Hey Bubble7777, I have about 5 tell-tales on the leech of the main that extend past the end of the sail. When the sail is set correctly, these little fellow stand straight out. If I bring the main in, they tend to fold back away from the centre line of the boat (for want of a better reference point) and if I ease the main too much then they tend to curl back in towards the centre line of the boat.
Its a bit like reading the luff on a head sail when you compare the tellt-ales on both side of the sail. But with having them on the leech of the main, the one tell tail in each location is influenced by air from both sides of the sail.
Disclaimer. Probably wrong again but works well on my boat. 
And beside, in any discussion "The Captain is always right"
One problem with boat that heave big overlapping head sails is that they are unable to read the Main Sail Luff due to the head sail influence. This is why you need to have the tell-tails on the leech to set the sail correctly.
I think Ill add those tell tails Cursoe
Hes a couple of short articles
www.rya.org.uk/knowledge-advice/cruising-tips/Pages/hub.aspx
www.rya.org.uk/cruising/handling-sail/Pages/Trimmingthemainsail.aspx
Back to basics. The sail is a wing. Wings stall if the angle of attack is too great. So as the wind moves from a beating position to a reaching position, the sail needs to move too. Hence typically the boom and main sheet is eased out on a reach.
However, if you have a twist in the sail from top to bottom, the top of the sail will not be driving when the boom is eased out. I think this is what you are observing. The twist may be caused by a numer of things, but usually if you tighten the boom vang it straightens some of it out. A similar effect can be achieved by easing the traveller instead of the main sheet.
thanks for everyones replies.
I played around with the sails yesterday on a 6 hour sail down to peel island in 18 = 25 knots I applied the boom vang and it made a big difference to the sail shape and the tel tails where streaming better. as the wind was so strong it was hard to tell if any trim was making much difference. there was still a need for much improvement but it was a step in the right direction.
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Finally got a great day. Sailing along on a beam reach from Hunter Island to Kepple.12 knots wind on the beam and sailing along at 9 knots. Champaign sailing, have a good day at work. 
Select to expand quoteJode5 said..
Finally got a great day. Sailing along on a beam reach from Hunter Island to Kepple.12 knots wind on the beam and sailing along at 9 knots. Champaign sailing, have a good day at work.
This is what a main should look like on a beam reach, all tell tails, including leach flowing.. This main is a Norths 3DL moulded carbon main so it is much easer to get every thing flowing.
Select to expand quotebubble7777 said..
thanks for everyones replies.
I played around with the sails yesterday on a 6 hour sail down to peel island in 18 = 25 knots I applied the boom vang and it made a big difference to the sail shape and the tel tails where streaming better. as the wind was so strong it was hard to tell if any trim was making much difference. there was still a need for much improvement but it was a step in the right direction.
.
Like I said, vang for sail shape, sheet and traveller for angle of attack.
Select to expand quoteMcNaughtical said..
I still don't understand all this terminology.. I just move stuff till the sails look right and the wind is pushing us along..lol.. 
Haha im exactly the same, i dont even know what my boom vang does, i pulled on it a few time didnt make any difference , so i dont use it now
Bubble,
Your boat is different. Its all about sail balance. A balanced rig, with neutral helm will sail fastest. A ketch without a mizzen, is going to tend to not have weather helm, but rather lee helm.
With the ketch rig, when the wind gets up, normally you would reef the main and carry on. In your case, reefing will tend to increase the lee helm. However, if you ease the boom vang, and let the top of the sail spill, the balance is better. Hence a looser vang may be the better solution in a heavy breeze. Letting out the traveller will still drive you faster if you can do it and not have a completely flapping sail.
However, in your typical 10 to 15 knot breeze, pulling the vang on and getting the right shape with the boom out, will no doubt be the most efficient solution.
From what i gather so far my mizzen should be dropped when beating
And used on runs and reaches
Also option for heavy weather
Drop the main and use the mizzen
Select to expand quoteYara said..
Bubble,
Your boat is different. Its all about sail balance. A balanced rig, with neutral helm will sail fastest. A ketch without a mizzen, is going to tend to not have weather helm, but rather lee helm.
With the ketch rig, when the wind gets up, normally you would reef the main and carry on. In your case, reefing will tend to increase the lee helm. However, if you ease the boom vang, and let the top of the sail spill, the balance is better. Hence a looser vang may be the better solution in a heavy breeze. Letting out the traveller will still drive you faster if you can do it and not have a completely flapping sail.
However, in your typical 10 to 15 knot breeze, pulling the vang on and getting the right shape with the boom out, will no doubt be the most efficient solution.
damn wish I read this 5 hours ago as I was beating into 30 knt slop
so I think I experienced lee helm today for the first time. basically close hauled it was balanced but would round up with a little bit of weather helm (edit: I mean if I took my hand off the tiller it would round up slowly). however if I wandered into a beam reach or a close reach the rudder was unresponsive and would not turn back onto the close haul easily ( edit: and if I was to take my hand off the tiller it would have pulled me down wind hard) ... I have not experienced this before and at one point I was thinking "have I lost half the rudder or something" as this cant be right.
Hi bubble777. If you yacht was originally ketch rigged but has mizzen removed, if the main mast has not been moved aft to compensate or more correctly, to convert it to sloop rig, you are behind the eight ball and will always have trouble balancing the boat.
You might consider properly converting her to sloop rig as your next project. Fair few dollars involved as apart from the rig there will be some sail work involved too. Maybe the boat is ready for some new sails anyway.
Walker ketch and walker sailmaster sloop with 3/4 keel
I can recall some one who sails his Walker H28 ketch regularly saying he drops is mizzen when beating as the mizzen slows it down.
Then look as both these side profiles
Found one shaggy Walker H28 sloop
http://yachthub.com/list/yachts-for-sale/used/sail-monohulls/walker-h28/172961
Now THAT is a great conversion "before and after" shot on the mast position HG! Nice.
Edit: I should say a good explanation on the different mast positions for balance, but you know what I mean...:)
Select to expand quoteShaggybaxter said..
Now THAT is a great conversion "before and after" shot on the mast position HG! Nice.
Edit: I should say a good explanation on the different mast positions for balance, but you know what I mean...:)
Kan Walker made both these yachts Shaggy the Walker H28 and later the walker sailmaster he altered the hull shape on the sail master and moved the mast maybe 1/2 a meter to the stern.
I know where there is a original walker H28 Sloop Ill try and find a photo some time
Found Walker sloop photo added it to the above thread
Select to expand quotecisco said..
Hi bubble777. If you yacht was originally ketch rigged but has mizzen removed, if the main mast has not been moved aft to compensate or more correctly, to convert it to sloop rig, you are behind the eight ball and will always have trouble balancing the boat.
You might consider properly converting her to sloop rig as your next project. Fair few dollars involved as apart from the rig there will be some sail work involved too. Maybe the boat is ready for some new sails anyway.
Cisco,
If you look at the internal pics of the Walker cutter design, you will see that there is also a stainless steel post inside the cabin. Moving the mast will also entail moving the chain plates, so the whole deal is not easy. Bubble has some videos on Youtube of him sailing, and you can see that whilst there is some lee helm, it is not too bad. Guess that is the advantage of a long keel.
Select to expand quoteYara said..cisco said..
Hi bubble777. If you yacht was originally ketch rigged but has mizzen removed, if the main mast has not been moved aft to compensate or more correctly, to convert it to sloop rig, you are behind the eight ball and will always have trouble balancing the boat.
You might consider properly converting her to sloop rig as your next project. Fair few dollars involved as apart from the rig there will be some sail work involved too. Maybe the boat is ready for some new sails anyway.
Cisco,
If you look at the internal pics of the Walker cutter design, you will see that there is also a stainless steel post inside the cabin. Moving the mast will also entail moving the chain plates, so the whole deal is not easy. Bubble has some videos on Youtube of him sailing, and you can see that whilst there is some lee helm, it is not too bad. Guess that is the advantage of a long keel.
I remember you mentioned the lee helm last time from the videos. I just watched it again and your right it does look like there is a bit of lee helm.
