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Flat bottom vs double concave hulls
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waterloo



Joined: 25 May 2012
Posts: 21
Location: Australia

PostPosted: Sat Aug 29, 2015 5:58 pm    Post subject: Reply with quote

I was going to chime in with exactly that! I have both the Exo 11'8 Wood and the Starboard 12'2 Freeride WindSUP (with the retractable daggerboard).

The Exo 11'8 is great all-rounder and has a good turn of speed for the type of board it is - I wind her up into the 25-26 knot range in moderate chop. But compared to some other boards it is not the best schlogger in light winds.

The 12'2 Freeride, however, is a real pleasure to sail in light winds, it is not as tippy as the old race boards and also doubles as a reasonable SUP. I mostly sail it with a 8.0m SuperFreak Ultralight in 8-12knots but it will take bigger sails (google the board and starboard forum). This board has a gradual movement onto the plane and is not an "on-off" sensation you get with modern wider boards (including the 11'8 to a certain degree).

I often find myself out with a "planing sensation" while the kiters are rigged and still on the beach waiting for wind, and I'm 100kgs. Its limitations are its top speed which, for me, is around 17knots, and so no need for footstraps.

The 12'2 is a dead easy, fun board to sail Smile
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adywind



Joined: 08 Jan 2012
Posts: 665

PostPosted: Sat Aug 29, 2015 7:36 pm    Post subject: Reply with quote

Hey how much for the Bic and the Exo? The Starboard with a center fin is 1104$ at Isthmus:
http://www.isthmussailboards.com/2015-Starboard-Windsup-Freeride-ASAP-PLANING/productinfo/SB15WSFA/
PS: Isn't mono concave the best shape for sub planing?
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konajoe



Joined: 28 Feb 2010
Posts: 506

PostPosted: Sat Aug 29, 2015 9:22 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.


There are no displacement hull boards.

Ittiandro, your mistral competition IS a planing hull. Look around on the internet for division II or Div2 or D2 boards. THOSE are what they called displacement hulls.

When you say that you have a Mistral Competition, does it say Superlight on it somewhere?

How are the retractable centerboards on those 2 Wind/SUPs you are considering?
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dllee



Joined: 03 Jul 2009
Posts: 4669
Location: East Bay

PostPosted: Sat Aug 29, 2015 10:12 pm    Post subject: Reply with quote

I thought Serenity was still around?
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whitevan01



Joined: 29 Jun 2007
Posts: 605

PostPosted: Sat Aug 29, 2015 10:21 pm    Post subject: Reply with quote

spend more time sailing the Mistral, you will eventually get used to it. If I could do it, you can. forget the windsup thing for sub-planing.
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beaglebuddy



Joined: 10 Feb 2012
Posts: 1120

PostPosted: Sun Aug 30, 2015 2:24 am    Post subject: Reply with quote

whitevan01 wrote:
spend more time sailing the Mistral, you will eventually get used to it. If I could do it, you can. forget the windsup thing for sub-planing.

I think this is the best advise. The windsups bow will push some water subplaning. Get the Starboard if you really want a new board, I have looked at these and to me it's a bit similar to an old Mistral Superlight I have, just a bit wider and a bit flatter on the bottom but the overall shape, nose and tail are very similar.
I wouldn't put off purchasing an Exocet 11'8" because of perceived quality issues. There have been a few problems but Exocet has made good in every case including mine. It's a great board but better in a bit more wind.
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ittiandro



Joined: 22 Nov 2009
Posts: 255

PostPosted: Sun Aug 30, 2015 9:28 am    Post subject: Reply with quote

konajoe wrote:
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.


There are no displacement hull boards.

Ittiandro, your mistral competition IS a planing hull. Look around on the internet for division II or Div2 or D2 boards. THOSE are what they called displacement hulls.

When you say that you have a Mistral Competition, does it say Superlight on it somewhere?

How are the retractable centerboards on those 2 Wind/SUPs you are considering?


Oops, I was not logged in. I'll re-post.

Except for Health Care which, thanks God, is absolutely free here in Canada and has saved me thousands, if not tens of thousands of dollars so far , even for the most routinely ailments and treatments,( and I am in excellent health, mind you!), for everything else, at least cost-wise,( including windsurfing equipment), living I the U.S. is a real boon: prices are a lot cheaper than in Canada, if anything because the vast majority of products are imported from the U.S. , sometimes as far as from the West Coast and freight costs add up considerably, without counting the exchange rates and the M.R.S.P. increases, reflecting the demographics of the limited Canadian market,..
To come to my windsurfing issue, The Starboard, Exocet , Konas and other similar SUP’s or longboards I am considering as alternatives to my Bic 293 Core, hover around 2000 $ CAD if not more in Canada, which is beyond my budget. The cheapest I could find is a 2015 Bic ACE 11’6 SUP , but the dealer told me that the pricing for 2016 will probably go up in September allegedly due to the exchange rate and other “ policy” reasons ( usually only profitable to the manufacturer )…
By the way, both the Bic SUP and the Exocet SUP have retractable centerboards.
In the circumstances, I have only two choices left: buying Bic SUP or keeping the Bic Core 293 which is very sluggish in light winds and severely limits my time on the water. ..
In the end, the deciding factor for me will be: will the Bic Sup, if anything because of its length, and in spite of its flat planing hull significantly improve the sub-planing performance as compared to the Core? Short of planing conditions, will the Bic Sup extend my time on the water ?

As to the Mistral Competition I have, it is a SST. Somebody gave it to me for a very reasonable price, but to gibe and tack on it (which I can easily do on the Bic Core and other similar wide boards) would require a lengthy course in…high-wire acrobatics, which will only improve my swimming ability, but erode precious windsurfing time from our already very short summers..If I start learning to gibe on the Mistral at the beginning of the summer, by the time I’ll have learnt summer will be probably over..

Thanks for your comments, as usual

Ittiandro


Last edited by ittiandro on Sun Aug 30, 2015 10:31 am; edited 1 time in total
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adywind



Joined: 08 Jan 2012
Posts: 665

PostPosted: Sun Aug 30, 2015 9:48 am    Post subject: Reply with quote

I'm afraid that only you alone can answer that question. It's too personal.
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wernerhickey



Joined: 13 Jun 2015
Posts: 68

PostPosted: Sun Aug 30, 2015 10:11 am    Post subject: Reply with quote

i have the Exocet, Bic wind 10 6 and the Fanatic Fly with the mast insert. The Exocet is very stable - I can stand with feet either side of the mast or even in front with no issue, jibing is forgiving with enough float to muscle the board through fluffed turns. The Bic is fine but IMO needs bumps to make it fun due to the rocker line. The Fly is a lovely non- full planing board, light and easy to gybe - not as forgiving to tack as the Exocet - but one of the easiest most forgiving boards if non planing is all you want to do. For me thought it is the Exocet.
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ittiandro



Joined: 22 Nov 2009
Posts: 255

PostPosted: Sun Aug 30, 2015 10:17 am    Post subject: Reply with quote

boardsurfr wrote:
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).



Boardsurfer,

I do agree that in some ways water resistance increases with the wetted surface: certainly a 65 cm wide hull offer less water resistance than a 1 mt wide hull. From the standpoint of physics, however, the forward motion of a hull through the water wouldn’t exist without water resistance.
In physics, especially in an upwind course, but also to a certain extent , in a downwind course, forward motion of a sail craft through the water is the combination of two vectorial forces: the wind pushing laterally (leeward) on the sail and the water which counters this lateral pull with an equal force in the opposite direction ( windward) by the 3rd law of Newton. The combination of these two forces results in a different median direction, which is forward motion. It wouldn’t happen if there were no such lateral resistance! To this you have to add, of course, the pressure differential between the two sides of the foil ( the sail) and in the end, from this perspective, the craft moves not because of the “ push” of the wind on the sail as we commonly think, but the PULL, analogous to the upward thrust of an airplane’s wing. The airplane wing is “ sucked up” while the sail is “ sucked” forward.
It is exactly what happens when you squeeze a wet soap bar with your hand and the soap bar flies off your hand and forward. In terms of physics, the soap bar, squeezed between the inner palm of the hand and the outer fingers, is subjected to two forces: the inner palm pushing laterally on one side of the bar and the fingers pushing laterally on the opposite side with an equal force . These two forces do not neutralize one another but they are expended in a combined forward motion. This is why the bar flies off your hand, just as the board moves forward..
But, with the qualification in physical terms I provided above, you are right, too, when you say quote More surface under water => more wetted area => more friction => less speed unquote. In fact, if you look at a catamaran, it moves so much faster because the wetted surface is minimal, relative to its size, being limited to the narrow edges of the hulls cutting through the water. However it wouldn’t move forward if it were not for the lateral resistance of the water against them..

Ittiandro
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