On most non-racing boats the rudders are too short (ie don't go down into the water deep enough) so when the boat heels, the rudder is partially lifted out of the water. This allows aireation and this in turn encourages cavitation. The result being that the helm has to be pulled further and further to weather as the effective area gets smaller and smaller. I have yet to see any boat that hasn't been improved by having a deeper rudder.
Often people confuse weather helm with weight on the tiller. Boats are said to have heavy weather helm, when in fact as the boat heels a bit the tiller just weights up. This is invariably caused by the rudder not having enough balance on it. I know several boats that have been dramatically improved by having an inch or so added to the leading edge of the rudder (mind you this can be overdone - I recall sailing an MG34 a few years ago thast had the rudder so overbalanced that when motoring it would try to snatch the tiller out of your hand and do a hard over turn - not funny).
In 2006 Jac de Ridder won the TP 52 Class World Championships and one thing that was noticeable about his boat was that it had a tiller rather than a wheel (on a 52 footer!).
He commented (as the Designer as well as the owner & helmsman) that if you couldn't design a rudder that was properly controlable by a tiller on a 52 ft boat, you shouldn't call yourself a yacht designer!
Today with the rather curious fashion for putting wheels on nearly all yachts (I guess so car drivers can think they can sail) my belief is that a lot of yacht designers are either getting lazy with their design work or are deliberately engineering load on the rudders to stop car drivers wandering around in a series of zig zags. The trouble with this approach is that in a breeze with a decent bit of heel these boats become very hard work as the load goes on and comes off in big lumps every time the boat goes over a wave.
BTW if you want to reduce weather helm, reduce genoa/jib leech tension move the genoa car back (aft) a bit, if you want more weather helm - in the light stuff for example, move it forward a bit.
With regard to rudders being 'too small' - I think Peter Poland on Sailing Today pointed out that the best way to sail a boat is upright. The modern beamy production boats may look cool heeled over but are actually ginding to a standstill. Slab and roller reefing are wonderful, especially when used in time.
Another tip to reduce weather helm that worked on my last boat is to rake the mast forward slightly.It only took an inch or so but the result was dramatic.
That's an interesting point David. My mast is a little backward leaning, and I do suffer from a little too much weather healm and have difficuly in getting her balanced in the way that has been suggested. Scotty
JR, I'd be very wary of an owner adjusting standing rigging - how can you tell that your mast is leaning backward. Is the vessel slightly bow up?, who decided that the boot stripe/anti-fouling line was correct? I'd be very nervous of putting extra strain on stay chainplates - I think on this years ARC a Westerly Corsair had to be ababdoned with chainplates pulling out (the mast came down eventually)
I wonder how do professionals decide on whether a mast is perpendicular as a starting point?
You will find that raking the mast either forward or aft will have virtually no effect on weather helm, the amount (distance) that the CE (Centre of Effort) can be moved is marginal in the extrme - only a few inches at best.
If you have too much weather helm in medium winds, and you can only remove it with the genoa leech all wrong, and, you don't want to mess about playing with rudders or welding strips of steel on the back edge of the keel (both work really well) then you should look at how you have got your gear/weight stowed on board. Too much weight for'd will give weather helm, too much weight aft will give lee helm. Lots of boats were never originally designed with anchor wells full of chain right in the eyes of the bow. If you have a lot a chain and weather helm, as a experiment, take it out and move it amidships, if that gets rid of the weather helm, you know you've got to either move the chain locker or carry more weight aft to compensate. If you have ever raced a dinghy, you will know that in lighter winds you move the crew weight forward to induce weather helm (feel) as it gets windier you move aft a bit to reduce it! It doesn't matter how big the boat is - the same rules apply!
Hi Anthony. Thanks for your thoughts. I put a plumb line down the mast whilst on my mooring to check the lean last season. It was only about 2 cm from the cross trees to the deck. It has always seemed to have a very slight lean when i approach from a dinghy. It was also set up with the top of the mast ( from the cross trees upwards ) with a very much more prominent lean back which when looking up the mast seemed to be about 4-6 cm The Twister has very solid chainplates and fixings but I take your point about putting incorrect strain if wrongly set up. By the way, most Twister owners find their boats very easy to get balanced so I'm obviously doing things wrong.
What David has said also makes sense. Crossing the channel and down to the Channel Isles last season, I experienced a little more weather helm than normal. We were loaded fairly heavily - a lot of the load going in the bows. It's a problem on Twisters that stowage in the centre of a 5'8" width boat, 28' long is difficult. I am however thinking of moving the chain locker in from the very bow of the boat by about a metre which will help. I will obviously rethink the rest of my stowage too. Probably to put the lee cloths up and stow bags etc midships will be best whilst at sea.
Another thought David, my Twister has a very tall mast compared to the norm, by about a metre. I have been looking at the development of the Twister from its early years and it seems that when slightly taller masts from the original were put on, they were stepped back a few inches to help them to be balanced when under sail. Does this make sense to you? If this is the case, maybe my mast needs to be stepped sternwards a small amount?? Thanks David, Scotty.... (It gets a bit confusing as my computer at home will not log on as Scotty so I use JR )
p.s I forgot to add...my normal practice to balance has been to spill wind off the main by letting the boom go to leeward and not knowing much about genoa leech etc
Sory about being so verbose but my reply is in two halves - it was too long
The trouble with all classes of yachts that have been raced is that with every one launched they will have been tinkered with to optimise performance against rating. Now as we know, Twisters were extremely sucessful in their day (and I suspect that stripped out with a modern rig could do very very well under IRC - just look at how the Round the Island race is won year after year by Folkboats and Contessa 26s - admittedly helped a bit by the tidal conditions experienced by the slower boats).
Back to Twisters - in the years after the Twister was 1st sucessful, it was noticed that the old RORC and then IOR Rules didn't really penalise larger and larger foretriangles, and gave a rating reduction for smaller and smaller mainsails, so guess what - foretriangles got bigger, mains got smaller. So over time Twisters (like most long lived classes) got developed and the foretriangles got bigger and bigger and mains got smaller. That included moving the mast position aft to again make the foretriangle bigger.
Now under IRC where all area is measured (irrespective of where it is on the boat) we have arrived at what is currently believed to be the most efficient use of sail area - 9/10ths height foretriangles, very large, fairly low aspect ratio mains with long boom and large roaches BTW an absolute bugger to control on a fetch in a breeze! and gybing in wind can be a bit hairy as well!). Genoas are about 110 - 120% and very high aspect ratio.
So we can see that the rigs on boats of the 60's & 70s were really driven by rating rule distortion rather than efficiency ( it is also a consideration that until mylar laminates and composite sail material these modern shaped sails couldn't really be built - certainly not to lkeep their shape for more than a couple of weekends).
Back to your boat, moving the mast in itself a few inches really wont make a lot of difference either way. If you are troubled by excessive weather helm (knowing Twisters and similar boats fairly well) the probable reason is that you are suffering from a roller headsail, that when rolled a bit is too full, the consequences of this are that you can't point high and yet the genoa has to be oversheeted ( at the aft end) to prevent it luffing, because of this the main is also oversheeted to stop it backwinding. Most cruising sails are cut way to full, if you take a look at a modern racing boat the sails are almost completely flat.
So if she were my boat, I would be looking at a foam luffed genoa and ensuring that the genoa isn't too full and that the sheet lead is spot on. Make sure that when on the wind you absolutely murder your backstay, this keeps the forestay tight and you get a better flatter roll-up. If you talk to any sucessful racing skippers they will all tell you that they set the genoa cars so that the top tell tales break first (not how all the magazines tell you with them all breaking together). The other thing to look at is your mainsail and the sheeting and kicking strap arrangements.
Your main should be very flat, and you need leech tell-tales. Set up the mainsheet tension so that the bottom 3 telltales stream and the top one oscillates between streaming and hiding behind the main. This is the point of maximum power. as you get overpowered, murder the clew outhaul, really tighten up on the main halyard &/or cunngham if you have one, as you get more overpowered, drop the traveller down so the boom is over the leeward quarter, but with the leech still fairly hard (but not bar tight) it doesn't matter if the front half of the sail is backing, and you will find that the weather helm disappears. If you have a horse and cannot drop the traveller, pretty much (though not quite) the same effect can be achieved by putting a serious amount of kicker on and then letting the boom end down over the quarter by paying out the mainsheet a bit,
One other thought, make sure that your lowers shrouds are not too tight, I am assuming that you have double (fore and aft) lowers, If the forward ones carry too much load, tightening the backstay will never have any effect on the forestay tension, it will just try to bend the mast and with your large sectioned stick - it'll never bend, so youll just try and bend the boat and nothing will happen to the forestay.
BTW trying to keep all of the heavy stuff in the centre of the boat will give you a considerable improvement in performance, particularly upwind in a chop.
many thanks for that David....I think!? I'm so envious of those with the experience and knowledge that makes sailing even more satisfying and challenging. All i need is another 20 years experience and i may understand half of it. If you'r in the South any time this season after Easter, you will be welcome to come show me cheers, Scotty.
Lovely boats Twisters - you'll get there eventually - I've always found fdling withthe rig and boat in general is in some ways the most enjoyable bit of sailing.
There is no right way, its down to what you want. You only have to see how well a Thames Barge tramps along to windward in a breeze to realose that it really is a black art and there is never anything "new".
Take a look at some of the turn of the Centuary ( 19-20th ) designs particulary some of the "Raters", you will find designs from the 1890's , deep thin keels with torpedo bulbs, masinsails with tiny horizontal gaffs (look just like a modern America's Cup boat), Plus of course we seem to have re-invented the bowsprit in the last few years.
So fiddle with it, make it efficient for your sort of sailing.
Raking mast IS a proven way to affect weather or lee helm.
Second a rudder coming out of water is actually a good thing - as when the boats heels too far by being over-pressed - if rudder is coming out of water - the boat will often lose steerage and round up. In this respect - I actually feel the twin rudder boats are lethal in that .. they do not lose grip on rudder and reluctant to round up under own action.
Jib and Main leech adjustment ? I've raced and cruised for more years than I care to remember and I have never heard that one before. IMHO leech lines should be banned ! They cause more hooked leech's and poor sails than literally any other item. Now moving the leech fwd or aft by reefing the sail - that's a different matter and I agree with that !
People also forget that a too large Genny can increase weather helm by assisting to have CofE aft of where it should be ... so reefing main may not be enough .. reef that big genny as well .. so you get a good movement of CofE forward. Sound daft ? Think about it ...
Another item - leave sails as is - but change genny sheeting point ... move car fwd tightens leech and sail but lets foot slack ... CofE moves fwd ... move car back ... foot tightens, leech slacks - CofE moves aft then fwd.
Nigel, you're right to deplore hooked leeches, but there's nothing more annoying than a sail "motorboating" because the leech is too slack. So I'll resist banning the leech line (but remember to let it off when off the wind).
The leech actually when vibrating is working at best ... Ok not when its near tearing itself apart !
My ban is based on seeing so many boats with tightened leech lines to stop the vibrating. Let's be honest until the advent of lighter stronger sailcloth - there literally was not a problem with leech. The cloth weight was enough to stop it.
My leech line has never been altered since the day I set it on first buying the boat. My race boat - we never touched them either. Never seemed to cause us any losses in placings !
Yes the books say that raking the mast is a way of inducing or reducing weather helm, but frankly it is B******X!
Do the maths
Raking the mast aft a lot might move the C of E 3 rr 4 inches aft maximum on a 35 footer!
It makes no difference, what does make the difference is the changes made to the sheeting angles and the fact that once iot is done the sheeting points are set up properly.
You have mis understood what I wrote, I said Genoa and leech tension, not leech line tension.
I am glad that you think that moving a genoa car forward (so tightening the leech) decreases weather helm! Also that having a boat that gripes is good, I look forward to racing against you!
My last race was in 2003 and I won the Baltic Regatta Cup ...... Adding to the long list of wins with the boat over some years ...
Now I take a more leisurely approach to boating ! My idea of a good day out on the boat is with tillerpilot connected, bench cushions in place, sails set so she is sailing comfortably and not pressed, beer in hand and sun beating down. I'll let all the others have the adrenaline rush now !
Oh - reason for my mentioning the cars fwd and CofE moving - is based on the sheeting angle changing such that the sail will be more curved, leech is more fwd and tighter, sail is depowered enough to act so. A shape that is not ideal and only in my book used as a last resort as in hanked on sails etc.
Funny that many tricks we did with hanked on sails are lost in the world of furling gear and such !
