Mast Rake

[Joust]

My boat has been set up with what i would call cosiderable mast rake

 

Does any one have a setting for mast rake say at 15Kts

 

I have used the settings from J boats to tune rigging but i dont believe the rake is correct

 

Regards

 

Joust

[Max]

These guys seem to know their stuff (I understand they are ex-elvstrom uk) :

http://www.ultimatesails.co.uk/sails/ultimate-sailing-guides/j92s-tuning-guide

ciao

max

--
You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.
To post to this group, send email to j92o...@googlegroups.com.
Visit this group at http://groups.google.com/group/j92owners?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.
 
 

[Joe Cooper]

1. Why do you not believe the rake info you have been using/given from J boats?
2. What is going on to make this suspicious for you?
3. Too much/not enough wx helm?
4. Speed problems?
5. Has something else been changed?
6. Has there been a sudden difference in the boat that can be attributed to something else-New sail etc?

Can you elaborate please?

In any event:

The Ultimate guys seem to have a complicated way to deal with rake.
A  couple of easier ways I have used.

1. With boat at rest in the water. hang a weight on the main halyard-Tool bag, gallon jug of water beer fuel etc. Let the halyard come to rest across the boom with the weight under the boom- the main halyard is being used as a plum bob.
when the halyard is steady measure from the point at which the halyard crosses the boom, forward to the aft side of the spar.

J boats in general seems to need lots of rake in my experience.
The number found above might be anywhere from 12-18 inches. This was the most common way to describe the rake to our sail designers when I worked for a sailmaker

Second method.
Simply attach a measuring tape to the jib halyard, (off the furler) and hoist. Cleat and apply tension to the halyard/tape and measure to an easily duplicate point on the boat. I would use the deck sheer at the bow. Don't know what this number ought to be though.

A third way is to do a similar measurement but using the main halyard and measuring to the transom. We used to measure the rake for Finn rigs this way.

In the end, the rake needs to be enough to give the boat a slight wx helm upwind in 12 knots true fully powered up.
Amount of rake will also change with wind speed, (main) sail design, rig tension and so on.
cheers
Coop

--
Joe Cooper

C: 401 965 6006
www.joecoopersailing.com

[RJA Armstrong]

What does your sail maker recommend for your particular sails?

Bob A

--

[Ragtime!]

The earlier posts have given the technically right answers but
generally, most J Boat designs have famously well-balanced helms. The
problem is, especially with the J/92, they don't point quite as well.
Thus the almost universal use of lots of rake, inducing weather helm
to improve pointing.

With the #1 genoa and a gust in light to moderate air, I still get lee
helm. Since I often race in heavier air and usually without crew
weight, I've compromised at mast butt full forward, but mast only
slightly aft of center (of hole) at the deck. My mains were then cut
for that, with zero pre-bend. Some owners start with a little pre-
bend but I wanted maximum backstay travel.

Since the 92S uses only small jibs you may need a bit less rake - but
I suspect not.

It was always easy to spot my J/33 in any harbor - it was the rig with
the most rake. North Sails (CT) set it up and they won KWRW, BIRW,
etc. multiple times with that boat, so I knew it was right. Seems to
be mostly true on the 92 as well.

[Grizzly]

The Ultimate J92S tuning guide is very helpful, thanks for posting it.  It is the first tuning guide I have ever seen published for the 92S, other than the old one posted by Jeff Johnstone after KWRW.

I notice that the Ultimate guide advises a change in headstay length of 0.05 metres (2 inches) between light and heavy air.  I think that changing headstay length by that amount might be difficult with the OE Harken furler mounted, although I have never tried it.  Anyone tried it and if so, can you tell us about the experience?

Grizzly

[Max]

12-18 inches rake seems far off from what we are using down here (Italy)

27-31 should be the proper range (for the 92S), corresponding to approx 3-3.5 deg inclination

for the classic 92, to keep the same inclination angle, the above numbers should be corrected (reduced) in proportion to the slightly shorter rig

max

www.furkolkjaaf.net

[Andy S]

Has anyone tried moving the mast butt farther forward than the factory base adjustment would allow?

[Andy Oeftering]

Yes.  I set my at maximum forward and have been happy with the results.  Unless your mast step bolts haven’t seized, getting those bolts to loosen will be your biggest challenge.  Ended up breaking one and retapping a new hole.  Recommend soaking bolts with PB Blaster or Liquid Wrench then tapping the bolt heads with a ball peen hammer BEFORE attempting loosening.  Repeat this process for a few days.  Then see if the bolts will loosen.

--

You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.
To post to this group, send email to j92o...@googlegroups.com.

Visit this group at https://groups.google.com/group/j92owners.
For more options, visit https://groups.google.com/d/optout.

[Andy S]

Andy O.  what do you mean max forward?  I was talking about drilling new holes in the beam so I could go even farther forward than the current step allows.  what's the distance from the main bulk head wall to the back of the mast?

Andy S.

[Andy Oeftering]

Well.. I suppose that’s one way to go max forward.  I’ll measure my rake. 

 

From: j92o...@googlegroups.com [mailto:j92o...@googlegroups.com] On Behalf Of Andy S
Sent: Tuesday, April 4, 2017 10:57 AM
To: J/92 Owners <j92o...@googlegroups.com>
Subject: [j92owners] Re: Mast Rake

 

Andy O.  what do you mean max forward?  I was talking about drilling new holes in the beam so I could go even farther forward than the current step allows.  what's the distance from the main bulk head wall to the back of the mast?

Andy S.

 

--

[furkolkjaaf]

Talking about "S" : what's your distance from mast to main bulkhead ? Mine is at 10 cm or 3.94". It's in its stock position (photo). The "S" doesn't seem to allow different positions. Has any "S" owner tried to move the must butt (drilling new holes ?).

[Sting]

Mine has definitely been moved forward quite a bit and we have a lot of rake:

Considering I didn't measure exactly the same, I'd estimate that we are around 6" (15.25 cm).   Id be interested to compare measurements such as forestay length as well.

[Massimo Polo]

Thanks Mark, that sounds interesting. 

I'll have a look to my headstay measurements toninght...and I'll share them.

cheers

max

--

You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/84bcdb1b-4852-44ea-9190-17dff15bbcd1o%40googlegroups.com.

[Philipp]

Good to see some talk about J/92s. :-)
The aft side of our mast sits at about 11cm from the bulkhead. Mast step has NOT been moved by us or the previous owners as far as I can see.

Looking forward to compare mast rake. Will measure next time when on the boat.

Cheers Phil

[furkolkjaaf]

So here is my headstay length : 12900 mm or 507.97". I'm also attaching a sketch (sorry for the comments in italian) showing where the 12900 mm are taken from.

In my mind this should be a medium-high rake, but not extreme (I have calculated it to be approximately 3.3°).

However, given that the mast butt has not been moved forward accordingly, I fear that headstay tension might result being a bit slack (and/or mast too much pre-bent), thus hampering pointing ability.

I think I'll have to experiment, moving mast butt forward...

[furkolkjaaf]

by the way, here is a picture of an extreme rake ... boat is a UFO 28 sport boat, rake from picture is in excess of 6° !

Il giorno lunedì 11 febbraio 2013 10:23:24 UTC+1, Joust ha scritto:

[Rich Craven]

Now that's rake! 😊 

--

You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/187db813-64d3-4271-9975-44eb782fb418o%40googlegroups.com.

[Rich Craven]

Now that's rake!

--

[Sting]

Furkolkjaaf - wow - how did you manage to get that headstay measurement with the stick up?   I was planning to do it the easy way by using this method from the Elvstrom guide:

"Take the Jib halyard to the top of the mast band at goosneck height, lock clutch off and swing the halyard to the forestay, mark the forestay where the halyard meets it. Measure down from the mark to the deck just behind forestay."

Base setting on the guide (12-16kts) is 1.92m for that last measurement.

To get an idea of how much rake is in my mast, here is a pic:

I'll try to get to the boat tomorrow to get a measurement.   My guess is that with more rake (and longer forestay), more shroud tension needs to be added to take out the same amount of headstay sag.    So far I have run with the Elvstrom numbers and it seems to do well.

[Massimo Polo]

Well, I am not that smart...actually I measured the length with the forestay laid on the ground after the mast was removed (for some work I had to do). I did use the Elvstrom procedure, and my set up seems in line with what you say. However the Elvstrom guideline does not seem to mention the mast butt... I tend to think that moving mast butt forward is better especially for light air conditions (that is what we frequently have here). Your rake seems higher than mine judging from the picture. My guess it's > 4° (I have 3.3°) that should be better for light airs. Just guessing !   :-)

max

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/21251c81-6f74-4fc0-a0d6-01652324967dn%40googlegroups.com.

[Mark Camilleri]

I went up the mast and held a tape measure to the foot of the head stay 

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/21251c81-6f74-4fc0-a0d6-01652324967dn%40googlegroups.com.

--

Mark Camilleri

00356 99404089

[Todd Aven]

Gravity and simple trigonometry give us an easy way to measure rake.

We already know "P", the length of the main luff, which is the hypotenuse of a triangle.  Suspend a bucket of water from the main halyard, measure the distance at the boom from the halyard to the mast ("D"), then apply the following calculation:

Rake in degrees = arcsin(D/P)

Cheers,
Todd

On 7/28/2020 7:46 AM, Massimo Polo wrote:

Well, I am not that smart...actually I measured the length with the forestay laid on the ground after the mast was removed (for some work I had to do). I did use the Elvstrom procedure, and my set up seems in line with what you say. However the Elvstrom guideline does not seem to mention the mast butt... I tend to think that moving mast butt forward is better especially for light air conditions (that is what we frequently have here). Your rake seems higher than mine judging from the picture. My guess it's > 4° (I have 3.3°) that should be better for light airs. Just guessing !   :-)

max

Il giorno mar 28 lug 2020 alle ore 03:29 Sting <mark.w...@gmail.com> ha scritto:

Furkolkjaaf - wow - how did you manage to get that headstay measurement with the stick up?   I was planning to do it the easy way by using this method from the Elvstrom guide:

"Take the Jib halyard to the top of the mast band at goosneck height, lock clutch off and swing the halyard to the forestay, mark the forestay where the halyard meets it. Measure down from the mark to the deck just behind forestay."

Base setting on the guide (12-16kts) is 1.92m for that last measurement.

To get an idea of how much rake is in my mast, here is a pic:

I'll try to get to the boat tomorrow to get a measurement.   My guess is that with more rake (and longer forestay), more shroud tension needs to be added to take out the same amount of headstay sag.    So far I have run with the Elvstrom numbers and it seems to do well.

On Monday, July 27, 2020 at 4:28:49 PM UTC-4 oldsa...@gmail.com wrote:

Now that's rake!

On Mon, Jul 27, 2020 at 9:02 PM furkolkjaaf <eliomas...@gmail.com> wrote:

by the way, here is a picture of an extreme rake ... boat is a UFO 28 sport boat, rake from picture is in excess of 6° !

Il giorno lunedì 11 febbraio 2013 10:23:24 UTC+1, Joust ha scritto:

My boat has been set up with what i would call cosiderable mast rake

 

Does any one have a setting for mast rake say at 15Kts

 

I have used the settings from J boats to tune rigging but i dont believe the rake is correct

 

Regards

 

Joust

--

You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/187db813-64d3-4271-9975-44eb782fb418o%40googlegroups.com.

--
You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/21251c81-6f74-4fc0-a0d6-01652324967dn%40googlegroups.com.

--
You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/CAMtH7wNzt5yiBcLwYByPXz%3D7qVnga99FGcsQLT%2BXb8sgdCvqqQ%40mail.gmail.com.

[Massimo Polo]

Indeed…

in my case D is about 72-75 cm (bucket wobbling around)…so 3.4 ° approx

ciao

max

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/fa0d91df-6224-fa5e-d618-ab921b0a3e28%40avenshaven.net.

[Phil]

Hi Todd.

Where do you store the beer for the measurement? In the front or in the back of the boat? ;-)

Anyway, here are some numbers I took on our boat yesterday. Since we are only into our second season with this boat I can't really say much about performance on these settings, but last year it didn't feel too bad for us. This year, with new standing rigging, we haven't had any chance to compete against any boat with this pandemic thing going on.

Mast step: see photo above, back of the mast sits at about 11cm from bulkhead.

Mast rake: took main halyard to band just above the gooseneck, then swung back and measured down to trailing edge of transom: 290cm

Headstay length: took jib halyard to band just above gooseneck, then swung forward to headstay and measured down to deck level (a bit vague with the fuller drum in the way): 192,5cm.

Shroud tension: measured with "Loose gauge PT2M". Uppers: 35 - Mids: 16 - Lowers: 22. 

I tried to get to something similar as the Elvström guide and the one from Jeff Johnstone from Key West. The mast seems quite straight at these settings without much, if any, prebend. 

I am aware that all the measurements above are not perfectly scientific, but I guess it's a start.

Looking forward to your numbers. :-)

Cheers. Phil

Am Dienstag, 28. Juli 2020 14:20:20 UTC+2 schrieb Thin Man #14:

Gravity and simple trigonometry give us an easy way to measure rake.

We already know "P", the length of the main luff, which is the hypotenuse of a triangle.  Suspend a bucket of water from the main halyard, measure the distance at the boom from the halyard to the mast ("D"), then apply the following calculation:

Rake in degrees = arcsin(D/P)

Cheers,
Todd

On 7/28/2020 7:46 AM, Massimo Polo wrote:

Well, I am not that smart...actually I measured the length with the forestay laid on the ground after the mast was removed (for some work I had to do). I did use the Elvstrom procedure, and my set up seems in line with what you say. However the Elvstrom guideline does not seem to mention the mast butt... I tend to think that moving mast butt forward is better especially for light air conditions (that is what we frequently have here). Your rake seems higher than mine judging from the picture. My guess it's > 4° (I have 3.3°) that should be better for light airs. Just guessing !   :-)

max

Il giorno mar 28 lug 2020 alle ore 03:29 Sting <mark....@gmail.com> ha scritto:

Furkolkjaaf - wow - how did you manage to get that headstay measurement with the stick up?   I was planning to do it the easy way by using this method from the Elvstrom guide:

"Take the Jib halyard to the top of the mast band at goosneck height, lock clutch off and swing the halyard to the forestay, mark the forestay where the halyard meets it. Measure down from the mark to the deck just behind forestay."

Base setting on the guide (12-16kts) is 1.92m for that last measurement.

To get an idea of how much rake is in my mast, here is a pic:

I'll try to get to the boat tomorrow to get a measurement.   My guess is that with more rake (and longer forestay), more shroud tension needs to be added to take out the same amount of headstay sag.    So far I have run with the Elvstrom numbers and it seems to do well.

On Monday, July 27, 2020 at 4:28:49 PM UTC-4 oldsa...@gmail.com wrote:

Now that's rake!

On Mon, Jul 27, 2020 at 9:02 PM furkolkjaaf <eliomas...@gmail.com> wrote:

by the way, here is a picture of an extreme rake ... boat is a UFO 28 sport boat, rake from picture is in excess of 6° !

Il giorno lunedì 11 febbraio 2013 10:23:24 UTC+1, Joust ha scritto:

My boat has been set up with what i would call cosiderable mast rake

 

Does any one have a setting for mast rake say at 15Kts

 

I have used the settings from J boats to tune rigging but i dont believe the rake is correct

 

Regards

 

Joust

--

You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/187db813-64d3-4271-9975-44eb782fb418o%40googlegroups.com.

--
You received this message because you are subscribed to the Google Groups "J/92 Owners" group.

To unsubscribe from this group and stop receiving emails from it, send an email to j92o...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/21251c81-6f74-4fc0-a0d6-01652324967dn%40googlegroups.com.

--
You received this message because you are subscribed to the Google Groups "J/92 Owners" group.

To unsubscribe from this group and stop receiving emails from it, send an email to j92o...@googlegroups.com.

[rob...@epogue.com]

Todd's J/92 is in my hands now. Mast rake is 3.6 degrees (D=29").

Robert

[Joe Cooper]

Ladies and gentlemen,

As a frame of reference folks, almost all sailmakers (including this one) measure rake as follows:

1. Set up the main halyard as a plum bob.
   
2. Take the main halyard, 
   
3. place a weight, cooler of beers, tool bag etc on the shackle,
   
4. lower the weight till it is underneath, and clear of, the boom. (Secure the halyard)
   
5. Let the halyard come to rest with weight under boom.
   

Rake is the distance between the aft face of the mast and where the halyard crosses the top surface of the boom.

Cheers.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/fffd216a-23d3-4f3b-8853-9cf8d6ae1e1cn%40googlegroups.com.

--

Joe Cooper

Bushra...@gmail.com

C: 401 965 6006

[Phil]

Hi Joe.

Measuring rake this way you really need to have an empty boat or define weight distribution. Having a few sails (or beer) in the front or the back of the boat can make quite a difference if you think about how far the masttop moves if anything moves on the boat. Don't you agree?

In the Melges24 class, where forestay length is easily adjusted and hugely contributes to being able to hold your lane off the start line, they measure and compare mast rake as I explained above (main halyard to band above gooseneck, lock halyard, then measure distance to trailing edge on the transom).

Having said that, a couple of weeks ago we measured our headstay length with the mast down. pin to pin was 12,79m

Would be interested to know of a few others now that most boats might be in winter mode with the stick down? 

Cheers.

Phil

[bushra...@gmail.com]

Phil,

Giday mate.

Ah yes, all you note is true.

Having sailed Finns for way too many years, the masthead to transom is the default method. The plum bob method is widely used in the sail measuring or rather the boat measuring for sails game (mine) to get a data point. IS it Gospel, no but it is a data point. All you describe is true and has greater impact, the smaller (lighter disp.) the boat of course.

Happy Turkey Day all.

C

 

From: j92o...@googlegroups.com <j92o...@googlegroups.com> On Behalf Of Phil
Sent: Wednesday, November 25, 2020 5:22 AM
To: J/92 Owners <j92o...@googlegroups.com>

Subject: Re: [j92owners] Re: Mast Rake

 

Hi Joe.

Measuring rake this way you really need to have an empty boat or define weight distribution. Having a few sails (or beer) in the front or the back of the boat can make quite a difference if you think about how far the masttop moves if anything moves on the boat. Don't you agree?

 

In the Melges24 class, where forestay length is easily adjusted and hugely contributes to being able to hold your lane off the start line, they measure and compare mast rake as I explained above (main halyard to band above gooseneck, lock halyard, then measure distance to trailing edge on the transom).

 

Having said that, a couple of weeks ago we measured our headstay length with the mast down. pin to pin was 12,79m

Would be interested to know of a few others now that most boats might be in winter mode with the stick down? 

 

Cheers.

Phil

bushra...@gmail.com schrieb am Donnerstag, 30. Juli 2020 um 18:28:27 UTC+2:

Ladies and gentlemen,

As a frame of reference folks, almost all sailmakers (including this one) measure rake as follows:

1. Set up the main halyard as a plum bob.
2. Take the main halyard, 
3. place a weight, cooler of beers, tool bag etc on the shackle,
4. lower the weight till it is underneath, and clear of, the boom. (Secure the halyard)
5. Let the halyard come to rest with weight under boom.

Rake is the distance between the aft face of the mast and where the halyard crosses the top surface of the boom.

Cheers.

 

 

On Thu, Jul 30, 2020 at 10:57 AM rob...@epogue.com <rob...@epogue.com> wrote:

Todd's J/92 is in my hands now. Mast rake is 3.6 degrees (D=29").

 

Robert

 

On Tuesday, July 28, 2020 at 5:19:51 PM UTC-4 Phil wrote:

Hi Todd.

Where do you store the beer for the measurement? In the front or in the back of the boat? ;-)

 

Anyway, here are some numbers I took on our boat yesterday. Since we are only into our second season with this boat I can't really say much about performance on these settings, but last year it didn't feel too bad for us. This year, with new standing rigging, we haven't had any chance to compete against any boat with this pandemic thing going on.

 

Mast step: see photo above, back of the mast sits at about 11cm from bulkhead.

 

Mast rake: took main halyard to band just above the gooseneck, then swung back and measured down to trailing edge of transom: 290cm

 

Headstay length: took jib halyard to band just above gooseneck, then swung forward to headstay and measured down to deck level (a bit vague with the fuller drum in the way): 192,5cm.

 

Shroud tension: measured with "Loose gauge PT2M". Uppers: 35 - Mids: 16 - Lowers: 22. 

I tried to get to something similar as the Elvström guide and the one from Jeff Johnstone from Key West. The mast seems quite straight at these settings without much, if any, prebend. 

 

I am aware that all the measurements above are not perfectly scientific, but I guess it's a start.

Looking forward to your numbers. :-)

 

Cheers. Phil

 

 

Am Dienstag, 28. Juli 2020 14:20:20 UTC+2 schrieb Thin Man #14:

Gravity and simple trigonometry give us an easy way to measure rake.

We already know "P", the length of the main luff, which is the hypotenuse of a triangle.  Suspend a bucket of water from the main halyard, measure the distance at the boom from the halyard to the mast ("D"), then apply the following calculation:

Rake in degrees = arcsin(D/P)

Cheers,
Todd

On 7/28/2020 7:46 AM, Massimo Polo wrote:

Well, I am not that smart...actually I measured the length with the forestay laid on the ground after the mast was removed (for some work I had to do). I did use the Elvstrom procedure, and my set up seems in line with what you say. However the Elvstrom guideline does not seem to mention the mast butt... I tend to think that moving mast butt forward is better especially for light air conditions (that is what we frequently have here). Your rake seems higher than mine judging from the picture. My guess it's > 4° (I have 3.3°) that should be better for light airs. Just guessing !   :-)

max

 

Il giorno mar 28 lug 2020 alle ore 03:29 Sting <mark....@gmail.com> ha scritto:

Furkolkjaaf - wow - how did you manage to get that headstay measurement with the stick up?   I was planning to do it the easy way by using this method from the Elvstrom guide:

"Take the Jib halyard to the top of the mast band at goosneck height, lock clutch off and swing the halyard to the forestay, mark the forestay where the halyard meets it. Measure down from the mark to the deck just behind forestay."

Base setting on the guide (12-16kts) is 1.92m for that last measurement.

To get an idea of how much rake is in my mast, here is a pic:

 

 

I'll try to get to the boat tomorrow to get a measurement.   My guess is that with more rake (and longer forestay), more shroud tension needs to be added to take out the same amount of headstay sag.    So far I have run with the Elvstrom numbers and it seems to do well.

 

 

 

On Monday, July 27, 2020 at 4:28:49 PM UTC-4 oldsa...@gmail.com wrote:

Now that's rake!

 

On Mon, Jul 27, 2020 at 9:02 PM furkolkjaaf <eliomas...@gmail.com> wrote:

by the way, here is a picture of an extreme rake ... boat is a UFO 28 sport boat, rake from picture is in excess of 6° !

 

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/a9cd8a30-6813-4730-b486-6c53709abb92n%40googlegroups.com.

[Massimo Polo]

mine (J/92S) is pin-to-pin 12898 mm (45 mm shackle included)

max

<~WRD0000.jpg>

 

Robert

 

On Tuesday, July 28, 2020 at 5:19:51 PM UTC-4 Phil wrote:

Hi Todd.

Where do you store the beer for the measurement? In the front or in the back of the boat? ;-)

 

Anyway, here are some numbers I took on our boat yesterday. Since we are only into our second season with this boat I can't really say much about performance on these settings, but last year it didn't feel too bad for us. This year, with new standing rigging, we haven't had any chance to compete against any boat with this pandemic thing going on.

 

Mast step: see photo above, back of the mast sits at about 11cm from bulkhead.

 

Mast rake: took main halyard to band just above the gooseneck, then swung back and measured down to trailing edge of transom: 290cm

 

Headstay length: took jib halyard to band just above gooseneck, then swung forward to headstay and measured down to deck level (a bit vague with the fuller drum in the way): 192,5cm.

 

Shroud tension: measured with "Loose gauge PT2M". Uppers: 35 - Mids: 16 - Lowers: 22. 

I tried to get to something similar as the Elvström guide and the one from Jeff Johnstone from Key West. The mast seems quite straight at these settings without much, if any, prebend. 

 

I am aware that all the measurements above are not perfectly scientific, but I guess it's a start.

Looking forward to your numbers. :-)

 

Cheers. Phil

 

<image005.jpg>

<image006.jpg>

 

Am Dienstag, 28. Juli 2020 14:20:20 UTC+2 schrieb Thin Man #14:

Gravity and simple trigonometry give us an easy way to measure rake. 

We already know "P", the length of the main luff, which is the hypotenuse of a triangle.  Suspend a bucket of water from the main halyard, measure the distance at the boom from the halyard to the mast ("D"), then apply the following calculation:

Rake in degrees = arcsin(D/P)

Cheers,
Todd

<~WRD0000.jpg>

On 7/28/2020 7:46 AM, Massimo Polo wrote:

Well, I am not that smart...actually I measured the length with the forestay laid on the ground after the mast was removed (for some work I had to do). I did use the Elvstrom procedure, and my set up seems in line with what you say. However the Elvstrom guideline does not seem to mention the mast butt... I tend to think that moving mast butt forward is better especially for light air conditions (that is what we frequently have here). Your rake seems higher than mine judging from the picture. My guess it's > 4° (I have 3.3°) that should be better for light airs. Just guessing !   :-) 

max

 

Il giorno mar 28 lug 2020 alle ore 03:29 Sting <mark....@gmail.com> ha scritto:

Furkolkjaaf - wow - how did you manage to get that headstay measurement with the stick up?   I was planning to do it the easy way by using this method from the Elvstrom guide: 

"Take the Jib halyard to the top of the mast band at goosneck height, lock clutch off and swing the halyard to the forestay, mark the forestay where the halyard meets it. Measure down from the mark to the deck just behind forestay."

Base setting on the guide (12-16kts) is 1.92m for that last measurement.

To get an idea of how much rake is in my mast, here is a pic:

 

 

I'll try to get to the boat tomorrow to get a measurement.   My guess is that with more rake (and longer forestay), more shroud tension needs to be added to take out the same amount of headstay sag.    So far I have run with the Elvstrom numbers and it seems to do well.

 

 

 

On Monday, July 27, 2020 at 4:28:49 PM UTC-4 oldsa...@gmail.com wrote:

<image007.jpg>

Now that's rake!

 

On Mon, Jul 27, 2020 at 9:02 PM furkolkjaaf <eliomas...@gmail.com> wrote:

by the way, here is a picture of an extreme rake ... boat is a UFO 28 sport boat, rake from picture is in excess of 6° ! 

 

<image008.jpg>

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/003801d6c330%24f16bf900%24d443eb00%24%40gmail.com.

[Dan Stone]

Hi All,

So this was all about the J/92S.  Having bought my J/92 last year at this time, I'm curious what a "fast" headstay length would be for it.  This boat had previously been sailed on a big lake where the wind rarely was over 10 knots, so I think the headstay is set for that.

Thanks,

Dan

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/D6F2DF0A-7513-4DFE-A2F4-AA3B5A5C6C56%40gmail.com.

[JohnAttewell J92JAZZ]

I had 27inches on rake, taken plumb bob on the boom with main halyard. Too much WH as it moved the COE further aft, helped pointing but had to wrestle the helm too much which effectively is like sailing with the hand break on. Also the jib kept sitting on the lower inner shrouds with that much rake. 

Regarding the WH, we have now fitted a better inhaul system so that will help with pointing and balance a bit. As others here have said, the J92 is a well balanced boat, and balanced means fast. I still can’t quite get Jazz set up quite right....yet.

[Massimo Polo]

I am at 28inches (but it’s the 92S, not the classic) and the boat goes fine, no excessive weather helm

Max-Furkolkjaaf

--
You received this message because you are subscribed to the Google Groups "J/92 Owners" group.
To unsubscribe from this group and stop receiving emails from it, send an email to j92owners+...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/c1b51ca6-ac06-4fba-89bd-601e5a852806n%40googlegroups.com.

[Tim Roche]

On my 92 classic I have close to 48 inches of rake, the mast butt is forward of the stock holes by about 3 inches. Its an absolute weapon in light air, but anything above 8 kts weather helm gets to be excessive, and I stop pointing well.  

I'm planning on resetting the whole mess a bit, moving the butt back to the stock position and seeing how that changes things, dialing in rig tune is my least favorite part of boat setup, so I keep putting it off.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/B8C626F8-781B-4E50-BCD1-1DFFA08D026A%40gmail.com.

[dest...@gmail.com]

Hi All,

If I remember correctly, Todd Aven. of Thin Man fame, had a headstay length of 38' 3.5".   I have not checked where my mast butt is nor have I checked my mast rake, but last Wednesday night we lost the spin halyard up the mast in our Wednesday night race (hoisted on the spare genoa halyard).  

That sent me up the mast after the race and on this very calm night, I measured my headstay to 38' 9.75"!!  Seems absurdly long.   Now, this boat came from Lake Lanier where I guess the winds rarely get above 10 knots so every little thing is geared towards light air, from pencil thin spinnaker sheets to a 155% genoa, and what looks like a #3 that has never seen the light of day...

Thoughts?

Thanks,

Dan Stone

Triple Play #9

[Dan Stone]

Hi All, 

I finally did the bucket thing on my J/92 classic.  D is roughly 46" which comes out to about 5.79 degrees of rake.  My mast butt is roughly in the middle, about 5.25" from the buckhead (not the head "tray" for lack of a better word).  My headstay is as the previous email said, about 38' 9.75 inches pin to pin.  All this explains why it points really well in under 8 knots, even with an old 155.

Thanks,

Dan Stone

Triple Play J/92 #9

You received this message because you are subscribed to a topic in the Google Groups "J/92 Owners" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/j92owners/BX8X7fhNLm4/unsubscribe.
To unsubscribe from this group and all its topics, send an email to j92owners+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/18032f66-d61c-4234-9c81-4dfb54431899n%40googlegroups.com.

[dest...@gmail.com]

Hi All,

Todd, if you are still reading this list, do you happen to have the luff length of your 145% genoa?

Thanks,

Dan Stone

J/92 #9

[Todd Aven]

My 2013 IRC application shows the luff length as 36.03 feet. Keep in mind the sail was cut for the roller furler.  I'd expect a longer luff length for a non-furling jib.

To view this discussion on the web visit https://groups.google.com/d/msgid/j92owners/834b212c-816d-47b4-8a2f-b151750198a0n%40googlegroups.com.