Badly conceived rudder project

V21

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344
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So my little trailer sailer has quite bad weather helm at times, mainly due to some badly conceived rig modifications.

I think I am out of rig options to try to remedy, but think that there maybe improvements to be made in the rudder dept. The original appears to have been "designed" in about 5 seconds on a Friday afternoon, it is a rectangle and there is no foil shape in the cross section.

So I perused the second hand world for a better rudder and found that people really like to ask a lot of money for second hand bullshit and that it wasn't going to find an easy replacement on the cheap.

I did however end up with a rudder from a bigger boat for not too much money thinking about using the bottom part for a blade, ok, I didn't think about it at all, I just hit buy it now. When it arrived it looked way too big, so I put it in the shed for a few weeks.

Got some bad news yesterday so I fucked off the afternoon and took a six pack into the shed. I hope I haven't trashed a perfectly good rudder........ But this thing might work, maybe.

The first round of questions relate to whether it might even work, due to the foil shape the blade is clearly a lot fatter than the original, is that a problem ? My half assed theory is that there is clearly more drag, because it's fatter, but if I'm not constantly yanking the tiller maybe it will even out. The new blade tapers towards the bottom , but will be a bit deeper so area should be similar.

The aim is to reduce weather helm, not really to increase performance.

Or is this a shit idea because it's too far?

PXL_20220408_220420944.jpg

PXL_20220408_220406479.jpg

 

slug zitski

Super Anarchist
5,046
798
worldwide
So my little trailer sailer has quite bad weather helm at times, mainly due to some badly conceived rig modifications.

I think I am out of rig options to try to remedy, but think that there maybe improvements to be made in the rudder dept. The original appears to have been "designed" in about 5 seconds on a Friday afternoon, it is a rectangle and there is no foil shape in the cross section.

So I perused the second hand world for a better rudder and found that people really like to ask a lot of money for second hand bullshit and that it wasn't going to find an easy replacement on the cheap.

I did however end up with a rudder from a bigger boat for not too much money thinking about using the bottom part for a blade, ok, I didn't think about it at all, I just hit buy it now. When it arrived it looked way too big, so I put it in the shed for a few weeks.

Got some bad news yesterday so I fucked off the afternoon and took a six pack into the shed. I hope I haven't trashed a perfectly good rudder........ But this thing might work, maybe.

The first round of questions relate to whether it might even work, due to the foil shape the blade is clearly a lot fatter than the original, is that a problem ? My half assed theory is that there is clearly more drag, because it's fatter, but if I'm not constantly yanking the tiller maybe it will even out. The new blade tapers towards the bottom , but will be a bit deeper so area should be similar.

The aim is to reduce weather helm, not really to increase performance.

Or is this a shit idea because it's too far?

View attachment 503546

View attachment 503547
Don’t know your system 

transom hung rudders are not balanced and have no end plate effect 

tip forward plus a end plate always improves  there characteristics 

277FA724-DB23-42D4-884C-F6F35AD5449B.jpeg

 

Sail4beer

Super Anarchist
9,656
3,168
Toms River,NJ
Sounds like the top of the mast is too far back. Can you tighten the forestay more or has the forestay been replaced? My trailer sailor had a neutral to lee helm. A new, longer forestay solved that problem and gave me a little weather helm, which is good for “feel”.

 

V21

Member
344
74
GA
Sounds like the top of the mast is too far back. Can you tighten the forestay more or has the forestay been replaced? My trailer sailor had a neutral to lee helm. A new, longer forestay solved that problem and gave me a little weather helm, which is good for “feel”.
Yeah, no. I put a small jib and roachy main on. I really like the ease of tacking. I rig to what my aye appears to be 0 rake.

 

V21

Member
344
74
GA
Don’t know your system 

transom hung rudders are not balanced and have no end plate effect 

tip forward plus a end plate always improves  there characteristics 

View attachment 503549
The old one looks like pic 2. The new one is also larger fore and aft so a certain amount of the leading edge will be under the boat and fwd of the pintle, hopefully giving some balance

 

V21

Member
344
74
GA
The old one looks like pic 2. The new one is also larger fore and aft so a certain amount of the leading edge will be under the boat and fwd of the pintle, hopefully giving some balance
See pic 2

 

Marty Gingras

Mid-range Anarchist
Let's see the original rudder, current main, and current rig profile.

Neither a bigger rudder nor a balanced rudder will reduce weather helm, though a balanced rudder reduces the force the driver has to apply to try to counteract it.  You OK with fingertip control of the rudder, even if the boat rounds up anyhow?

image.gif

 
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bgytr

Super Anarchist
4,854
498
Simplest way to find out is try it.. to me it looks like the biggest hurdle will be structural, not hydrodynamic.  It looks like a decent foil, so would see how it works before making any changes to it.

As far as the structure goes, joining so you get structural continuity at the joint could be tricky, as at that connection is where the peak loads and moments will be.

 

Overbored

Anarchist
711
59
So. Cal
A balanced rudder will not fix a weather helm problem , only makes it easier for a person to turn the rudder when it is used to correct for weather helm. if you don't fix the weather helm problem with the rig and sail balance you will still need a lot of rudder no matter what rudder you use.

 

bgytr

Super Anarchist
4,854
498
A balanced rudder will not fix a weather helm problem , only makes it easier for a person to turn the rudder when it is used to correct for weather helm. if you don't fix the weather helm problem with the rig and sail balance you will still need a lot of rudder no matter what rudder you use.
Maybe. Making the rudder bigger can help move the CLR aft to balance the boat too.  Depends on how out of alignment the CE and CLR are currently.

 

V21

Member
344
74
GA
A balanced rudder will not fix a weather helm problem , only makes it easier for a person to turn the rudder when it is used to correct for weather helm. if you don't fix the weather helm problem with the rig and sail balance you will still need a lot of rudder no matter what rudder you use.
Yep, just want it to feel better, I know it's masking the symptoms not curing it

 

Meat Wad

Super Anarchist
Sounds like the top of the mast is too far back. Can you tighten the forestay more or has the forestay been replaced? My trailer sailor had a neutral to lee helm. A new, longer forestay solved that problem and gave me a little weather helm, which is good for “feel”.

Yeah, no. I put a small jib and roachy main on. I really like the ease of tacking. I rig to what my aye appears to be 0 rake.
weather helm is typically a sail balance issue. But a poor rudder design does not help.

get a tape measure and a plumb-bob. I find it amazing how may people tune their rigs by eyeing. Sorry it does not take much at the top to screw you. Also how much vang or not, do you use a traveler or just the sheet? My boat has a huge main for it's size and sail trim is critical or the help is lost. At starts I have a guy do nothing but main so I can drive. Once we get going upwind and the trim is set, the boat balances out and points like a bat out of hell. It almost sails itself.

When I was sailing the 2.4mR (mini 12), the rig was within a mm side to side and we had fore/aft shims and movable mastbase. It is amazing what you can learn by sailing little boats.

 

Sail4beer

Super Anarchist
9,656
3,168
Toms River,NJ
How about what kind of boat and rig setup. I turbo’d a boat a few years back to a roachy main and blade jib and it balanced the boat wonderfully. 

 

V21

Member
344
74
GA
Gives an idea of how small the jib is This is the main apparently 4% larger and fully battened

main.JPG

 
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