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Old 9th May 2007, 02:26 PM   #11
Roger
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Default RE: Serenity questions

Hi Jay,
I'll have to move my trailer in the morning (to get the Serenity out) but I'll make a valiant attempt to give you a number.
Yes, I like 54-60 cm fins about the best. Works great with the 7.5 m2 rigs.
Well, I was thinking of doing some testing on the static and moving roll rates of the Serenity, and perhaps taking a big fin and casting a lead tip with the same profiles.
But the bulb idea is good for getting the max weight at the farthest distance from the roll centerline.
I had a fairly heated discussion on static vs moving "roll rates" with Jim Drake last month, and now I'm interested in finding out how much the big fin reduces the roll rate when the board isn't moving.
Jim thinks something like 20%..... I think the number is significantly smaller.
Be interesting to see if the weighted tip fin (or the bulb fin) reduces the roll rate significaly more.
Making a test rig is going to fun on this one...!
R
P.S
Jay:
If you store the Serenity with the deck down, then I'm pretty sure you can get it in 7.00 inches if your rack bars are only 5-6 feet apart.
You can easily store it above other boards, as the parts that will hang down are about 3-4 feet further out from the rack bars.
I'll work on getting you real numbers!
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Old 9th May 2007, 05:45 PM   #12
Jean-Marc
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Default RE: Serenity questions

Jay,
Roger,

When laying the Serenity upside down on a flat floor, the minimum clearance is about 19 cm around the mast track and 18 cm around the finbox. Adding 1 cm as safety margin or 2 cm with the boardbag, a clearance of 20-21 cm should be the bare minimum.

As to further dampen the rolling-over of the hull, I think a wide and long 80 cm fin should be even better than a lead bulb because increasing width generates more lateral resistance through water than a narrow and slender fin (to be done on the increasing list of test to do when I'll get mine...) when the board is not moving. The other side of the coin is that when moving, such a big fin might be more prone to flip over the hull when it is angled during a turn.

Cheers !

JM
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Old 9th May 2007, 11:22 PM   #13
Roger
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Default RE: Serenity questions

Hi JM,
I don't want to "dampen" the roll rate.
I have no problems sailing the Serenity with the current 70 cm wide fin (except for the way it "catches" after the board rolls through neutral).
I beleive that the huge wide fin is being provided to give a slower roll response when the board isn't moving, and to give it that last tiny bit of upwind angle.
Once moving, the board does not seem to need the big fin and it becomes a liability in terms of control and speed once the water getss flowing past.
Using a smaller 54-62 cm fin with a significantly reduced area and chord makes the Serenity alot easier to sail, doesn't seem to hurt the static roll rate (no water flowing by the fin) very much, and gives better speed and jibing.
Perhaps a tiny loss in upwind angle, but the Serenity goes upwind on "bite" at the nose and will easily head up so high the rig stalls with almost any fin I've tried.
I did try a tiny 29 cm weed fin and that was indeed too small as the leeway became a problem.
So, I wish to prove/disprove that the huge 70 cm wide blade fin really does slow/dampen the "static" roll rate.
The ability of the big fin to allow you to roll the Serenity slightly to leeward and "set" the roll angle is not in question.
It works almost too well in this mode.
But when the board rolls the other way (midpoint or downwind in a jibe) through neutral (where the fin is vertical and not loaded on either side) it "bites" sharply as soon as the foil begins to work on the new lee side of the fin.
Smaller fins do not do this, making me think the stock fin is a little too big.
Hope this helps,
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Old 10th May 2007, 05:45 AM   #14
Randy
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Default RE: Serenity questions

Roger,

What kind of fins are you using in the 54-62 cm range. I've not sailed the big fin as much as the smaller one, but I do think it gives a lot more power, though this is very hard to judge accurately. Wind strength changes can make a big difference. Today I sailed with the big fin, the small fin and a 58 cm North Shore Maui race blade. Can't say it was any better than the small fin. Of the three, today I was happiest with the big fin. Though at times it can be a little overpowering, and it does make it harder to control. If the wind picks up, it seems better to "fin down" to a smaller fin, than to "rig down' to a smaller sail.

I'm wondering if a more flexible fin might work? I've got a Curtis Mongo 70 cm, which seems to have more flex than the 70 cm Drake. I'll probably try it next time out.

As for the static rolling problem, I'm not sure exactly what your referring to. To me uphauling, etc is not very difficult. Perhaps at my weight (60 kg, 133) I can get away with more than others. I do notice that jibing is not easy, however, I've improved on that score as well. Flat water is much easier to jibe than choppy water, for sure. What's really cool is that sometimes when it seems like a jibe is being blown, you have enough speed to push the sail down, and then it will come back up on its own - a sort of Serenity Laydown jibe
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Old 10th May 2007, 06:21 AM   #15
Roger
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Default RE: Serenity questions

Hi Randy,
I've used Deboichet Concepts (not the custom Debo's), stock OEM Starboard fins from older formula boards, GO's and such, and some pretty special System B CNC custom fins I got from over on Maui.
I've also used some Curtis Prototype fins, and smaller 40-48 cm SR-6b
slalom race fins.
I think you are giving up alot of speed with the big fin as I find it very "draggy" in light winds with smaller rigs, and just too hard to control in higher winds at higher speeds.
You've almost "proved my point" here.
Uphauling, if you stay over the Serenity's fore and aft centerline, is very easy.
So, providing the huge fin, which is supposed to make the board more stable at rest (zero speed roll rate would be the same as static roll rate here) doesn't seem to add any appreciable (maybe not even measureable) decrease in roll rate, but as soon as you begin moving, the big fin takes a bite and reduces the roll rate almost too much.
I have not found the Serentiy to be even slightly easier to uphaul with any smaller fin vs the 70 cm wide blade, so unless you are racing, against other Serenities with the big fin, there's no advantage to the big fin for recreational sailing.
I can jibe the Serenity dry nearly all the time, even with the big fin, but it's much smoother and easier with smaller fins.
And, yes, I know that "push the sail over and down, and have it pop back up.
Hope this helps,
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Old 10th May 2007, 01:26 PM   #16
Jay
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Default RE: Serenity questions

Thanks JM for your input.

I was measuring my rack tonight and it's going to be tight.

Roger, if it's not too much trouble, I would appreciate your measurment. I hope lack of sapce doesn't keep me from getting this great board...

Jay
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Old 11th May 2007, 02:12 AM   #17
Roger
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Default RE: Serenity questions

Hi Jay,
Sorry for the delay, but I'm in the middle of Texas (Abilene) and a look at the Weather Channel will dhow you that we've had several days of severe thunderstorms so I wasn't to thilled about trying to take any measurements in nasty T'Storms and heavy rain.
Got a little "break in the weather" a few minutes ago and I got some
measurements for you.
With the board sitting on a piece of carpet about 3/8" thick, the nose meausures 27 cm from the parking lot (asphalt).
The tail measures about 13 cm from the same surface.
I'm not totally sure how flat the parking lot is, but it's reasonably flat.
So, if you have 11" of vertical space and 14' 11 5/8" of horizontal space the board witll fit nicely.
If you have less vertical space, then store the board upside down and
it will fit nicely in about 8" of vertical space, but you may have to slide it into your rack tail first.
Hope this helps,
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Old 11th May 2007, 02:30 AM   #18
Jay
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Default RE: Serenity questions

Roger, you are a life saver, thanks!
It was the nose height I was particularly interested in; the nose rise is a bit more than I had guessed based on the other measurements available. Now I've got to see if I can make that work, but now thanks to you I know exactly what I am trying to fit and won't have any nasty surprises.

Last question - do you have any thoughts on the technora vs wood construction for this board? The wood is 25% more expensive but significanly lighter and probably stiffer. The lightness would be nice (it also looks great) but I don't know how important the added stiffness is in a board like this. Is the wood more durable and if so is that even an issue in a light wind board like this? In the light winds I would think that I would be less likely to damage the board (I'm sure I'll fall but not likely to catapult so the mast shouldn't be breaking the nose I would think).

Jay
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Old 11th May 2007, 05:16 AM   #19
Roger
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Default RE: Serenity questions

Hi Jay,
I've never had the opportunity to sail the Technora Serenity.
The one I have is wood.
The WOOD construction is for sure lighter and perhaps a bit stronger
(impact type dings) so if you can afford it, I think that's the way to go.
On the other hand, the Technora will be easier to repair nicely.
Funny thing you should ask about dings and mast "slams" in very light winds.
They happen, more than you think, because peoplre don't think there'[s much force in the wind, so the board won't get dinged, but 'if you drop the boom head on the deck (often happens when you run aground coming in or going out) you will get some damage. That's what happened to my demo Serenity. I didn't do it, but someone at one of the demo's in florida sure did. I'm waiting for a new piece of wood and a new Tiki sticker to have mine repaired to look like new. I fixed it, but it's only watertight, not pretty.
I'd recommend some sort of multi density EVA pad to protect the area where the mast or boom head is likely to strike, at least at first until you get dialed in on "Serenity sailing".
Besides, you think you are getting the Serenity for very light winds (probably < 12 knots) but I&#39;ll bet that once you get it you&#39;ll "push it&#39;s limits" and probably sail it up to around 20 knots, just to "explore" what that&#39;s like.
Hope this helps,
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Old 11th May 2007, 09:08 AM   #20
Jay
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Default RE: Serenity questions

Roger, thanks for that input. Great advice as always. Sorry to hear about your board damage. That&#39;s a shame for such a beautiful board. The tiki sticker is a great idea to cover it though.

I was going to put on a mast and a boom pad, thinking that would be enough but your idea of putting on some additional padding on the deck (at least temporarily) is a very good idea.

Do you know where I could buy the multi density foam?

I would prefer to put on such a pad in a totally removable way such as using clear silicone. Do you know if that part of the deck is rough (non-skid)? If smooth, then silicone would come off completely (otherwise maybe not). Do you have any other tricks for temporary adhesion?

Regarding sails, I was going to use Retros which I currently own (great sails). I&#39;m curious if you have any thoughts on how well the Huckers would work on this board? For example, I would think that a 6.6 Hucker would have tons of low end power and deliver the pull of a 7.5 Retro at the weight of a the weight of a 6.5 Retro. Have you ever trided it?

Jay
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