Are "Performance Cruising Catamarans" safe?

[Lee Jerry]

Originally Posted by CaptainMarkS

Wow. That's quite the debate going on here! As a fellow liveaboard Antares owner (in support of Mark Silverstein), I'm super happy I can't fly a hull in my home. I admit, there are times I wish we could beat upwind better, or sail faster in lighter winds. I'm super happy when I can tune our rig to cruise at 10-11 knots and get 250 miles under the keel in a day. I miss the adrenaline rush I got sailing thousands of miles in my Hobie 16. However, in higher winds and heavier seas, our "plodder" feels super safe and well balanced, and our short handed crew remains better rested (an element of safety) knowing we don't have to fiddle with sails as much because our vessel is more "forgiving" (as someone mentioned). At anchor (where we spend most of our time anyhow) we enjoy our comfort, the heavier displacement translating to less response to waves. I'm that minivan owner who sometimes wishes his car had the performance characteristics of a Ferrari, but wouldn't trade for one because this driver (me) would definitely push the car harder in search of excitement, placing himself and his crew in harm's way. I'm super happy for the Ferrari owner who enjoys his/her car. As with the debates on multihulls vs monohulls, or galley up or down, one can articulate pros and cons for each.

[Lee Jerry]

Originally Posted by boatman61

Ahh.. the benchmark for good catamarans, height of bridgedecks, beam to length ratio and more..

Yeah, OK. But I don't see your point, or how it relates to the topic.

[boatman61]

Originally Posted by Lee Jerry

Yeah, OK. But I don't see your point, or how it relates to the topic.

Its called an opinion..
Relation is design methods.

[Lee Jerry]

Originally Posted by SoPacBound

I appreciate everyone's input and that is what makes this forum great, different perspectives.

I'm leaning towards the lighter, faster side of things. I think I would get frustrated on a catamaran that struggles to sail in light winds and not able to achieve high average speeds in the right conditions.

The search continues....

Good luck with your search.

Remember, of course, that between the "low performance" boats of Lagoon, Leopard, etc. and "high performance" boats of Outremer, Gunboat, etc. are the newer "medium performance" boats like Seawind, Nautitech, etc.

I don't think you mentioned what your time frame is or whether you're looking for new, used or either. If new, then remember to consider the lead times for many brands these days. For example, both the Seawinds (1260 and 1370) and Nautitech (42 and 46) are nice looking boats, but a large part of the reason we ruled them out were both the price of a new boat and the long wait for delivery. A friend of ours has a SW1600 on order, placed the order well over a year ago, for original delivery date this fall (last I heard still on track). So like a two-year lead time; I think the 1370 used to be even longer.

[chubby]

Originally Posted by fxykty

..... From Multihull Dynamics, the two stability figures for our cat (2003 Outremer 55L, though we have less sail area with our self tacking jib), a new generation Outremer 55 (18.5 ton vs our 11.5 ton), and an Antares 44.

SSpd (wind speed at which windward hull begins to lift): O55L 22.91, O55 24.86, A44 25.00

KSI (resistance to sideways capsize): O55L 38.59, O55 41.88, A44 42.11

I don’t see a vast spread in these numbers, i.e. what better margin of safety for the heavier, slower cat? ..

with all due respect.. i'm not sure how anyone could suggest any 44 foot catamaran is anywhere near comparible to ANY 55 foot catamaran.
not even close in weight class.
not comparable in terms of size y loads involved..


for an actual comparable...
the same sized outremer as the antares 44 has a KSI of 25 knots. (!!)
meaning an unexpected 25+ knot gust could potentially turtle you...


ksi= more or less the wind spead where you can expect you can expect to capsize (with wind on your bean...and sails 100% up)



this is exactly why (some) of these "performance cruising cats" are NOT safe (for many)


(to be more precise)they are not appropriate(imo) for the typical cruising family that may want to relax on passages....




data for a lagoon 440..


i remember being informed that 50+ knot gust was enough to flip my old lagoon(never knew the exact data)


..so i know (err believe) it is possible to turtle a fat cat...
but does anyone have any links or examples of a leopard, FP, or lagoon getting capsized by a gust?(or nonhurricane wind)?
i searched google.. but could only find examples of the usual suspects .(outremers, marsaudons, gunboats, DIY one-offs..)

[Chotu]

I want to calculate these for my boat. To see where it fits in.

Self tacking Jib area: 398sqft (max)
Main area: 627sqft (old triangle top still)
Total main and self tacking jib: 1025sqft
Displacement: 18,000lbs max (hope for less)
LWL: 50ft
BOA: 25ff
Hull centerline beam: 19.5ft
Hull beam approx 5ft
LWL to Bh Ratio: 50/19.5? =2.56

Want to see how the boat fits in the chart.

LWL/Bh seems wrong.

Unless they mean individual hull beam. Mine is 5ft max

So LWL/Bh would be 10. That seems better.

Are there some formulas for coming up with KSI, Sspd and Bspd?

[smj]

Originally Posted by Chotu

I want to calculate these for my boat. To see where it fits in.

Self tacking Jib area: 398sqft (max)
Main area: 627sqft (old triangle top still)
Total main and self tacking jib: 1025sqft
Displacement: 18,000lbs max (hope for less)
LWL: 50ft
BOA: 25ff
Hull centerline beam: 19.5ft
Hull beam approx 5ft
LWL to Bh Ratio: 50/19.5? =2.56

Want to see how the boat fits in the chart.

LWL/Bh seems wrong.

Unless they mean individual hull beam. Mine is 5ft max

So LWL/Bh would be 10. That seems better.

Are there some formulas for coming up with KSI, Sspd and Bspd?

SSpd. = 8.23805*((0.5*Bcl*Disp*2240)/(SA*HCE))^0.5

KSI: Kelsall Stability Indicator

= 13.73(D*Bcl/2SA*Hcl)^0.5

= 13.73(Displacement *half Bcl/SA*Hcl)^0.5

BSpd. = 1.7*(Lwl^0.5)*(SA^0.352)/((Disp.*2240)^.253)

[AKA-None]

To change it up a bit
Does a performance anything encourage you to something you might, with thought, consider riskier?

[Chotu]

Originally Posted by AKA-None

To change it up a bit
Does a performance anything encourage you to something you might, with thought, consider riskier?

I feel like it’s going to help me have more comfortable times sailing. I can go out when it’s not that windy. At least that’s the hope.

i’d say that’s a lot more safe than going out when it’s blowing like crazy because that’s the only thing you can sail in.

[Chotu]

Originally Posted by smj

SSpd. = 8.23805*((0.5*Bcl*Disp*2240)/(SA*HCE))^0.5

KSI: Kelsall Stability Indicator

= 13.73(D*Bcl/2SA*Hcl)^0.5

= 13.73(Displacement *half Bcl/SA*Hcl)^0.5

BSpd. = 1.7*(Lwl^0.5)*(SA^0.352)/((Disp.*2240)^.253)

Thank you! 10:24 PM. I think I’m done for the night. Calculating that right now will result in errors. Ha ha I will take a crack at it in the morning.

have you done your boat?

[smj]

Originally Posted by Chotu

Thank you! 10:24 PM. I think I’m done for the night. Calculating that right now will result in errors. Ha ha I will take a crack at it in the morning.



have you done your boat?

Don’t have to, it’s on Multihull Dynamics!
Bspd: 12.44kts
SSpd: 15.12kts
KSI: 25.47kts

[fxykty]

Originally Posted by chubby

with all due respect.. i'm not sure how anyone could suggest any 44 foot catamaran is anywhere near comparible to ANY 55 foot catamaran.
not even close in weight class.
not comparable in terms of size y loads involved..


for an actual comparable...
the same sized outremer as the antares 44 has a KSI of 25 knots. (!!)
meaning an unexpected 25+ knot gust could potentially turtle you...


ksi= more or less the wind spead where you can expect you can expect to capsize (with wind on your bean...and sails 100% up)



this is exactly why (some) of these "performance cruising cats" are NOT safe (for many)


(to be more precise)they are not appropriate(imo) for the typical cruising family that may want to relax on passages....

…

I compared the two as they have similar displacement (10 ton vs 11.5 ton) which is a proxy for load carrying capacity, and because it’s a boat I own so can speak with experience about it. The differences in their stability numbers is negligible.

As with other posters, your comment about performance cats being unsafe and not appropriate for passaging is incomplete. Yes, when you compare indicators at full sail area, which is part of what allows performance cat to sail well at lower wind speeds, the differences in stability indicators are quite big. That is what caught out the Outremer 45 that capsized in the Med last year. But the reality is that during passages, when not racing, the vast majority of the time we, and from their comments other performance cat owners, are reefed well down in the kind of conditions a less performance oriented cat must use full sail area to achieve any sort of speed. So rerun the formulae with half the sail area for the performance cats (typical for offshore passages) and you’ll see numbers that don’t differ much from the accommodation oriented cats.

[Matt Johnson]

Originally Posted by chubby

with all due respect.. i'm not sure how anyone could suggest any 44 foot catamaran is anywhere near comparible to ANY 55 foot catamaran.
not even close in weight class.
not comparable in terms of size y loads involved..


for an actual comparable...
the same sized outremer as the antares 44 has a KSI of 25 knots. (!!)
meaning an unexpected 25+ knot gust could potentially turtle you...


ksi= more or less the wind spead where you can expect you can expect to capsize (with wind on your bean...and sails 100% up)



this is exactly why (some) of these "performance cruising cats" are NOT safe (for many)


(to be more precise)they are not appropriate(imo) for the typical cruising family that may want to relax on passages....




data for a lagoon 440..


i remember being informed that 50+ knot gust was enough to flip my old lagoon(never knew the exact data)


..so i know (err believe) it is possible to turtle a fat cat...
but does anyone have any links or examples of a leopard, FP, or lagoon getting capsized by a gust?(or nonhurricane wind)?
i searched google.. but could only find examples of the usual suspects .(outremers, marsaudons, gunboats, DIY one-offs..)

There is basically zero chance a Outremer 45(2 whatever that is) has a displacement of 10,000 lbs. And the Balance numbers seem off too. So that changes things a lot.

[Matt Johnson]

The correct heavy or full displacement weight for the Outremer 45 is 24,477 lbs and the Balance 482 is 33k or 38,000 depending on what you look at on the Balance site. Not even close to those in the chart.

I think this person mixed up kgs and lbs.

[ozolli]

There is also zero chance the Antares 44 lwl/bh is 11.2.