Mast rake back more weather helm?

I have a NACRA 14sq. It is a one sail boomless boat. When I bought the boat it had a heavy weather helm so I move the mast forwad. It almost seemed worse.
The boat has a name for wanting to bury the nose and my boat certainly displayed that characteristic.
I decided to move the mast right back as it is my basher and I would fix the rudders after establishing best mast angle.
Why has the weather helm gone?
The boat is sailing very well in the heavy and no NACRA people have answered the queery. mast back, LESS weather helm?

Mast back will result in more load on the rudders when going to weather. This will typically increase weather helm - but that depends on how far forward the rudders are raked under the boat. If you have heavy weather helm it is possible your rudders are not raked forward enough.

On some rudder designs this is directly adjustable (e.g. later model Hobies), on others it may require filling and redrilling the holes in the blades.

Sometimes as a rudder system wears it allows the blades to be pushed back by the drag of the water when sailing, and this can increase the weather helm.

Chris.

It seems to be working the wrong way from what you've described, raking aft should increase weather helm.

The only explanation I can come up with is that the further you rake the mast aft, the earlier your mainsheet blocks out, meaning less leech tension, meaning the centre of effort of the sail moves forward, which reduces weather helm.

However I'm not 100% familiar with the Nacra 14sqm and whether or not it can block out with lots of rake.

From what I can see the 14sq is based on the 4.5, a skeg not a dagger board hull.

In extremely simple terms, to get rid of weather helm, you want to match the center of effort(Ce) to the center of force(Cf) of the sails. The Ce is the point along the hulls where the average effect of the rudders, skeg, sides of the hulls to resist lateral movement is located. If the Cf is aft of the Ce you get weather helm.

With skeg hulls the Ce moves around a lot. The side of the hulls, especially the sides of the bow on NACRA's, act like keels. With the bow down the Ce moves WAY forward. When you rake the mast back and move your weight back, the Ce moves back faster than the Cf.

If I am right, the weather helm should come back if you move your weight forward, at least this is my theory.

I don't know if the theory is true but I have found that on Waves and my 14, get the bows up and the weather helm goes away. On my 14 I found if I hiked really hard on the back corner, I could pull the bow up and sometimes even have lee helm for a few scary seconds.

That info sounds good. Try moving your body weight around to balance the helm.

So, the way I have it figured, the more you rake forward, the less helm?

correct, rake forward = less weather helm or more lee helm.

But for cats, especially without centreboards, the position of the crew weight also effects the helm.

more correct to say the 4.5 is based on the 14sq I think. Whatever the 14sq has very deep daggers for its size and vintage. Yes, I think the very aft and a flat sail might help the nose but most sailors have gone to the 16sq which has more bow.

more I rake froward the MORE weather helm???

This is why I have posted the question. The boat has deep daggers and the more the mast goes forward the more weather helm...what the?

It sounds like it is operating backwards. Without experiencing the effect first-hand and trying a number of options, it is difficult to remedy.

I cant say my 16 sq works that way as I found I had more weather helm the further back I rake my mast.

However I would recomend checking you toe in and out of your rudders and also see if your hulls are aligned corectly its possible one has shifted or is set incorrectly. Once forward pressure pushes the bow down it may be digging in on a bad angle and pushing the boat upwind...
As to the correct setting for the toe in and out I can't help you but perhaps someone else may help answer this?

Generaly, more mast rake does give more weather helm IF all other things stay equal....
Dont forget that by changing the rake of the mast, you are changing the sheeting angle of the mainsail. with an upright mast, the sheet is pulling down more and inducing leech tension which will be a factor in giving weather helm. By raking the rig, the sheet is flattening the sail more and letting the leech open up = less weather helm.
It is always a problem in boomless cats that as you hit a gust, you become overpowered and sheet off, this lets the sail get fuller and more powerful and also gives weather helm. so what you need to do in a gust is sheet IN !

YES! You are the first I've heard say this (except for me). It took me about 3 years to realize this. There is a rapid bad sequence of gust, sheet out, fat main, excess heel,rounding up (like weather helm), sheet out more to depower which slows you down, then foot off to regain speed, often driving bows under. This often repeated sequence is low, slow, and the boat hobby-horses causing weather helm and/or a bow stuff. It also makes people hate boomless boats.

Instead, if you sheet IN (or just hold it) and move weight forward, the bows don't stuff, the boat doesn't heel, and you point higher and increase speed. This is NOT pinching. It's faster and the weather helm and tendency to stuff a bow eases off. Steady speed, no excess steering, higher pointing. Eases pucker factor in high wind gusts as well! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> However, it takes balls of steel to NOT sheet out the first few times you try it in a gust.

working the downhaul on and off in the gusts helps greatly too.

Little solo boat, remember. Can't be done solo. Two hands, 3 jobs. No can do.

I was wrong the 14sq has daggerboards.

My 14 has boards too and the same problem. If I rake the mast forward, the bow goes under before the helm changes.With my boat I could look at it two ways. The Ce goes way forward or I never notice the helm changing because the boat keeps trying to pitchpole.

I ended up raking the tip mast back about 30 cm and tweaking the boat with weight placement and muscle. The boat is so light and short, what I did had the greatest impact.

That is a cool boat you have. If I could have bought one like it, I probably would not have built a 14.

Hmmm, don't ever recall that type of action on my 6.0. If over powered letting the main off opened up the top of the sail dumping wind and depowering very nicely. I suspect if dumping the main powers and rounds you up that maybe you weren't trimmed properly to start (over trimmed a bit maybe, or maybe the sheeting angle wasn't set right). Also, the only time I've experienced a boat rounding up like that was either in a monohull or on my H-18 with the molded rudders. On the monohull the rounded shape of the hull itself lends to weather helm when you heel excessively. On the 18 the rudders deflected and boat would skid the stern. If you're getting excessive weather helm helm when overpowered perhaps the rudders are loosing bite, for a variety of reasons. At least upwind. Downwind sheeting can stall the back of the sail and depower things well, and over sheeting the jib can give the same effect - closing the slot and stalling both sails. I guess nobody has asked whether this is an upwind or downwind problem, or a problem all the time.

But just to make sure the terminology is correct here - weather helm is when the boat wants to turn into the wind on its own. Lee helm is when the boat wants to turn away from the wind on its own.

It has everything to do with the balance between the center of effort on the sailplan versus the center of effort of the underwater portion of the boat. Line up the centers of effort and the boat is neutral (my H-20 was this way, downwind it would transition to lee helm if a wave got you just right), sail effort behind the wet effort and the boat will tend to round up giving weather helm, the other way results in lee helm. But again, it's the balance between the hull center of effort and the sailplan's. What's going on with the boat at a particular time can affect that balance.

Sail trim definitely affects this - we know it's easier to turn down if the main is eased, easier to turn up if the main is trimmed. You should be able to steer the boat with sail trim alone.

So, given all that, is it possible raking forward is sinking the bows a bit, effectively moving the wet center of effort forward as well as the center of effort of the sail plan? Maybe, I'd have to see what your boat looks like and how you're sailing it. It could be just that your boat likes the mast forward more and is more powered up, giving you the feeling that helm has increased when maybe you just need to get your rudders raked right. Again, my 18 was like this - mast forward meant more power, and it emphasized the weaknesses in the rudder system. So many variables...

Improperly raked rudders can give the feeling of horrible weather helm, when in reality it's not affecting the balance of the boat that much, but is affecting the effort required on the helm, again giving the feeling that weather helm is bad.

"Hmmm, don't ever recall that type of action on my 6.0. If over powered letting the main off opened up the top of the sail dumping wind and depowering very nicely. I suspect if dumping the main powers and rounds you up that maybe you weren't trimmed properly to start (over trimmed a bit maybe, or maybe the sheeting angle wasn't set right)."

Keith
It is not a case of my trimming method stops rounding up - it just makes the boat GO faster.

I agree with Jake that the downhaul has to come it to play aswell

This does make sailing the 6.0 to windward a bit like working on a chain gang, but its pretty satisfying when it comes together

I agree with you. Rudder systems that are sloppy or not toed in enough will cause this problem.

Make sure the system is tight and try 3/8" toe in at least and see what happens. The weather rudder should not be toed out when going up wind with the weather hull light.

I thought that too. Because the rudders rough the water up more than I like but they are strait as.
I don't need a remedy guys as the boat is for heavy weather and it operates great now. I am just saying..it seems to have worked backwards to what everybody says.. it is just an odball thing and I wondered if someone knew why.

wow..THAT is news. Can't wait to get out and try it.

So all I needed was balls of steel! I'll go and get some. 316 stainless?
Thanks for that. It is a really important bit of info as I am sure you understand.
Both are counter intuitive. stay tight and move forward.... you'er not taking the p*** are you? : )

Downhaul is an important meidum of contro on the boat as it has no rotation restricter as such. I quickly realised that the mast rotation could be set buy more mainsheet tension but then realised also that the downhaul affects the rotation as well.

Standing the mast up straight also increases the sail power. Depending on the wind o' the day, you may need to rake the mast back for better control.
Figure out your rudder problem with the mast raked 10 degrees and then you can tune the rudders to the rake.

Yes. it is a cool boat. I was really surprised by it as I only bought it for the beach wheels! I was going to sell it on but had to go for a ride first. It is strong and loves deep water and big swells and is in the water in about 12 minutes.
I have found it had a lot of eronious controls on it and have been very happy with simpler set up. It reacts very well to mostly inhaul and main and body weight.

I have sailed round hull and hard chine monos a lot in my youth and would suggest the rudder losing bite causes round up more than hull shape as the healing action is accellerated. I don't have a jib on this boat. I am very concious of keeping boat flat and rudders tightly set and very concious of the inhaul setting and trialling different settings for that.

Oh, is weather helm when the boat wants to turn INTO the wind...just kiding..

I think the boat wanting to bury is very connected to the mast rake forward. I was drag racing a H16 in 25 and it was happy and I was driving my boat with both noses underwater! Their mast has the crazy rake for that reason I am sure and I thought to rake back and put a hooter/jib on for downwind and light weather. So far it has worked well but I was just surprised by the opposite rule on my boat.

This is interesting. The rudders are exactly strait and even and I have believed that the lee rudder is just not quite happy when driving up wind! It is messy and noisey. I had been wondering if it was just the drag of water until the stern lifts out.
Can anyone else confirm I might need toe in?

Even toe is essential to tracking ability. Mast Rake and rudder rake need to mimmick each other to maintain balance of power.

Unless you have shared lift................

On rudder tow in....Bill Roberts told me that you want between 1/16" to 1/8" toe in...that is... the distance between the rudders center to center is 1/16 to 1/8" shorter on the leading edge than the trailing edge. At least that is what he recomended for my Supercat.

When I bought my boat the former owner he had them set up all wrong...so bad I couldn't even tack the boat...on every point of sail it felt like I was pulling a 5 gallon bucket behind the boat... that all went away with tunning in the rudder tow in.

Regards,
Bob