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Weather Helm #85194
09/22/06 12:12 PM
09/22/06 12:12 PM
Joined: Sep 2006
Posts: 12
West Point, Utah
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MikeG Offline OP
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West Point, Utah
In Light and mediem air I have too much weather helm as I am always pulling on the helm to keep it straight. I have read that I need to rake my rudders forward, but I don't seem to have the adjustment screws in the rudder castings. Can I reduce mast rake and get the same effect? Are the adjusting screws a mod to newer boats? I've only had it out twice in the last couple of weeks, but it is really tiring to have to pull on the helm all the time.

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Re: Weather Helm [Re: MikeG] #85195
09/22/06 12:14 PM
09/22/06 12:14 PM
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Posts: 3,528
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Quote
In Light and mediem air I have too much weather helm as I am always pulling on the helm to keep it straight. I have read that I need to rake my rudders forward, but I don't seem to have the adjustment screws in the rudder castings. Can I reduce mast rake and get the same effect? Are the adjusting screws a mod to newer boats? I've only had it out twice in the last couple of weeks, but it is really tiring to have to pull on the helm all the time.


Mike, what boat are you sailing, this will help us to give you some help, but racking the mast more forward sill help.


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Re: Weather Helm [Re: MikeG] #85196
09/22/06 12:17 PM
09/22/06 12:17 PM
Joined: Mar 2002
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Dan_Delave Offline
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There are two ways to adjust for weather helm. One is the rudder and the other is the mast. Yes you sould be able to get some of the weather helm out by raking the mast more forward. If you are not in race mode and only looking to have a nice time sailing it should be fine. If you are racing then you will want to set up your boat the way the fastest do. If that means that the mast rake is where they place it then you will have to work the rudders, even if that means you have to do some drilling and filling.

Later,
Dan

Re: Weather Helm [Re: Dan_Delave] #85197
09/22/06 12:39 PM
09/22/06 12:39 PM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline
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The only way I know to reduce weather helm is by raking the mast forward. By raking the rudders forward you can remove the symptoms, but the boat will still not be in balance.

A certain degree of weather helm is desireable, but not more than 1 or 2 degrees.
If your jib is sheeted too loose and main too tightly, you can also get excessive weather helm. Crew position also affect weather helm, and this can can change for different windspeeds. But not enough to make it a problem.
Some designs like the Hobie16 load up their rudders a lot to make up for the lack of centerboards/daggerboards, so if you sail one of these designs, you would have to accept the mast rake and remove the symptoms by raking the rudders forward instead. If you lack adjustment screws on the rudderheads, you might have to re-drill the rudderblades.
We have had lots of discussions on the open forum earlier, so a search will surely yield results.

Re: Weather Helm [Re: Rolf_Nilsen] #85198
09/22/06 03:04 PM
09/22/06 03:04 PM
Joined: Sep 2006
Posts: 12
West Point, Utah
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MikeG Offline OP
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Thanks for all the help so far. Yes, I sail a h16 and am just learning the go fast setups. I will also do some searching here in the forum for more info. Thanks again. M.G.

Re: Weather Helm [Re: MikeG] #85199
09/22/06 07:04 PM
09/22/06 07:04 PM
Joined: Jul 2006
Posts: 1,147
Bay of Islands, NZ
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dagger boards will also affect weather helm. Drilling and filling is always an option but I would try mast rake first and see it as a season long trial to find how you personally make the boat go fast. The more work you do on it the more you will understand the boat and the faster you will go... and yes, sometimes you have to go slower before you go faster.

Re: Weather Helm [Re: MikeG] #85200
09/22/06 07:06 PM
09/22/06 07:06 PM
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Take a look at the Hobie Forum at http://www.hobiecat.com/community/ . I remember something about templates being available to drill the rudders to reduce weather helm. Matt Miller of Hobie may also provide the link here if he drops by. The other trick is to find someone who has resolved their weather helm problems and use their rudders as a template.


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Re: Weather Helm [Re: hobie1616] #85201
09/22/06 08:33 PM
09/22/06 08:33 PM

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Guys:

Once you get the mast back as for as you can go without block to block sheeting, you will need to adjust your rudder rake. Raking the rudders under the boat will help with weather helm. Good luck and good sailing.

Doug Snell
Hobie 17 "Stress Free" #007
Mystere 4.3 #149
Sunfish

Re: Weather Helm [Re: ] #85202
09/22/06 08:55 PM
09/22/06 08:55 PM
Joined: Jan 2005
Posts: 169
Santa Barbara CA
sbflyer Offline
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An old main with the draft drifting back from the mast makes it worse too...

Re: Weather Helm [Re: Rolf_Nilsen] #85203
09/24/06 11:26 PM
09/24/06 11:26 PM
Joined: Jun 2001
Posts: 733
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Will_R Offline
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The only way I know to reduce weather helm is by raking the mast forward. By raking the rudders forward you can remove the symptoms, but the boat will still not be in balance.


Not true, not true, not true!

Regardless of where the mast is, the shared loading on the boards is the same. The mast being more forward will make the boards cary more and less on the daggers, but the total force will be the same. By raking the rudders you move the center of effort on the rudders closer to or further from the pivot point in the gudgeons. So, in essence the torque is the same, but if you feel it or not is the difference.

Adjust the mast for speed/power, adjust the rudders for helm.

Re: Weather Helm [Re: Will_R] #85204
09/25/06 12:23 AM
09/25/06 12:23 AM
Joined: Jun 2005
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By raking the rudders you move the center of effort on the rudders closer to or further from the pivot point in the gudgeons. So, in essence the torque is the same, but if you feel it or not is the difference.


Absolutely true! So the same forces that were fed back through the tiller as 'weather helm' are still acting on the boat; the boat is 'fighting itself' and you are going slower as a result. This feedback is actually useful for trimming the boat properly. The trick is to resolve these forces rather than make the rudders more balanced WRT center of lift and center of pivot thus reducing the feedback. Give the engineers some credit for having supplied the correct amount of feedback before you go changing it. Moving the center of effort of the sails, especially the main, is usually the best way to do this. Changing the mast rake is one way. The solution might be as simple as releasing the traveler a couple of inches to the lee side.

Jimbo

Re: Weather Helm [Re: Will_R] #85205
09/25/06 03:16 AM
09/25/06 03:16 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline
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Quote

So, in essence the torque is the same, but if you feel it or not is the difference.

Yes?

Quote

Adjust the mast for speed/power, adjust the rudders for helm.


Rake the mast for speed/power, adjust the rudders for helm until almost neutral and proceed to rip the rudders off the gudgeons or break the rudderblades becose the load was too high. Tried and tested.. Or build the rudder system/transom bulletproof, rake the mast enough aft, overload the rudders so they ventilate and loose control. Tried and tested..
Raking the mast aft will increase loads on the rudders, and by raking the rudderblades forward you will only remove the symptoms. Boat will still not be in balance. With balanced rudders, you will not feel the imbalance as weather helm, but you can see it when looking at the rudderstocks wether the boat tracks straight or if you need to correct it by sailing with a constant rudder angle. 1-2 deg of weather helm is OK, and helps you go to windward, but not more (perhaps the H16 can use more with an advantage, as the water comes off the asymmetric hulls in a different way than symmetric hulls. I dont know for sure). Overdo mast rake and bad things happen becouse the boat is not in balance, and you will be slower than the rest becouse of the extra drag from the rudders.

Re: Weather Helm [Re: Rolf_Nilsen] #85206
09/25/06 03:27 PM
09/25/06 03:27 PM

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Lets not forget here guys that we are talking about a Hobie 16.

With this in mind you have to consider the following.

1. The hobie 16 main is far more efficient if you can get the leach as close to vertical as possible.

2. The rudders are far more efficient at producing lift than the hulls (no boards remember).

So while many of the opinions stated are correct for better designed more modern boats. It also remains true that to maximise performance from the 16 you need to move the CE aft as far as possible and then play with the rudders to suit. If you go to the nearest club where 16s are racing and ask around someone will be able to lend you a template.

Re: Weather Helm [Re: Jimbo] #85207
09/25/06 05:35 PM
09/25/06 05:35 PM
Joined: Jun 2001
Posts: 733
Home is where the harness is.....
Will_R Offline
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Give the engineers some credit for having supplied the correct amount of feedback before you go changing it.


Oh, I'm sorry, are you the only engineer here? Guess I'll need to get my boss to order me new business cards....

Sailing is just like the flight of a plane, but you have one set of foils producing lift and drag in one fluid and another in a different fluid. The sails produce the defining set (maximum lift to be overcome by the boards) while the underwater appendages produce at best equally offsetting lift. If I took your assertion about balancing the boat, then all forces would be equal and you would not need daggers. Regardless of the location of the CE, it's the same quantity of force that has to be overcome to keep the boat from sliding. ALWAYS tune the sails for speed and rudders for helm. CA Marchaj has some great books on this subject.

When the "balance point" between the daggers and the rudders is too far aft and the rudders are carrying more load, the CE is further aft and therefor the CE on the rudders is further aft (behind the pivot point). They only produce as much lift as is required by the sail plan b/c they are reacting to the water flow and the force exerted on them by the sail plan. If you move the CE of the rudder forward, you will cause neutral helm b/c now the torque is in alignment with the gudgeon. The force is always there, just what you feel is relative to the pivot point. You have to pull on the stick to counteract the location of the force and that is what makes you slow, not the fact that the rudders are carrying more load... that part is irrelivant.

Ventilation and transome destruction will occure, but... I've sailed in some WILD sh*t and haven't seen anyone rip the gudgeons off yet with the sails. I did see some broken I20 rudders, but that appeared to be a problem with the foils, not the sail setup.

If you rake further forward, now the daggers are carrying more load, but the total load is the same.

I guess all the fast I-20, H20, N6.0... etc guys have it wrong then... Seems to me like increased rake is fast in a lot of conditions on a lot of boats. We added an extra extender to the forestay on the H20 (hobie has lengthened it stock now) to get the mast further back. On the 6.0 we added a chainplate and ground out part of the rudders to increase rake. On the I-20 we added a chainplate or bought a longer forestay. I'll just say that as a general rule of thumb, the bottom tip of the dagger is the average setting for mast rake.... guess we'll all be standing the masts back up straigher to go faster.

Re: Weather Helm [Re: Rolf_Nilsen] #85208
09/27/06 09:38 AM
09/27/06 09:38 AM
Joined: Jun 2002
Posts: 1,658
Florida Suncoast, Dunedin Caus...
catman Offline
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Rake the mast for speed/power, adjust the rudders for helm until almost neutral and proceed to rip the rudders off the gudgeons or break the rudderblades becose the load was too high. Tried and tested.. Or build the rudder system/transom bulletproof, rake the mast enough aft, overload the rudders so they ventilate and loose control. Tried and tested..


Rolf,

I don't believe sail load is breaking foward raked rudders regardless of make rake.

When you put the tip of the rudder foward in relation to the top the load on the rudder greatly increases. Similar to foward swept wings on a aircraft.

I think what needs to happen is the front of the rudder head needs to be shaved so the whole rudder is moved foward closer to the pivot point to reduce helm. If you want to improve helm response rake the tips foward.


Have Fun
Re: Weather Helm [Re: MikeG] #85209
09/27/06 11:35 AM
09/27/06 11:35 AM
Joined: Jan 2004
Posts: 330
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srm Offline
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Since I don't think anyone else mentioned it, I'll add that I believe Hobie makes an upgrade kit for the older 16 rudder castings which allows rudder rake adjustment.

sm


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