I have been using the Severne Foilglide 2 in 7 and 8 with a 460 RDM for a while. I appreciate their light weight, low end power and superb camber rotation, but feel they lose a bit of stability and increasing backhand pull in the gusts (compared to for example Overdrives).

Has anyone tested SDM vs RDM on the Foilglides, or can anyone make a qualified guess on potential stability improvements? And if so, what is sacrified?

My sailing is more in the Freerace rather than Freeride category, using Patrik F-ride 145/ SB GT-R.

I think stability comes from wide luff of the race sails, so SDM will not give the magic you are looking for, at best, minor change with rotation getting dramatic down grade

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miamiwindsurfe said..
I think stability comes from wide luff of the race sails, so SDM will not give the magic you are looking for, at best, minor change with rotation getting dramatic down grade

Stability comes from a number of things and the better bend characteristics of an SDM (even with identical bend "numbers) at the limit helps. More battens, carbon battens, more cams, higher rig tension all contribute. imho, wide luff sleeves are more about reducing drag than improving stability. I'm not even sure the FG2 even takes an SDM, though, so it may be a moot point.

What will help that is inexpensive is an adjustable outhaul if you aren't already using one.

The foilglide comes with rdm cams. You need to buy extra sdm cams. 4 for the 8.0, 3 for the rest

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Paducah said..

miamiwindsurfe said..
I think stability comes from wide luff of the race sails, so SDM will not give the magic you are looking for, at best, minor change with rotation getting dramatic down grade

Stability comes from a number of things and the better bend characteristics of an SDM (even with identical bend "numbers) at the limit helps. More battens, carbon battens, more cams, higher rig tension all contribute. imho, wide luff sleeves are more about reducing drag than improving stability. I'm not even sure the FG2 even takes an SDM, though, so it may be a moot point.

What will help that is inexpensive is an adjustable outhaul if you aren't already using one.

All i can say, when while back in formula era, we switched to wide luff sails, magic did happen regarding stability/range/angle

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Paducah said..

miamiwindsurfe said..
I think stability comes from wide luff of the race sails, so SDM will not give the magic you are looking for, at best, minor change with rotation getting dramatic down grade

Stability comes from a number of things and the better bend characteristics of an SDM (even with identical bend "numbers) at the limit helps. More battens, carbon battens, more cams, higher rig tension all contribute. imho, wide luff sleeves are more about reducing drag than improving stability. I'm not even sure the FG2 even takes an SDM, though, so it may be a moot point.

What will help that is inexpensive is an adjustable outhaul if you aren't already using one.

Good point about the adjustable outhauls, I will try that. FG2 with SDM mast is possible according to Severne, however RDM recommended. (But they don't explain why....)

I use sdm for my foilglides, but for stability, they're never gonna be anything like a race sail.

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miamiwindsurfe said..

All i can say, when while back in formula era, we switched to wide luff sails, magic did happen regarding stability/range/angle

Range and angle are also going to be related to low drag, cleaner aero. And, I presume, like in the formula days, going to a big luff foil sail is a revelation when you point high, go deep or glide through a lull*.

However, I'm willing to admit that there's something else going on that I'm not aware of on the stability front (I'm open to a explanation of why it would be so) but other pieces, imho, are going to be more important eg. the number and composition of battens.

*I'll leave it to the user to weigh the advantage of these vs the disadvantages of weight, cost, rigging complexity, etc. They aren't for everyone, even me at times.

Great foil freeride sail with lightweight construction that keeps customers buying regularly, best purchased new

Funny (and correct) that we now talk about the race sail wide luff sleeve contributing to lower drag and cleaner aero. Back in the formula days the sail manufacturers talked about the wide sleeve being for easier rigging, and they never mentioned the aero advantage. Check out some of the old Maui Sails videos. It was all about rigging. I kept looking for Phil to say something about aero, but he never did.

To me as a retired Boeing scientist, the aero advantage is obvious. Heck, the AC sails have taken this wide luff thing to the extreme and have sails with two surfaces. Now THAT'S an aero advantage. People experimented with this for windsurfing, but they were too heavy.

Big fan of FoilGlide 7.0 - have both V1 and V2 (!)
Originally used RDM, but at 95+ kg I have never liked RDMs in slalom sails etc
Much preferred feel/stability of SDM in 7.0 V1, cam switch is simple
Now use SLAKE MDMs for all my foil and slalom sails over 6.0 - best of all worlds, gives fantastic range in the FG 7.0

Segler, you only need to remember Aeroforce and some Freedoms to know the aero advantages were beaten to submission.....verbally and in ads, by 1986.
When they reappeared 17 years later, they did talk about aero AND easier rigging.
Hype is only important if it proves advantages in the water.

From other threads it seems like the common theory is that SDM masts flex faster and RDMs have a softer feel and 'breaths off' gust power supposedly benefitting lightweights (I'm 75 kg myself). But I wonder if this is more important on a fin than on the foil (due to lower resistance with foiling).

So the question is maybe if this 'breathing' or other RDM charasteristics impacts the sail profile and thereby increase backhand pull in the gusts more than a SDM setup. Or if it is negligible compared to other parameters mentioned in this thread (cams, battens, luff sleeve, etc). Hopefully I will be able to do a test in the coming week or so.

I have to wonder whether the performance gap between SDM and RDM is narrowing. My newer Flyer 7.0 (5-batten) is supposed to rig on a RDM 430. It was not good. Way too noodly and too hard to handle on the water. Sailworks recommended I try a RDM 460. I borrowed one. It was not any better. However, then I got the NoLimitz FAST 460 cm 95% RDM Mast. Holy cow, what a difference that made. The sail was quiet in gusty winds. Steady power to make for an easy ride.

So I got the opportunity to test a Apex 460 SDM mast with the FG2 8.0. Overall it works well, although only a marginal (if any) improvement in stability. Slightly worse cam rotation, so I will stay with the Severne RDM Red mast, and just accept it's not a race sail.

On another note I find the gap between the FG2 8 and 7 to be way too small, but the gap between FG2 8 and Overdrive 7 to be perfect. The stability of the Overdrive is better for high wind foiling, and when the wind really hits I just change the foil board for a 100 liter slalom board. And that is my two sail, two board combo that covers 90% of my sailing time.

It's necessary to change the rdm cams to use the sdm mast?
thx

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AndyPandy said..
So I got the opportunity to test a Apex 460 SDM mast with the FG2 8.0. Overall it works well, although only a marginal (if any) improvement in stability. Slightly worse cam rotation, so I will stay with the Severne RDM Red mast, and just accept it's not a race sail.

On another note I find the gap between the FG2 8 and 7 to be way too small, but the gap between FG2 8 and Overdrive 7 to be perfect. The stability of the Overdrive is better for high wind foiling, and when the wind really hits I just change the foil board for a 100 liter slalom board. And that is my two sail, two board combo that covers 90% of my sailing time.

Yeah, the FG2 7.0 is at least a 7.4 and maybe bigger. Dimensions are way off from other brands 7.0 and even from Severne's other lines. I think it's deliberate: "I can foil up in 8 on my 7.0.". It's like the golfer who hits his pitching wedge 150 - because at 42 degrees it's practically an 8 iron. The FG2 8.0 is a legit 8.0, so as you point out the gap is too small.

FG2 7.0 dimensions are 488/204. Overdrive 7.0 is 461/189. Overdrive 7.8 is 489/200. Roach and luff curve aren't that different, so the 7 meter foil sail is just misnamed relative to other setups.

This is probably the most relevant thread as I recently picked up a 6.0 foil glide to give me something a bit more smaller and still cammed for when it's really going. This was after running the 725 front wing with my 7.0 foil glide and finding it really nice on an 95cm board. Way less stressful and more fun than sticking with a 9.0 HGO in higher wind.

Anyway, some sail comparisons below.

7.5 Gator on top of an 8.0 Foil Glide


7.0 foil glide on top of an 8.0 foil glide. Not the similarity in clew position and the leech extension above the boom



6.0 foil glide on top of the other two. Similar cut to the 7.0 but less luff length as well. 7.0 and 8.0 have similra luff length. Also I tried to line up the feet and wasn't perfect but I do think there's some difference there too


Also, grabbed a 550 front as the cheapest pathway to a new PB. I cracked a new minimum jibe speed of 11.3kts with this 7.0/725 setup. I think there's a lot of room to get better on that stat on all the race wings, but I was surprised at how good I was doing having never run that setup before and getting about 30% of my jibes above the 9kts threshold.

I think that will be sufficient gear to basically keep extending and wearing out these sails until the next gen of foils comes around, or maybe the one after that...

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aeroegnr said..
This is probably the most relevant thread as I recently picked up a 6.0 foil glide to give me something a bit more smaller and still cammed for when it's really going. This was after running the 725 front wing with my 7.0 foil glide and finding it really nice on an 95cm board. Way less stressful and more fun than sticking with a 9.0 HGO in higher wind.

Anyway, some sail comparisons below.

7.5 Gator on top of an 8.0 Foil Glide


7.0 foil glide on top of an 8.0 foil glide. Not the similarity in clew position and the leech extension above the boom



6.0 foil glide on top of the other two. Similar cut to the 7.0 but less luff length as well. 7.0 and 8.0 have similra luff length. Also I tried to line up the feet and wasn't perfect but I do think there's some difference there too


Also, grabbed a 550 front as the cheapest pathway to a new PB. I cracked a new minimum jibe speed of 11.3kts with this 7.0/725 setup. I think there's a lot of room to get better on that stat on all the race wings, but I was surprised at how good I was doing having never run that setup before and getting about 30% of my jibes above the 9kts threshold.

I think that will be sufficient gear to basically keep extending and wearing out these sails until the next gen of foils comes around, or maybe the one after that...

Found the STEM guy Meanwhile, me over here drawing with crayons if not eating them. (Nice write up.)

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Paducah said..

aeroegnr said..
This is probably the most relevant thread as I recently picked up a 6.0 foil glide to give me something a bit more smaller and still cammed for when it's really going. This was after running the 725 front wing with my 7.0 foil glide and finding it really nice on an 95cm board. Way less stressful and more fun than sticking with a 9.0 HGO in higher wind.

Anyway, some sail comparisons below.

7.5 Gator on top of an 8.0 Foil Glide


7.0 foil glide on top of an 8.0 foil glide. Not the similarity in clew position and the leech extension above the boom



6.0 foil glide on top of the other two. Similar cut to the 7.0 but less luff length as well. 7.0 and 8.0 have similra luff length. Also I tried to line up the feet and wasn't perfect but I do think there's some difference there too


Also, grabbed a 550 front as the cheapest pathway to a new PB. I cracked a new minimum jibe speed of 11.3kts with this 7.0/725 setup. I think there's a lot of room to get better on that stat on all the race wings, but I was surprised at how good I was doing having never run that setup before and getting about 30% of my jibes above the 9kts threshold.

I think that will be sufficient gear to basically keep extending and wearing out these sails until the next gen of foils comes around, or maybe the one after that...

Found the STEM guy Meanwhile, me over here drawing with crayons if not eating them. (Nice write up.)

Thanks, I was really curious about what the differences were. Now to use them for more speed...