If I was to post a bunch of pictures of my boat would it be possible to tell me why I seem to have more weather helm(yea,still that) than I should? If so, what pictures would you want?
Last ditch effort
Thanks
Don
First, take a picture of the boat with mast, sails, fin, rudder all in place. A side view is what we need.
Next, Take the boat outside. Have the sails in place as if you were ready to sail. That is to say, have the vang, outhauls, downhauls, topping lifts, etc adjusted as if you were ready to wet the boat. Trim the sheets to close hauled position. Prop the boat suitably so that it will be heeling at 30 to 40 degrees. Take a picture of the sails from the front of the boat slightly to one side. What we are doing is examining sail set. It is helpful if you have some draft lines drawn on the sails, like with a magic marker. If you do not have them already then do so. These lines are helpful when you are sailing also. The lines should be parallel with the boom or club. About three lines per sail spaced evenly as you go up the lifts.
With those pix we may or may not be able to make some intelligent observations.
Here ya go. I have some from the back and from slightly different angles if you want. The boat sails pretty good like this but if I try to move the sails back to where they belong(about an inch forward of the keel) I get weather helm. Even with the sails this far forward there is no sign of lee helm unless it’s just drifting.
Don
Out of curiosity, how far forward of the keel is the mast in the pictures (2"?)?
Does the boat sail well with this configuration? Is it well balanced (if you ignore the really light stuff)?
Does it have any bad behaviors in this setup?
If the boat sails just fine in this setup, why do you feel the mast is too far forward?
I am no expert on balance, so I typically go for the “mess around with it until it works” method. If it’s balanced in the current configuration, I wouldn’t mess with it.
That being said, if you want to move the rig back, why not cut down the main or bulk up the jib or both?
Not particularly original, I know, but I’m just curious why you feel the mast is too far forward.
Graham
Don,
Looking at the side view positions of the rig and keel/rudder, I would not think weather helm would be a problem.
Therefore I am thinking your mainsail is quite powerful with a tight leech compared to your jib. (hard to tell from photos)
Try flattening and twisting the main as much as possible (tighten backstay, flatten foot) and reduce twist and increase depth on jib.
I have found sails from different “sailmakers” can alter trim significantly.
Does weather helm persist in all breeze strengths?
Jon
Don, from the bow on view, the sails are not in to close hauled. They are cracked off quite a bit.
Can you trim in the sails to close hauled and then lay down the boat on its side and take a photograph looking down the mast.
What I would look for is the twist in the two leaches, the position of draft in the sails, the amount of depth at the foot of the two sails, and the size of the slot. This view would also show any mast bend (fore/aft) or any sagging to leeward in the middle of the mast)
The side view shows a lot of ‘lead’ (a mast that is a long way forward of the keel). I don’t know your boat to know if that is normal. However, if that’s where the mast wants to be to get the correct amount of weather helm, then that’s fine.
The side vew makes it look like the mast tip is raked slightly forward of the line of the front of the fin.
Forgive me for asking a dumb question but here goes. With that much lead, and the forward rake, I would expect the boat to have a lot of lee helm. I just want to make sure that you are using the term weather helm correctly. Does the boat round up when closehauled and sailed 'hands off? or does it bare away? The former is weather helm. Also is it the same on both tacks?
Almost 3"
Does the boat sail well with this configuration? Is it well balanced (if you ignore the really light stuff)?
Yes, pretty good
Does it have any bad behaviors in this setup?
Not really, It does round hard in a puff
If the boat sails just fine in this setup, why do you feel the mast is too far forward?
Well, the plans call for an inch forward of the keel and if everybody else is happy with the stock location it means there is something wrong with something. Granted, I did change the deck shape which might change the rocker a smidge.
I am no expert on balance, so I typically go for the “mess around with it until it works” method. If it’s balanced in the current configuration, I wouldn’t mess with it.
That being said, if you want to move the rig back, why not cut down the main or bulk up the jib or both?
Not particularly original, I know, but I’m just curious why you feel the mast is too far forward.
Graham
I’m in the middle of my next boat from the same mold. If the mast has to be this far forward then the chain plates also have to be forward. I would like to tie the chain plates to the bottom of the keel trunk but having them this far forward makes a long angle on the braces and I think that would compromise the stiffness of the mast,shroud,keel assembly. But the biggest thing is that it just seems to be wrong. I have never seen a boat with this much mast lead. I was talking to a friend with an IOM and he says with his boat if he moves the mast 3/4" he goes from lee to weather helm. I can’t get to lee helm and if you can’t adjust to extremes you don’t know when you’ve got the middle. Also if I can’t tell ahead where the mast is going to be there is no chance of keel stepping a mast. Not to mention it’s a pretty poor boat builder/designer that doesn’t know where to put the mast.
Don
To many quotes in the last post, I won’t bother this time.
I would have thought that I had tried every sail setting by now but next time out I’ll try that.
I’ve made about half dozen different sets of sails and they have all behave the same.
Yes it seems to. Anything over a whisper and it gets worse as the wind goes up.
Don
I pulled them in a bit.
Yes it is weather helm.
Try to just look at the boat and ignore my messy shop. I aimed the shot in the tidiest direction.
Don, thanks for that top view photo. The biggest thing I see is that there is far too much twist in the main, and a bit much in the jib.
In increase the tension in the boom vang to close the main leach quite a bit. The main top batten should be almost parallel to the main boom.
Here is a photo of Peter Van Rossen’s IOM winner of the 2007 Canadian IOM Championship. Although the sails are not quite closehauled, you can see the amount of twist.
Also ease the jib boom topping lift to allow the jib leach to close a bit.
There is also a bit of sag in the forestay, but that can be dealt with later.
Here is the photo of Peter’s boat.
But if I take the twist out of the main won’t that power up the main and cause more weather helm?
Don
Edit:Now I see the picture. It looks like I have too much camber also. Time to clean off a flat surface and make some more sails. These sails were a bit of an experiment in that the camber increases as you go up the sail. All that camber up top builds twist into the sail and it’s tough(read impossible) to get them flattish. I’ll shoot for about 8-10% next time, maybe even less. Do you think that flatter sails would help the weather helm problem?
Thanks
Don
Don,
If you take the twist out of the main it will definitely power up the main and cause more weather helm.
I think you are on the right track with the main being too powerful, and that flatter sails will reduce weather helm.
A full main “appears” to have a tight leech and will increase weather helm. You can gain some weather helm with a flatter main by easing the foot to increase low down depth.
Jon
Yes, that’s true, but you will also be getting more power from the jib.
There is little point in trying to set the amount of ‘weather helm’ until you have the sails trimmed much closer to optimum.
I cannot see your sails well enough in your photograph to comment on the draft. However remember that curve on the jib luff. That is telling you to add more backstay. That will bend the mast a bit and flatted the main at the same time. Once you have applied more backstay, you may have to apply a bit of luff tension on the main to pull the draft forward a bit.
I’m going to try to go sailing this morning. It’s -1 degrees C. out so I won’t be there long. I’ll report back. I’m going to move the mast back to what I think it should be and then try to tune the W. helm out of it.
Don
Hi Don -
not sure if you got out on the pond and found better performance, but a couple of my thoughts that mirror those of others.
First reactions…
A LOT of camber (power) in the main. Along with the twist, I would guess the center of effort of your sails, set like this would be quite far back. - which would explain why you have a lot of weatherhelm in puffs and gusts - which then would explain why you have to move the mast so far forward. (in essence, by moving mast forward, you are moving center of effort (COE) forward in relation to your center of lateral resistance (CLR) to try to balance your helm - which you say works in light winds, but not heavy gusts. Those gusts are what is driving the COE toward the stern and inducing weather helm. (my opinion)
If you can hit some open water and decent temps, I would suggest as a start …
- Clew outhaul to flatten main
- A bit of downhaul to move camber forward in main (toward mast)
- Some vang tension to remove the twist in your main.
If my guess is correct, this would provide you with a more neutral weathterhelm (if not excessive lee helm) in medium to light stuff. If a neutral helm or “slight” weatherhelm is still there or only in gusts, you may need to flatten the jib a little as well. If you now have lee helm, it is then time to move your mast back to a location closer to front of the keel.
If you do get a blast in a gust, the boat will still have a tendency to work towards weather, but the constant weatherhelm should go away during staedy, but strong breezes.
Hard to see and work from photos, but flattening the sails is where I would start. Again, just my opinion based on what I see. Good luck
Don; Good looking boat.
Looking at the side view it appears that the mast is indeed farther forward than it would seem necessary. The pic is not entirely clear but I think you need to move the jib pivot forward a fair amount. In this side view the slot is parallel from top to bottom. If you move the pivot forward the slot will open more at the foot. Moving the jib forward will change the helm in the direction you are after.If you can not live with a tapered slot then make a longer crane. Keep in mind that the slot is two dimensional and the offset between jib and main determines the behavior of air within that space.
Hiljoball may be onto the real problem. From the top view pic you can see that the leech of both sails are soggy. That will not do very well for helm, the boat will be slow to windward, and the leeches may flutter in a moderate breeze. Those are all no-no’s.
I’m guessing that white stuff in the picture background is snow. That is also a no-no for a Florida guy like me. Fortuneately the snow will not keep your boat from sailing well. Keep at it, the problem will soon be resolved and not only will the boat go better but also you will have gained additional tuning expertise.
No wind today. the weatherman lied:mad:, maybe tomorrow.
Don
Three days calm and now Mom Nature makes up for it.
Don
Looks like the waves might be a little big for an IOM Don… 