Topping Lift - Mainsail Trim - Light winds...

[arsenelupiga]

Originally Posted by 2Hulls

I think you're wrong here. Only very light weight boats can benefit from angles downwind vs dead down wind. And certainly not cruising boats. It takes a lot of boat speed to turn the wind to gain any advantage. I raced beach cats for several decades and know how to do it. I have not been able to do it on my cruising cat.

Dave

ok, let me try. i will report back, especially if you wrong. have finally my speedo working properly. Polars, agree look inflated. However, at least at lower wind speeds and flat water seem quite accurate. Easy to beat them with 100 L of diesel and 200 L of water in the boat.

Waves take knot or two or more out of speed. Which may be why DDW wins in real sea conditions for gybe vs DDW.

Races are usually done in flat water.

[2Hulls]

Originally Posted by arsenelupiga

Races are usually done in flat water.

[arsenelupiga]

Originally Posted by 2Hulls

no need to stress. happens to the best of us.

enjoy

https://www.youtube.com/watch?v=QHdmviq1kyg

[2Wind]

Originally Posted by 2Hulls

There are very few cruising cats that can gybe downwind and make better VMG than dead down wind. There is no shame here - the vast majority of cruising cats are simply too heavy to generate the speed necessary to bring the apparent wind around far enough on the beam to do this.

Dave

I agree entirely with you here 2Hulls but with one or two caveats.

1. DDW with a symmetric SPI is one thing but not so ideal with ASI, so it depends somewhat on what sails you have in your inventory.
2. Sea state really matters in a slower cruising cat. DDW in shallow water with steep waves and short wave length, or in wind against tide situation sees the boat wallow and become very slow whereas deep tacking down wind is in fact somewhat faster IMHO in such conditions.
3. In deeper water with longer wave length its often a more comforatble ride to be running at 155 to160 degrees, wallowing less not to mention being easier on the AP too.

But as for seriously bringing the apparent wind forward when running deep, you need a boat that will sail fast (say 60% or more of TWS down wind) as tigonometry and vector analysis will determine. Not to mention the need for very active steering (to take advantage of surfing) that most cruisers are not going to be interest in doing even if the boat is fast enough. I've never been able to "heat up" a 10-12 ton 40+ footer down wind! It might be me and not the boat but.....

[pbr]

Originally Posted by 2Hulls

I think you're wrong here. Only very light weight boats can benefit from angles downwind vs dead down wind. And certainly not cruising boats. It takes a lot of boat speed to turn the wind to gain any advantage. I raced beach cats for several decades and know how to do it. I have not been able to do it on my cruising cat.

Dave

Sorry Dave, I totally disagree, I raced monohulls as well as cats for 35 years, higher performance cats benefit greatly, however the heaviest displacements monohulls that I have raced benefit too just not as much. You need to look at some polar charts and educate yourself. Then there is playing the windshift thingy.......

[malbert73]

You guys are both right.

With the right spinnaker almost every boat benefits from sailing angles downwind. A poled spinnaker especially rewards this since it can be set out to windward out from behind the main. So heading up 10-15 degrees gets flow over both sails and improves vmg.

With no spinnaker (ie main and headsail only) virtually no boat benefits from angles. This is because to get the headsail out from behind the main's shadow, you have to head up too far, like 30 degree to get the Genoa drawing. Do the trigonometry on that and almost no boat can make that up.
Even racing dinghies in college (non spinnaker FJs and 420s which can plane) we sailed wing on wing for ddw legs. This is also the case in keelboat non spinnaker fleets where all boats sail with poled out Genoa wing on wing for ddw legs.


Sent from my iPhone using Cruisers Sailing Forum

[2Hulls]

Originally Posted by pbr

Sorry Dave, I totally disagree, I raced monohulls as well as cats for 35 years, higher performance cats benefit greatly, however the heaviest displacements monohulls that I have raced benefit too just not as much. You need to look at some polar charts and educate yourself. Then there is playing the windshift thingy.......

Educate myself? Demeaning comments like that are inappropriate and not conducive to discussion.

The "heaviest displacements monohulls" you raced must have been able to substantially exceed their hull speeds rather easily. Otherwise they could not possibly have traveled further gybing downwind vs dead downwind at hull speed and make better VMG. In winds too light to make hull speed DDW they'd have to be about 41% faster on the angles vs DDW to make up for the 41% further distance, assuming a 90* gybe that doesn't waste time.

When I started racing beach cats in the late '70s, it didn't take long to learn that gybing downwind was the way to go. In the years before beach cats started carrying asym spis, the best downwind angle was that which brought the apparent wind right on the beam - focus on the bridle fly and wiggle the stick to keep it sideways. This could vary a little from cat to cat (designs) and within designs, from sea state to sea state. Any time you could grab a wave, it pays off to momentarily dive deep, then harden up as the surf ends to put the AWA back on the beam. On the infrequent occasions when I've raced my cruising cat on buoys courses we've learned that the best DDW strategy is wing-on-wing with the genny sheeted with a temporary outboard sheet back to the spi sheet block. A virtual whisker pole. Using a sym spi could be a little faster, but the added complexity to hoist, set, douse, and drop creates too many opportunities to screw it up when using casual volunteer crew, not to mention the rating penalty. For me, not worth it.

Dave

[mark_morwood]

Originally Posted by arsenelupiga

this are polars Lagoon 41, simlar to Lagoon 400. Looks like 140 - 150 true is the answer.

As it doesn't say on those polars I'm assuming they are for Jib and Main, not Spinnaker. You'd need the polars for spinnaker to decide what angle was worth sailing with one.

Like many of the others in this discussion who are actually out cruising with catamarans, I find that sailing the angles is almost never worth it cruising. If we stripped our boat out (a Catana 48) it is possible it would be worth it, but we are currently world cruising with a family of 4 so are certainly heavier than is optimum. But our boat is no slug, we have a suite of light weather sails and use them.

If our destination is dead down wind and we can fly the spinnaker, we sail almost dead down wind. We do come up about 10 degrees or so as we have an asymmetric not a symmetric spinnaker and it seems to sit a little better, but I don't consider that sailing the angles as it is normally thought of. Note we are flying the asymmetric off a bridle pulled towards the windward bow as one would normally do for a symmetric, not the sprit.

[2Hulls]

Originally Posted by pbr

Sorry Dave, I totally disagree, I raced monohulls as well as cats for 35 years, higher performance cats benefit greatly, however the heaviest displacements monohulls that I have raced benefit too just not as much. You need to look at some polar charts and educate yourself. Then there is playing the windshift thingy.......

I should have added, that with regards to cruising cats, it sounds as if you don't disagree with anything. So what exactly do you "totally disagree" with?

Dave

[mark_morwood]

Originally Posted by pbr

A solid vang will give you the same result with a lot less hassle and infinitely more adjustment when it comes to twist.

Except for boats with a roller furling main, solid vangs, or vangs or any type are quite uncommon on cruising catamarans. On most cruising catamarans I am familiar with the main can not be eased far enough forward because of the swept back shrouds, for a vang to be really useful the way it is on a mono-hull or boats without swept back spreaders in general.

We have a 20' traveler which gives us plenty of control without a vang. Many other "performance" cruising catamarans have a twin main sheet solution which also gives them good control through the whole range of usable boom angles.

It's easy to forget that on most cruising catamarans there is a wide range of downwind angles where it is not possible to ease the main as much as you would like - in our case past about 120 apparent the main is not trimmed optimally because to ease it further would have it chafing on the shrouds.

Mark.

[pbr]

Well I assumed we were talking about wing on wing or spinnakers of course, Dave doesn't believe whisker poles are needed either though. As for jib and main, you would have to sail higher angles to get the jib to work at all, unless you sheeted to the windward hull wing on wing which will work, but not as well as with whisker pole. Needless to say the foil boats will sail downwind with good vmg quite well with just a jib and main.

[pbr]

Originally Posted by mark_morwood

Except for boats with a roller furling main, solid vangs, or vangs or any type are quite uncommon on cruising catamarans. On most cruising catamarans I am familiar with the main can not be eased far enough forward because of the swept back shrouds, for a vang to be really useful the way it is on a mono-hull or boats without swept back spreaders in general.

We have a 20' traveler which gives us plenty of control without a vang. Many other "performance" cruising catamarans have a twin main sheet solution which also gives them good control through the whole range of usable boom angles.

It's easy to forget that on most cruising catamarans there is a wide range of downwind angles where it is not possible to ease the main as much as you would like - in our case past about 120 apparent the main is not trimmed optimally because to ease it further would have it chafing on the shrouds.

Mark.

Lots of cruising cats come standard with a vang. Voyage, Manta, St. Francis, Yapluka, Endeavour, Tag, etc. 99% of the cruising cats I have seen without a vang would benefit from one since the travelers are not long enough to control twist on anything outside of a close reach. There is also the added benefit of eliminating the need for a topping lift. I just finished raising the boom and adding a vang to a new Helia, and I will guarantee it will be faster off the wind. The double bridle system works to a point but still allows more twist than desired at deeper angles. All cruising cats should have chafe covers on the cap shrouds so you can allow the main to touch the rig, with a vang there is even less potential for chafe since it keeps the boom from moving up and down and can eliminate twist so the main can be eased more before laying on the shrouds.

[pbr]

Originally Posted by 2Hulls

Educate myself? Demeaning comments like that are inappropriate and not conducive to discussion.

The "heaviest displacements monohulls" you raced must have been able to substantially exceed their hull speeds rather easily. Otherwise they could not possibly have traveled further gybing downwind vs dead downwind at hull speed and make better VMG. In winds too light to make hull speed DDW they'd have to be about 41% faster on the angles vs DDW to make up for the 41% further distance, assuming a 90* gybe that doesn't waste time.

When I started racing beach cats in the late '70s, it didn't take long to learn that gybing downwind was the way to go. In the years before beach cats started carrying asym spis, the best downwind angle was that which brought the apparent wind right on the beam - focus on the bridle fly and wiggle the stick to keep it sideways. This could vary a little from cat to cat (designs) and within designs, from sea state to sea state. Any time you could grab a wave, it pays off to momentarily dive deep, then harden up as the surf ends to put the AWA back on the beam. On the infrequent occasions when I've raced my cruising cat on buoys courses we've learned that the best DDW strategy is wing-on-wing with the genny sheeted with a temporary outboard sheet back to the spi sheet block. A virtual whisker pole. Using a sym spi could be a little faster, but the added complexity to hoist, set, douse, and drop creates too many opportunities to screw it up when using casual volunteer crew, not to mention the rating penalty. For me, not worth it.

Dave

In ANY monohull racing NO ONE sails dead downwind and ignores the polars with any hope of winning a race, particularly with asymmetricals on a bow sprit. Since cruising cats laden with gear are in about the same performance range as a high performance monohull, they too can benefit from sailing polars. Needless to say it is kind of hard taking advantage of windshifts sailing the rumbline .

[monte]

Mark the polar shown is white sails until around 90 degrees then gennaker where you see the sharp rise in speed

[pbr]

Please don't misunderstand me though, I advocate for most cruisers sailing the rumbline is the way to go, just a lot easier and safer and less potential to make a windshift mistake. That is why I advocate whisker poles or a device like a Hoyt boom or Camber Spar. The question was " Is sailing polars faster"? And the answer is YES.