Surprising results looking at Catamaran Performance Numbers

[jdmuys]

Originally Posted by NevilleCat

Is that the upside down one?

Sorry, trolling, but it does expose the reality of the 2nd part of the equation... comfort and safety.

I get the sarcasm. So no it's not the same. The one which capsized is Hallucine, the larger model (Orc 50), that won the ARC 2019.

Hallucine apparently capsized after hitting an UFO, therefore coming to a sudden stop and then possibly pitchpoling. this is just speculation as the accident report has not been published yet as far as I know.

Hitting a UFO is potentially a catastrophic event for any boat. All the more so for a fast boat, of course. Since we are looking at fast catamarans here, it necessarily implies either we are okay with the increased risk, of we are ready to slow down the boat.

[jdmuys]

Originally Posted by fivecapes

AND have crew willing to keep full sails overnight, and probably, uncleated traveller ready to be dumped.

IMO, you are totally right. These are the end of the spectrum. However, this is still interesting because it shows that the Marsaudon cats *can* do that. Most others can't. Most monohulls can't either.

That said, sailors always have the option to reduce the speed to alleviate these concerns. You still have the choice.

In contrast, on a slow boat, you don't have the option to go fast.

[NevilleCat]

Originally Posted by fivecapes

AND have crew willing to keep full sails overnight, and probably, uncleated traveller ready to be dumped.

True, as subsequently proven.
But what if they put in a reef and slowed down by about 4kn for 12 hours overnight. Say they lost 50 miles so 234miles per day, that brings the average back to 9.75 kn so getting pretty close actually.
However the OP was talking a different budget I think, sadly.

[fxykty]

Originally Posted by jdmuys

as a data point, a Marsaudon Orc 42, 42-foot cruising catamaran, crossed the Atlantic in the ARC 2020 in 10d 21h 3m and 56s while sailing 3090.7 nautical miles.

This is an average of 284 nm per day and an average speed of 11.84 knots.

So yes this is possible. Similar results were achieved by other Marsaudon cats.

Of course, you need to choose a fast cat.

Another ARC BS datapoint - a predominantly downwind passage and an implicit racing crew on the boat (no way to other explain the average speed that high) shows that ARC results have nothing to do with the real world of cruising, particularly for short handed crews with two adults or a family with two adults and some kids.

As others have pointed out, 200nm average of 8.33 knots is close to the limit of comfort for boats under say 60+ feet in ocean conditions that include windward and on the beam seas. And even that relatively modest average is rarely attained by most boats.

But if you want to fall for marketing spin by the manufacturer, OK.

[jdmuys]

fxykty I respectfully disagree: this is no marketing by the manufacturer who has nothing to do with this. Same for Hallucine in 2019, who was crewed by two middle-aged couples. This was no racing crew.

Now of course, both Banzai and Hallucine were crewed by very competent sailors who wanted to push their cats as much as they could.

And of course this was a downwind passage, as most passage by blue-water sailors. Nobody claimed that similar average speeds could be achieved upwind.

So if you want a qualification, you got it: Marsaudon cats can achieve 11+ knots average speed on long downwind passages when crewed by competent and motivated sailors.

Happy?

[Sos]

Originally Posted by jdmuys

fxykty I respectfully disagree: this is no marketing by the manufacturer who has nothing to do with this. Same for Hallucine in 2019, who was crewed by two middle-aged couples. This was no racing crew.

Now of course, both Banzai and Hallucine were crewed by very competent sailors who wanted to push their cats as much as they could.

And of course this was a downwind passage, as most passage by blue-water sailors. Nobody claimed that similar average speeds could be achieved upwind.

So if you want a qualification, you got it: Marsaudon cats can achieve 11+ knots average speed on long downwind passages when crewed by competent and motivated sailors.

Happy?

But the OP is talking about a used boat and sailing with a family. I think this proves that his objective of approx' 10 knots average is not feasible or sensible!
I also think that looking at a Bali as a fast offshore cruiser needs a bit more studying by the OP.

[jdmuys]

Originally Posted by Sos

But the OP is talking about a used boat and sailing with a family. I think this proves that his objective of approx' 10 knots average is not feasible or sensible!
I also think that looking at a Bali as a fast offshore cruiser needs a bit more studying by the OP.

Well, you can argue that there is absence of evidence, but certainly not that there is evidence of absence.

(I agree on your Bali statement).

Now you can certainly argue that the OP question's answer is probably no:

- few catamarans have even the potential to reach 10 knots average
- certainly not upwind (I don't think the OP mentioned upwind situations)
- those catamarans are rarely found on the used markets
- many families will not have the skills or the motivation to drive that fast (OP did not say anything about their family). It would also possibly depend on the children's age.

But given enough caveat and conditions, it might still be yes.

[Dragon701]

Just to add one data point from a third-hand Atlantic 55 designed by Chris White (old, but after a refit). We averaged 210 miles per day offshore during approximately 10,000 of cruising with two kids (12 & 14) aboard. Crossings from US Northeast to Nova Scotia, Bermuda, Virgin Islands, Columbia, Panama, Honduras, Guatemala, Belize, Mexico and return to US Northeast.

Breaking the 200 mile a day average threshold, while cruising safely short-handed, is entirely possible, however I would suggest that you need to be looking at the "performance-style" catamarans rather than those designed more for "Caribbean chartering." Just one view.

[GRIT]

Wow. Dragon, that's amazing.

We don't have enough experience to comment on our passage speeds, but so far we've only averaged above 9 knots once, and it's usually between 7 and 8.

We're short on multihull experience, but we're learning...

Thanks for sharing. It gives me a target speed to shoot for.

Cheers.
Paul.

[rexripley]

Originally Posted by fivecapes

eg. you've used max upwind sail areas for all the Bali's when the others are using working jib areas.
ie Bali 4.8 upwind sail area is only 118m2, not 179m2

I used the numbers from the specs I got from manufacturers, where I could, or from spec databases where I couldn't. Intention is to use max upwind sail area for all of them. If you have specific errors to point out, please feel free to provide corrections. Thanks!

https://www.bali-catamarans.com/en/catamarans/bali-4-8/

[rexripley]

Originally Posted by Dave852

On our St. Francis 50 “Ovive” we had some 240 mile days but it always averaged out to 200 mile days once you accounted for all weather conditions over a 3 to 15day passage. So 8 knots. Some days faster than others. https://youtu.be/WFqm48C2BPk

The St Francis 50 shows respectable results all around. Unfortunately, there are not as many on the market as I would like. However, there is a nice looking St Francis 48 for sale right now.

[rexripley]

Originally Posted by django37

The weights and sailareas given by designers or boatbuilders are not usefull in such calculations. We (designers and boatbuilders) are all optimist with weights - some more than others, and sailareas are given/measured differently. Use result from weighed and rated boats, or use results from many races - yes not only the ARC. I have an Excel file with 98 cruising cats in 39 races, but its 498 kb, so it cant be uploaded here

I agree. I built this sheet just to test a hypothesis-- that a larger slow boat would match the theoretical speed of a smaller fast boat.

If you want to share your spreadsheet, you can probably upload it to google docks and then share it there. (Please share it allowing people to download, if you do.)

This coverage of ARC results is what got me started: https://youtu.be/UQNx85pQvDI

[rexripley]

Originally Posted by Paul L

10.5kts is 250 mile days. You are dreaming if you think you will average this on real life passages. That's the bad news. The good news is you don't need 250 mile days to have safe passages.

Several people have missed that these base speed numbers are just an arbitrary formula (derived for monohulls, I believe) I am using to compare catamarans relative speed to each other.

It's not a number to be used in navigation or to set expectations. I consider it completely arbitrary-- just way to compare DLR & SAD in one number.

I'm not counting on doing any specific number of knots per day, I don't think that it is useful to do so, as every day is different and the appropriate distance to go in a day is different every day.

I am, however, quantifying the specs to give an approximate value for comparing boats to test the hypothesis that a longer "slow" boat can give the same performance as a shorter fast boat.

[rexripley]

Originally Posted by Hoodsail

Cant speak to Cat performance, but curious the 10.5k as providing a safe weather window. Basis for deciding on that speed? Not that I will ever average that, but determined by "average" rate of storm systems movement? Vary by ocean? hemisphere? time of year? barometric pressure? Dont know but curious.

That was just a hypothetical that has apparently thrown people off. Base speed is not a real speed in real conditions and not something you can navigate from, it is an arbitrary formula and I am using it only to compare relative performance of different boats. It's a short cut for "DLR combined with SAD".

[Paul L]

Originally Posted by rexripley

Several people have missed that these base speed numbers are just an arbitrary formula (derived for monohulls, I believe) I am using to compare catamarans relative speed to each other.

It's not a number to be used in navigation or to set expectations. I consider it completely arbitrary-- just way to compare DLR & SAD in one number.

I'm not counting on doing any specific number of knots per day, I don't think that it is useful to do so, as every day is different and the appropriate distance to go in a day is different every day.

I am, however, quantifying the specs to give an approximate value for comparing boats to test the hypothesis that a longer "slow" boat can give the same performance as a shorter fast boat.

That sounds a lot more reasonable. The confusion in your OP is that you were applying this arbitary speed number as the required speed for safe navigation away from weather. It seems like you could leave out the passage weather and just say you want a fast cat.