Which Cats can actually sail?

[Tupaia]

Originally Posted by ozolli

My choice went to Current Marine, who built the Arrow 1200 you put on video in an post yesterday.
With the boss Julian we co-designed a new boat, the CM50, a shorter version of the CM52 with the CM46 rig.

Sounds like a good choice, all sorts of things kick in at 50ft, berthing, insurance and pollution liability, even pilotage in some places, especially in OZ, Ozolli, are you from OZ by any chance?


A light boat with a smaller rig is also better for long distance sailing, less stress on everything, easier handling and cheaper, sails and rigging are a big expense.

[Rorke Miller]

Otolli, thank you for sharing your effort here. This is certainly information to be considered. Wow.

[ozolli]

Originally Posted by Tupaia

Ozolli, are you from OZ by any chance?

No, I'm French

[Tupaia]

Originally Posted by ozolli

No, I'm French

My bad.
Who is the designer of CM's?

[ozolli]

Schionning

[Tupaia]

Originally Posted by ozolli

Schionning

Excellent designer. The only thing that put me off was his preference for balsa core over foam. What are CM using in the 50?

[Matt Johnson]

Originally Posted by Tupaia

Excellent designer. The only thing that put me off was his preference for balsa core over foam. What are CM using in the 50?

Julian uses foam core in the CM series. He made the flat panels for Schonning if you wanted to build their Arrow design in foam instead of balsa.

[ozolli]

Matt is right, 15mm foam core
For my boat mostly carbon except the hulls outer skin s-glass and one Kevlar layer.

[fcftampa]

I'll try to add more disinformation to the thread with this 3rd chart/list. An image which I've saved a while ago and didn't take note of the source.

[catsketcher]

Thanks for the chart Ortoli. I got a little lost with the units being different on the two axes but got there in the end. I popped the data from my cedar/ply/E glass Chamberlin 11.6 m cat on there. I know the mast is a little stumpy but the data has me dreaming of the new main with a bit more area. Try to get her up into the mid range for SA/D, but in the end she is lovely to sail and this racer still gets a big kick sailing her offshore.
BUt what I love about your chart is that it shows that there is a wide spread of power to weight and length to weight ratios. There is no specific cut off for "performance cats". The Schionning Waterlines are in the middle of the range - which is why they make good cruisers and are quite quick. As Tupiaia says, there are also other design inputs that are vital for good performance and many of these cost nothing extra when you build.
But for me the cheapest way to go fast - is to leave extraneous stuff behind, clean the bum, and have a boat that you love to trim well.

[ozolli]

This chart is performance biased on purpose. Slow boats don't appeal me so I only put a few of them just for comparison.
You may notice that some of them are here for a reason, like the Seawind 1370, the HH44 and the McConaghy 52 ;-)
It is more important to be located on the right than on the top. Adding more sail area is easier than building a light boat.
There is nonetheless a tendency that is easy to notice : Bottom left to top right. You can draw a line in the middle of the points cloud.

For anyone who wants the chart details it's here :
https://e.pcloud.link/publink/show?c...KsNouKKhQqGKY7
This is a LibreOffice file. It may not render well on your side...

[fxykty]

It’s not that difficult to build a light cat out of traditional materials by not having large accommodation spaces and complex interiors. It’s also easier the longer the hulls are, if keeping the accommodations of a smaller, shorter boat. For example, Danson Outremers have pretty much the same bridgedeck and salon space whether 45 foot or 55 foot.

By keeping the lightship displacement down and making the boat easily driven a more modest rig can be specified in a virtuous circle of less weight less power less scantling less weight. With care a larger rig can be specified (watch out, the scantlings have to increase to handle the bigger rig loads) and used reefed except in very light winds.

What is a bad way to add performance is to pile on a big rig onto a medium displacement platform. That can make for a very powerful boat that requires sail area to keep going. Fun, but can be dangerous for two-up sailing couples when the conditions pick up. Unfortunately, because of perceived accommodation requirements, most of the newer performance cats are relatively heavy and require big rigs.

[Tupaia]

Originally Posted by ozolli

For anyone who wants the chart details it's here :
https://e.pcloud.link/publink/show?c...KsNouKKhQqGKY7
This is a LibreOffice file. It may not render well on your side...

Thanks for the chart.

Would be an interesting exercise to plot the full load, WLD (water line displacement) and draw a line between that and the Light Displacement plot.

[Eric Jan]

Originally Posted by Tupaia

Thanks for the chart.

Would be an interesting exercise to plot the full load, WLD (water line displacement) and draw a line between that and the Light Displacement plot.

Cool & interesting chart AND cool to see that the Fountaine Pajot Venezia 42 is in there as well (we have one ).

Not sure about all the data as I think it says we are faster than an Excess 15 (which I would find hard to believe). (maybe also as the venezia is listed with being 6.8 tons and well, no way 9 tons empty empty at best i would guess).

still, cool to see

[django37]

Originally Posted by Tupaia

Thanks for the chart.

Would be an interesting exercise to plot the full load, WLD (water line displacement) and draw a line between that and the Light Displacement plot.

Not just full load, but weighed full load. Most cruising multihulls weigh several tons more than designers estimate - which is often the data used i charts and brochures.