QB2 Posted April 19, 2013 Report Share Posted April 19, 2013 Can any AO owners or sailors confirm or deny a statement in a below post that AO 's may have an inherent steering and balance problem? That AO's have a tendency to lee helm. I have had steering problems with mine since purchase but put that down to having different rudders, an untuned sail and rig. I either had massive lee or weather helm but noticed especially on a beam reach that the cat would suddenly steer downwind. Just recently I had to use both hands on the tiller to stop massive lee helm pressure whether sailing to windward or on a reach during gusts. I have made many adjustments to the rig and rudder rake, angle and balance but can't find an effective solution. I couldn't figure out why with a balanced helm the rudders load up suddenly and the bows head downwind. It takes both hands to push the tiller away to steer up again. I have always thought the centreboards are too close to the sterns to counter the centre of effort force from the sail pushing the bows around. Has anyone moved the centreboards forward and where is the best location? I recently got new longer rudders to try to sort out the problem but if there is still a centre of effort balance problem I will have to again start from scratch. Link to comment Share on other sites More sharing options...
tonyquoll Posted April 19, 2013 Report Share Posted April 19, 2013 The only other AO F14 I know of is Tom Tester at Wagga. Not sure if he uses this forum. I have experienced this issue on a Paper Tiger; "the rudders load up suddenly and the bows head downwind." It turned out that the foils were badly shaped, and would randomly stall or generate lift at different speeds and different steering angles. It wasn't noticable at low speeds, but once cranking it on a reach or downwind the boat suddenly turned left! Replacing the rudder blades and ensuring the steering geometry was symmetrical fixed the problem. Typically you can treat the issues of steering effort and helm seperately. Bringing the tips of the rudders under the boat will reduce steering effort. If you sight down the rudder pin/steering axis, the bottom tip of the blade should be just in front of this line. If you bring them under too far, then they pull themselves into a turn, making it hard to sail a straight line. An easy test is to just let go of the steering. If the boat starts to turn and then the steering swings hard across, the tips are too far under. With the blades raked at the right angle, the steering will be light, no matter how much weather/lee helm the boat may have. AO's typically have the centreboards, beams and rig very far aft. One I saw recently also had so much rake, that the sail's leech was actually aft of the rudders! Unsurpisingly, the skipper had troubles with the boat going into irons. Your target is to have some weather helm when going upwind. So, if you were let go of the steering the boat would round up and stall. To sail a straight line requires a constant pull on the tiller, which means the rudders are generating lift to windwards. That helps you point. If the lee helm you describe occurs going to windwards, then more mast rake is probably required. There are other factors to consider: - if you have the jib tight and main loose, the boat will bear off no matter how much rake is applied. Try to sheet the main in harder, or sail cat-rigged and see if helps. - where you sit on the boat affects helm. Move forward and the boat will round up, move back and it will bear off. Try moving further forwards when you go upwind. Next to the rear side-stays is the usual spot. If the lee helm occurs off-wind, pull the centreboards up. Hope that helps! Link to comment Share on other sites More sharing options...
QB2 Posted April 19, 2013 Author Report Share Posted April 19, 2013 Thanks Tony.. The AO is a uni rig- mainsail only. I think you are right on the money regarding rudder stall. The cat handles well most of the time and has good speed BUT I get more than edgy when it takes big effort to stop it suddenly heading off the wind. AO designer Darryl Barret said to bring the rig back to vertical to get rid of the weather helm which is what Ive done, and I adjusted the rudders using differing bolt holes and tucking 20-25 mm of the leading edge forward of the centreline pivot line. This got rid of most of the weather helm but I think the slight difference in rudder profiles meant the stall conditions remained. If anything I've adjusted the rudders too much and now don't have enough weather helm. So much so that when the rudders lose flow or grip we go into the death spiral downwind. Must do lots more fine tuning. Link to comment Share on other sites More sharing options...
knobblyoldjimbo Posted April 19, 2013 Report Share Posted April 19, 2013 What you're saying there Q is exactly what I did on my Maricat. Using another, far faster boat as a guide I put the tips 25mm further forward and have spent the last two seasons struggling with odd behaviour, not so bad as you describe though, just as annoying. Just recently I repositioned the blades in their original holes. I now get quite 'healthy' weather helm but I CAN TACK now!! I'm in the process of filing the blade and the stock just gently. The boat is definitely better to handle, and more consistent - even though I have to keep a firm hold on the tiller to prevent quick trips into the back of the committee boat (missed it by a gnat!). Someone else said that 5mm is a better guide, I'm at about 1mm at the moment but haven't sailed with this yet. Not sure about the AO but without a reasonable rake you're likely to be trapping off the transom to avoid any mining incidents. KO Link to comment Share on other sites More sharing options...
QB2 Posted April 19, 2013 Author Report Share Posted April 19, 2013 5mm or 1mm! what are we talking here, rudder adjustment of 5mm in front of the rudder centreline? Link to comment Share on other sites More sharing options...
knobblyoldjimbo Posted April 19, 2013 Report Share Posted April 19, 2013 Try 1mm first Link to comment Share on other sites More sharing options...
korwich Posted April 23, 2013 Report Share Posted April 23, 2013 I have found that slop in the rudder pintles and gudgeons can contribute to wayward movements of the boat and erratic weather helm at times, sometimes its there, some times its not, by taking out some of the play it seems to have lessened those on the reach moments of "hey boat why are you acting like this, you are normally so good", and then its gone? Did my brain is the first time it happened, there I was looking for what went wrong, then it did'nt happen for the rest of the day????? Phil Link to comment Share on other sites More sharing options...
QB2 Posted April 24, 2013 Author Report Share Posted April 24, 2013 thanks phil ..I hadn't even considered that looseness as a problem. The 'stern and rudder pintles/gudgeons do allow a little bit of side and for and aft movement in the housings and the RF254 gudgeons appear to be original and have a bit of slop from wear and tear so will have to see how to take the slack out. Haven''t had the cat back in the water after installing the new rudders ás yet. hopefully next weekend Link to comment Share on other sites More sharing options...
QB2 Posted October 1, 2013 Author Report Share Posted October 1, 2013 The question is now academic as the Ao has gone to NNSW Link to comment Share on other sites More sharing options...
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