myiW Current Conditions and Forecasts Community Forums Buy and Sell Services
 
Hi guest · myAccount · Log in
 SearchSearch   ProfileProfile   Log in to check your private messagesLog in to check your private messages   RegisterRegister 
Flat bottom vs double concave hulls
Goto page 1, 2, 3 ... 11, 12, 13  Next
 
Post new topic   Reply to topic    iWindsurf Community Forum Index -> Windsurfing Discussion
View previous topic :: View next topic  
Author Message
ittiandro



Joined: 22 Nov 2009
Posts: 251

PostPosted: Sat Aug 29, 2015 10:32 am    Post subject: Flat bottom vs double concave hulls Reply with quote

I do mostly subplaning ( both by choice and necessity, given the prevailing conditions here) and the Bic 293 Core I have is a very poor performer in sub-planing. Currently I am looking at the Exocet Wind SUP 11”8” and the 11”6 Bic ACE TEC Windsup. I could get the Bic Windsup for about $ 300 less than the Exocet. What worries me, though, is that the Bic Wind SUP still has the same( just longer) flat bottom of her “ planing” sister Bic293 Core I want to get away from, and I wouldn’t want to trade a one dollar bill for ..four quarters. The Exocet, on the other hand has a double concave hull, which should ensure a better gliding in sub-planing.
I weigh 85 kg, I don’t do wave sailing, mostly flat water or small waves, speed or planing are not my priorities, but stability is, especially when gybing and tacking.
I wonder if there is really a substantial difference on account of the hull design between the Bic Wind Sup and the Exocet Wind Sup. Definitely, if I compare my 293 cm flat bottomed Bic 293 with the double concave hull of the old 12 ‘ Mistral Competition I tried, there is a HUGE difference in subplaning.But perhaps the 12’ length of the Bic Wind SUP makes up for it.
Can you or anybody comment on this?

Thanks
Back to top
View user's profile Send private message
whitevan01



Joined: 29 Jun 2007
Posts: 605

PostPosted: Sat Aug 29, 2015 11:31 am    Post subject: Reply with quote

here we go again. I am sure others will chime in here with a lot of stuff, but here are some basic facts:

the longer narrower lower drag hull of the mistral gives it better glide characteristics than the shorter wider higher drag hull of the Techno, not so much the bottom shape.

the concaves in the bottom are really to promote earlier planing. as the water rushes underneath the board, the concave shape helps to provide lift (run water over the concave portion of a spoon to feel this effect.)

another benefit to the concaves is that they help the board to cut through chop.

just the bare bones of this discussion. let the games begin!
Back to top
View user's profile Send private message
ittiandro



Joined: 22 Nov 2009
Posts: 251

PostPosted: Sat Aug 29, 2015 12:37 pm    Post subject: Reply with quote

whitevan01 wrote:
here we go again. I am sure others will chime in here with a lot of stuff, but here are some basic facts:

the longer narrower lower drag hull of the mistral gives it better glide characteristics than the shorter wider higher drag hull of the Techno, not so much the bottom shape.

the concaves in the bottom are really to promote earlier planing. as the water rushes underneath the board, the concave shape helps to provide lift (run water over the concave portion of a spoon to feel this effect.)

another benefit to the concaves is that they help the board to cut through chop.

just the bare bones of this discussion. let the games begin!


Fine, I am really looking forward for the others to" chime in" with a lot of interesting stuff about the hydrodynamics of different boards with different types of hulls.
Bottom line however, before the conversation as usual spins off and away from my initial concern, I want to know whether or not I should expect the double concave hull of the Exocet to perform better in SUBPLANING than the flat hull of the Bic SUP, considering that they both have the same length and width.

For my light-wind, sub-planing requirements, as stated in my initial post, is it really worthwhile to spend $ 300 more on the Exocet because of its double-concave hull? Or would the difference be really marginal?

This is all I want to know.

Ittiandro
Back to top
View user's profile Send private message
LeeD



Joined: 12 Jun 2008
Posts: 1175

PostPosted: Sat Aug 29, 2015 1:18 pm    Post subject: Reply with quote

Sub planing, more surface area underwater allow for higher sideslipping resistance, so it would end up faster, the double concave.
How much faster? About the difference of 6" in hull length, or negligible.
Sub Planing, a D-2 board like a Lechner or a Crit would blow doors on either the boards you mentioned, but it's round bottom AND 12+ in length.
Back to top
View user's profile Send private message
NOVAAN



Joined: 28 Sep 1994
Posts: 1240

PostPosted: Sat Aug 29, 2015 2:28 pm    Post subject: Reply with quote

In the conditions you are talking about, The bottom shape of a board will make about zero difference. Rocker line will make a very small difference.
Weight makes very little difference. Except carrying and loading. Durability however makes a big difference. Bic makes great boards. I have sailed just about every offering since the early eighties. It a shame they don't still offer a high performance line of boards. The Bic E-Rock and Astro Rock are legendary. If your a beginner or sail in a rocky beach area, The Bic is the way to go. You can beat them up and they will last for years. If you search this form for Exocet, you will find there have been many problems with this line of boards. Their 11'6 windsup has way to many issues with cracks and delamination's. The dagger board area and rails are highly suspect. I have had my share of issues with this line of boards and would be hard pressed to recommend one. Buck for buck, go for the Bic.
Back to top
View user's profile Send private message
swchandler



Joined: 08 Nov 1993
Posts: 9517

PostPosted: Sat Aug 29, 2015 2:46 pm    Post subject: Reply with quote

Two things that are important to consider when contrasting different products are construction and weight. One product might be very durable, but it may also be a bit less lively and slower to get up to speed. A lighter less durable board might offer the greatest potential for speed and maneuverability, but you have to be very careful about handling and damage. With every upside, there is usually a downside that goes with it.

Do you want a board that acts more like a shortboard once up to speed and planing? The Exocet has the step tail which reduces overall length once up on a plane, and it will tend to initiate jibes more like a shortboard. It's not like the Bic doesn't perform and that it would be hindered by its extra weight and different bottom shape, as it just may offer the smoothest most comfortable ride.

Overall, you need to review your goals and follow the best path.
Back to top
View user's profile Send private message
boardsurfr



Joined: 23 Aug 2001
Posts: 1219

PostPosted: Sat Aug 29, 2015 2:46 pm    Post subject: Reply with quote

LeeD wrote:
Sub planing, more surface area underwater allow for higher sideslipping resistance, so it would end up faster, the double concave.
How much faster? About the difference of 6" in hull length, or negligible.
Sub Planing, a D-2 board like a Lechner or a Crit would blow doors on either the boards you mentioned, but it's round bottom AND 12+ in length.

Quite the opposite. More surface under water => more wetted area => more friction => less speed. D2 boards have a shape that minimizes under-water surface area. One reason D2 boards are fast in light wind. The other one is that the round shape is more efficient in displacing water than flat shapes are (which are better for generating lift).

Back to the OP:
Quote:
I want to know whether or not I should expect the double concave hull of the Exocet to perform better in SUBPLANING than the flat hull of the Bic SUP, considering that they both have the same length and width.


Short answer: wrong question! Flat vs. double concave is just one of many factors that determine glide in sub-planing conditions; most of the other differences between the boards will be more important. whitevan01 summarized the important points nicely. The double concave is there to improve planing, not non-planing.

I can't talk about the long versions, but I happen to own the 10.6 versions of both the Exocet and the Bic. Rather than giving you my impression, I'll relay what a much better windsurfer (and former successful longboard racer) said after sailing them. He did not care at all about the Exocet. But he was amazed how about how nice the BIC glides. Others have expressed the same sentiment when sailing the Bic. But who knows, maybe that's different for the longer boards.
Back to top
View user's profile Send private message
beaglebuddy



Joined: 10 Feb 2012
Posts: 1120

PostPosted: Sat Aug 29, 2015 3:07 pm    Post subject: Reply with quote

If you are primarily sub planing as you stated then neither board would be the correct type of board to buy because they have planing hulls. They work OK sub planing because they are very long not because of the hull shape.
You need either a board with a displacement hull or at least a similar length board that is much narrower.
Back to top
View user's profile Send private message
ittiandro



Joined: 22 Nov 2009
Posts: 251

PostPosted: Sat Aug 29, 2015 4:10 pm    Post subject: Reply with quote

beaglebuddy wrote:
If you are primarily sub planing as you stated then neither board would be the correct type of board to buy because they have planing hulls. They work OK sub planing because they are very long not because of the hull shape.
You need either a board with a displacement hull or at least a similar length board that is much narrower.


Your comment is quite appropriate: yes, a true displacement hull would be the best for sub-planing, like the longboards of yesteryear. In fact, I do have an old Mistral Competition with this type of hull. It glides effortlessly in the lightest of winds( and with smaller sails !) like no other shortboard does, not even a self-styled longboard like the Bic Core 293, but the big problem I have with this Mistral longboard is its instability. With a 65 cm width, my 85 kg weight and perhaps ( I must admit) my less than perfect technique ( although I am not a beginner) it is so wobbly that tacking and gibing become a real chore!

I know that you can't have it both ways and that perfection does not exist. I was thinking however that a Wind SUP would perhaps be the best compromise: very stable, while offering a better sub-planing performance than the shortboards because the sheer length of the hull, even if it is flat and a far cry from the displacement hulls.
You and the folks who have commented on this forum have been of big help and I'll probably go for the Bic because, aside from the problems with the Exocet somebody has pointed out, the difference in performance would be in the end minimal between the two and the Bic is cheaper.

If somebody has any other comments, I'll love to hear them

Ittiandro
Back to top
View user's profile Send private message
Wind-NC.com



Joined: 30 May 2007
Posts: 975
Location: Formerly Cape Hatteras, now Burlington, VT!

PostPosted: Sat Aug 29, 2015 5:36 pm    Post subject: Reply with quote

Starboard makes the Freeride 12'2" x 30", which might be another really nice option for you. You can get an epoxy or inflatable one. Displacement nose, but a flatter bottom and thick square rails for the rear 2/3. Glide and tracking of a race board, stability of a flat bottom all around board, so it's kind of a blend between an old D2 and a board like the bic or exocet.

http://star-board-sup.com/2015/products/freeride-12-2x30/

_________________
formerly known as hodad.andy

http://wind-nc.com
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    iWindsurf Community Forum Index -> Windsurfing Discussion All times are GMT - 5 Hours
Goto page 1, 2, 3 ... 11, 12, 13  Next
Page 1 of 13

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum

myiW | Weather | Community | Membership | Support | Log in
like us on facebook
© Copyright 1999-2007 WeatherFlow, Inc Contact Us Ad Marketplace

Powered by phpBB © 2001, 2005 phpBB Group