Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 19-03-2016, 05:42   #31
Registered User

Join Date: Sep 2014
Location: Sydney
Boat: Lagoon 400
Posts: 1,104
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by StuM View Post
Again. Link please.
Sorry, that was many moons ago and Lerouge and his page seem to be retired now. His keels are shallow and long so it is 1.1m low point.

Fixed keel also has around 500 kg more payload which is nontrivial for such sporty design.
__________________

__________________
arsenelupiga is offline   Reply With Quote
Old 19-03-2016, 06:04   #32
Marine Service Provider
 
Factor's Avatar

Join Date: Dec 2006
Location: Brisbane Australia
Boat: Corsair Dash MKII
Posts: 4,088
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by StuM View Post
Have you got a link to that article?
Here is what Grainger said'

Quote:
I generally recommend that daggerboards are a worthwhile investment if the owner has a preference for sailing to windward rather than motoring or waiting for a favourable breeze, and if the boat is going to be kept light enough to have a power to weight ratio that will do justice to the dagger board configuration.
As a rough guide I would suggest that a 40í cat which had a sailing weight of six tonnes or less would benefit from dagger boards, while a relatively heavy cruising cat would gain very little benefit from the more efficient foils. On a 50í cat the cut off point is probably about 10.5 to 11 tonnes.
__________________

__________________
Factor is offline   Reply With Quote
Old 19-03-2016, 18:01   #33
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,715
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by Factor View Post
Here is what Grainger said'

Quote:
I generally recommend that daggerboards are a worthwhile investment if the owner has a preference for sailing to windward rather than motoring or waiting for a favourable breeze, and if the boat is going to be kept light enough to have a power to weight ratio that will do justice to the dagger board configuration.
As a rough guide I would suggest that a 40í cat which had a sailing weight of six tonnes or less would benefit from dagger boards, while a relatively heavy cruising cat would gain very little benefit from the more efficient foils. On a 50í cat the cut off point is probably about 10.5 to 11 tonnes.
__________________
Do you have a link?

As you have illustrated; it's easy to quote-mine to support any own viewpoint.

I have learnt to put little weight on any quote which doesn't include a link to the source.
__________________
StuM is offline   Reply With Quote
Old 20-03-2016, 00:24   #34
cruiser

Join Date: Aug 2014
Posts: 506
Talking Re: 45' (or so) Performance Cruising Catamaran

Or you could try this SAIL interview with Chris White where he states....

Likewise with daggerboards: ďI spent the first 15 years of my career trying to convince people they need efficient foils. And now Iíve spent the last 10 years telling them the foils donít need to be daggerboards. Thereís this mindset now that a performance cruiser without daggerboards must be a disaster, but itís really not true.Ē

See Different Strokes: A profile of multihull designer Chris White - Sail Magazine

__________________
Seaslug Caravan is offline   Reply With Quote
Old 20-03-2016, 00:35   #35
Registered User

Join Date: Sep 2014
Location: Sydney
Boat: Lagoon 400
Posts: 1,104
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by StuM View Post
Do you have a link?

As you have illustrated; it's easy to quote-mine to support any own viewpoint.

I have learnt to put little weight on any quote which doesn't include a link to the source.
you can as well see some race results, better than anything. This is old spreadsheet that measures performance of cats MULTI2000. Appendages like catana factor 1.048, lagoon 41 1.016, so difference in overall performance across all conditions is 3-4 % draggerboard vs fixed.
Attached Files
File Type: xls Copy of MULTI2000.XLS (206.5 KB, 27 views)
__________________
arsenelupiga is offline   Reply With Quote
Old 20-03-2016, 00:49   #36
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,715
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by Seaslug Caravan View Post
Or you could try this SAIL interview with Chris White where he states....

Likewise with daggerboards: ďI spent the first 15 years of my career trying to convince people they need efficient foils. And now Iíve spent the last 10 years telling them the foils donít need to be daggerboards. Thereís this mindset now that a performance cruiser without daggerboards must be a disaster, but itís really not true.Ē

See Different Strokes: A profile of multihull designer Chris White - Sail Magazine

You see, that's the advantage of a link to the original quote. You missed out the next bit:

Though Chris has put daggerboards in several boats he has designed for clients, as a cruiser he doesnít like their vulnerability when grounding and prefers to have centerboards on his own boat.

So it's because of fragility, not comparable performance. I feel the same way and wouldn't have daggerboards for the same reason.


Heís also beginning to play with another idea. To complement the new MastFoil rig on his latest Atlantic 47 design, he has put on a pair of generous fixed keels, also with trailing flaps.
ďThe jury is out on the new keelís performance,Ē he concedes. ďWe havenít really had a chance to test it yet, but Iím convinced with the flaps it will do as well as a daggerboard.Ē


So generous fixed keels, with trailing flaps may do as well as daggerboards, but there is no evidence as yet.

That's along way from:
Quote:
I find it difficult to understand with all the information now available, that people can still believe there is a performance differential between Daggerboard and mini keel boats that could be considered significant for a cruiser.
I'm still waiting for someone to link to information showing that the performance difference between daggerboards and mini keel boats is insignificant.
__________________
StuM is offline   Reply With Quote
Old 20-03-2016, 01:38   #37
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,715
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by arsenelupiga View Post
you can as well see some race results, better than anything. This is old spreadsheet that measures performance of cats MULTI2000. Appendages like catana factor 1.048, lagoon 41 1.016, so difference in overall performance across all conditions is 3-4 % draggerboard vs fixed.
There's a lot more to the "Correction d'appendices" figure than just daggerboard v fixed keel:

"IF(R7>0,1.048,IF(Q7>0,1.048,IF(P7>0,1.036,0.907+1 .55*(O7/M7)-4.449*(O7/M7)^2)))"

Daggerboards get 1.048.
Fixed Keels get a variable figure based primarily on draft/LOA. It can be as low as 0.974

So in "overall performance across all conditions" for some boats, daggerboards can be 7.5% better than fixed keels.

But when discussing daggerboards v mini keels, the question is not so much about "overall performance", it's about such things as pointing higher and making less leeway when beating into the wind. In those conditions, you will frequently see much more than that 7.5% overall improvement in VMG.

Edit: And just to clarify, that spreadsheet doesn't "measure performance" or show any results. It is purely a mechanical rating formula and anyone who has raced extensively is well aware of the problems with any individual measurement rating system.
__________________
StuM is offline   Reply With Quote
Old 20-03-2016, 02:31   #38
Registered User

Join Date: Sep 2014
Location: Sydney
Boat: Lagoon 400
Posts: 1,104
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by StuM View Post
There's a lot more to the "Correction d'appendices" figure than just daggerboard v fixed keel:

"IF(R7>0,1.048,IF(Q7>0,1.048,IF(P7>0,1.036,0.907+1 .55*(O7/M7)-4.449*(O7/M7)^2)))"

Daggerboards get 1.048.
Fixed Keels get a variable figure based primarily on draft/LOA. It can be as low as 0.974

So in "overall performance across all conditions" for some boats, daggerboards can be 7.5% better than fixed keels.

But when discussing daggerboards v mini keels, the question is not so much about "overall performance", it's about such things as pointing higher and making less leeway when beating into the wind. In those conditions, you will frequently see much more than that 7.5% overall improvement in VMG.

Edit: And just to clarify, that spreadsheet doesn't "measure performance" or show any results. It is purely a mechanical rating formula and anyone who has raced extensively is well aware of the problems with any individual measurement rating system.
not saying differenece is small 1 deg app makes 10% diff in VMG against wind.
verified by race results, else these factors got amended.

However on average 3-4% faster in all conditions, if you do analysis. This is
same contribution as folding props.

Conditions where draggerboards have large edge is not common else that contribution would be larger.

Justy look at latest ARC results. L38 vs Catana, both sailed well. Differnece should be larger if your theory right.
__________________
arsenelupiga is offline   Reply With Quote
Old 20-03-2016, 04:18   #39
Marine Service Provider
 
Factor's Avatar

Join Date: Dec 2006
Location: Brisbane Australia
Boat: Corsair Dash MKII
Posts: 4,088
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by Seaslug Caravan View Post
Considering most cruisers motor in the light stuff, including our beloved 44c, who has motored past us on a couple of occasions ( possibly due to his unwillingness to fly a spinnaker / carry a spinnaker?) Its hard to understand where this great difference lies.
Still waiting to see when it was that 44C was motoring.
__________________
Factor is offline   Reply With Quote
Old 20-03-2016, 04:29   #40
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,715
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by arsenelupiga View Post
Designer of the boat has excellent articles regarding fixed keel vs draggerboard. Difference is indeed minimal. 1 degree or so.

Quote:
Originally Posted by arsenelupiga View Post
not saying differenece is small 1 deg app makes 10% diff in VMG against wind.
Minimal, small? What's the difference.

Still waiting for all this information showing that the difference between daggerboards and mini keels is insignificant.
__________________
StuM is offline   Reply With Quote
Old 20-03-2016, 04:40   #41
Registered User

Join Date: Sep 2014
Location: Sydney
Boat: Lagoon 400
Posts: 1,104
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by StuM View Post
Minimal, small? What's the difference.

Still waiting for all this information showing that the difference between daggerboards and mini keels is insignificant.
you may just need to take it easy and maybe will come to you one day.
__________________
arsenelupiga is offline   Reply With Quote
Old 20-03-2016, 04:44   #42
cruiser

Join Date: Aug 2014
Posts: 506
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by StuM View Post
Minimal, small? What's the difference.

Still waiting for all this information showing that the difference between daggerboards and mini keels is insignificant.
Yes, I'm still waiting for all this information showing that the difference between daggerboards and mini keels is SIGNIFICANT
__________________
Seaslug Caravan is offline   Reply With Quote
Old 20-03-2016, 05:21   #43
Marine Service Provider
 
Factor's Avatar

Join Date: Dec 2006
Location: Brisbane Australia
Boat: Corsair Dash MKII
Posts: 4,088
Re: 45' (or so) Performance Cruising Catamaran

So Mr Slug

I take it your suggestion that 44C had passed you many times whilst motoring was a furphy? A load of codswallop, rubbish and just basically internet trolling?
__________________
Factor is offline   Reply With Quote
Old 20-03-2016, 07:04   #44
Registered User

Join Date: Jun 2010
Location: Sailing the Caribbean
Boat: Switch 51
Posts: 1,498
Re: 45' (or so) Performance Cruising Catamaran

The Chris White quotes are not supportive of the idea that keels are just as good. First, he said he preferred centerboards to daggerboards, nothing about keels. Second, at the time of that interview he is selling his 47, which has keels with little flaps. So he would of course argue the benefits of keels.
__________________
SVNeko is offline   Reply With Quote
Old 20-03-2016, 07:35   #45
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43
Posts: 6,715
Re: 45' (or so) Performance Cruising Catamaran

Quote:
Originally Posted by Seaslug Caravan View Post
Yes, I'm still waiting for all this information showing that the difference between daggerboards and mini keels is SIGNIFICANT
You're the one that claimed that there was lots of information showing that it was insignificant. So let's see some.
__________________

__________________
StuM is offline   Reply With Quote
Reply

Tags
catamaran, cruising

Thread Tools
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
Dean 365 Catamaran Performance ? Crystalbleu Multihull Sailboats 52 06-10-2014 19:11
For Sale: Chris White Atlantic 42 performance cruising catamaran for sale Atlantic42 Classifieds Archive 16 06-11-2013 21:36
Cruising Cat vs. Cruising Mono Performance ssullivan Multihull Sailboats 100 03-01-2010 14:05



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 14:22.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.