From the photo: those red spinnaker sheets are the original and very heavy polyester sheets - they have to go! The original black one-piece trampoline lacing - that's gotta' go too!
We are on our third Corsair 750 Series.
We started with ‘The Dash’ where we evolved our mast rake and rudder set up.
Then we got Ding Hao and on this platform we further developed the sail package as well as played with the rigging systems.
So now we can tell you the ‘basic’ setup that you will need to allow you to get more out of the boat. In order of importance,
Rudder rake and mast rake - If you only did one thing from this list, this would be it!
Rig tension - we’ve adapted the “split side stay” system back onto the boat
Halyards - ensure you have really good cordage, add the masthead halyard
Trampolines - tension them properly, do it ‘offshore’ style
We’ve effected a lot of other changes but the above items are good enough for the newbies shortlist.
1. Rudder rake and mast rake - If you only did one thing from the list, this would be it!
First of all, definition. Rake, refers to the amount the rudder or mast is raked (vertical plane).
Photo below: extending a line directly through the rudder pin to the top of the rudder, in this case there is no blade ahead of this axis line. That's an "unbalanced" blade.
Centre of Effort
Here’s where things will get a little complicated. If we look at a sail plan e.g. mainsail and jib, if we added up the forces that they generate we could summarise that they act through point and call it the Centre of Effort.
A boat designer knows where the CoE will be located and then sets about designing the underwater appendages to balance the CoE. The appendages are the daggerboard and rudder. In a similar way, we add up the forces acting through the daggerboard and rudder and summarise it to be acting through one point and call this the Centre of Lateral Resistance.
Remember school, “for every action there is an equal and opposite reaction”. So as the CoE tries to push the boat in sideways, the CoLR acts equally against it. This is what gives us our forward motion. It’s as if you are squeezing a watermelon seed between your thumb (CoE) and finger (CoLR), the resultant action is rapid forward speed - that’s a sailing boat!
So, these two forces are the MAJOR ones. Obviously having them in harmony is going to create more forward motion than if they are not in sync!
Getting the mast rake in sync is going to have a greater benefit but the CoE and the CoLR are inextricably linked - just like the watermelon seed example.
Mast rake refers to the amount of off vertical ‘lean’ that the mast has. Consider,
No rake = vertical mast i.e. one that is perpendicular to the waterline
Aft rake = a mast leaning aft
Forward rake = a mast leaning forward
In the case of,
No rake, the helm will be neutral i.e. it will sail a straight line when sailing upwind with no push or pull on the tiller
Aft rake, the tiller will have a ‘pull’
Forward rake, the tiller will have a ‘push’ feeling
Most desirable is, to have a little weather helm (tiller pull) when the boat is sailing hard.
Least desirable is, to have lee helm i.e. tiller is always ‘pushing’ you and the boat wants to bear away.
Most beginner sailors prefer the neutral setting which is ok but you’ll never get max out of the platform.
As the mast is rake aft the first thing that will happen is,
We move the CoE aft as well
A small weight transfer aft as the CoGravity moves back
The thrust component of the sail drive moves into a ‘lift’ component
Without being too crazy about the science involved, suffice to say as you rake the mast aft you will experience better upwind pointing ability, better speed and better handling.
So raking the mast back has a benefit but comes with a caveat.
As the mast goes back, so to does the CoE. This is the same as taking some side load away from the daggerboard and placing it on the rudder. This generates the weather helm feeling. More rake, more weather helm.
Having the right amount of mast rake means having to offset the weather helm with a ‘trick’. The trick is to rake rudder under the boat i.e. rake the rudder tip forwards. This creates a greater Angle of Attack on the blade and goes some way to re-balancing the blade.
Sounds complicated but if you have taken over one of the boats in our fleet, chances are, it’s been sorted out so you are off to a better start! This was one of the first mod’s we made to our platform and once we had it working, we moved the mod onto all our Corsairs that were actively racing. Those not actively racing, missed out!
At the beginner level… The top gudgeon fitting of the rudder should have block under it. Some boats will have bigger blocks than others and that depends on the sails you have on the boat. Suffice to say, the top gudgeon needs at least 30-60mm of block. If you are unsure, ask and we’ll take a look.
Photo: These are the blocks that were slowly added to Ding Hai our Dash 750. We played with the amount of rudder take until we were happy with the overall feel and the upwind ability.
Photo: the blue line is the way the original rudder hung off the transom. The red line is with the blocks added under the top gudgeon, as you can see it rakes the rudder to eat under the transom.
2. Rig tension - we’ve adapted the “split sidestay” system back onto the boat
All our Corsairs use synthetic rigging (Dyneema textile instead of stainless steel wire). The reason for this is simple, the life cycle of Dyneema is 10 x greater than stainless steel and its a fraction of the weight.
All of the side stays on our Corsairs have the Colligo system where the side stay terminates with a specialised lashing system. This makes it very easy to setup and change.
Photo: this is the Colligo side stay adjuster. It's a 6:1 system. Onto the tail end of this we've added a 2:1 system that terminates in the cockpit and gives us control of the tension. Better still is the split system.
In light wind we don’t need as much side stay tension as we do when the wind is high.
The tension in the side stays will determine how tight the forestay is. A tighter forestay i.e. no sag in it, creates a better leading edge and is necessary for good upwind angles. A soggy forestay will not point as high into the wind as a non-soggy one! But as most folks just jump on their Corsair and head out sailing, they seldom spare any thought for the rig tension!
As the wind gets higher, loads on the mast, sails and rigging go up exponentially, This will mean more sag in the forestay and an even worse upwind performance!
So, when you get really good, you will be changing the rig tension according to the conditions on hand. Now this might seem like a lot of bother but there’s ba cheat way to achieve it!
Essentially, the mast needs to be in the center of the boat, laterally. Make sure you have an equal measure from side to side. Do this using the main halyard measure from a fixed point on the side of the boat and transfer to the other side. Do this until you have the rig centred laterally and mark the side stays so that you can always spot it.
With it centered you can then think about the tension. Light wind days use less and never use so much that the mast can not rotate!
What I like to do is sail the boat upwind, go forward and sight up the forestay, yes you will have to go to the front of the boat. A foot (25-30cm) of forestay sag is to much and a couple of inches (10-15cm) is ok.
As you sail upwind you might notice the leeward side stay goes slack. A little is normal this is for to flex and compression on the rig/platform. What I like to do is, as the boat is sailing along go and re-tension the leeward stay. Just make it hand tight. When you make a tack, observe do the same to the other side.
For this reason we have reverted back to the original split side stay system. This is a much easier way to gain control of the sidestays. Easy to tension for sailing and really easy to ease off at the end of the day or for folding the boat.
Ensure you have really good cordage. Over time we changed all the original ripped to Maffioli high-tech textiles. First of all this shaved about 30kgs off the boat. Next, it absorbs less water so it's much easier to work with especially when wet. But the biggest advantage of these textiles is really a safety factor. 8mm Dyneema Halyards have a breaking strain of 6000kgs. That is as strong as the side stays. In case you ever have an issue with the forestay or side stays, you can use the Halyards.
Why we love Dyneema... During a week of sailing in wings of 25-35 knots of Bintan, Riau Archipelago, Indonesia we blew out the stainless steel forestay. That is relatively common after a few years on boats with furling headsails as the extra stress from the furling can take away some life from the forestay wire... Here's a little story,
The boat comes with 4 halyards,
Mainsail , 8mm Dyneema (tapered)
Screecher, 8mm Dyneema (tapered)
Spinnaker, 7mm Dyneema (tapered)
Jib, 7mm Dyneema (tapered)
You will notice we use tapered halyards, thick where you hold the rope (8mm) and thin at the top where it goes into the mast (6mm). This saves us weight but gets rid of a lot of friction so makes it easier to get the sails up and down.
We add one more Halyard to the mix. This is a Mast Head Halyard. If you look at your halyard set up, the standard Spinnaker halyard is the highest of the foresails.
Adding the Mast Head Spinnaker halyard gives us another option to fly the Spinnaker from but also adds an extra halyard which is always handy.
We developed a large Spinnaker specially for our predominantly light air. This sail had been nick named Big Boy and it's designed for 2-14 knots True Wind. Big Boy allows us to easily sail at 140-160 degrees Apparent Wind Angle which is a huge advantage!
As the strings wore out on our platform, we upgraded them to more high-tech versions. The high-tech solutions are easier to handle with less friction while offering a longer service life.
From the photo: we've removed the trampoline plastic 'mushrooms' and toe rail from the gunwhale replaced with a simple hole and individual lashing arrangement.
These are mostly over looked by all our owners but was amongst the first things we altered. Essentially the trampolines are your work place so having them properly secured is just a nice thing to work on.
The standard setup has the main lacing (along there side of the mainhull) as one 'string'. This works ok but it's,
Polyester, stretches and makes for saggy nets.
It finally wears away and when I breaks in one point, that whole side of the trampoline comes lose.
Offshore racing multihulls must have individual lashing lines on each eyelet. You break one, it's no disaster. So for safety, longevity reasons it's good to swap to the offshore style. A note on that, we've done this on every Corsair we've owned. It takes 3 days to set the nets up properly but once it's done, that's it.