Wess

Polars for I550? Any decent data set for VMG beating or running?

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Anybody got a good set of polars for an I550?  Or any decent data set?  I am mostly interested in the I550's VMG beating and running numbers.

Got a popcorn and beer match upcoming; my Laser vs friend's I550. Yea, yea, I know what PHRF or Portsmouth ratings would say but I think I got a chance for various reasons.  Anyway, just trying get a data based handle on how steep a climb this will be. Truth is I win either way but that is a longer story and regardless I want to crush him on the water. :P:ph34r:

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Every sail and rig is a different choice. So are the foils and rudders, for that matter... I think the laser would out point the 550, downwind the 550 has more sail area. Let us know how it turns out!

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Light air the Laser will be tougher to beat with a bad start but medium to heavier air the i55O should walk away.

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Thanks for the responses thus far

But yo, yo, yo @couchsurfer, @Gladiator Sailing and the rest of you left coast I550 dudes.  Little help here.  Give me your I550 tacking/gybing angles, and targets up and down wind VMG sailing in 5-15 knots of breeze.  I got a tough task ahead of me.  Just trying to figure out how tough.  I550 owner specified breeze >4 and <15.  WW/LW short course w 3 laps. Oh and at what wind sped in flat water you do guys start planing on typical VMG running angles? Debating if I need to break out my secret weapons for the Laser.

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...sorry Wess,, can't help much.  I'm much too much a seat of the pants sailor to have any idea of such technical details.  :mellow:

You're trying to design sails for a customer?   Clues I can share........

   Melges 20 sails seem to be a good cut, depending on the mast used.    A 49er chute, much smaller than most chutes on the westcoast seems to have a major handling and flying advantage.... in light winds, it flies more readily while others are hanging limp.   In stronger winds, it handles well,,quite an advantage when sailing 2up, often leaving the boat upright and moving while others are...on their ear.    I use one 49er chute as 'stock' in heavy wind,, and one shortened ~2 1/2' from the middle.

 

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14 hours ago, Lock said:

Light air the Laser will be tougher to beat with a bad start but medium to heavier air the i55O should walk away.

Humm, I tend to think most anything is faster than an 18' shoebox upwind.

....and I'd like to see you in an i550 'walk away' from me in a laser in 25 to 45   :rolleyes:

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Light air the Laser will be tougher to beat with a bad start but medium to heavier air the i55O should walk away.

I think Lock has been sailing one of the PDX i550 boats as long as Gladiator. Part of the original group of builders there. Correct me if I am wrong. I know Couch has the carbon offset up for sale, and Gladiator may have sold his boat as well. Sounds like wind strength will be the deciding factor. Shoebox couch? Sorry it isn't a mini scow....

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Humm, I tend to think most anything is faster than an 18' shoebox upwind.

....and I'd like to see you in an i550 'walk away' from me in a laser in 25 to 45   :rolleyes:

Couch and others.... am I misunderstanding?  What is with the hating on the I550 (and everybody selling??)?  The I550 I am racing against is not mine (belongs to a friend) but seems like a great design.  Good enough for the Gougeons to build and sail one - says enough for me!!

Given its 18 feet - shoebox or not - its got 5 feet of waterline length on my Laser (that I am racing his I550 with) and waterline rules upwind. Points to the I550. The Laser might have better tacking angles but from what I have seen in videos the I550 (in 7-10) looks to be about 1 knots faster than the Laser.  Downwind I suspect the Laser will sail deeper (at optimal VMG) but I am pretty sure the I550 is getting up on plane in far less breeze.

And Couch if you can keep a Laser upright in downwind legs when its blowing "25-45" you are a better sailor than me.    

I suspect the I550 is going to crush me but I will not go down with a fight.  This is actually more than a battle of boats.  For various reasons its a battle of design, build (re-build), and sailing skills. Si I have a chance on many levels and I do still have an additional secret weapon.

But dang I am surprised that nobody has any numbers/targets.

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Glad and his wife went cruising the world.

The P'land boat for sale was an extra build.

I'm trying to divest of large hiking boats since knee surgery. If I race a boat with straps, I'm gonna hike, and torque steering that size of boat is not a good plan.   Most 550 sailors come from keelboats, don't really hike anyways,, so not a problem for most.

i550's ARE a sweet boat, and yah,, I was exaggerating a bit about upwind speed, but not a lot.   First time racing, I was rather shocked at having J24's passing, I'd haveta say.   Downwind?...great fun....my claim to stay ahead in a laser relies on boat handling above 20 knots,, 550 would tromp a laser downwind, IF it keeps the hull under the rig.

And yup, it sounds like I'm a better sailor than you.  What can I say!?  :mellow:.    It's likely only 'memory lane' that my only worry in 45 is whether the mast blows out or not on a laser, used to have a reinforced topsection and Aussie bottom section for those daze.   Just got back from 2 months in Baja with the laser, my knee flexibility and crunching up in light winds is a near impossible match, but I'm still 6'3",, and still have fun in a breeze when I can stretch out,, just have to remember to ease the vang for tacks, just like back in Finn days....gets rather ugly when I forget.   :unsure:

 

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Original vpp by Beckwith

i550vpp.pdf

6923-001.jpg

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If I remember a conversation with Beckwith there was comment about the computer at that time was not up to the task of predicting planing behavior or speeds. 

 

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If I remember a conversation with Beckwith there was comment about the computer at that time was not up to the task of predicting planing behavior or speeds. 

 

...that'd depend a LOT on the seaway condition.   :mellow:

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...that'd depend a LOT on the seaway condition.   :mellow:

what? we don't live in a perfect world?

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13 hours ago, timber said:

what? we don't live in a perfect world?

I spose not, or we'd all be helming Volvo 60's  :mellow:

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11 hours ago, couchsurfer said:

I spose not, or we'd all be helming Volvo 60's  :mellow:

In perfect hawaiian conditions?  I'd like that

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On 3/23/2018 at 7:45 PM, timber said:

Original vpp by Beckwith

i550vpp.pdf

6923-001.jpg

Thank you @timber.  That is a useful data set for any I550 owner, at least as targets though it does appear there are perhaps some errors (they are replicated) in either the 6 or 8knot velocity tables if I am reading it correctly.

Either way comparing it to Laser polars, I look to be quite disadvantaged. Doubt planing conditions come into play as the I550 owner specified 5-15 knots of breeze and there are not much in terms of waves in the limited fetch of our W to E river and typical S breeze.  My hope was simply having more experience in the Laser than he and his crew would have in the I550 might give me an edge on the water.  There was also the question of if he could have his boat ready in time but my advantage there was just lost when my Laser returned home after a fun sail in breeze yesterday with quite a bit of damage and repairs needed.  The I550 owner's build/repair skills far exceed mine so I am now doubly disadvantaged but have not surrendered.  I shall source some West System and associated stuff, or if desperate and failing in my repair attempts, look to source a new Laser.  I will not give up the ship... err LASER!!

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Grasshopper, a few corrections:

- I never "specified" anything.  The so-called "NOR" was entirely your concoction, conceived and inked out of your deranged noggin.   

- Apparently, you recently tried to change the course configuration. Some folks have asked, "why" and figured it's to optimize the angles you'd want for the so-called "Laser."

- You're toast.

Thanks for this kind opportunity to address these matters, and I wish you all a happy Monday (as if that's even remotely possible) 

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Sensei,

While my noggin is indeed deranged, and my steed broken and likely over-matched, the 3 lap ww/lw concept was indeed agreed by you, or some other more lovely and intelligent thing with access to your phone no?  And Sensei, it was you who taught us to watch the hips.  But you have fallen for the head fake.  While  I have recently explored and documented the fun of flying - it was on the bucket list and so had to be done - I would not bring that to our race.  It will be a class legal Laser (well as much as that is possible these days given the supply of spare part from LPE) with class legal foils! Come on you know I am an OD kinda guy!  The course change you reference was not to provide a more reachy, foiling friendly location.  Heck I will have a near impossible time beating your boat in a ww/lw race, never mind reaching. It was merely to move the rendezvous from mark A to the flashing red #10, but still run a 3 laps ww/lw, with your cheering section now able to enjoy my beat down while they drink beer and scotch while spectating from the community pier.  If you run it out at "A" I might still claim to have won even if I only sail 2 laps to your 3 and you would have no witnesses.

And, yes it is indeed an unhappy Monday given the repairs I must make.  I need not worry about your lack of knowledge re rule 14 even if you do catch me and could get the bow low enough to the water to hole me... this damn Laser is so old its self destructing faster than I can repair it.  T minus 39 and counting @BeerDidClam.  Now sadly it is me worrying about if I can be ready and/or not sink.

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I would like to think that drone footage will be shown on the evening news.

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The evening news would be boring @timber.  Nothing of interest for a while I am guessing. Suspect all there would be to see from both of us is fiberglass drying and sanding dust flying (at least from me)... and he would tell me to get a vacuum for the sander but I am cheap.

Hey Sir Clam, and while I may be toast as you say, anyone who has sailed Lola should know why  "mmmm toast" has special affinity for a certain group of pickle fork lovers. Free cross if you can ID and link the reason (I know, I know; you are going to say I will be so far behind you will not need the free cross).

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