Battens tapered and CE

Just glancing at the sail, it appears the draft at the top two battens are too far aft, 3 and 4 look pretty good, but should not be moved forward, Then the rest of the bottom of the sail has the draft way too far forward which will cause a backwinding by the jib (overlapped or self-tacking makes no difference -- the jib is still throwing air across the mainsail down there.)
Rick

Thanks to all .....
I don't have a pic with mast properly rotated, the sail is in dracon, the battens are soft and if tightening create more draft;
In this pic no downhaul and sheet.

that really doesn't look too bad. Iwouldn't try to move the draft any more forward....but even if you did try to fix it with battens, it wouldn't have too much effect. A sail with a bad draft position is just that...the battens won't change it an incredible amount..but again, that doesn't look too bad.

Jake is right IMO. Sail dosent look too bad I'm sure the winkle blow out especialy when you consider that it's Dacron. Battens simply hold the sail in shape it was designed.

Like the other guys said rake your rudders more under the boat. Think about it if you have a problem steering you should probably start with your rudders.

Think about it if you have a problem steering you should probably start with your rudders.

Count me FIRMLY in the sails and mast trim first camp! Whenever I have a problem steering it is always because I have too much tension on the main sheet or too little jib tension, too late.. But I have to admit I'm no expert on cats yet having gained most of my experience on mono's. By all means, check your rudders for normal trim, but I wouldn't be taking a file to them unless it was a last resort. Raking forward does not improve anything IMHO. It just masks a trim problem by adding more force in the opposite direction (AKA drag). Its a bit like

shooting the messenger

, if you ask me. Ie: The rudder tells you something is wrong so you take a sharp tool to it and

make him an offer he can't refuse

!
Rick and Marys book has some excellent explanations of the theory behind it all on page 72 and 73.
Dennis

I agree <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />

I would agree with messing with rudders but since you used the word

prototype

I would ask if you have tried to sail the boat upwind without the rudders down? Is the front beam too far back on the hull? Does the main have too much roach? Are the boards in the right place? Good luck with your project!

Front beam and boards are in the right place, what do you mean for

too much roach

?

Meaning the center of effort in the sail does not balance with the Center ofd lateral resistance on the boat and so you get weather or lee helm. More roach will give you more weather helm as more sail goes into the top aft portion of the sail. Pin head sails have little roach, the sail you show has a fair amount as it is a fairly

fat head

sail. Fat head sails have a LOT of roach. By adding more roach, you move the COE back.

A boat will exhibit weather / lee helm whet the boat is not balanced with the sails.

As I am sure you are aware this is because the center of effort / blanace of the sails does not balance where the center of lateral resistance of the hull is acting.

This can be for a number of reasons

1, COE of sail in in front or behind CLR of hull or visa versa

How do we fix this?

1.1 Rake the mast fore or aft to move the COE of sail
1.2, Change the shape of the sail by changing the camber position and thus COE. You get this to happen by adding more downhaul, but the sail also flattens. YOu are sailing with enough downhaul to remove most creases in the sail?????
1.3, Changing the shape of the sail by adding or removing cloth to move the COE
1.4, Moving the mast forward or backward on the platform (move beam(s))
1.5, Moving the position of the dagger/centerboards or skegs
1.6, changing the length of the hulls
1.7, Moving the position of the rudders further aft by adding gantrys (it's difficult to move them forward without removing hull!!)

2, Rudders are not correctly trimmed, with the tip in the incorrect fore/aft position

2.1 Adjust them via designed adjustments within the rudder system or get the files / wet and dry out or make the rudders bigger.

I would suggest that if your mast is vertical and you still have issues with weather helm you have the following possible problems

a, Dagger boards are in the wrong place - you state this is not the case
b, Mast (so front beam) is in the wrong place - you state this is not the case
c, Hulls are the wrong length
d, Sail is the wrong shape, too much roach maybe? (as stated above), too full too far back.

e, all of the above!

If you were to sail in

normal trim

and let go of the tiller, how long does it take to go head to in say 10 kts of wind?

I think is the sail with wrong shape; the max draft is at 40% with 10% camber.
you have seen the pic?
you it seems too much roach?

If you were to sail in normal trim and let go of the tiller, how long does it take to go head to in say 10 kts of wind?

5/7 seconds.

Without seeing a full picture of the boat, with the mast rotated from full on side view, front and looking up the boom, it's impossible to shay what is wrong.

5 - 7 seconds is not THAT extream.

As I stated abouve. WH results from an unbalanced boat. Could you take a few pictures showing the WHOLE boat from one side with the sails up and mast rotated correctly; same from the front (again showing all the boat). Same from the back shwoing the whole boat, same from the back, but focusing on the sail (please sheet in to

normal

upwind tensions) and finally lying on the tramp, looking up the sail, ideally showing as much of the sail as possible.

ALL with mast rotated. and main sheeted in.

IF you have the time can you do all the above for the following settings

1, Light wind setting - Downhaul on just enough to take most horizontal creases out; mainsheet as you would have it for sailing up iwnd
2, Medium wind setting - Downhaul on

medium

and sail sheeted for upwind
3, Strong wind setting - Downhaul on MAX and sail sheeted for upwind

Remember to also change the outhaul to the proper setting for upwind in each one.

this will give a total of 15 pics

Side, front, bacl all boat, back just sail, lying on tramp looking up for Light, med and strong wind trim.

Cheers

Simon

5 to 7 seconds for the boat to round up in nice wind.. That is not bad, that sounds about perfect to me. Move the crew a bit forward and you will track straight.
A natural round up can be a safety feature if you fall off the boat.

Thanks to all
I will try to apply the councils and will make the photos as soon as possible.