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#79191 - 07/27/06 10:05 AM Re: Measuring Mast Rake [Re: Jamie]  
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tback Offline
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Orlando, FL
Quote
I'm carrying a lot of mast rake with the trapeze going 6 inches down the back of the transom. The boat feels good with very little weather helm.


Holy S%*^t, That seems like alot


Quote
I did rake one of the rudders more forward to match the other.


How much forward of vertical are your rudders?


USA 777
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#79192 - 07/27/06 12:10 PM Re: Measuring Mast Rake [Re: tback]  
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Mark P Offline
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Mumbles Y.C Wales U.K
Call me old fashioned, or just plain stupid but I measure my mast rake between the bottom of the forestay and top of the bridle. Its very quick and easy to adjust. I also think that the new fat/square top mains don't require as much mast rake as the older designs but again I'm not a sailmaker and have no means to prove this theory. For me I just feel the boat settles in the groove quicker and for longer with minimum rake.


MP*MULTIHULLS
#79193 - 07/27/06 02:48 PM Re: Measuring Mast Rake [Re: Mark P]  
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scooby_simon Offline
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Quote
Call me old fashioned, or just plain stupid but I measure my mast rake between the bottom of the forestay and top of the bridle. Its very quick and easy to adjust. I also think that the new fat/square top mains don't require as much mast rake as the older designs but again I'm not a sailmaker and have no means to prove this theory. For me I just feel the boat settles in the groove quicker and for longer with minimum rake.


BUT you cannot compare that with anyone else as your wires may be of differing lengths !


F16 - GBR 553 - SOLD

I also talk sport here
#79194 - 07/27/06 05:12 PM Re: Measuring Mast Rake [Re: scooby_simon]  
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Mark P Offline
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Mumbles Y.C Wales U.K
Exactly!!!! We've previously seen that sails can't be made the same. so don't fool yourself neither are hulls, hardware, masts or rigging.
I do accept that using the trap wires is the most accurate method due to "blar, blar,blar" but lets be fair we are not Olympic Sailors.
I'm sorry I seem like a killjoy but I have yet to be convinced that Club sailors who take moor interest in boat tunning rather than boat handling win races?
Where I sail there is a F18 sailor who has digested every F18 tunning/racing guide and he is fast when he's not upside down.


MP*MULTIHULLS
#79195 - 07/27/06 05:44 PM Re: Measuring Mast Rake [Re: Mark P]  
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scooby_simon Offline
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Quote
Exactly!!!! We've previously seen that sails can't be made the same. so don't fool yourself neither are hulls, hardware, masts or rigging.
I do accept that using the trap wires is the most accurate method due to "blar, blar,blar" but lets be fair we are not Olympic Sailors.
I'm sorry I seem like a killjoy but I have yet to be convinced that Club sailors who take moor interest in boat tunning rather than boat handling win races?
Where I sail there is a F18 sailor who has digested every F18 tunning/racing guide and he is fast when he's not upside down.


Boats are built to a LOT higher tolerances as they would not go together otherwise, wires only need to be about right.


F16 - GBR 553 - SOLD

I also talk sport here
#79196 - 07/27/06 06:22 PM Re: Measuring Mast Rake [Re: scooby_simon]  
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Mark P Offline
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Mumbles Y.C Wales U.K
Boats are built to a LOT higher tolerances as they would not go together otherwise, wires only need to be about right. [/quote]

I see what you're getting at but I'm not convinced that the manufactures work to absoulute dead millimeter tolerances day in and day out when it comes to a fairly trivial thing such as a trap or stay wire for a beach cat.


MP*MULTIHULLS
#79197 - 07/28/06 02:40 AM Re: Measuring Mast Rake [Re: Mark P]  
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scooby_simon Offline
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Boats are built to a LOT higher tolerances as they would not go together otherwise, wires only need to be about right.


I see what you're getting at but I'm not convinced that the manufactures work to absoulute dead millimeter tolerances day in and day out when it comes to a fairly trivial thing such as a trap or stay wire for a beach cat. [/quote]

Excatly, so there is no point using these as the actual measuremnet menthod. Where they bi-sect the hull, YES as this is (more) constant as (having measured many boats) the trap lines are just used to provide the sides of the triangle and so need to be lengthened anyway by adding string to get to the bridal point on the hull.


F16 - GBR 553 - SOLD

I also talk sport here
#79198 - 07/28/06 03:50 AM Re: Measuring Mast Rake [Re: scooby_simon]  
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alutz Offline
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Switzerland
In the 18HT class, the italians measure the distance between the top and the mainsail track.

They simply pull up a long measurment tape with the mainsail halyard.


Andi, Switzerland
Team OST
#79199 - 07/28/06 04:23 AM Re: Measuring Mast Rake [Re: alutz]  
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In the 18HT class, the italians measure the distance between the top and the mainsail track.

They simply pull up a long measurment tape with the mainsail halyard.


I assume you mean the traveller on the back beam.

This is another valid method, you just need a long tape measure; the "trapeze wire" method can usually be done with a bit of rope and a ruler !


F16 - GBR 553 - SOLD

I also talk sport here
#79200 - 07/28/06 05:51 AM Re: Measuring Mast Rake [Re: scooby_simon]  
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alutz Offline
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Quote

I assume you mean the traveller on the back beam.

Right!

Quote

This is another valid method, you just need a long tape measure; the "trapeze wire" method can usually be done with a bit of rope and a ruler !

I guess many ways lead to Rom <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />


Andi, Switzerland
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#79201 - 07/28/06 07:21 AM Re: Measuring Mast Rake [Re: tback]  
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Jamie Offline
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Wilmette, IL
Quote

How much forward of vertical are your rudders?


With a yardstick against the transom and taking a point 23" below the rudder stock, the stock position had the starboard rudder at 1 7/16" forward and the port at 3/4" to 7/8" forward. With the stock settings, I had weather helm even with the short forestay and staymasters at 7-7.5. In two increments, I moved the port to 1 7/16" and at the same time of the last adjustment, moved the forestay down one hole, which took care of the tiller pull.

Jamie
Blade USA 714

#79202 - 07/28/06 03:57 PM Re: Measuring Mast Rake [Re: tback]  
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Simon Offline
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On the Spitfire we tie a rope to the trap line, pull it tight to the top of a rudder pintle, then take this forward to the foremost point where it will touch the seam on the top of the same hull. This point is measured backwards from the bridle tang. Recommended setting at 10-15 inches.

Now, I have a question - I have set my boat up the same every time since I got it 2 years ago, based on the same holes on the sidestays and then applying rig tension using the forestay. I figured if I set the boat the same all the time I could focus on sailing (rather than tuning) skills. This setting has been successful for me at club level.

Imagine my surprise then when I got home from the Spitfire Europeans, to find that rather than having somewhere between 10 and 15 inches, I had 0 / zero / none / nada / no rake whatsover by this measure. So I changed it to midway between 10 and 15 and guess what - I am convinced we were slower, actually coming second in 2 races for the first time this series!

What is going on?

Cheers


Simon
Shadow 067
#79203 - 07/28/06 07:15 PM Re: Measuring Mast Rake [Re: Simon]  
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tback Offline
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Seems to me if you rake your mast forward ... you'd have more trap line to extend back to your rudder pintle ... and consequently more trap line (and less distance to cover) to extend forward towards your bridle tang.


USA 777
#79204 - 08/26/06 08:05 PM Re: Measuring Mast Rake [Re: tback]  
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JJD Offline
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Orange County, CA, USA
Took some measurements and photos today of my setup.
The furthest forward toward vertical I can rake the mast is to get the front stay adjuster into the 8th of 10 holes. This is with the Sta/Masters slackened to the 10 mark (any further and I'd be using less than the full threads on the adjustment nut). I tensioned the rig by adjusting to 8.5 then measured the rake using the forward trapeze line.
Started at top centerline of hull in line with bridle tang.
Took this reference back to where I could touch top centerline of hull near transom. That turned out to be almost exactly 3 inches forward of the transom or about 2 inches aft of the edge of the inspection hatch ring.
Does this sound reasonable? There is no way I can go any further toward vertical unless my side stays are made longer and I shorten the forestay.
I'l attach photos in subsequent posts.
John, Blade 720 (still in drydock but closer to launch) <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />


#79205 - 08/26/06 08:08 PM Re: Measuring Mast Rake [Re: JJD]  
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JJD Offline
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Photo shows boat with maximum forward rake possible with current shrouds. Hull top is level at C/B trunk.

Attached Files
84238-Bladeprofile.jpg (203 downloads)
#79206 - 08/26/06 08:24 PM Re: Measuring Mast Rake [Re: JJD]  
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JJD Offline
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Orange County, CA, USA
This photo show the Sta/Master fully slackened to produce previous photo.

Attached Files
#79207 - 08/26/06 08:26 PM Re: Measuring Mast Rake [Re: JJD]  
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JJD Offline
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JJD  Offline
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This photo shows the position of the forward stay. Pin is in hole 8 of 10.

Attached Files
#79208 - 08/26/06 10:54 PM Re: Measuring Mast Rake [Re: JJD]  
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Edmonton, Alberta, Canada
So your rake is somewhat less than mine. Put some sails on and take her for a rip. See how it feels to you.



F16 Blade 716
#79209 - 08/27/06 11:01 AM Re: Measuring Mast Rake [Re: bobcat]  
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DougSnell Offline
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Seabrook, TX
Bruce:

Do you still have the logo you sent me that says
"If it's not a Cat it's a Dog" with the bobcat with the red eyes?
If so sent it to me again. Computer crashed and I lost it.

Doug Snell
dsnell4 at houston dot rr dot com

#79210 - 08/27/06 02:06 PM Re: Measuring Mast Rake [Re: JJD]  
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Wouter Offline
Carpal Tunnel
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North-West Europe


It is always easy to lengthen your sidestays. Just put a shackle there (on both sides !)

It is best to have some safety margin with the staymasters. Adding two shackles will allow you that. Don't worry about the forces on the sides stays these are low enough to handled by any normal sized shackle.


Quote

Started at top centerline of hull in line with bridle tang.
Took this reference back to where I could touch top centerline of hull near transom. That turned out to be almost exactly 3 inches forward of the transom or about 2 inches aft of the edge of the inspection hatch ring.
Does this sound reasonable?


Sounds a reasonable starting point to me. Try it in that position and see how it sails/feels

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
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