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Old 01-03-2012
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Quote:
Originally Posted by EricKLYC View Post
....

Concerning genoa’s versus non overlapping jibs, it will probably very much depend on the basic design of the rig and thus the sailplan.

Both headsails are less efficient on a fractional rig, especially upwind, because they take lesser profit from the upwash of the main. Mast top rigs now seem old fashioned, but in this concept the small, tall main (short boom, high aspect ratio) gives little power but creates upwash along the full lufflength of the genoa, which provides most of the power. This is one of the many reasons why IOR designs perform well upwind.
This configuration has been given up in modern designs, racers following rules when the IOR rating disappeared. And for cruisers because reducing sail meant frequently changing the headsail.

Then came the fractioned rigs, allowing to tune the mast rake -and trim the shape of the main- much more efficiently. And roller reefing systems, which do not work well with big genoa’s.
Mainsails are now much larger, generating more power and much better to trim to very different shapes. Subsequently foresails become smaller, less powerful but also better manageable when tacking and easier to reef with a roller.

I think Paulo’s example of the Bavaria 36, a very successful design, might illustrate the latest stages of this evolution.
Already a fractioned rig but still with a genoa (36 m2) significantly larger than the main (30 m2). Shrouds are built inwards to allow a correct sheeting angle of the genoa upwind.

In the sailplan of the latest version of the 36 the mast has moved forward, with a longer boom, bigger main (42 m2) with a lower aspect ratio and smaller jib (27 m2).
Shrouds are now fitted on the toerail which prohibits headsails overlapping more than 5 to 10 %.

The total sail area has grown a little from 66 to 69 m2. The displacement much more so the sailplan by itself cannot explain differences in performances, but it seems Paulo’s 36 must be quite faster than the latest version because of an much better S/D ratio.

But the issue in this discussion is that the main has grown from 45% to 61% of the total upwind sail area. The headsail shrinked from 55% to 39%.
The mainsail is now privileged for power, the question is whether this will impair performance upwind, even against a heavy sea. My personal feeling is that this would not be the case with a fractioned rig, because it pays less to favor the headsail for power.

Downwind is a very different matter. A big main will very soon screen off a smaller jib, which becomes mostly useless when sailing lower than a beam reach.

For some time an genoa behind a smaller main will perform better, certainly if a sufficiently long track rail is fitted to control the sheeting angle. But at some point the genoa will need a pole, which can also be used with a code D.
Dead downwind, nothing beats a symmetric spinnaker. But I think this is way off David’s LIM concept.

In conclusion, don’t you think a modern design with the shrouds on the toerail, a forward placed fractioned rig, a big main for power and a small headsail for handling, a code D for fun and a staysail (+ a deep third reef in the main) for security can work very well for cruising in most conditions?

Best regards,

Eric
Hei Eric, great post!

That analyses of the evolution of the rig and main sail versus front sail is very good and in my opinion accurate but that is a very recent tendency that was started by Hanse some years ago when they come with self-taking small jibs and huge mainsails (for the time).

It seems that they got it right and everybody is following. As I have said, for most, in what regards mainstream cruising, I think it is a better solution: more manageable front sail and an easy reefing mainsail, now that almost all main market cruising boats come with a furling mainsail.

But of course this only applies to very recent boats that were designed to have a big main and a smaller front sail.

But if we look at performance cruisers, that many times are also used fort club racing or are de-tuned versions of boats more used for racing than for cruising I think the tendency has also much to do with the bad handicap a big genoa has today under most rules. Regarding using such a rig mainly for performance cruising, and off course on these cases you have a non-furling main, another problem arises: Automatic furling (only one 1 line to pull the reef in) only permits two reefs on the main and almost all boats come standard with only two reefs on the main and that is not enough for safety on a big main.

Of course you can mount a two line small third reef to really bad weather and you should but the fact is that most boats come without one.

But I was assuming a small choice of sails (4) that is what most cruisers have, when do they not have only two and that is about that situation I am talking about regarding what is the more flexible choice, a big genoa or a noon overlaping front sail.

The 4 sails I am talking about are these: a small front storm sail, a non overlapping front sail or a 135/150%) and a downwind/upwind bigger sail for light wind.

As you have said regarding the configuration of your boat, if instead of a single sail for light wind you have two as you say, a code 0 for upwind sailing and an asymmetric spinaker for downwind sailing, that configuration could be more versatile but you have already one more big expensive sail. And I would say that you need another one, a smaller asymmetric spinnaker for strong downwind sailing that is where you would have more fun with your boat

That big asymmetric spinnaker for light winds is to be used till 16K winds and you can risk it till 18/20k winds but with more than that is of no use.

As your small jib has not enough power for a decent speed (and to have fun downwind) you would have to use a relatively big area of the main and that is a bad idea downwind. A strong genoa would have been a much better option and for strong I don't mean the dracon sails that come standard with the boat but the options that almost all brands have for more performant and stronger sails (sandwich pentex sails or mylar sails).

If the wind picks up, at 35K or more, alone or with your wife, you would have trouble to de-power the main and to bring it down. With the huge wind force on the sail it would not come down from the last reef unless you have rigged a line on top of the sail to do just that (almost nobody has it and it would not be easy anyway) and you will find that with a small jib and a too much main sail area out, the boat will be very hard to turn to the wind to take the main down, even with the engine at full power.

I had experienced some troubles with that and even if I was not in danger it was probably one of the two situations were I felt not very confortable with the handling of my boat:

I had come out of Morocco with a Force 7 warning but as I would have it downwind I sailed away, for crossing the Gibraltar strait heading to Portugal.

I has having fun with 25/35K wind with a 3 reefed main and a partially furled genoa on a bumpy sea when, near the Spanish coast, that Force 7 upgraded for a Force 9/10 with winds of about 50K or more (I confess that looking at the wind force was the last of my concerns).

That was not gradual but come just in some seconds and without warning. The sea state become nasty, kind of Colorado river if you know what I mean, the boat had too much main and I was not able to maintain the course downwind, the boat turning to the wind, and of course, I could not pull the boom in and complete the turn because with that wind I was afraid to capsize the boat.

With that sea state I was afraid to let the boat on autopilot and go forward to pull the sail down (remember that the boat was turning on the wind and was unable to maintain course and that the spreaders made impossible to de-power the main). Finally at the third or 4th attempt with the engine full on and pulling the boom in as much as I dared and deeply heeled I managed to complete that turn and put the boat against the wind to take down the main.

After that, with the main rolled to the size of a small towel I was able to purse in complete safety doing 9K downwind and having fun in that very agitated sea, with lots of power and complete control.

This talked a lesson to me: Never to be caught in strong winds with the main on and as a preventing measure, if sailing alone, over 25/30K to sail downwind only with a genoa, instead of a main and genoa.

Later I talked with some friends that are experienced solo sailors and all have passed by this situation and knew precisely what I mean and I guess that they had got their lesson too

This problem is just a bigger problem if you have only a small jib that would not give you the power to sail fast downwind with 25/30K without the main and you would have to use it also, so you cannot avoid this unless you have a small dedicated spinnaker to go downwind..

I guess that I am not going to be caught again in a situation like the one I have described, at least in a boat that was a 135% genoa because with that sail I can go downwind fast with a 25K wind, but with a non overlapping small sail I would not have enough front sail and I would have to use the mainsail, so I cannot avoid it unless I have a dedicated strong wind small asymmetric spinnaker.

That would make 6 sails against 4, I mean:

1 - dedicated storm jib, 2 - non overlapping front sail, 3 - mainsail, 4 - asymmetric spinnaker, 5 - code 0 and 6 - small asymmetric spinnaker for winds over 20K.

Against: 1 - dedicated storm jib, 2 - 135% or 150% genoa, 3 - mainsail and 4-Code D.

With the last configuration the need of a third reef would also be smaller.

Of course you will sail faster with the 6 sails, the 4 are only a compromise that will not give the same performance but if you are only going to have 4 sails on board the second choice is much more flexible and even more easy for short sailing.

Remember you have to go out of the cockpit to rig that asymmetric spinnaker for strong winds with 20/25K and the sea is not always nice with that wind.

On the other option the genoa is already in place and you will only need to furl and unfurl it from the cockpit. You will only need to go forward for mounting the storm sail if things really turn out really nasty.

Hey guys, remember I am talking only in what regards performance sailing.

With 25K winds Eric's boat will go probably over 8K downwind even with only that small non overlapping head-sail but I guess that he don't want to see me passing him downwind with a big genoa and doing 10K. So he has to put the turbo on and rig a proper asymmetric spinnaker, one that can take 25 to 35K wind and go away doing over 14K, or it has to sail with the main and the small front sail and it will be exposed to a sudden rise of wind force.

Not a problem if you have a crew and not a very frequent situation but one that will eventually happen if you sail enough time and are not afraid of winds over 25K.

Of course, in what regards mainstream cruisers the modern tendency of the smaller front sail and bigger main makes all the sense, specially with furling mainsails and that's why practically all modern cruisers have gone that way.

Regards

Paulo

Last edited by PCP; 01-03-2012 at 08:23 AM.
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