About two years ago I managed to put our Legend 40 hard aground. The result was no apparent hull damage, but a badly bent rudder. We replaced the rudder with a new one. The problem is that since the replacement the boat now has excessive weather helm while sailing. Under power the there is an immediate pull to starboard of at least a quarter turn of the wheel. At first I thought it was just me, but I have come to believe it is more of a problem than that. I have a month old bottom job on the boat and thought that the problem would go away with the growth that was discovered on the rudder, but it has not. I did not notice anything that looked to be wrong with the rudder during the haul out.
Weather Helm
- Thread starter Cheers14182
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How Did you get Off??
If you needed a tow to get off how hard was the tow?? My thought is that you damaged the keel or the standing rigging. The details of how you got off might help figure out what's wrong. Wing keel?? Did you lean the boat over to get off?? I leaned my boat over to get off a grounding and had to retune the rig. But there was a storm that might have messed up the rig tuning. Anyway after I realized that the rig was off I got out my Loos gauge and quickly made things right.
If you needed a tow to get off how hard was the tow?? My thought is that you damaged the keel or the standing rigging. The details of how you got off might help figure out what's wrong. Wing keel?? Did you lean the boat over to get off?? I leaned my boat over to get off a grounding and had to retune the rig. But there was a storm that might have messed up the rig tuning. Anyway after I realized that the rig was off I got out my Loos gauge and quickly made things right.
Your problems ....
The quarter turn of the wheel when powering is prop walk. Could be that the new rudder is slightly closer to the prop. For the weather helm .... increase your mainsail halyard tension (stretch an additional 4 or 5 inches of halyard tension !!!!!) until the boat's helm goes 'dead fish' neutral ('dead fish' -- when you let go of the wheel the boat goes straight - no weather nor lee helm) then 'back off an inch or two of halyard tension to get a 'very slight weather helm'. If the mainsail is 'bolt-roped' (with slugs) the sail is typically ****designed**** to be stretched on the luff by 1" for every 10-11 ft. of luff length when sailing in 15-18 kts. If you dont stretch out this 'preload' that the sailmaker designs into the sail it will be toooooo full draft, draft aft in shape, will cause excess heel, the aft end of the boom will be lower than the gooseneck .... and the boat will have increased weather helm. 1 inch of luff stretch-out for every 10-11ft. of luff length (called luff preload).... or the sail will not have the shape that the sailmaker designed. lIf you a have a roller furling mainsail .... not much increase in halyard tension possible or the furler will jam, so you will have to either rake the mast forward, fly a larger headsail or have some roach slashed off the mainsail.
The quarter turn of the wheel when powering is prop walk. Could be that the new rudder is slightly closer to the prop. For the weather helm .... increase your mainsail halyard tension (stretch an additional 4 or 5 inches of halyard tension !!!!!) until the boat's helm goes 'dead fish' neutral ('dead fish' -- when you let go of the wheel the boat goes straight - no weather nor lee helm) then 'back off an inch or two of halyard tension to get a 'very slight weather helm'. If the mainsail is 'bolt-roped' (with slugs) the sail is typically ****designed**** to be stretched on the luff by 1" for every 10-11 ft. of luff length when sailing in 15-18 kts. If you dont stretch out this 'preload' that the sailmaker designs into the sail it will be toooooo full draft, draft aft in shape, will cause excess heel, the aft end of the boom will be lower than the gooseneck .... and the boat will have increased weather helm. 1 inch of luff stretch-out for every 10-11ft. of luff length (called luff preload).... or the sail will not have the shape that the sailmaker designed. lIf you a have a roller furling mainsail .... not much increase in halyard tension possible or the furler will jam, so you will have to either rake the mast forward, fly a larger headsail or have some roach slashed off the mainsail.
alignment?
I'm wondering whether this is a simple problem of the kingspoke on the wheel no longer being in line with the new rudder. As an experiment, tape the wheel while motoring to indicate when the rudder is centered. Then use that tape as a reference when sailing to determine whether what you're perceiving as increased weather helm isn't just a misalignment between the kingspoke and the rudder post. Best to do this test while reefed so that you're underpowered, that way you'll know you haven't really got weather helm.
I'm wondering whether this is a simple problem of the kingspoke on the wheel no longer being in line with the new rudder. As an experiment, tape the wheel while motoring to indicate when the rudder is centered. Then use that tape as a reference when sailing to determine whether what you're perceiving as increased weather helm isn't just a misalignment between the kingspoke and the rudder post. Best to do this test while reefed so that you're underpowered, that way you'll know you haven't really got weather helm.
My old 376......
.. had pronounced weather helm as well. Although, when under power, I don't know if you still call it weather helm or not. My boat would do a full 360 turn if I let go of the wheel when motoring, and, had excessive weather helm when sailing. I tried all of the items list above with no benefit. I would guess that you are NOT experiencing prop walk. Prop walk is most pronounced in reverse, and, in forward would actually push the bow to port anyway. In addition, prop walk effects the boat without turning the wheel. I became convinced that my rudder was not symetrical, and the flow of water over one side was different than the flow over the other side. There seemed (to an untrained eye) to be a slight cup or concaveness to one side of the rudder. Never had a chance to test my theory as I bought a new boat, but I still remember the abrupt turn to the right if I let go of the wheel. Good luck......... Jeff
.. had pronounced weather helm as well. Although, when under power, I don't know if you still call it weather helm or not. My boat would do a full 360 turn if I let go of the wheel when motoring, and, had excessive weather helm when sailing. I tried all of the items list above with no benefit. I would guess that you are NOT experiencing prop walk. Prop walk is most pronounced in reverse, and, in forward would actually push the bow to port anyway. In addition, prop walk effects the boat without turning the wheel. I became convinced that my rudder was not symetrical, and the flow of water over one side was different than the flow over the other side. There seemed (to an untrained eye) to be a slight cup or concaveness to one side of the rudder. Never had a chance to test my theory as I bought a new boat, but I still remember the abrupt turn to the right if I let go of the wheel. Good luck......... Jeff
Prop walk works in both directions
The basic concept is the flow coming off the edges of the prop. It is not only in reverse. When motoring most boats with port prop walk will want to to the left (prop's pushing the stern to starboard) so the wheel has to set somewhat off center to counteract the prop spinning effects. It's not called weather helm, it's called physics.
The basic concept is the flow coming off the edges of the prop. It is not only in reverse. When motoring most boats with port prop walk will want to to the left (prop's pushing the stern to starboard) so the wheel has to set somewhat off center to counteract the prop spinning effects. It's not called weather helm, it's called physics.
New vs old rudder
Does the new rudder look similar to the old one? If the size is reduced or length is reduced than the rudder will not be as effective and you will have to dial in more angel to get the same effect. Long skinny rudders are more efficient than broad short ones.
Does the new rudder look similar to the old one? If the size is reduced or length is reduced than the rudder will not be as effective and you will have to dial in more angel to get the same effect. Long skinny rudders are more efficient than broad short ones.
rudder size and shape
Thanks for the replies guys. Bill The rudder appeared to be the same size and shape as the old one although I did not measure it. It was made by Foss Foam to the same specs they used for the original. Jeff What you describe is exactly what happens, if you let the wheel go under power the boat will end up in a very tight circle. Rich I'll give more attention to the sail trim next time out. Under power is really where I have noticed the biggest unexpected change. Moonsailor We ended up powering and being bounced by the waves over the bar. It was not pretty. I've had the boat out twice since the incident and have not seen any keel damage and the surveyor did not note any when checking the damage. I'll check the rig to see if it will help while sailing, but that will not effect the motoring. Stu I'm looking for what caused the change in the physics and how to address it to get back to the feel of the boat I loved to sail.
Thanks for the replies guys. Bill The rudder appeared to be the same size and shape as the old one although I did not measure it. It was made by Foss Foam to the same specs they used for the original. Jeff What you describe is exactly what happens, if you let the wheel go under power the boat will end up in a very tight circle. Rich I'll give more attention to the sail trim next time out. Under power is really where I have noticed the biggest unexpected change. Moonsailor We ended up powering and being bounced by the waves over the bar. It was not pretty. I've had the boat out twice since the incident and have not seen any keel damage and the surveyor did not note any when checking the damage. I'll check the rig to see if it will help while sailing, but that will not effect the motoring. Stu I'm looking for what caused the change in the physics and how to address it to get back to the feel of the boat I loved to sail.
alignment
John, I thought that might be the problem up front, but the spoke is close enough to center that I don't think it is the problem. Like I answered Jeff if I let go of the wheel for a second under power we do circles.
John, I thought that might be the problem up front, but the spoke is close enough to center that I don't think it is the problem. Like I answered Jeff if I let go of the wheel for a second under power we do circles.
Tech questions for your supplier ....
Question For Foss Foam - What is the exact NACA profile shape number of the replacement rudder? then, Question For Hunter Marine - What is the exact NACA profile shape number for their Legend 40 original rudder. See if both manufacturers are using the same NACA 'number' ... such as NACA0010, etc. which is the most common foil form used for 'all purpose shape' on sailboats. Different foil profile shapes (numbers) although similar to the 'untrained eyeball' may perform radically differently from one another under the dynamnic conditions while moving through the fluid that they were designed for, etc. . NACA is the predessor agency of NASA. The NACA0010 foil shape is the one most selected for sailboats because its optimization best matches the common speeds of displacement sailboats sailing in 'normal' water. FWIW .... Usually a tech library in an engineering university will have the NACA foil data (by number). Very brief 'history' of the NACA series foils ----- http://en.wikipedia.org/wiki/Foil_%28fluid_mechanics%29 .... sorry this website ALWAYS 'truncates' complicated links.... Go to wikipedia.org and enter "Foil (fluid mechanics)" in that sites search box. If Foss Foam's reply of NACAxxxx number ****is not in EXACT agreement**** with the Legend 40 NACAxxxx number .... that may be the 'tech' explanation of why you are experiencing the difference. Without a reply of the exact 'number' .... replies such as 'we measured the original', etc. DOES NOT COUNT as an answer.
Question For Foss Foam - What is the exact NACA profile shape number of the replacement rudder? then, Question For Hunter Marine - What is the exact NACA profile shape number for their Legend 40 original rudder. See if both manufacturers are using the same NACA 'number' ... such as NACA0010, etc. which is the most common foil form used for 'all purpose shape' on sailboats. Different foil profile shapes (numbers) although similar to the 'untrained eyeball' may perform radically differently from one another under the dynamnic conditions while moving through the fluid that they were designed for, etc. . NACA is the predessor agency of NASA. The NACA0010 foil shape is the one most selected for sailboats because its optimization best matches the common speeds of displacement sailboats sailing in 'normal' water. FWIW .... Usually a tech library in an engineering university will have the NACA foil data (by number). Very brief 'history' of the NACA series foils ----- http://en.wikipedia.org/wiki/Foil_%28fluid_mechanics%29 .... sorry this website ALWAYS 'truncates' complicated links.... Go to wikipedia.org and enter "Foil (fluid mechanics)" in that sites search box. If Foss Foam's reply of NACAxxxx number ****is not in EXACT agreement**** with the Legend 40 NACAxxxx number .... that may be the 'tech' explanation of why you are experiencing the difference. Without a reply of the exact 'number' .... replies such as 'we measured the original', etc. DOES NOT COUNT as an answer.
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