[Rhodes22-list] Go Faster

Wed Oct 13 19:29:28 EDT 2021

Hi Lee,

It all depends if your genoa size is > 100% .  If the genoa is greater than 100%; then, it must go outside of the spreader.  This means the sheets run outside of the lifelines.  The maximum you can trim the sail is such that the windward side of the sail is just off the tip of the spreader.  You don’t want to trim it in any tighter because the spreader tip will damage the sail in pretty short order.  That’s where the term “close hauled” come from – you have hauled or trimmed the sail as close to the spreader tip as you dare.

If the genoa is < 100%; then you would switch to the inboard genoa tracks that run along the side decks.  Now the foresail can be trimmed in tighter, with the limit usually being rubbing up against the forward lower sidestay.

On a beat or a close reach, the genoa usually operates in cleaner, faster air vs the mainsail.  Since the thrust generated by a sail goes up as the [wind speed]^2, think of your genoa as the primary engine.  That’s why your boat went a little faster when you put out more genoa.  Despite the name, the mainsail’s primary function is to balance the sailplan so the helm is close to neutral or even with a little lee helm.

The Rhodes 22 is unusual among production boats in that it is possible to adjust the feel of the helm from lee to neutral to weather.  Most boats have built-in weather helm because it is thought to be safer and you are stuck with it.

Because of the slot effect, it is not desirable to run the genoa and the mainsail at the same angle of attack vs the wind.  In general, you want to establish your course 1st, then trim the genoa, and finally the mainsail.  The optimum mainsail trim will include slot effect interactions from the genoa.

Roger Pihlaja
ASM T767

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows

From: Lee Kuhn<mailto:lvjkuhn at gmail.com>
Sent: Wednesday, October 13, 2021 5:54 PM
To: The Rhodes 22 Email List<mailto:rhodes22-list at rhodes22.org>
Subject: Re: [Rhodes22-list] Go Faster

Roger,

See attached.  When sailing on a close reach I typically balance the main
and Genoa so the helm is pretty neutral, but I've found that I can
sometimes go faster if I put out more Genoa which gives the boat lee helm.
Does that make sense?

On boats other than the Rhodes, can't you sail closest to the wind when
your sheets are pulled as tight as possible?  To have the angle of attack
hit both sails evenly on our boats, wouldn't you need to run the Genoa
sheets between the mast and inside shroud?

Thanks.

Lee

On Wed, Oct 13, 2021 at 2:05 PM ROGER PIHLAJA <roger_pihlaja at msn.com> wrote:

> Hi All,
>
> The Rhodes 22 sails fastest and points highest if it is sailed with as
> little heel as possible and a slightly bow down fore/aft trim.
>
> The shape of the wetted surface of the hull becomes very asymmetric as the
> angle of heel increases.  Without going into the physics, this asymmetry
> tends to increase weather helm.  It also adds lots more drag with
> relatively little increase in lift to windward.  So, the hot setup is to
> sail as upright as possible.  Note, because of the tendency to increase
> weather helm as the boat heels over, it is desirable to have as much sail
> area as possible in the genoa.  This strategy keeps the center of effort
> (Ce) of the sailplan ahead of the center of lateral resistance (Cr) of the
> hull.  Adjust your IMF mainsail area to balance the helm while keeping the
> genoa area as big as possible for the conditions.  Use your genoa track
> lead position and backstay tension adjuster to adjust the shape of the
> genoa for the conditions.  Be ready to dump the mainsail first in gusts,
> followed by the genoa if necessary to keep the boat on her lines.  I like
> to dump the traveler to leeward; but, some people prefer to use the
> mainsheet.  My experience is the traveler responds faster and keeps the
> mainsail shape closer to optimum.  After the gust has past, the traveler
> allows you to trim the mainsail back in and working faster than the
> mainsheet.  If the traveler doesn’t dump enough wind; then, you can dump
> some genoa sheet.
>
> The OEM standard roller furler doesn’t keep a good sail shape beyond the
> 1st few turns of the furling drum.  It loses luff tension and the point of
> maximum draft in the genoa moves too far aft.  This is true even if you
> move the genoa sheet lead position forward on the track.  ( As you should
> )  The resulting poor sail shape will dramatically affect your ability to
> point to windward.  It also narrows the “groove” - the angle of attack
> between luffing and stalling the genoa, thus making the helmsman’s job more
> difficult. Therefore, you want to fly a genoa that is matched to your
> conditions.  That way, you will be able to fly it fully unfurled most of
> the time.  For your conditions, it sounds like the 130% genoa is the best
> compromise.
>
> You need a slight bow down trim because the hull’s wetted surface aft of
> the fixed keel will start to act like a set of landing flaps on an
> airplane. There is so much wetted surface back there; that, the resulting
> drag is huge.  A slight bow down trim allows the flow to smoothly exit the
> stern with minimal drag.  However, be careful with too much bow down trim
> because you still need enough floatation and freeboard in the bow to be
> able to punch thru waves.  If the bow should happen to submarine; then,
> you’ve set yourself up to pitch pole.  That’s nearly always the start of a
> bad day on the water!
>
> There is also some adjustment possible in the fore/aft rake angle of the
> mast.  Increasing the rake angle aft increases weather helm.  Since we are
> trying to decrease weather helm, we want to adjust the mast rake angle to
> give neutral helm or even a slight lee helm under light air.  Note, that
> this will make the boat’s steering less intuitive for a novice helmsman.
> But, we are talking about a racing setup here and presumably an experienced
> helmsman.  Between the mast rake angle and the genoa/mainsail area
> distribution, you want the boat to have virtually no tendency to round up
> until the leeward rail is in the water.  This will keep you climbing to
> windward as much as possible.
>
> Note that these adjustments are counter to conventional sail rig tuning
> wisdom.  But, like Stan always says, “When it comes to the Rhodes 22, it
> pays to not listen to the experts!”
>
> If they have assigned you a PHRF rating of => ~260 sec/nm, your bottom is
> clean, the rig is adjusted properly, and your sails are in good condition;
> then, your poor results are on you, not the boat.
>
> Roger Pihlaja
> S/V Dynamic Equilibrium
>
> Sent from my iPhone
>
> > On Oct 13, 2021, at 11:57 AM, Rick Lange <sloopblueheron at gmail.com>
> wrote:
> >
> > Hi Jeff,
> >
> > I respectfully disagree with much of what you said about weight on the
> > boat.
> >
> > The bow anchor and other weight forward, like the water tank, help with
> > pointing if you have IMF.  In winds 15kt+, two crew forward on the rail
> are
> > needed to keep the boat flat at all points of sail.  Reduce crew to
> minimum
> > allowed below 10kt.
> >
> > Regards,
> >
> > Rick Lange
> >
> >
> >> On Tue, Oct 12, 2021 at 6:44 PM Jeff Smith Photo <
> jeffsmithphoto at gmail.com>
> >> wrote:
> >>
> >> For Racing.
> >> Keep crew amidships and out of the cockpit. Even the helms person
> should be
> >> as forward as possible. If racing, take everything non essential off the
> >> boat. Especially in the ends. Forward cushions can usually be removed.
> >> Check your PHRF rules; how many anchors and rhodes are required? For
> >> successful racers all weight aboard is the enemy! Especially in the
> ends.
> >> Think about your bow mounted anchor and the rhode in the lazarette.
> Success
> >> in racing  involves a ton of small improvements.
> >>
> >> Best Regards
> >> Jeff Smith
> >>
> https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.http%2F%2FJeffSmithPhoto.Net&data=04%7C01%7C%7C0a52e2a84dc74b6d3d4008d98e940ff1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637697588859362564%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Fe0lr9vueOSjdphfxORC0Uc0wS3cojmwxVlF91Wb%2BN0%3D&reserved=0
> >> 732-236-1368
> >>
>
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