[Rhodes22-list] IMF "Reefing"

Sun Feb 18 08:08:14 EST 2007

Bill, First as you know I do like IMF....  My original post stated you may 
have to reef sooner with IMF than standard. I wasn't really commenting about 
reefing sail shape or configurations.

One thing you need to consider is the cut of the sails unfurled and/or 
reefed. This is just important as the size. To my eye it looks like the 
belly on most IMF sails (ours included) is higher than standard main and 
perhaps a little further aft. With standard main you can further tweak with 
downhaul, halyard, and cunningham controls.

Also my boat likes a little heel and in light air I sit on lee side to 
create heel....and I go faster.

Wally

>From: Bill Effros <bill at effros.com>
>Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>Subject: Re: [Rhodes22-list] IMF "Reefing"
>Date: Sat, 17 Feb 2007 10:51:09 -0500
>
>Jim,
>
>I think you must add the optimal heeling angle to your equations.
>
>Since the R-22 is designed for 0 degree angle of heel, none of the weight 
>aloft matters to the angle of heel, whether a standard or an IMF is 
>deployed.
>
>With a 175 Genny the boat has so much more sail than it needs that it can 
>always reach hull speed in 10 kts. of wind--the only significant variable 
>is the skill of the captain.
>
>At 0-5 degrees of heel it is possible to bring the boat on plane.  As the 
>heel becomes greater I don't believe you can make the boat plane--at least 
>I've never heard of anyone doing it while heeled over.
>
>Bill Effros
>
>Jim Connolly wrote:
>>It seems to me that the difference between IMF and conventional from a
>>weight distribution standpoint is two fold:
>>
>>1.  The furling tube which is negligible and the weight of the mast
>>extrusion, heavier than standard.  Both of these are fixed weights (fixed
>>height above deck with the mast raised in sailing position) and can be
>>approximated by a weight "x" at the midpoint of the mast (i.e., center of
>>gravity or CG).
>>
>>2.  The weight of the sail (less than conventional, because it is 
>>smaller).
>>Since it reefs and furls on a vertical roller, the CG of the sail also 
>>stays
>>at the same height above the deck.  The center of effort (CE) of the 
>>furling
>>sail will move down and forward as the sail rolls into the mast.
>>
>>Net effect, furling the IMF lowers the center of effort and not the center
>>of gravity of the mast and sail combination, while furling the 
>>conventional
>>sail lowers both the CG and CE.  The CG of the conventional mast/sail
>>assembly is lowered by the weight of the sail, which is not likely a
>>significant part of the whole.
>>
>>It seems then to come down to the additional weight of the IMF assembly 
>>with
>>sail vs. the conventional mast and sail.  I don't know this, but I am sure
>>somebody here does.  Likely windage of the thicker mast extrusion might be 
>>a
>>factor in some wind conditions.
>>
>>For me, convenience trumps all.
>>
>>Jim Connolly
>>s/v Inisheer
>>'85 recycled '03
>>
>>-----Original Message-----
>>From: rhodes22-list-bounces at rhodes22.org
>>[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Bill Effros
>>Sent: Saturday, February 17, 2007 9:55 AM
>>To: The Rhodes 22 mail list
>>Subject: [Rhodes22-list] IMF "Reefing"
>>
>>Wally,
>>
>>Comparing "reefing" on standard sails vs. IMF sails is very hard to do 
>>when
>>discussing among sailors some of whom have never even seen an IMF.
>>
>>"Reef Points" result in noticeable changes in sail size. The IMF is
>>infinitely adjustable. I often adjust my sail in increments of 5% of total
>>sail size. I suspect most IMF sailors change the size of their sails 
>>instead
>>of using the traveler. We don't think of it as "reefing" -- it is an 
>>adjustment the sailor can quickly make in response to changing
>>conditions.
>>
>>The extra weight of the mast is insignificant. Remember that your sail is
>>larger, adding weight aloft compared to the smaller IMF sail. But, since 
>>the
>>boat is designed to be sailed upright, and can easily be trimmed to sail
>>upright, the difference in performance due to weight is probably no 
>>greater
>>in an IMF boat than the difference of carrying an extra bottle of rum. Or
>>not.
>>
>>I carry my extra sail on the Genoa instead of the main sail. Both are
>>infinitely adjustable while single handing. When conditions change, I 
>>change
>>the set of my sails, all by myself, so easily that even a lazy sailor will
>>do it.
>>
>>I think the biggest surprise about the IMF is how well it works
>>mechanically. The sail and mast are made for each other. There is no
>>compromise here, and it is easy to extend and retract the sail under any
>>conditions. My wife enjoys doing it.
>>
>>Our harbor is busy on weekends with a very narrow neck, rocks all over the
>>place, and a 10 foot tidal variation every 6 hours. It is irresponsible to
>>sail into the harbor if you've got a motor, and most experienced larger 
>>boat
>>sailors take their sails down just outside the neck, and motor to their
>>moorings. We turn on the motor and don't even stop while we retract our
>>sails. When my wife sees other wives trying to control flopping sails 
>>inside
>>lazy jacks she shakes her head in disbelief. When other wives see my wife
>>roll up our sail they ask their husbands why they don't have sails like
>>ours.
>>
>>Bill Effros
>>
>>
>>
>>
>>
>>TN Rhodey wrote:
>>
>>>Bill,
>>>
>>>Well I may be wrong here .....I guess it would depend upon how much 
>>>smaller the sail is verses the extra weight of mast. Way back when (on 
>>>the sailnet list) there was discussion about this. In my opinion even if 
>>>the mast weighed the same you still might need to reef sooner with IMF. 
>>>Pure speculation on my part and I will admit I may be totally wrong.
>>>
>>>The R22 is small enough to be quite sensitive to subtle changes in weight 
>>>and trim adjustments. You pay a price with IMF in mast weight, sail cut, 
>>>no downhaul, no cunnungham, no battens (except for the new rev). If you 
>>>know how to use all these controls you can create a much flatter sail. 
>>>You would be surprised at the difference adding a vang made even with 
>>>IMF. I could still flatten the sail enough to make a big difference 
>>>...sailing much flatter, fast, and higher into the wind.
>>>
>>>Everything is a trade off and for me the pros for IMF are well worth any 
>>>cons.
>>>
>>>
>>>Wally
>>>
>>>
>>>
>>>>From: Bill Effros <bill at effros.com>
>>>>Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>>>>To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>>>>Subject: Re: [Rhodes22-list] Harken Lazy Jack
>>>>Date: Fri, 16 Feb 2007 09:02:30 -0500
>>>>
>>>>Wally,
>>>>
>>>>Why would a smaller sail need to reef sooner?
>>>>
>>>>Bill Effros
>>>>
>>>>TN Rhodey wrote:
>>>>
>>>>>Joe, There are some performance trade offs with IMF. The sail is 
>>>>>smaller and I would think an IMF R22 would need to reef sooner but I am 
>>>>>just guessing. That extra weight aloft must have some effect on 
>>>>>balance.
>>>>>
>>>>>Wally
>>>>>
>>>>>
>>>>>>From: Joseph Hadzima <josef508 at yahoo.com>
>>>>>>Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>>>>>>To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>>>>>>Subject: Re: [Rhodes22-list] Harken Lazy Jack
>>>>>>Date: Thu, 15 Feb 2007 16:45:37 -0800 (PST)
>>>>>>
>>>>>>I've seen some other cool sail systems, some with sail covers so you 
>>>>>>only need to zip it closed. Several replace the slot in the main with 
>>>>>>a track system so even a kid could hoist the main, and it drops into 
>>>>>>right into the sail cover.
>>>>>>
>>>>>>A BIG advantage of the IMF (I believe) is the unlimited reef points. 
>>>>>>Another is that is remains protected in the mast during transport.
>>>>>>
>>>>>>I've only heard one mild complaint that the IMF mast is thicker, and 
>>>>>>thus hinders pointing performance a little, but like Stan says there 
>>>>>>are trade-offs ... unlimited easy to set reef points, or slightly 
>>>>>>better pointing with the possibility you'd need to bring down the main 
>>>>>>completely because you couldn't depower enough.
>>>>>>
>>>>>>
>>>>>>And I only had a minor problem with lazy Jacks where one of the lines 
>>>>>>got wrapped around part of the sail, and we had to lower and raise it 
>>>>>>again. But this was aboard a 65 foot Schooner with gaft. So it was a 
>>>>>>little more trouble than if it was a Rhodes with lazy jacks :-)
>>>>>>
>>>>>>Speaking of the A28 video ... I like the piston powered Hoyt Jib boom 
>>>>>>for down wind sailing .. very nice feature.
>>>>>>Notice it's a working Jib and NOT 175 gennoa!
>>>>>>
>>>>>>
>>>>>>--- "Michael D. Weisner" <mweisner at ebsmed.com> wrote:
>>>>>>
>>>>>>
>>>>>>>While viewing the AE28 video, I was impressed with the ease with 
>>>>>>>which the owner was handling the main. He was using a Harken Lazy 
>>>>>>>Jack system (installation manual at
>>>>>>>http://www.harken.com/pdf/4058.pdf.) At West Marine, the small Harken 
>>>>>>>Lazy Jack is about $200.
>>>>>>>
>>>>>>>Has anyone ever used the Harken Lazy Jack on an R22 main sail? Does 
>>>>>>>it interfere with boom movement? Does it jam easily?
>>>>>>>
>>>>>>>I know, with IMF, you have no need for it. I still haven't been able 
>>>>>>>to justify the cost of the new IMF mast & hardware on our R22.
>>>>>>>
>>>>>>>I was just thinking that the Lazy Jack looked interesting. Maybe run 
>>>>>>>the control lines (downhaul &
>>>>>>>halyard) back to the front of the cockpit, next to the pop-top, 
>>>>>>>opposite to Genoa furling line. Comments?
>>>>>>>
>>>>>>>
>>>>>>>Mike
>>>>>>>s/v Shanghai'd Summer ('81)
>>>>>>>__________________________________________________
>>>>>>>Use Rhodes22-list at rhodes22.org, Help?
>>>>>>>www.rhodes22.org/list
>>>>>>>
>>>>>>>
>>>>>>__________________________________________________
>>>>>>Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>>>>>>
>>>>>_________________________________________________________________
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>>>>>
>>>>>__________________________________________________
>>>>>Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>>>>>
>>>>>
>>>>__________________________________________________
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>>>>
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