Heavy Monohulls vs Light Catamarans

[Jim Cate]

Heavy monos don't roll?? Ho, ho! Rolling is much more a factor of hull shape than displacement. I can not help remembering watching a Westsail 32 anchored in Atuona's little harbour literally rolling her gunnels under, and surely that boat qualifies in t he heavy mono ranks. Yes, Atuona is a rolly place, and many of the boats were rolling to some degree, but none nearly as bad as the hapless Westsail. Her crew didn't seem to mind, but they were subject of discussion at beach gatherings... a lot of admiration for their toughness!

Jim

[Capdave360]

Originally Posted by wingssail

When I look at that track closely I see tacking angles of more than 90 degrees, but on the whole, the track is not bad. Obviously this catamaran has some windward ability which would match many monohull sailboats. I am assuming that the added speed of a cat makes up for the lack of absolute windward angle. I do notice some odd knocks on some of the tacks which brings up another point: The track a boat sails is considerably affected by current and wind shifts. We really don't know how good this boat is from this track because we don't know what current or wind shifts were present, but mostly I'm impressed.

However, lets think about what we are talking about: A really excellent performance catamaran, 57ft in length. It has about 60% more livable space than a 57 ft mono, and is going to be, oh, probably 100% to 300% more expensive and cost a whale of a lot more to own and operate (moorage, haulout, sails, etc) than say a 57ft monohull, and it damn well better be fast.

Bragging about this is like bragging about a guy's Porshe Cayanne being better than my 2002 Toyota. Yeah, so what.

When we say a cat is as fast as a mono, lets see a comparison of equal length, cost AND suitability for cruising. I'm not saying that this Atlantic 57 isn't suitable for cruising, it certainly looks like it is. But lets see a performance catamaran of, say 40ft, which is both fast and suitable for cruising and living aboard, and then compare it's cost and sailing ability against the average 40 ft Beneteau or Jeaneau monohull.

Well my last boat was an Oyster 61 which I sailed 20K miles from England to Russia to New Zealand. The Atlantic 57 would sail rings around it on any point of sail by and large in any weather, it's a way more comfortable platform to live on and sail on, I wouldn't hesitate to take either boat anywhere (except I need 8.5' of water for the Oyster and 4.5' for the Atlantic), as another poster said we arrive sooner and less tired after passages on the Atlantic, and the costs are comparable. All first hand experience. So there you go.

To add further context to my experience, I attach below a picture of the first boat I owned, and a ketch I later captained while a working sailor. I've been fortunate to sail these boats, and many more.

[Buzzman]

Originally Posted by slug

If you enjoy sailing you choose a monohull

If you’re interested in a floating condo ,,,with maximum surface area for solar arrays, windmills, bbqs.... you choose a multihull

Ummmmm......what...???

I get the 'floating condo' notion, but *most* multihulls are faster than most multihulls of similar (if not longer) length.

So, perhaps define *sailing* as you understand it...??

If you'd said "if you enjoy sailing SLOWLY, get a monohull, then the statement would have made some sort of sense.

YMMV

[malbert73]

Originally Posted by Buzzman

Ummmmm......what...???

I get the 'floating condo' notion, but *most* multihulls are faster than most multihulls of similar (if not longer) length.

So, perhaps define *sailing* as you understand it...??

If you'd said "if you enjoy sailing SLOWLY, get a monohull, then the statement would have made some sort of sense.

YMMV

Assuming you were comparing multihulls to monohulls above and that was a typo, I disagree with your statement. In strong wind and off the wind sailing I would agree that the average cruising multi hull will be faster than your average cruising monohull.
Up wind and especially in light air, I think most cruising monohulls will be faster than most cruising multi hulls. And if you compare Performance boats to each other in mono and multihull there will also be similarities. Once you get to the top end of performance in multi hulls like gunboats and Atlantic, I think there are a few monohulls who can keep up. That performance comes at a price and weight is essential.

But as I said in another thread, comparing same length monohull to multihull is not valid in any way including price, accommodations, cost of upkeep, etc. To compare validly between mono and multis need to apply a factor of about 1.3 to mono length to get to similar and valid comparisons. Then any speed difference goes away generally. Ie production 40 foot cruising cat probably is same price as production 47-50 foot monohull. (Check for your self with new prices of lagoon cats vs beneteau/Jeanneau) or on YachtWorld in used listings

[rsementi]

Originally Posted by Dockhead

Implying that no one posting in this thread is entitled to a view on heavy vs light displacement boats, and the other very basic boat design questions being discussed?

A lot of people on CF not only have lifetimes of experience on different boats with different characteristics, but also are quite knowledgeable about at least the main principles of boat design.

I haven't noticed any ignorant comments in this thread. If you have some greater knowledge, then, by all means, enlighten us.

I’m hoping for the same thing. What are the basic principles of monohull design that increase stability to decrease rolling at anchor or at sea and what do you loose (speed?). What does the length vs beam vs weight do to stability? Common sense says the longer and wider = more stable, and slower. Does longer and narrower mean fast, yet rolls a lot?
Same questions for a catamaran.

[mikedefieslife]

Originally Posted by Rapanui

One factor regarding comfort has not been mentioned - sea sickness. Irrespective of whatever boat you are on, be it it heavy or light, being seasick is extremely uncomfortable. Rolling is a big factor in that. Given that a lot of people are sick on ferries and the ilk, particularly older designs with narrow beam and no stabilisation, even being excessively big and heavy does not seem to help much.

My wife who is a cat evangelist has in the past, invited 2 seperate mono cruiser couples where the wives suffered chronic sea sickness for a trial sail on our boat to experience catamaran sailing, both wives found it cured their seasickness and both couples ended up buying catamarans. It does seem from anecdotal evidence that people sailing cats are less prone to sea sickness. Having said that, I have sailed with a couple of girls on a small heavy cat and they were constantly sick - but I suspect they would have been sick on wet grass.

The types of conditions where someone (who isn't normally prone) would get sea-sick on a big ferry, say the Cap Finistere operated by Brittany ferries, are the type of conditions you'd probably be bunkered down in your boat wishing/praying for it all to be over.

My cat probably doesn't count being such an old design, but I've had experienced sailors (monos) get sea sick onboard with 2.4m waves 8 seconds apart on the beam.

Personally any movement annoys me. I'd probably prefer an oil platform.

[Dockhead]

Originally Posted by malbert73

Assuming you were comparing multihulls to monohulls above and that was a typo, I disagree with your statement. In strong wind and off the wind sailing I would agree that the average cruising multi hull will be faster than your average cruising monohull.
Up wind and especially in light air, I think most cruising monohulls will be faster than most cruising multi hulls. And if you compare Performance boats to each other in mono and multihull there will also be similarities. Once you get to the top end of performance in multi hulls like gunboats and Atlantic, I think there are a few monohulls who can keep up. That performance comes at a price and weight is essential.

But as I said in another thread, comparing same length monohull to multihull is not valid in any way including price, accommodations, cost of upkeep, etc. To compare validly between mono and multis need to apply a factor of about 1.3 to mono length to get to similar and valid comparisons. Then any speed difference goes away generally. Ie production 40 foot cruising cat probably is same price as production 47-50 foot monohull. (Check for your self with new prices of lagoon cats vs beneteau/Jeanneau) or on YachtWorld in used listings

I think you nailed it here.


It is wrong to compare multis and monos length for length, for any purposes whatsoever. A comparable mono will be longer of course.

Compared like this, speed differences will mostly favor the multi if it's a performance multi, and otherwise will favor the mono, unless the mono is a heavy cruising boat.

And a really high performance multi like an A57 is beyond reach of any mono other than something quite radical for a cruising boat (converted racing boats like Rocket Science?). But to achieve this level of performance, like you said, the A57 etc. has to be kept really light in relationship to its waterline plane area, and light enough to have really fine hulls. Like this waterline length effects almost disappear, and that's where the speed comes from.

I have lusted after an A57 myself. That must be really fun to sail.

[barnakiel]

Originally Posted by Dockhead

(...)



A comparable mono will be longer of course.


(...)

Then it will not be comparable ... ;-)


But seriously, depends on what you are comparing. You need some sort of denominator.


Say you compare by displacement, LOA may be different then.
Say you compare by LOA, displacement may differe.
Etc.


At least one thing must be kept fixed, then we can compare the other factors.


b.

[barnakiel]

From thousands of data points collected, an average cruising cat (say a typical Lagoon) is faster on the milk run route sailing. (Faster than what ??? = a same LOA mono).



This is very clear when you compare their days at sea sailing from say Canaries to Sta Lucia and then from say Virgins to the the Azores.


A factor that will blur our judgement is that many cat owners have condo mentality and will overload their relatively small cats with huge amount of extra gear and supplies. Which of course kills plenty of the boat speed potential.


Imho an overloaded cat suffers more than an overloaded mono.


I truly wish I had both. And I would not opt for a very light cat. I would rather have a havey cat like a Catana and I would KEEP MINE LIGHT.



b.

[Capdave360]

Originally Posted by Dockhead

And a really high performance multi like an A57 is beyond reach of any mono other than something quite radical for a cruising boat (converted racing boats like Rocket Science?). But to achieve this level of performance, like you said, the A57 etc. has to be kept really light in relationship to its waterline plane area, and light enough to have really fine hulls. Like this waterline length effects almost disappear, and that's where the speed comes from.

I have lusted after an A57 myself. That must be really fun to sail.

We do try to keep our A57 light - but that said we do carry a pretty big spares and tools payload. We also carry a lot of non-perishable food so we only have to shop for perishables as we travel. Happy Kindle readers, that saves 400 lbs! One trick for local sailing is not to carry a lot of fuel - with 200 gallon capacity, we only fill those tanks for a passage, otherwise going around with ~50 gallons is fine - so that's ~1,000lbs. The immersion rate on the boat is 1"/1,800 lbs, so it makes a difference. The trick is there really are few to no opportunities to take big chunks of weight off the boat; instead you have to scrutinize every little thing, and think weight first - that's the secret to keeping it light. Though I haven't cut the handle off my toothbrush yet. And of course for light air performance the boat is very sensitive to having a clean bottom.

She really is fun to sail - the boat just wants to go, and the acceleration is unreal. Really took me by surprise the first time upwind in higher winds - I thought I had the right sail area up doing about eight knots close-hauled in 25 true with 7-8' seas. Then a couple of waves would knock the bow off ten degrees and the boat would instantly accelerate to 12 knots and start launching off the waves until the autopilot got her headed back up. I couldn't do much better steering myself. Took a second reef in the main, settled her down, and still doing close to eight anyway.

The big fun is power reaching - just when you'd start blasting through stuff at 10 knots in a mono, the Atlantic just picks up and starts hitting 15, 17, 18 - and with an almost fingertip helm. That's sailing!

[Dockhead]

Originally Posted by barnakiel

Then it will not be comparable ... ;-)

But seriously, depends on what you are comparing. You need some sort of denominator.

Say you compare by displacement, LOA may be different then.
Say you compare by LOA, displacement may differe.
Etc.

At least one thing must be kept fixed, then we can compare the other factors.

b.

LOA is irrelevant; multis are -- well, multis. 2 45' hulls can't be compared to one 45' hull. That would be like comparing two houses by their depth without considering their width. But multis have finer hulls so you wouldn't just multiply the LOA by 2x, either. But the post above is approximately right in my opinion -- multiply by 1.3x to 1.4x -- something like that.



Someone choosing a boat, and considering both a mono and a multi, will want boats of similar interior volume. Not displacement, because multis don't have ballast; this is not comparable.



Compare boats of similar interior volume, and you will find that an average non-performance 45' cat will be similar to a 55' mono, will cost about the same. The mono will in most cases be somewhat faster and have greater load carrying capacity.


But performance multihulls are able to get away from waterline length effect, so all bets are off in that case. But in exchange for that, then load carrying capacity goes way down.



Plenty of qualities to choose from, when choosing a boat.

[john manning]

I own a heavy catamaran (Prout Escale). When people ask me if I think catamatans are better than monohulls I tell them I would look for a heavy monohull if I ever bought another yacht. Attached to that I would buy a catamaran if I ever bought a launch.

Catamarans are very uncomfortable yachts whenever the wind is forward of beam.

But I still keep the heavy catamaran and that's because of its ability to handle very rough weather. The sort of weather that makes you want to hide in the cabin. I have crewed on light monohulls but would never otherwise choose to go offshore in one. Light catamarans are more uncomfortable than heavy ones but for a much shorter time because of their speed.

[smj]

Originally Posted by john manning

I own a heavy catamaran (Prout Escale). When people ask me if I think catamatans are better than monohulls I tell them I would look for a heavy monohull if I ever bought another yacht. Attached to that I would buy a catamaran if I ever bought a launch.



Catamarans are very uncomfortable yachts whenever the wind is forward of beam.



But I still keep the heavy catamaran and that's because of its ability to handle very rough weather. The sort of weather that makes you want to hide in the cabin. I have crewed on light monohulls but would never otherwise choose to go offshore in one. Light catamarans are more uncomfortable than heavy ones but for a much shorter time because of their speed.

Do your catamaran experiences include only the Escale or have you sailed others? I would agree the Prouts are one of the most seaworthy of all Catamaran’s but probably not comfortable upwind.

[barnakiel]

Originally Posted by Dockhead

(...)

LOA is irrelevant; multis are -- well, multis. 2 45' hulls can't be compared to one 45' hull.
(...)


This is a fine rhetorical figure. Schopenhauer would be proud of you! But even so, LOA can always be one of the comparison criteria. Just like weight, SA, volume, wet area or live'able interior volume.


(...)
Someone choosing a boat, and considering both a mono and a multi, will want boats of similar interior volume.
(...)


Yes, someone. And someone else? Maybe our someone is not a cruiser, maybe they are a sailor?



(...)

Not displacement, because multis don't have ballast; this is not comparable.
(...)
Whether you have ballast or not, a boat weighs what she does and she will require proportional SA, engines, winch sizes, etc etc. So clearly, displacement counts.



(...)

Plenty of qualities to choose from, when choosing a boat.

Yes. Very many design factors and just as many lifestyles and preferences. We are blessed with having such a broad choice. We are.


Just think of poor Columbus, but very heavy monohulls to choose from, and most of these with very rotten planks.


And, interestingly, it was not the heaviest of the three that was his favourite!


b.

[malbert73]

I think heavy is not the way to go. That said, heavy displacement is more doable on monos to preserve performance in general.

But most folks are buying boats to a budget: acquisition, maintenance, and storage costs. And then the 1.3-1.4x LOA factor to compare monos to multis makes sense as a X foot multi is more boat in every way than a X foot mono (especially including cost)

And then once you apply that 1.3-1.4 factor most comparisons (speed, overall comfort, space, etc) tend to equalize and you’re left to decide based on preference.