing'.  But that can change.

There is no one answer, but the answer is in a rudimentary understanding of the relationship between the center-of-effort and the Center-of-drag and a few other centers.   If you do understand that you can figure out the best solution for a given boat.  Sometimes it's a simple fix, sometimes it's a combination of adjustments.

The problem is not that the boat has massive weather helm, the problem is that you do not understand the basics of sailing boats.  Asking questions is a good start I suppose.

 

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from having tons of little boat experience,  specifically Model yachts.

on boats with no keel and rudder adjust-ability,  and with a one design class where you can't play with the keel and rudder shapes  you begin playing with the sails and rig.

weather helm,  is when you have to much power(center of Effort, CE)  aft of center of lateral resistance (CL)  this is usually located around the aft edge of the keel, but its very fluid as the boat moves, and heels these points move around.  The sails dictate CE and the CL is dictated by all portions of the boat under water

on an RC boat  its very easy to move the rig around  moving  forward or aft,  or even changing the rake of the rig can make a huge difference in getting rid of a real bad weather helm.  Also sail tuning, powering up the jib a bit more or de-powering the main will help to move the center of effort forward to help better balance the underwater surfaces.

from a model yacht POV i like a small amount of weather helm. 

 

some basic info 

https://www.jordanyachts.com/4023

https://www.northsails.com/sailing/en/2019/05/achieving-balance-in-your-sail-plan

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5 hours ago, astro said:

Anyone who has this problem, has a very basic understanding of 'sailing'.  But that can change.

There is no one answer, but the answer is in a rudimentary understanding of the relationship between the center-of-effort and the Center-of-drag and a few other centers.   If you do understand that you can figure out the best solution for a given boat.  Sometimes it's a simple fix, sometimes it's a combination of adjustments.

The problem is not that the boat has massive weather helm, the problem is that you do not understand the basics of sailing boats.  Asking questions is a good start I suppose.

 

Hey hey hey, OP is a very experienced sailor, so the problem definitely does not lie with him, okay pal?

 

I find it a little bit funny that we're all going round and round about this or that extremely complicated solution to an extremely simple problem. 

I would point out he hasn't even responses to multiple suggestions about/questions about his center of effort, how much heel we're talking about, and whether he's got a reef in. He might just have a tender lady - not uncommon in that length - with a big behind, whose specific needs he is not accommodating.

If chappy thinks his rudder is lifting out, arrange to close-haul past a buddy who can check.

Otherwise I call bs on carpenters who say 'these boards keep not fitting, my tape measure just be broken'

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22 hours ago, Renegade-27 said:

Hi all - cruising boat/weekend racer here - a lifelong sailor with lots of experience.  I have a 35' 'production' boat shoal draft that I'm just not happy with its sailing characteristics.  Specifically, it rounds up constantly.  Other than alway pushing on how much sail we carry, I've come to believe this is because the rudder for this shoal draft version is cut short as well as stalls out easily even at 15 kts apparent.

What does the group think about replacing this with a deeper rudder to keep steering control in an upwind blow?

Also, is there more to it than depth and width?  Would I be able to use a well chosen rudder from a different boat - say a C&C110 rudder on a Beneteau 35?

The rudder depth could go from 4'9" to 6'... would this be enough of a difference to be worthwhile?

Hull speed upwind is pretty much all you’re going to get, so why not reduce sail and max it there?  Spinning out is incredibly slow, and you’ll have more control with less sail area, to say nothing of a dedicated jib (or a high wind main?) for bigger pressure ( cheaper than a new rudder anyway)  Bethwaite has some good stuff in this in High Performance Sailing.  Wheel or tiller?  

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Apparently it is a Sun Odyssey 35

sun_odyssey_35_photo.jpg

I just think that the OP needs to learn to reef. Also the boat has a wheel which is OTT for this boat size. I suspect that the OP is putting lot of pressure on this poor rudder which just stalls without realising it...

Edit : crosspost with mathystuff.

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19 minutes ago, climenuts said:

Can someone explain what rudder ventilation is?

I'm assuming it's air getting pulled from the surface down the low pressure side of the rudder causing a stall?

that's about it.

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Ventilation is most common with transom-hung rudders where a 'fence' can be useful in preventing the air from getting sucked down.

Where the rudder is slung below the boat itself acts as a 'fence' unless the boat is heeled sufficiently to expose the top of the rudder.

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1 hour ago, bgytr said:
2 hours ago, climenuts said:

Can someone explain what rudder ventilation is?

I'm assuming it's air getting pulled from the surface down the low pressure side of the rudder causing a stall?

that's about it.

Yep, zackly.

Water doesn't like to go around sharp corners, so if it can get air to fill in the gap, it will.

And air doesn't turn the boat nearly as well

FB- Doug

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yeah, but a double-reef in 12-13?? I'd sure like to see a picture of the OP's specific boat under sail.

But then... maybe that's what it really takes:

76f02c4b32ea2dc9e90745995a96c6bb.jpg

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2 hours ago, climenuts said:

Can someone explain what rudder ventilation is?

I'm assuming it's air getting pulled from the surface down the low pressure side of the rudder causing a stall?

Some people mistakenly call it cavitation (which is like nails on a blackboard to me).  Similar root cause but completely different phenomena.

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Thanks again everyone.  Learned quite a bit.  Even got to tolerate insults by someone hiding behind big technical words and without actually offering any suggestions.   This MIT PhD in Mechanical Engineering : Fluid Mechanics and Heat Transfer (really) with 55 years of competitive sailing has learned that usually its the smallest people who like to throw around the biggest words. 

Some comments, like feather to weather, are great, but miss the point that the rudder is going useless.  When I can sit on the edge and feather its great - a gust can cause me to lose that edge.

I really appreciate the perspective about overall balance and what is needed is to stop the weather helm.  Heel and sailplan.  Balance the boat.

I'm usually singlehanded so weight on the rail isn't much of an option, but I'm going to dramatically reduce main (reef at 10-12; 2 x reef at 13-14 true).  I can't shorten my forestay easily (fixed length) but the next step would be to have the yard shorten it.  Lastly if that still proves a problem, the 'Fence" seem interesting.  I bet I am lifting rudder out of the water and ventilating.  Just read a technical paper on ventilation in foils and I think that could well be what's happening when all else is unbalanced forcing a 20+ degree helm.

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23 hours ago, Breamerly said:

Remember, the lateral force applied by the rudder is *converted forward force* - so a bigger rudder will just convert more of your forward force (speed) into lateral (sideways force)*. In other words it might keep you from rounding up but it won't make you go much faster. 

I'm no engineer, but isn't this backward? forward force is converted lateral force. The boat goes sideways before it goes forward. Sure, a larger rudder induces more drag, but there's a bucket where the lift is higher than the drag. this is the case on my freedom 45, which also has a shoal draft (winged) keel and a rudder that is nearly as deep as the keel. An N/A I know said I should be trying to generate rudder lift at around 4 degrees angle of attack - which is why that 20 - 30 degree threw me off so much. the 45 likes wind but if I were at 10-15 I'd be putting the first reef in.

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23 hours ago, Zonker said:

I'd concentrate on reefing the main early and dumping the traveller more agressively. If necessary, change purchase on trav to make it easier to dump and then haul upwnd as gust passes.

Another thought - it wouldn't be impossible to glass on another foot of foam and glass to the bottom of the rudder (don't need a stock because bending loads are so low at the tip) and extend the rudder yourself without changing the rest. You are increasing loads at the lower bearing doing so so keep it reasonable but there is probably no difference in bearing size between shallow and deeper rudder option.

My first take is that he is ventilating the rudder with excessive heeling and then stalling it by using it as a brake at 20° not as a foil.  Adding depth may keep some additional rudder in the non-ventilated/non-turbulent water.  Adding a horizontal fence near the top of the rudder to stop the ventilation from sucking down along the lee side of the rudder might also work.

Ooops, I see I'm late to the ventilator and fence building party.  

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11 minutes ago, ryley said:

I'm no engineer, but isn't this backward? forward force is converted lateral force. The boat goes sideways before it goes forward.

Im no engineer either, so congrats, we're the blind debating the blind on the merits of basquiat vs monet.

That being said: yes-yes-yes...no, I think we're both right.

Yes, The wind is coming from the side, and does exert lateral force on the boat. Yes, the sails do convert that to forward motion. And Yes, the force created by the rudder is also lateral. But... No... I do believe the rudder bleeds off specifically some of the boat's forward energy, considering that the fluid it acts on (or rather, the fluid which acts on it when it's orientation is changed) is fluid it is being dragged forward through. Or another way to put it: the boat moving forward is prerequisite to the rudder working, the presence of the lateral force of the wind is not (the rudder works, after all, when you're under power).

Confused yet? I sure fucking am

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34 minutes ago, Kenny Dumas said:

A non-obvious relationship is that displacement hulls turn opposite the direction they lean. That’s what generates the weather helm. Exactly opposite a planing hull or surfboard 

Well, yes and no. The asymmetric transformation of the waterline caused by heeling does create a turning moment, but the larger turning moment in most situations is created by the center of effort being displaced aft and leeward, namely resulting from the different and imbalanced force being exerted on/created by the main and jib, but also caused by the balance/imbalance of lift generated by the keel and rudder surfaces*. That's why it's also possible to have a lee helm - even when the boat is heeling somewhat - resulting from the opposite imbalance.

*Lift/wetted surface/etc is all basically Chinese to me I know it exists but do not understand it.

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4 hours ago, Renegade-27 said:

Thanks again everyone.  Learned quite a bit.  Even got to tolerate insults by someone hiding behind big technical words and without actually offering any suggestions.   This MIT PhD in Mechanical Engineering : Fluid Mechanics and Heat Transfer (really) with 55 years of competitive sailing has learned that usually its the smallest people who like to throw around the biggest words. 

Some comments, like feather to weather, are great, but miss the point that the rudder is going useless.  When I can sit on the edge and feather its great - a gust can cause me to lose that edge.

I really appreciate the perspective about overall balance and what is needed is to stop the weather helm.  Heel and sailplan.  Balance the boat.

I'm usually singlehanded so weight on the rail isn't much of an option, but I'm going to dramatically reduce main (reef at 10-12; 2 x reef at 13-14 true).  I can't shorten my forestay easily (fixed length) but the next step would be to have the yard shorten it.  Lastly if that still proves a problem, the 'Fence" seem interesting.  I bet I am lifting rudder out of the water and ventilating.  Just read a technical paper on ventilation in foils and I think that could well be what's happening when all else is unbalanced forcing a 20+ degree helm.

Something else to mess around with (that is kind of old school) is something Elvstrom did with the Dragon class upwind in higher winds- he used the Genoa, and let the unreefed main out until it developed back wind that was called ‘the Bubble’, so it wasn’t flogging.  Anyway, I was a kid and crewing for anyone who’d have me, and anything Elvstrom did was God himself dispensing wisdom, so I finally (^_^) talked one guy into trying it.  (His boat was a wide tubby 26’ (?)  thing and would spin out At the drop of a hat in anything over 15k TW.). And we spun out a little less, so we put in the first reef, and then the second.  (His mast was, um, thick, so we didn’t worry about it: I don’t know if your mast would handle loads like this)  I think the jib was a 130 or 140%. Played with the bubble, and damned if it didn’t work, steadying out the helm, and giving a more power to punch her into waves.  Had to really pay attention to the main controls, but the nice thing about reefing is that it gives you power down lower, which means your boat’s various stabilities have a bit more leverage over the sails.  The Dragon has a fractional rig , and the boat above was a stubby masthead, but it might be something to carefully and progressively mess with, assuming your jibs aren’t blown out.    Besides, Marchaj thought that lower aspect ratio was better in heavier air.  

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The Bubble hey ... what a revelation.

Sounds like a good concept to sell basic sail tuning.

Backs up the first point I made here.

I have sailed with some blue and brown water ocean/passage racers that hed no fucking idea about sail tuning after decades of experience.  I know, it's hard to believ but true.  They just repeated the same old same old because that's what you do.  They too had no cure for too much weather helm.

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1 hour ago, astro said:

ocean/passage racers that hed no fucking idea about sail tuning after decades of experience

I mean honestly I've been sailing off and on for 15 years or so, plus grew up sailing, and I still find this to be my major weak point. My dad, rest his soul, pretty much trimmed with the three sheets and that's it. Maybe I was just too little, but I don't I think I recall him once adjusting the outhaul or even moving the genny blocks on their tracks, let alone fooling with the backstay or the leech tape. 

I've been backfilling my knowledge from books and it's been great to be able to put words and concepts to all the stuff I had always seen but not completely understood.

(All of that said, I could triangulate with a compass on land or water before I was a teenager, and pretty soon after that was able to do a decent job at DR to boot, so dad wasn't slacking!)

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6 hours ago, Renegade-27 said:

I really appreciate the perspective about overall balance and what is needed is to stop the weather helm.  Heel and sailplan.  Balance the boat.

I'm usually singlehanded so weight on the rail isn't much of an option, but I'm going to dramatically reduce main (reef at 10-12; 2 x reef at 13-14 true).

I'm going to assume I'm not the Boogeyman you mentioned and instead that I get some of the nice complimenty things ;-)

I will say that I sailed for years umder the belief that it wasn't fun until the girls asked a second time if i was *sure* it was supposed to tip like that. Like, rail in the water, stupid sailing. Going out in heavy weather just for the fun of fighting the stick. 

When I finally mellowed out I was really surprised to realize how much earlier I should have been reefing. Nowadays as often as not I raise with a reef in. Easier to shake one out than tuck one in, as they say. Maybe something to do with having a toddler along most of the time now?

Anyway, happy sailing. I think you're on the right course.

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55 minutes ago, Breamerly said:

I mean honestly I've been sailing off and on for 15 years or so, plus grew up sailing, and I still find this to be my major weak point. My dad, rest his soul, pretty much trimmed with the three sheets and that's it. Maybe I was just too little, but I don't I think I recall him once adjusting the outhaul or even moving the genny blocks on their tracks, let alone fooling with the backstay or the leech tape. 

The people who really understand sail trim come from one-design fleets.  Where all the boats are the same, including the sails.

So the difference between winning and being a wood-duck is sail trim and of course, tactics.  When you have to focus on those two things you learn a lot.  Millimeters of trim, rig adjustments and sail shape changes for each different wind and wave combination.  Some are so good that it becomes intuitive, like not thinking about hitting a tennis ball.

When you are in the performance handicap scene the often does not happen.  As we see here people hunt for a boat that will sneak though some chink in the handicap rating system.

So it depends on what you need.  Your skills right now suit your sailing, enjoy.

Edit: My comments are supported by what skills are valuable for some crewed around the world races.  Top skippers want some successful dinghy/cat sailors on the sheets.  Take a look are the crew on the last America's Cup winner.

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1 hour ago, astro said:

The people who really understand sail trim come from one-design fleets.  

[...]Some are so good that it becomes intuitive, like not thinking about hitting a tennis ball.

[...]As we see here people hunt for a boat that will sneak though some chink in the handicap rating system.

So it depends on what you need.  Your skills right now suit your sailing, enjoy.

Thanks I guess?

For the record, I wasn't being self-deprecating, for your benefit or anyone elses.

My vocation I can do well, the rest I can do well enough...

...(especially considering I bet I can lay a kedge to beat the best of them ;-).

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Maybe the jib has too much twist in it, and it is letting the bow come up.  Get the lead correct on the jib and see if helps hold the bow down instead of fighting the boat with that much rudder.  Then trim the main correctly and drop the traveler to leeward to reduce the weather helm.

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Wow - really great dialog.  Thanks all so much.  I'm learning quite a bit!

On 7/24/2020 at 4:13 AM, Mid said:

Ease .......

On 7/23/2020 at 2:41 PM, European Bloke said:

Let the main sheet out.

14 hours ago, Amati said:

... main out until it developed back wind that was called ‘the Bubble’, so it wasn’t flogging.  

I generally sail at 10+ with the traveller full down and a good healthy bubble in the luff.   Main out/ carrying a bubble doesn't seem to help much.  Maybe the highly loaded leach? I really don't understand why!  As does (doesn't?) the first single reef seem to make a dramatic difference.  

10 hours ago, astro said:

The people who really understand sail trim come from one-design fleets...  Where all the boats are the same, including the sails.

So the difference between winning and being a wood-duck is sail trim and of course, tactics.  When you have to focus on those two things you learn a lot.  Millimeters of trim, rig adjustments and sail shape changes for each different wind and wave combination. ,,,

I definitely agree about one-design.  When I was ~20 (~40!) years ago I was globally competitive crewing on Solings.  Did a summer foredeck crew for Peter Isler at the Olympic Sailing Clinic.  I learned SO much - was a much better sailor then.  Still, singlehanded sailing for me now is to put the boat in autopilot and continuously experimenting with the sails - as said, "mm adjustments".  Usually trying to measure differences with instruments since I don't have a sparring boat, but yes, I also am, however, always looking to "sneak though some chink in the handicap rating system"  :)

14 hours ago, Breamerly said:

...The asymmetric transformation of the waterline caused by heeling does create a turning moment, but the larger turning moment in most situations is created by the center of effort being displaced aft and leeward, ...

The comments on the asymmetric waterline while healing also intrigues me.  I sail in very variable wind surrounded by mountains.  The dynamics of a gust laying the boat over further causing rotation to weather requiring significant helm plays out all the time.  In steady winds I can often get control of the boat, but the gusts are often present and associated with roundups.

 

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45 minutes ago, Renegade-27 said:

 

Wow - really great dialog.  Thanks all so much.  I'm learning quite a bit!

I generally sail at 10+ with the traveller full down and a good healthy bubble in the luff.   Main out/ carrying a bubble doesn't seem to help much.  Maybe the highly loaded leach? I really don't understand why!  As does (doesn't?) the first single reef seem to make a dramatic difference.  

I definitely agree about one-design.  When I was ~20 (~40!) years ago I was globally competitive crewing on Solings.  Did a summer foredeck crew for Peter Isler at the Olympic Sailing Clinic.  I learned SO much - was a much better sailor then.  Still, singlehanded sailing for me now is to put the boat in autopilot and continuously experimenting with the sails - as said, "mm adjustments".  Usually trying to measure differences with instruments since I don't have a sparring boat, but yes, I also am, however, always looking to "sneak though some chink in the handicap rating system"  :)

The comments on the asymmetric waterline while healing also intrigues me.  I sail in very variable wind surrounded by mountains.  The dynamics of a gust laying the boat over further causing rotation to weather requiring significant helm plays out all the time.  In steady winds I can often get control of the boat, but the gusts are often present and associated with roundups.

 

Twist has been mentioned, so there’s something to play with.  Is there a difference in gust response depending on which tack you’re on (gust cell rotation is what I’m getting at here)?  Mountain sailing can be incredibly gnarly, what with wind  barreling out of valleys, or getting messed up by geography and temperature. What kind of wind direction fluctuations are you getting?  20-30 degrees?  I switched to a Gunter rig on our L7 just to be able to scandalize quickly for remote Rocky Mountain lakes.  I don’t think I’d use an autopilot much on mountain lakes in bigger pressure- direction changes in wind can be huge and very quick.  I remember when I was a kid watching one guy who was sailing on a starboard tack get flattened by sudden wind from his port. Started sheets for the main at least, maybe, should be the order of the day?  I don’t think a wheel would be quick enough- if you can rig a tiller, it might be worth a try.  Keeping your head outside of the boat is going to be really important, so you can see what’s coming, which is going to slow down experimenting, but I think you’re going to have to concentrate on rig and sail controls being as fast as possible.  I don’t think traveller control will be adequate- mainsheet and vang might be better, as well as a blade jib (~95%? So it doesn’t get pinned (jammed) on the mast) that you can blow quickly.  

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