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ittiandro
Joined: 22 Nov 2009 Posts: 294
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Posted: Sat Feb 08, 2020 11:23 am Post subject: Stress on the finbox and sail size |
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Hi
I windsurf but I am thinking of going hydrofoil. I can’t afford a foil-dedicated board, though, just a regular shortboard.
Given the fact that some do not recommend, regular, non-dedicated boards because of the high stress generated by the foil, I’d like to know what are the real risks: I’d sail in light winds ( 10-15 knts) and I am not a speed or acrobatics buff, as long as the board planes above the water.( not necessarily 80 cm, though..If I could plane 1 ft above it it would be great..)
I wonder if there is a correlation between the size of the sail ( =the power) and the stress in the finbox.
If this is the case, I could perhaps rig the smallest possible sail, as long as it gives sufficient lift to raise the board above the water. At 85 kg, I normally windsurf in light winds ( 12-15 knts) on my 11 ft Bic with an 8.0 or a 6.3. Below 12 knts it is almost mission impossible and this is why I was thinking hydrofoiling..
Here are my questions:
1.In these conditions, if a small sail really reduces the stress on the fin box ( which I am not too sure about, maybe an engineer can tell.) can I still expect to foil in light winds with a 5.0 or even less, given the fact that for foiling you can safely scale down the sail by two sizes?
2.As I understand, the lift of the foil is also in function of the wing’s size. Can somebody give me the wing size range of the commercially available foils? What size is considered more “ powerful”?
3. If I am to shop for non-dedicated 2nd hand board, which one is recommended in terms of length, width, finbox, etc. Is a Deep Tuttle more recommended because of the depth of the box?
Thanks
Ittiandro |
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dllee
Joined: 03 Jul 2009 Posts: 5293 Location: East Bay
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Posted: Sat Feb 08, 2020 11:48 am Post subject: |
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Big foils cause stress.
Big guys cause stress.
Then big sails, last.
Foils come from 600 sq.cm to 2,500 sq.cm.
The smallest of the 1st 3 cause the least stress and the least lift. |
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boardsurfr
Joined: 23 Aug 2001 Posts: 1266
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Posted: Sat Feb 08, 2020 11:48 am Post subject: |
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I have sailed about 50 sessions on an old 71 cm wide slalom board without any problems. It has a deep tuttle box, but not a foil box - it was built years before foiling became popular.
How well this works depends partially on the connection between the foil and the board. Some, but not all, companies like Slingshot have a flange at the top of the mast which sits on the underside of the board. If you get a foil that does not have this, there is a good chance that the foil with push the fin box through the top of the board.
When you are learning, you'll probably be on a freeride foil, like the Slingshot Infiniti or a Naish. With a freeride foil, the upward push of the foil with be the same as your weight plus the weight of your gear. Wing and sail size do not matter in this respect; larger wings just reduce the speed you need for takeoff, and make it easier to glide through lulls. I doubt that using a smaller foil or smaller sail has any effect on how well the fin box will hold.
For the board, get one with at least 70 cm width and 115 l volume (more if you are 200 lb plus). More width and volume will make the initial learning easier. Lots of beginners had great success on old formula boards. The big issue with those are the outboard straps, which are not beginner-friendly (that's also true for bigger slalom boards). Depending on which foil you get, they may also be too far in the back (check the images of Slingshot foil boards for comparison).
If you can spend a bit more and get a 120+ liter board made in the last 2 years, there's a good chance that it has a foil-ready box. If not, make sure it is a deep tuttle. |
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ittiandro
Joined: 22 Nov 2009 Posts: 294
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Posted: Sat Feb 08, 2020 7:55 pm Post subject: |
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Thanks Boardsurfr
I'm glad that all the info I need is beginning to trickle in. I might get a good deal locally on a NP RS One foil.
Ittiandro |
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grantmac017
Joined: 04 Aug 2016 Posts: 946
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Posted: Sat Feb 08, 2020 11:50 pm Post subject: |
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I'd be looking at a first generation RF91 in AST construction. You can likely find one for about the same as a shortboard, they weren't expensive new.
Then you'll want a larger foil, the RS One isn't very big. It also doesn't have a flange so I'd avoid it on a standard fin box.
Some guys like slingshot gear, personally I'd look at the NP Glide.
I'm your weight and using the Slingshot 76cm wing I'd be rigging a 7.0 in 10kts, 5.3 in 15kts. |
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LUCARO
Joined: 07 Dec 1997 Posts: 659
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Posted: Sun Feb 09, 2020 11:23 am Post subject: |
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Just try and find a used green slingshot wizard (I just sold mine for $750). That board is all most freeride foilers will ever need and you can learn to foil on it.
Another option is a used slingshot dialler. Cheaper and reasonable for learning but you will probably want to upgrade to a wizard later.
The NP glide does look pretty cool and the price is right, but as far as out of the box function I don't see any reason not to go with a used slingshot hoverglide system.
Slingshot nailed the wizard, but it's finbox doesn't fit all foil brands (different version of the tuttle).
Otherwise just get the cheapest used formula board you can find and ride it to the box fails? With a foil pedestal mount you can also just drill holes through a junk board and bolt it on.
PS: apparently the dialler is better than I thought
Last edited by LUCARO on Sun Feb 09, 2020 8:41 pm; edited 1 time in total |
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ittiandro
Joined: 22 Nov 2009 Posts: 294
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Posted: Sun Feb 09, 2020 12:48 pm Post subject: |
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grantmac017 wrote: | I'd be looking at a first generation RF91 in AST construction. You can likely find one for about the same as a shortboard, they weren't expensive new.
Then you'll want a larger foil, the RS One isn't very big. It also doesn't have a flange so I'd avoid it on a standard fin box.
Some guys like slingshot gear, personally I'd look at the NP Glide.
I'm your weight and using the Slingshot 76cm wing I'd be rigging a 7.0 in 10kts, 5.3 in 15kts. |
Thanks
The 2nd hand NP RS One foil I am envisaging comes with a DeepTuttle head. I know that it does not have a flange, but can I use a Powerplate ( Deep Tuttle) to reinforce the finbox of the new board.
The question I have is : is the NP foil Deep Tuttle head ( the male ridge) designed to slide into the Powerplate Deep Tuttle female housing, the whole assembly to be finally bolted into the board Deep Tuttle finbox?
I Don’t know what are the standard measurements, because neither the NP Foils site nor the Powerplate site give information on this, but I want to be sure before buying.
Thanks as usual
Ittiandro |
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grantmac017
Joined: 04 Aug 2016 Posts: 946
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Posted: Sun Feb 09, 2020 2:27 pm Post subject: |
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That's not how the powerplate works, it requires a 4-bolt mast like SUP or Kite foils have and some wind foils are starting to use.
The RS ONE just isn't a good foil. On seabreese there is a whole thread about modifying them to function correctly and even then the wings are best suited to going fast rather than learning in light winds. |
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boardsurfr
Joined: 23 Aug 2001 Posts: 1266
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Posted: Sun Feb 09, 2020 4:11 pm Post subject: |
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If the deal is exceptionally good, there may be a reason for it! Of course, the seller will give you a reason, but that may not be the real reason.
The thread that grantmac17 is referring to is probably this one. This might describe a different NP foil, like the one you can get new for $449. However, comparing pictures and specs, the only obvious difference is the coloring. There are indeed many reports about the "NP Pinky" being a bad foil.
The newer NP foils look quite different from the old pinkie, and reports from users are better. The NP Glide Wind has 4 different sizes of front wings, and every one of these is larger (more area) than the front wing on the RS:One. Larger wings make it easier to get going in light wind, and to stay up in lulls. |
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ittiandro
Joined: 22 Nov 2009 Posts: 294
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Posted: Mon Feb 10, 2020 1:45 pm Post subject: |
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grantmac017 wrote: | That's not how the powerplate works, it requires a 4-bolt mast like SUP or Kite foils have and some wind foils are starting to use.
The RS ONE just isn't a good foil. On seabreese there is a whole thread about modifying them to function correctly and even then the wings are best suited to going fast rather than learning in light winds. |
Indeed, the rating was not too good for the previous design, called the "pink " RS One because of the color.
However NP has now redesigned the foil making the wing 40 mm wider. This should help. This latest version has a blue color and is called NP RS One Blue. Seabreeze rating is now good.
Anyway, there is always a good amount of subjectivity in the ratings.
The question is not whether the NP RS One is good or bad in absolute terms, but rather how well it meets the diverse needs and abilities of different windsurfers, including me..
I know NP is a very reputable company and my only worry, as beginner, is the challenge of learning how to foil...
I know there might be better choices" by the book" and I value as usual the opinion of experts in this Forum or elesewhere , but unfortunately my choices are limited by my budget. In the end, my real choice is between giving up foiling because of the high cost, or taking a chance...For a $ 400 ( CAD ) investment in a 2nd hand NP RS One foil, I think it is worthwhile. I am prepared to regret my choice, but I hope I won't...
This is in the end how my windsurfing story has unfolded so far: caught in the shortboard and planing craze and unable to enter this " paradise" partly because of my skills but also because of the prevailing light wind conditions, I wasted money in buying one shortboard after the other, in the hope to find the " best" one, to eventually find out that planing and shortboarding here ( mostly with 10-12 knts winds) is like trying to sell a refrigerator to an Inuit in the North Pole..
Eventually I bought an 11 ft Bic Behemoth ( sort of wind-adapted paddleboard) with which at least I windsurf when others can't..., albeit at the price of a slow pace and..some boredom when winds are really slow.
With foiling, I hope to break this barrier ( if I don't break something else when falling from a height of 85 cm..), but I take risks and at my age I have nothing to lose, even $ 400 is not a big deal, should I find out that foiling is not for me ...
Just some oldtimer's thoughts
Ittiandro |
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