In a previous post I described what happened to us when we were sailing in northern Sardinia, and how the extreme helm pressure required to head up into the wind caused the rudder linkages to slip on the rudder shaft. The rudder slipping was a symptom of a sailplan balance issue. In this post I will explain what happened and what we can do to fix it.
Our current sailplan is unbalanced in strong conditions
A balanced sailplan is important. In basic terms, we need to have the force that’s trying to turn the boat into the wind, balanced by the force that’s trying to turn the boat away from the wind. The mainsail is behind the center of the boat, so when the wind blows from the side, it will push on the mainsail and rotate the bow upwind (this effect is called weather helm). The headsail (jib) is forward of the center, so the wind blowing on the headsail will push the bow downwind (lee helm). If these forces are not balanced, the rudder must be used to counter the unbalanced force and keep the boat moving in a straight line. Rudder pressure acts as a brake and slows the boat down, so unbalanced sailplans are not efficient, and create more work for the helm and autopilot.
A sailplan is balanced when the center of effort (CE) is in line with the center of lateral resistance (CLR). If the CE main is too great the boat rounds up to weather. If the CE jib is too great the boat bears off to leeward.
Here’s a good article that explains weather helm and lee helm and the importance of a balanced sailplan.
Most boats are well designed, and their sails are balanced in most conditions. Wildling is like this, she is a very balanced boat, requiring virtually no rudder pressure to keep her sailing straight. Our last boat was not well balanced and had too much pressure from the mainsail, so she kept trying to steer up into the wind.
The problem becomes how to keep these forces balanced as the sailplan changes. On Wildling this is a problem when we reef the mainsail without changing the headsail. As the mainsail is reefed, it gets smaller, so the force pushing the bow to the wind gets less. Since the headsail hasn’t changed, it’s force starts to overcome the mainsail and we have the bow constantly turning away from the wind. If the wind gets strong enough, the amount of rudder pressure required to point up into the wind becomes considerable. If we reef the jib, the problem gets even worse, because we move the force on the bow forward, so it has a greater lever effect. This is what happened to us in Sardinia.
The solution is simple, and is what Outremer recommends: When the mainsail is reefed, you switch to a smaller headsail positioned further back towards the mast. In this configuration it’s possible to keep a balanced sailplan upwind in winds up to 45 knots.
Double reefed mainsail with staysail for conditions up to 35 knots. Because we have the self tacking jib, which is a bit smaller than the genoa, we are very balanced with full main and with the first reef, so we don’t need to change to the staysail until we get to the 2nd reef on the main.
Triple reefed mainsail with storm jib for conditions up to 45 knots
Wildling was built to have the staysail and storm jib added, but I haven’t ordered them yet, because I wasn’t sure how I wanted to incorporate them into the sailplan along with our self tacking jib (which I LOVE by the way).
Attachment points on the longitudinal beam for the staysail and storm jib
Attachment points for the extra headsails on the mast
On the other 5X boats I have seen that have staysails, they have the inner sail setup on the auto-tacker, and a genoa that tacks manually around the staysail. Like this:
But on Wildling, we don’t want the staysails to interfere with the self-tacking jib, so we need a way to rig them when necessary that isn’t too onerous in strong conditions, and I would really like to be able to disconnect the sheets from the jib and connect them to the staysails, so we can autotack on all of the headsails. I’m not exactly sure how we will do all of this, so I’m going to work with the Outremer factory to see if we can find a good solution.
So although the rudder slipping problem was a hassle at the time, it was very easy to fix, and it helped me see clearly how important it is that we add a staysail and storm jib to our sailplan!
Nice article, Doug, good to hear Outremmer has things set up pretty well ‘out of the box’ for you.
I practice center of effort sailing all the time here in Colorado on the mountain lakes where the winds are constantly changing direction and swirling. I take a J-22 out on Lake Dillon which is known for it’s difficult winds … which makes for great practice. My wife, however, isn’t so keen on the 45 degree healing we do sometimes.
The J-22 of course is monohull with weighted keel which will behaves differently than the multihull. The goal, still, is to always balance the boat to where there’s little to no pressure against the tiller. It’s quite the workout. Sometimes we can simply move weight (bodies) to the front of the boat. And just when you’ve got it set, you’ve run out of lake and have to turn around and do it all over.
Good stuff.
Cheers.
great article Doug, I agree completely with your ideal layout and keeping the centre of effort closer to the mast as you downsize headsails; however like you I have not been in the position to be able to have a staysail in heavy weather and have just survived on a furling genoa in stronger winds. As you have shown, as the wind picks up and you furl the genoa the centre of force on the genoa shifts forward with the furling. However the force generated by the furled sail decreases rapidly as well (i.e. approaches 0 when sail fully furled), so there should always be a position where you can furl your headsail to that balances with the main (agreed poor sail shape and less sail out compared with a staysail) ; so keep furling! If possible would always go with the preferred Outrider option of removable staysail.
happy sailing and keep the posts coming!
regards,
Bill
Hi Bill, You make a really great point about restoring balance by furling the headsail further. Thanks for pointing this out!
Doug
Hi Swanie, I think your comments also point out how valuable it is to sail smaller boats in terms of learning great fundamental sailing skills!
Cheers,
Doug
Great article Doug, we never stop learning. It will be interesting to see how you sort it out.
Thanks Ben, I will post updates as I progress on this project!
You might want to take a look at these guys.
http://www.apsltd.com/aps-advisor/how-to-choose-and-use-soft-shackles/
http://www.apsltd.com/aps-advisor/when-where-and-how-to-use-spool-shackle/
I’ve seen them on some 30 – 40 foot racing boats, but I’m not sure if they could handle the loads on Wildling.
Hi James, thanks for the info. Some kind of soft shackle arrangement looks like what we need. I’m also looking at these blocks by Antal.
http://www.antal.it/eng/LS054_en
Really appreciate your work explaining things. Learning a lot. I’m dreaming about a 5x as well so it’s like you’re preparing me for mine. Always on the lookout for new videos on the youtubes, it’s where we first came across you.
Hi Doug,
Thanks for your very interesting and well documented blog.
Just a quick question: have you observed any change on the lee/weather helm balance of the 5x when you change the dagger board setting?
Hi Vincent, it’s a good question. I haven’t really paid attention to the effect of daggerboards on the helm balance. I will do some comparisons and report back!