Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 25-09-2009, 20:42   #1
Registered User

Join Date: Sep 2009
Posts: 1
Speed Statistics of Mono vs Twin Hull Cruisers

Hi,

I've read with great interest the mono vs twin hull thread. The issue of whether cruising cats are indeed faster than cruising monos seems to be contended with no statistics or facts being presented so far.

To shed some light, I pulled the results from the ARC 2008 (from their website) and entered it into Excel and plotted the actual hours used vs length of hull.
The data are not adjusted for use of engine, which averaged 11% of the time. I have just guessed the length of the boats from their names - perhaps it's slightly off in some cases.

Looking at the graph, it seems that cruising cats are slightly quicker than cruising monos, at least on this particular voyage. Are the data representative for long-distance cruising in general? At least the boats should be loaded down with cruising gear, killing the argument that "cats are only faster without load, as soon as you load them down with full cruising gear they slow down to mono speed".

What do you think? Any comments?

(I've included the full dataset if anyone wants to play with it)

Cheers
VikingCat
Attached Thumbnails
Click image for larger version

Name:	Mono vs Multi ARC 2008 speed.jpg
Views:	689
Size:	62.4 KB
ID:	10143  
Attached Files
File Type: xls ARC 2008 Results.xls (91.5 KB, 151 views)
VikingCat is offline   Reply With Quote
Old 26-09-2009, 02:17   #2
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Posts: 4,033
The normal way to assess vessel performance is to calculate it's 'hull speed factor' - that is what multiplier of square root of waterline it sails.

Doing that to this dataset the result is that both multi's and monos acheived exactly the same - averaged 1.27 times sq rt of waterline. To do that calcualtion I made some some average assumptions about waterline length because monos tend to have longer overhangs than multis.

So, I would have said the conclusion from this data is the two designs sailed pretty much the same speed (liven their length), within the data quality we have.

A second conclusion would be that these boats in the ARC are pushed harder (about 20% harder), normally with more crew, than typical cruising boats. When we have looked at average speed factors for typical hunsband and wife crews doing non-arc passages we typically find they sail at around 80% of 'hull speed' (or a speed factor of about 1.1).
estarzinger is offline   Reply With Quote
Old 26-09-2009, 02:33   #3
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,084
Images: 241
Greetings and welcome aboard the CF, VikingCat.

Interesting study.

I wonder what happens when you compare two equal “value” (cost, rather than length) boats?
When selecting a new (to me) boat, I’m more likely to be constrained by some minimum size, and some maximum cost, rather than by a maximum length.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is online now   Reply With Quote
Old 26-09-2009, 03:38   #4
Registered User
 
idpnd's Avatar

Join Date: Sep 2007
Location: Almería, ES
Boat: Chiquita 46 - Libertalia
Posts: 1,558
Nice work
idpnd is offline   Reply With Quote
Old 26-09-2009, 03:51   #5
Registered User
 
Jeannius's Avatar

Join Date: Dec 2005
Location: Worcester U.K.
Boat: Privilege 435 Now Sold
Posts: 1,060
Having done the ARC myself in 2002 and being loosely associated with the organising company for nearly 10 years I can say that Evan's suggestion that ARC boats are pushed harder is correct. I worked on averaging 6.5 knots over the course and achieved that (actually we averaged 7.1 but sailed 200 miles more than the rhumb line) In cruising mode my wife and I work on 5 knots as we sail very conservatvely when just the two of us are aboard.

Going back to the ARC though... Yes, most boats are pushed harder. But, there are a large number of fast, cruising monohulls amongst the fleet... Swans, Oysters and the fast versions of volume production boats. The catamarans are mainly out and out cruising catamarans and even condomarans so there performance is perhaps more impressive.

Incidentally, ARC2008 was the slowest for many years due to lighter than normal winds.
__________________
Mike

https://sailingjeannius.blogspot.com
Jeannius is offline   Reply With Quote
Old 26-09-2009, 04:48   #6
Registered User

Join Date: Jun 2009
Location: West Vancouver, BC, Canada
Posts: 195
The comfort or liveablity of each was not included. I don't care too much how long a crossing takes when it is liveable. Of course it was not in the question, so one day a thread on that subject could be started.
George Wade is offline   Reply With Quote
Old 26-09-2009, 06:47   #7
Long Range Cruiser
 
MarkJ's Avatar

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,822
Images: 25
Quote:
Originally Posted by GordMay View Post

I wonder what happens when you compare two equal “value” (cost, rather than length) boats?
.
Damn you, Gordy! I was just about to say that!

A 40 foot new Cat is worth a hell of a lot more than a new 40 foot mono.

A Lagoon 44 is DOUBLE the cost ofa new Beneteau 54

(Both are made by the same company)


__________________
Notes on a Circumnavigation.
OurLifeAtSea.com

Somalia Pirates and our Convoy
MarkJ is offline   Reply With Quote
Old 26-09-2009, 06:59   #8
Marine Service Provider
 
Factor's Avatar

Join Date: Dec 2006
Location: Brisbane Australia
Boat: Multihulls - cats and Tris
Posts: 4,859
Quote:
Originally Posted by MarkJ View Post
A 40 foot new Cat is worth a hell of a lot more than a new 40 foot mono.
Sure is.

But Of course the comparison is a little strange - MY 35 foot cat has more space than a 40 foot mono. Indeed for what I paid for my cat (new) I could have bought a new 40 foot dodgy french mono or a new 40 foot yank mono - roughly - with the same options etc. Give or take $10K
Factor is offline   Reply With Quote
Old 26-09-2009, 07:01   #9
Eternal Member
 
imagine2frolic's Avatar

Join Date: Feb 2008
Location: Las Brisas Panama AGAIN!
Boat: Simpson, Catamaran, 46ft. IMAGINE
Posts: 4,507
Images: 123
It cost about the same to make a Malibu as it does a Corvette. Because it is desirable to own, and not as many made. The Vette cost is many times the Malibu. Supply, and demand comes into play........i2f
__________________
SAILING is not always a slick magazine cover!
BORROWED..No single one of is as smart as all of us!
https://sailingwithcancer.blogspot.com/
imagine2frolic is offline   Reply With Quote
Old 26-09-2009, 07:34   #10
cruiser

Join Date: Aug 2005
Location: No longer post here
Boat: Catalac Catamaran
Posts: 2,462
Quote:
Originally Posted by GordMay View Post
Greetings and welcome aboard the CF, VikingCat.

Interesting study.

I wonder what happens when you compare two equal “value” (cost, rather than length) boats?
LOL, come on Gordo .. that's cheating
Tropic Cat is offline   Reply With Quote
Old 26-09-2009, 07:56   #11
Registered User
 
nautical62's Avatar

Join Date: Jul 2008
Location: Live Iowa - Sail mostly Bahamas
Boat: Beneteau 32.5
Posts: 2,307
Images: 12
I've owned both a 26 foot monohull and 26 foot trimaran pocket cruisers. With out a doubt, the tri was faster in flat conditions. However, this was reversed once there were any seas due to under deck slamming.

If you can reach hull speed, I think the hull speed formula is helpful: Max hull speed equals the K value for that hull(s) times the square root of the water line length. An average K value for a monohull might be something like 1.4 where as for a multi it's likely to be over 2. Of course, adding weight to a norrower hull will submerge more of it, thus usually decreasing the K value more for a multi-hull than monohull.
nautical62 is offline   Reply With Quote
Old 26-09-2009, 15:34   #12
Registered User

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,420
Well, I would chose a cat for the easy route anyway - think COMFORT.

Then, ARC is a downwind ride and downwind crossings tend to have too little wind rather than too much - this is true at least for the Atlantic crossing (Canary to West Indies) and the Pacific one (Panama to Aus).

The potential max speed of the design does not really matter - what matters is how easy it is for a specific design to achieve good speeds in light downwind situations. And nothing beats a cat in light conditions downwind. One could only argue that a Class 40 (or an Open 40) is just as fast. Yes, it is. But do not try to live in one.

I asked dozens of cruisers over 6 years and 3 oceans on how much time their passages took them and the cats always came on top, length per length.

BTW If you want to banish me to Jan Mayen for my glorifying of cats, then PLS send me there in a MONO ! ;-)))

b.
barnakiel is offline   Reply With Quote
Old 26-09-2009, 16:28   #13
Registered User
 
Eleven's Avatar

Join Date: Sep 2007
Location: Southampton UK
Boat: Jaguar 22 mono called Arfur.
Posts: 1,220
Images: 3
Quoting GordMay
"I wonder what happens when you compare two equal “value” (cost, rather than length) boats?"
Assessing value as more than just the cost?
Crewing with two while accommodating six. Changing sails single handed. NOT being laid flat or rolled over. Not sleeping in the cellar. Dry clothes. Not replacing crockery.
These things add up.
__________________
Ex Prout 31 Sailor, Now it's a 22ft Jaguar called 'Arfur' here in sunny Southampton, UK.
A few places left in Quayside Marina and Kemps Marina.
Eleven is offline   Reply With Quote
Old 26-09-2009, 17:27   #14
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: Eastern Tennessee
Boat: Research vessel for a university, retired now.
Posts: 10,406
I'm just thinking that perhaps there needs to be some sort of qualitative formula such as Speed x Comfort X Reliability X Safety X Quality/ Cost = X. Whichever X number comes out higher is the better boat.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 26-09-2009, 18:13   #15
Registered User

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,420
Quote:
Originally Posted by David M View Post
... Speed x Comfort X Reliability X Safety X Quality/ Cost = X. Whichever X number comes out higher is the better boat.
I would love to see the day when boats stop being seen as vessels traveling through the rarefied space of relative factors and start (once more) being taken for what they are - sailing vessels. And this 'sailing' thing is probably the first factor we should put into any (serious or only half so) equation.

So - whatever the god of moderation suggested, PLUS "divided by the body of water that is to be sailed in the craft".

Deal?

b.
barnakiel is offline   Reply With Quote
Reply

Tags
hull speed

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mono vs Twin Hull? xsquid77 Multihull Sailboats 40 25-09-2009 16:37
Cheap-ish Bluewater Cruisers with Speed scm007 Monohull Sailboats 40 16-05-2009 19:23
maximum hull speed for cat Nauti Cat Seamanship & Boat Handling 6 30-09-2008 15:31
Multi- or Mono-hull for a Circumnavigation? Stella Polaris Multihull Sailboats 69 24-05-2008 09:57
Catamaran Hull Speed JusDreaming Multihull Sailboats 6 15-08-2007 19:17

Advertise Here


All times are GMT -7. The time now is 03:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.