Noobie Question - Catamarans and boom vangs

[Zoid]

I just bought a catamaran and am still learning how she sails. The other day I was sailing in sloppy seas with winds of 8-12 knots on the beam then aft quarter. We were hobbyhorsing and the boom was whipping back and forth with the waves because the winds weren't strong enough to maintain shape as we bounced around. This got me to thinking about boom control and sail shape on Cats. I've noticed that 99%+ of the monohulls I see out there have a boom vang, but 90%+ of the catamarans I see don't have any mechanism to apply offsetting downward pressure on the sails like a boom vang. Is there some reasoning behind this or some trick I should use to better control the boom to shape the sails (and maybe add some control in sloppy seas)?

Any thoughts are appreciated,
Zoid

[mbuckely]

I'm interested in this topic too. Quiet annoying when the power boaters hit you with their wake am a light day

[Factor]

You only need a vang if you don't have a good long traveller. And any decent Cat should have a good long traveller.

For control in sloppy seas, power boat wakes etc, use a preventer, I have a tackle that clips on to the boom and a mooring cleat, easy to adjust and controls that slatting.

[jackdale]

The three point rig does not permit the boom to a catamaran to get out as far a monohull (unless mono has a B&R rig).

The traveler on a cat is much longer than the traveler on a monohull.

A vang really is not necessary.

Downwind you might consider a preventer.

[tomfl]

One thing I have noticed is many folks try and sail straight for their destination especially on a broad reach in a following sea. The result is that the cat can catch up with the wind and reduce the pressure on the sail, especially if the AW shifts forward as the boat speed increases as the boat is falling off the face of the wave. The result is an uncomfortable ride and the sail/boom bouncing around. If you alter your course a little you can keep the sails full of wind and reduce the up and down bouncing.

Modern electronics often let you set a destination and display not only SOG but VMG as well. I commonly find that my VMG is higher when I alter the course to keep the sails full than if I try and keep a more direct course to the destination. You can also get some apps that not only display these data but also will calculate the best course. These apps are very popular with not only with monohull racers but multihull racers and cruisers as well.

[colemj]

The Dutchman Boom Brake or similar does a great job of controlling the main/boom in conditions that you describe.

Mark

[Zoid]

Thanks for all of the great input. It sounds like my first option (and least expensive) might be to use a preventer and see how that goes. I'll look into the Dutchman Boom Brake as well.

TOMFL, I'd be interested in knowing which apps you use or recommend that help optimize the best course, can you reply with some suggestions?

[jackdale]

Originally Posted by colemj

The Dutchman Boom Brake or similar does a great job of controlling the main/boom in conditions that you describe.

Mark

+1 - moi aussi

[jackdale]

Originally Posted by Zoid

TOMFL, I'd be interested in knowing which apps you use or recommend that help optimize the best course, can you reply with some suggestions?

You do not need an app. Put in a waypoint destination into your gps and compare VMG at various sail angles and tacks.

[Bill4]

Originally Posted by Zoid

TOMFL, I'd be interested in knowing which apps you use or recommend that help optimize the best course, can you reply with some suggestions?

I'm very much looking forward to the reply to this, too. TOMFL / Anyone?

[tomfl]

Originally Posted by Zoid

SNIP

TOMFL, I'd be interested in knowing which apps you use or recommend that help optimize the best course, can you reply with some suggestions?

I have an older Garmin chart plotter that allows me to set a destination and then calculates the Velocity Made Good speed. The display is right by my helm and I use this most frequently. Chart plotters that display VMG are very common.

There are various apps depending on the device you are running them on. I have an iPad and use iRegatta. You can download a free version and if you like it up grade to the pro version. I am sure there are other apps others may like better and would be interested in their input.

But my main point was that sailing too far downwind can cause your sails to lose the wind, especially in a seaway. By heading up you can keep your sails full and have a more comfortable easier sail and often get to your destination just as fast, or even faster. The electronics are just to figure the fastest possible way, not the most comfortable.

[Mr B]

Tie the boom off to a mooring cleat, Solidly,
Then I just use the Genoa, Mines from the cockpit, and Its very easy to swing from one side of the boat to the other, depending on how fickle the wind is,

I adjusted my best speed from the GPS, 5 degrees at a time, Up or down, I ended up with the top speed Possible in the conditions,,

The main just flopped about, no matter where I put it, So I just left it down, and only used the Genoa,

I need 3 knots to move, Then it sits at 2 knots below actual wind speed,

[jackdale]

If you are using a preventer, run it through a block near the bow and bring it back to the cockpit. That way if you do get an accidental gybe, you can ease the preventer without going forward.

A boom brake may be the way to go. It will not prevent an accident gybe. But it will slow one down while keeping the main from bouncing around.

[Factor]

Originally Posted by jackdale

If you are using a preventer, run it through a block near the bow and bring it back to the cockpit. That way if you do get an accidental gybe, you can ease the preventer without going forward.

Preventer should be connected to the almost rear of the boom, never the middle, accordingly a webbing strap connection to an aft mooring cleat is a simple and cockpit adjustable solution. Really need to get a couple of photos of my set up. I have two preventer tackles - one each side of the cockpit, when off shore etc main is not only totally controlled but a have a redundant system should the traveller or similar have a failure,

[Zoid]

Would love to see any pictures of anyone's setup if possible. This has been very helpful and I will be coming up with my solution over the coming week or so.