Windage Problems

[tolly]

Living in Sweden with hardly any multihull history, it is hard to find adequate answers to specified questions, when it comes to catamarans.
Before I decided to buy a catamaran I tried to find out as much negative things as possible, to see if is was on the right track or not, looking for a catamaran after 30 years of sailing monohulls. I took just a little while to figure out that there wasn't so much negative to find as I could see it.

One thing I read about was the windage issue when it comes to high built modern catamaran (and older). Discussing this with the Swedish Lagoon seller, he hadn't any negative experience of that, even though they had sailed the Lagoons in various conditions.

Looking at the shape of the Lagoon, I would think it should suffer from high windage with those high vertical freeboards, but if all I hear here is that that's nonsense, I turn to you all to try to figure out what is right and what is not.

So, therefore under what circumstanses could widage be a problem on a catamaran, and on what grounds do you base you opinion?

[multihullsailor6]

tolly,

I would say that all catamarans have windage problems due to the relatively small amount of underwater resistance and also the reduced weight when compared to a monohull.

One situation where the windage of a catamaran comes into play is when manouvering in a harbour with strong wind. On my catamaran I have daggerboards which I fully lower before I start the docking process to give me as much underwater resistance as possible. But one gets the hang of the boat's typical movement fairly fast, helped in many instances by a twin-propellor installation. It also helps to manouver backwards against the wind as the props are then close to the boat's end in which you are going and you have more control.

Another situation is when you are at anchor and for this reason a typical catamaran's anchor is one size bigger/heavier than on an equal weight monohull.

[DRS]

I find that any close quarters windage issues are fully compensated for with the dual engines placed so far apart. The cat is probably easier to maneuver than a 40 foot power boat. I would much rather dock my cat with twin engines in any space over a mono. Its all what you get used to.

[Sand crab]

When Multihulls World did a review on the massive Lagoon 620 it was quite windy as in storm conditions which actually was a great time to do a test sail. The reviewer noted that the bow thruster option for this boat was a must have. Doesn't your dealer read this mag?
BTW The article did note that this boat did a great job of handling the rough conditions.

[mikefp60]

All of the above comments are accurate. I can, and have, gone 3 knots sideways in a 20 knot blow. Only really matters when trying to get into or out of a slip. After the first year of owning the boat I put bow thrusters on her. Worth their weight in gold when you need them.

Regards,

Mike
S/V Vivo

[tolly]

Thank you for clearifying this.
Then it is only when manouvering in a marina or other tight spots, where I might need to turn around in windy conditiions, that there can be problems, if I got you right?
No problems when sailing then?

[Factor]

Bow thrusters on a cat! wow.

Tolly if its got windage at the dock, then its got it at sea.

[boatman61]

Windage is also a problem when tacking... they tend to catch in the irons and sail in reverse if you don't get the momentum quite right... leaving the jib to back wind you round is the usual option...

[Factor]

Phil , I am not sure what you mean by "they" Some cats wont tack with a tug boat pulling them around, but they are a rarity these days.

[boatman61]

They = Cat's in general...
Thats why I love the Wharram Tiki's... tack a beaut..

[tamicatana]

even a beach cat needs to back the jib when tacking, it's SOP.

That said, I have a unirig cat. Trick there is to not throw the helm hard over - one makes a big U-turn. Then head down a bit, gain some speed, and then come up to course.

[Oliver L.]

Originally Posted by tolly

Thank you for clearifying this.
Then it is only when manouvering in a marina or other tight spots, where I might need to turn around in windy conditiions, that there can be problems, if I got you right?
No problems when sailing then?

Tolly,

I've sailed both monos and cats and I would always prefer a cat over a mono (without bow thruster) in tight conditions. Yes, it will drift a little faster sideways when backing in under adverse conditions, but you can turn on the spot and with the two screws and rudder you got control means which simply don't exist on a mono.

My biggest problem with windage is when anchoring next to monos: My boat will follow the wind while theirs will follow the current - which can produce rather interesting situations...

Oliver

[tolly]

Originally Posted by Factor

Tolly if its got windage at the dock, then its got it at sea.

That is what I have tried to say also, idespite the Lagoon seller's opinion. He on the other hand wants to sell cat's so he might not be that objective...or he hasn't got the experience of sailing various cats.
I have a Prout 50 Quasar, and one of the positive things (though not the most important) I took into consideration when deciding for this model was it's low windage. Since I haven't sailed any other cat type, except a 2-hours test 3 years ago on a Lagoon 38, I really haven't got anything to compare with.
Still I feel there should be some difference like when going up against wind, it should have more of a tendens to drift. Also like boatman61 says when tacking for example.

[tamicatana]

Originally Posted by tolly

Still I feel there should be some difference like when going up against wind, it should have more of a tendens to drift. Also like boatman61 says when tacking for example.

Since most cruising cats don't have deep underwater foils, they don't sail as high to weather regardless of windage. Windage doesn't help, but it's not the main player here.

The beam also makes tacking more difficult, hence I mention beachcats' tacking characteristics, and beachcats are certainly low to the water (and light)

[44'cruisingcat]

Originally Posted by tamif27

even a beach cat needs to back the jib when tacking, it's SOP.

That said, I have a unirig cat. Trick there is to not throw the helm hard over - one makes a big U-turn. Then head down a bit, gain some speed, and then come up to course.

Beach cats are generally trickier to tack than cruising cats are though. Far less momentum to carry them through the wind.