[Rhodes22-list] Hull Speed
Roger K. Pihlaja
rhodes22-list@rhodes22.org
Fri, 26 Jul 2002 16:05:11 -0400
Paul,
You bet! Especially sailing close hauled, the pop top is like a big
parachute that adds no thrust & lots of drag & heeling. Try sailing close
hauled with it up & down. I too cannot use my boom vang with the pop top
up. So, that's just another reason to lower it when you want to get serious
about sailing!
Roger Pihlaja
S/V Dynamic Equilibrium
----- Original Message -----
From: "Paul Grandholm" <PAUL@mi.chtechnology.com>
To: <rhodes22-list@rhodes22.org>
Sent: Friday, July 26, 2002 1:11 PM
Subject: RE: [Rhodes22-list] Hull Speed
> Roger,
>
> Do I understand you correctly that just by putting my pop top down
> (even with the boom in the upper position), I can increase my speed. I'm
> usually only cruising but there is one other boat in our harbor and when
> we're both out, the race is on! We're reasonably evenly matched, so
> something like that could give me a big edge.
>
> Thanks,
> Paul
> >
> >Steve,
> >
> >With a 20 foot waterline length, figure hull speed is 5.25 knots on a
Rhodes
> >22.
> >
> >Remember that Dynamic Equilibrium is a 1976 Rhodes 22. It's lighter &
has
> >the old style high aspect ratio centerboard vs. current Rhodes 22. Also
> >remember that we have a very roachy fully battened mainsail, a 150% genoa
> >made of Bainbridge Cruise-Lam (tm) composite sailcloth on a Harken unit 0
> >roller furler, & we're rigged to fly a tri-radial spinnaker. With the
> >current Rhodes 22 configuration & your individual driving habits, your
> >mileage may vary.
> >
> >In flat water, Dynamic Equilibrium can approach hull speed 1st on a broad
> >reach with a wind speed of about 8-10 knots while flying the tri-radial
> >spinnaker. Close reaching with the tri-radial spinnaker requires about
9-11
> >knots of wind to achieve hull speed. Our standard rig achieves hull
speed
> >on a broad or beam reach at about 11-13 knots of wind & about 12-14 knots
of
> >wind sailing close hauled.
> >
> >If you read my story about the weekend cruise on Saginaw Bay with my son,
> >Gary; then, you will note that by exploiting waves & surfing, the Rhodes
22
> >can significantly exceed its theoretical hull speed. This cut our
transit
> >time across Saginaw Bay (27 nm) by 20-25%. However, note that this
> >intrinsically involves sailing the boat "actively". It's great fun, but
> >demands concentration, experience, and close cooperation between the
> >helmsman & sail trimmers.
> >
> >It can be done with the boom in the upper position. We sail with the
boom
> >in the upper position up to about 15 knots of wind speed. On Dynamic
> >Equilibrium, lowering the boom is triggered by having to dump the
mainsail
> >traveler to leeward more often than about once per minute due to wind
> >direction shifts &/or wind gusts. Naturally, this trigger point is a
> >function of wind speed/direction, but is also affected by crew weight,
> >number of crew, & willingness of the crew to function as "live ballast".
In
> >passive mode (i.e. if you don't want to sail the boat "actively"), you
> >should lower the boom at about 8-10 knots wind speed.
> >
> >However, sailing with the pop top up &/or the bimini top is just a big
drag
> >& should be avoided if you care about going fast. If the order of the
day
> >is comfort, elegance, & entertaining friends out on the water in light
air;
> >then, by all means sail with the pop top & bimini top up. We do it all
the
> >time. The speed penalty is greatest sailing close hauled. With a wind
> >speed of about 10 knots, sailing close hauled with the pop top up will
cost
> >you about 1 knot of speed & increase the angle of heel by 5-10 degrees.
> >Under the same conditions & close hauled point of sail, the bimini top
costs
> >about 2 knots & increases the angle of heel by 15-20 degrees. As you can
> >see, sail close hauled with both the pop top & bimini top up & you can
end
> >up going pretty slow, heeled way over, with a huge weather helm.
Therefore,
> >try not to sail close hauled with the pop top &/or bimini top up. The
> >speed/heeling penalty from the pop top &/or bimini top is not so bad on a
> >beam or broad reach & almost negligible on a run.
> >
> >I've only sailed on IMF equipped Rhodes 22's in light air. So, I can't
> >comment on what conditions would be required for one of the new boats to
> >surf. I would think a big tri-radial spinnaker would be the sure cure
for
> >any inefficiency in the standard rig. But tri-radial spinnakers can be
> >tricky to sail, especially for a novice - the very antithesis of the way
you
> >have your boat set up.
> >
> >Steve, I hope this discussion gives you some idea of the trade-offs
involved
> >& the order of magnitude of the effects.
> >
> >Roger Pihlaja
> >S/V Dynamic Equilibrium
> >
> >----- Original Message -----
> >From: "Steve Alm" <salm@mn.rr.com>
> >To: <rhodes22-list@rhodes22.org>
> >Sent: Friday, July 26, 2002 5:41 AM
> >Subject: [Rhodes22-list] Hull Speed
> >
> >
> >> I've owned my R22 for less than a year and I'm still learning a lot
about
> >> the boat and still learning a lot about sailing. First, what is the
hull
> >> speed of the R22? I know there's a standard formula to calculate this
but
> >I
> >> can't seem to find it.
> >>
> >> Second, I have the IMF and the 175% Doyle genny. What's the
approximate
> >> minimum wind speed and optimum point of sail necessary to achieve hull
> >speed
> >> under full sail? I'm guessing a beam reach with winds at about 14-16.
> >> Would it be easier with the boom in the down ("first reef") position?
Can
> >> it be done safely with the boom in the up position? Some of you have
said
> >> that you ALWAYS have the boom down unless it's very light air. (I
prefer
> >to
> >> sail with the pop top up.)
> >>
> >> Third, without the standard main or a foam luff pad, is it possible for
me
> >> to pop over my bow wave and exceed hull speed? If so, under what
> >conditions
> >> could I safely do that?
> >>
> >> Sorry to sound like such a novice...I yam what I yam. I'd like to take
> >some
> >> lessons some day but in the mean time, I'd really appreciate a few
sailing
> >> tips from you experts.
> >>
> >> Anybody?
> >>
> >> Slim
> >>
> >> _______________________________________
> >> Subscribers, send mail to this address Rhodes22-list@rhodes22.org
> >> To change your options or unsubscribe from the list click on this link
> >> http://www.rhodes22.org/mailman/listinfo/rhodes22-list Check out our
> >> FAQ pages at http://www.geocities.com/blew_skies/topics.html
> >> http://www.sailnet.com/ -Where Sailors Get It! http://www.rhodes22.org
> >>
> >
> >_______________________________________
> >Subscribers, send mail to this address Rhodes22-list@rhodes22.org
> >To change your options or unsubscribe from the list click on this link
> >http://www.rhodes22.org/mailman/listinfo/rhodes22-list Check out our
> >FAQ pages at http://www.geocities.com/blew_skies/topics.html
> >http://www.sailnet.com/ -Where Sailors Get It! http://www.rhodes22.org
>
>
>
> ========================
> Paul Grandholm
> C&H Technology
> GrandPower Components Div.
> ========================
>
> _______________________________________
> Subscribers, send mail to this address Rhodes22-list@rhodes22.org
> To change your options or unsubscribe from the list click on this link
> http://www.rhodes22.org/mailman/listinfo/rhodes22-list Check out our
> FAQ pages at http://www.geocities.com/blew_skies/topics.html
> http://www.sailnet.com/ -Where Sailors Get It! http://www.rhodes22.org
>