[Rhodes22-list] IMF "Reefing"

Sat Feb 17 10:51:09 EST 2007

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
>>>>>>
>>>>>>             
>>>>> __________________________________________________
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>>>>>           
>>>> _________________________________________________________________
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