Catamaran tacking angles , really that bad???

[thinwater]

Are the new owners happy? Very likely, they are getting what they want:

• Huge salon
• Lots of appliances
• Comfort at anchor
• Adequate performance off the wind
• Big engines upwind

I once asked the designer of the "improved" Gemini about some of the changes that hurt sailing ability. He said "we build these to a different kind of sailor." I think that sums it up.



You simply can't have it all. If you make the boat longer and increase the power, you get a boat a only an experienced, motivated multihull sailors can safely handle in a breeze, and it will take two on watch. Otherwise, capsize is possible. Or you can reef early, but again, it requires an experienced hand. So most builders opt for slow and tame. It's just the market at work. Loose a few heavy amenities, focus on performance, and you can have a very nice sailing boat, as several posters here have.

[double u]

“...we build these to a different kind of sailor."

“sailor“??? Muhaha!

[StuM]

Originally Posted by double u

“...we build these to a different kind of sailor."

“sailor“??? Muhaha!

Yep a sailor, but a cruiser not a racer.


Someone who values comfort and safety as much or more than upwind performance.

[Kiwi Dave]

https://www.youtube.com/watch?v=EdReAXPhD5M

If it is of any help I have attached another video. CATMANTOO is 42 foot hard chine glass over ply cruising cat with low aspect keels. 20 knots of wind, flat water, typical cruising mode - full diesel & fresh water load, autopilot all the way and no sail trimming, just taking it easy.

[double u]

Originally Posted by StuM

Yep a sailor, but a cruiser not a racer.


Someone who values comfort and safety as much or more than upwind performance.

...just looking at the Lagoon 38(0?) anchored 100m on our quarter:
sailing/seakeeping qualities - how can they have been part of the decision process to buy the thing?
& this thread shows: these condomarans sail every bit as badly as they look

[mglonnro]

Originally Posted by Kiwi Dave

If it is of any help I have attached another video. CATMANTOO is 42 foot hard chine glass over ply cruising cat with low aspect keels. 20 knots of wind, flat water, typical cruising mode - full diesel & fresh water load, autopilot all the way and no sail trimming, just taking it easy.

I measure that to 106.7°.

[Kiwi Dave]

Thanks mglonnro
At that time true wind 20 knots, apparent wind angle 40 degrees and boat speed up to 8.5 knots. Using the VMG calculator on L-36.com I get a tacking angle of 109.8 degrees (2 x 54.9 degrees )the true wind angle))- so close enough to the measured angle from the chart plotter. The VMG to windward calculates at 4.6 knots. We can do a bit better than this, but this would be typical for a relaxing sail in these conditions.
https://l-36.com/polar_calculate.php...d=20&ws=T&bs=9

[fxykty]

Here’s a track (in red) tacking up the channel to Neiafu Harbour. Autopilot set to 37 degrees AWA, both boards 2/3 down, 15 knots true wind, moderate changing to flat water, 1 reef main and full self-tacking jib. 7.5-8 knots SOG, outgoing tide (minimal current though). Used auto tacks and due to the reefed main didn’t need to adjust the running backstays. Sailed all the way into the harbour before picking up a mooring. Haven’t measured but assume 105 degrees or so. Real world.

[earthbm]

Originally Posted by fxykty

Here’s a track (in red) tacking up the channel to Neiafu Harbour. Autopilot set to 37 degrees AWA, both boards 2/3 down, 15 knots true wind, moderate changing to flat water, 1 reef main and full self-tacking jib. 7.5-8 knots SOG, outgoing tide (minimal current though). Used auto tacks and due to the reefed main didn’t need to adjust the running backstays. Sailed all the way into the harbour before picking up a mooring. Haven’t measured but assume 105 degrees or so. Real world.

Attachment 203712

Thanks, this is great real-world data. The tack angle is 110 using L-36 VMG calculator, and 112.5 measuring the angles on the screenshot (so there was around 0.25kt current)

Was 37 AWA set to ease the auto-tack? Was the AP steering to wind or to bearing?

[fxykty]

Originally Posted by earthbm

Thanks, this is great real-world data. The tack angle is 110 using L-36 VMG calculator, and 112.5 measuring the angles on the screenshot (so there was around 0.25kt current)

Was 37 AWA set to ease the auto-tack? Was the AP steering to wind or to bearing?

36-38 AWA is as good as it gets for us, I suppose partly due to older sails. Anything tighter and we just slow way down. Even if VMG stayed the same or increased, it is no fun. So we romp along.

Auto-tack doesn’t care as it is set to turn to the same angle on the other tack. Typically we are fuller while slow so we ease headsail for better acceleration. Since we have a straight jib traveller that also allows the jib to cross sides - a bit of auto back winding until the sheet is eased.

We run the autopilot in AWA mode. If we aren’t particular on a course that’s typically what we use on passages as well. Broad reaching or downwind in relatively flat water we’ll use TWA, but if the waves/swells build we’ll go back to AWA for better handling of the waves/swells. We only ever use heading mode if it’s critical or we’re motoring.

[earthbm]

Thanks. Thought Neiafu was one such tight spot where heading is critical. The idea of wider tack angles on auto tack is that it leaves more margin for error. On my tri I would tack from 30 to -30 AWA by hand but 35 to -35 on auto, because at 29 AWA the speed would hit a wall.

[fxykty]

Originally Posted by earthbm

Thanks. Thought Neiafu was one such tight spot where heading is critical. The idea of wider tack angles on auto tack is that it leaves more margin for error. On my tri I would tack from 30 to -30 AWA by hand but 35 to -35 on auto, because at 29 AWA the speed would hit a wall.

The entry to Neiafu is narrow but not excessively so. We short tacked and went right to the edges based on sunlight navigation and sat photos. If we had been on a reach then we would have used heading, especially with greater speed.

[mglonnro]

Tacking angles. Didn't measure them

[Sand crab]

Originally Posted by mglonnro

Cool, thank you!

Add Maine Cat to the list.

FWIW Unfortunately Catana production has ceased because they only make Balis now.


And Fxykty, do you have Code 0 (the upwind kind) or something else for helping you upwind at low wind speeds?

[fxykty]

Originally Posted by Sand crab

Add Maine Cat to the list.

FWIW Unfortunately Catana production has ceased because they only make Balis now.


And Fxykty, do you have Code 0 (the upwind kind) or something else for helping you upwind at low wind speeds?

Yup, there’s an old, very big and heavy Dacron one that must have been one of the original sails from 2003. It’s cut flat enough that it can go to about 45 degrees AWA, so not super tight angles. Also, must be rolled up for tacking.

So in lighter winds (5 knots TWS and below) if we want to go to windward with tacking we use our jib and are under powered and going half windspeed. With the Code 0 (actually called a gennaker in French, but maybe predates code sails?) we sail wind speed, but VMG is not much if any better. The extra boat speed is great, but rolling it up for tacks seriously sucks.

I want to replace the one we’ve got with a laminate one, which would be a quarter of the weight and bulk, and would be easier to roll up, but there’s lots of stuff ahead of that on the refit list.