CATAMARAN DESIGN: Why Are Some Catamarans Safer Than Others? Ep. 4.

Welcome to part 4 of our catamaran design series, where we discuss righting moment and structural strength.

Righting Moment and structural strength of Catamarans is important to understand the possibility of a catamaran capsizing and whether it is suitable for offshore sailing. This episode we talk to Antoine Richer, one of Corsair marines Naval Architects to learn how the construction methods affect strength. We also discuss righting moment and how that is affected by the type of catamaran you are sailing.
We have learned so much by getting facts from a designer rather than a broker and we hope that you find this a valuable tool if you are considering buying a catamaran, whether new or used.

We have more episodes in this series to come, so please give us a like, a 👍 and subscribe to the channel if you like what we do.

Much love,

Nick & Terysa xo

[John-tzii]

Another strong presentation. This series should be required viewing for all potential cat owners. Even if you're buying used, buying "off the shelf", or buying a full custom rocket, this series helps educate them and function as a guide for better sailing. Examples such as "weight kills", how a "cruising bow" may respond to wave action, etc. should help people reevaluate how they sail, where they sail, what they bring, etc.

Well Done

[ITWUT]

one point. The narrower hull doesn't dissipate the wave energy, it takes less energy out of the wave

[TutaraTours]

Great discussion.
I'm a full time skipper a FP 47 Saona, and in heavy weather the Saona has very little under hull slap, it's very well designed, I've been very surprised how good it is.

[timothy]

This is exactly what I want to know about multihulls and their designs. Excellent!!

[JS-diqg]

This is why i am the very happy owner of a SMG50. The best built and safest blue water Cat I’ve ever sailed. The architect managed the magic of mixing and reducing all the compromises to perfection.

[DavidMartin-fksd]

I feel that Nick somewhat misconstrued what the naval architect was saying on the strength of performance versus cruisers. Weight for weight, then the performance cat is indeed going to be stronger. But if you are not so concerned with weight, as cruisers aren't, the structure can always be beefed up at the cost of more weight. The safety from that point of view is a result of 'how safe and strong do you want it to be?' versus 'how fast and inexpensive do you want it to be?' It is not that performance cats are inherently safer as Nick took it to be on that point, although of course they are weight for weight. And the shape of the lighter cat may cut through the waves more, which reduces stress, but the lighter cat will bounce around more, which increases it somewhat. Similarly on bridge deck clearance, the naval architect can choose that, and admittedly the designers of charter cruising cats often make them too low. But the worst of all world's in that respect would be an overloaded performance cat, sitting a lot lower in the water than it was designed to do.
The ability to carry a lot of weight is a good thing, not a bad thing, and there are all sorts of valid trade offs which can be made between that and speed.
If you want to get out of the way of storms by running fast reliably, there is a lot to be said for a big engine and plenty of diesel.
It is what you fancy far more than safety for performance versus carrying a lot of stuff.

[bradw.]

If you ever do a follow-up to this...I think it would be interesting to explore what it actually would take to flip one, picking a real world example or say a particular seawind model... what combination of wind speed and sail area...and then that coupled with tilt from a beaming sea?

[Memo_Sagun]

Thank YOU guys. Connecting with the professionals and publishing the interviews; rated the whole cat-manufacturing... Your view become a new and the best class for HOW TO Very much appreciated

[damondanieli]

Just a clarification from my understanding of the equation for Righting (or Restoring) Moment on a catamaran does not have anything to do with the sail area (or the height of the mast). I thought the formula was "weight * righting arm length" where "righting arm length" is the distance from the fall line of center of mass to the heeling pivot point. It is a torque vector measured in N * m. The sail area plays into the Heeling Moment which needs to be offset by the Righting Moment.

[rabukan]

Great series on cat design Nick! Interesting that performance cats are lighter, yet stronger, but for live-aboards, are they as comfortable as a heavier production cat? Terysa has said that you spend about 90% of your time at anchor, so does having a lighter performance cat, that might be more sensitive to the flux and pounding of the seas, matter if you're only sailing 10% of the time?

[YooooouKnowwwww]

older video but fantastic discussion thanks! Helps our for us folks trying to learn and get into sailing

[MrFurriephillips]

Where there is talk of “stringers”, and where the furniture is integrated into the mould & the design of the bridgedeck making it non-flat, is all about making the structure stronger by adding “compound curves” - they impart incredible strength, with minimal additional weight.

[db]

I'm really enjoying, and learning, from these Technical Mondays ;)
The next one looks to be very interesting.

[ddkxmdo]

Nick, this is incredible, all my nerdy questions answered in this series. Thanks mate.

[jimk]

Very informative video.. I’m learning a lot through this series. Thanks.

[mytreasurechess]

Righting moment brought tears, either it was funny or memorable, priceless tho. Its counterintuitive like the term Light crew. In interlake racing that means being the last nth degree crew weight allowed. Needed in big windy days and out on the rails. Little youth in other words.
Skipper screaming. Holding on, hoping and praying. Mostly that if it tips it doesn't turn turtle. Fun times.

[ericjohnson]

Amazing presentation. Thank you! Looking into a leopard 46 for our first cat!

[h.v]

Excellent episode with very informative content. Thank mate!

[billheffernan]

good talk for the general cruising fraternity some of the cats i have seen and worked on beggars belief some of the construction and layups of laminate are not good long term for dealing with high loads

[stephenshort]

I felt like you had to pull answers from the "Navel Architect" and often he answered "yes or no ". You had some VERY GOOD POINTS to make . Interesting to me. 🤔⛵🤠🌵