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E-Scow Tuning

Well I bought an E...
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5/6/2014 9:25 AM
Its not too hard to make a foam plug this shape and then make a mold to make a couple of foil rudders. 
The foil rudder shaft NEEDS to be out of stronger aluminum alloy than what is listed in the scantling rules - those shafts have bent in the past. Here is some more recent information for foil rudder construction information. 

Engineering Data on Aluminum and Bonding Thereof - The following was
supplied to various parties.

Aluminum Alloys - 2024 T6 (yield of 50 ksi) and 2024 T8 (58 ksi) series
alloys have good corrosion resistance characteristics.  The 2024 T3 (45 ksi)
and 2024 T4 (42 ksi) do not.  Either the T6 or T8 material would be
significantly better than 6061 T6 (35 ksi).  7050 T7 (63 ksi) and 7075 T6
(66 ksi) are also good for corrosion resistance, but are probably overkill.
These yield strength numbers are for 1 in. dia. rolled rod.  The numbers for
extruded rod will be somewhat higher, but that product form is probably more
expensive.

Adhesives - Dexter Hysol adhesives are the best ones from Boeing experience,
and are now owned by Henkel Aerospace Corp. in California at 925-458-8000
(source of technical info).  The midwest distributer is Rudolph Brothers in
Ohio at 614-833-0707.  There are two room temperature cure materials which
you could use, EA9321 or EA9360.  These are two part adhesives, and are
available in pints and quarts, I believe.  We use the EA 9321 at Boeing for
general purpose aluminum bonding with good success.  There is also an
ahesion improving primer that may be used in the process, 9203 primer.  The
bonding process goes as follows:

1. De-grease parts with alcohol.
2. Sand with Scotch Brite pads until parts are bright and pass a
water-break test (water poured over parts sheets instead of forming beads).
3. Wipe immediately with alcohol to remove any water, and flash dry,
then bond immediately.
4. Apply 9203 primer per manufcturers instructions, if desired.  This
step is not mandatory, but will improve the bond to some degree for the long
term.  The military recommends this, but it is not absolutely necessary.
5. Bond parts with adhesive per manufacturers instructions.
6. Allow to set at room temperature for I hour (to prevent adhesive
from bubbling/outgassing), they cure at 190F (heat lamp) for one hour to
complete cure.  Entire cure may be accomplished at room temperature in 5
days instead of using the elevated temperature.  Parts may be handled and
rudder fab completed after 24 hours at room temperature, but should not be
subjected to high loads for 5 days unless heat cure is used.
7. If primer is used, exposed shaft may be painted as further corrosion
inhibition instead of anodizing.

Here is the Scantling Rule section on the Rudders:
D. Rudders
1. Number - 2

2. May be made from aluminum plate or foil shaped of fiberglass and foam about an aluminum center plate.

3. Rudder shafts shall be of solid aluminum with properties equal to or better than #6061- T6 alloy. Shaft diameter shall be 1 in. ± 1/16 in.

4. Aluminum Rudder
a. Extension beyond hull when in fore and aft position 13 in. max.
b. Material - Aluminum alloy with properties equal to or better than #6061-T6.
c. Thickness - 3/16 in. plus or minus .010 inch.
d. Sectional shape - flat to within 4 in. of the edge with all edges rounded to no less

than 1/32 in. radius.
e. May be painted, anodized or plated; built up rudders prohibited. Fillets may be

added to the rudder to streamline that joint between the rudder and the rudder post and may not exceed three inches in any direction from the point defined by the intersection of the central line of the rudder post to the top edge of the rudder.

f. Outline shape - blade must fit within rectangle 21 in. fore and aft by 12 in. deep.

page3image40568

page4image7560 page4image7720 page4image7880 page4image8040

5. Foil Shaped Rudder. All length dimensions are inches.

  1. Material - Aluminum alloy of minimum tensile strength equivalent to #6061-T6

    alloy for the center plate inside rudder. Fiberglass, polyester, vinyl ester, epoxy resin, gelcoat, or LP paint is allowed to fabricate the foil shape of the blade. The coring material is optional. Carbon fiber is not allowed for body or core.

  2. Weight - Minimum weight per rudder is 3.5 lbs for blade plus shaft.

  3. Extension beyond hull, and overall rudder span when in fore and aft position shall

    be 16.0 in. maximum.

  4. The leading edge, trailing edge, and line of maximum thickness shall be fair

    curves. Sectional shape shall be a fair foil shape with no hollow more than 0.063. The leading edge shall be rounded to no less than 0.10 radius. The trailing edge may be of squared, circular, or 30 deg. angle cut with cross section of 0.10 ± .05 minimum thickness or diameter.

  5. The following dimensions (in.) at the indicated spanwise offsets shall be met. Semicords are referenced to a spanwise baseline 3.5 in aft of the leading edge at zero span and running perpendicular to the inboard closure plane:

  6. The rudder shaft shall be perpendicular to the inboard closure plane with its centerline on center laterally and 1.1 ± 0.06 in. forward of the baseline.

  7. On existing yachts with rudders that are canted with respect to the rudder post, the inboard closure of the blade may be cut back up to one inch to allow foil shaped rudders to be laid up over the existing cut-down rudders 
4/26/2014 7:36 PM
Anyone got a foil profile for the rudders that you could share? Thanks

lonbordin at hot mail dot com
8/29/2013 8:33 PM
Johnson has aft chainplates... no need to change those. 420 spreaders and diamond wire's a couple hundred bucks buying it from APS.  I can DIY.  Plenty of folks in the E Reporter running this setup pretty successfully.

I have a year old jib and a brand new mail (been used a handful of times).

I have several nice spinnakers (and other jibs and mains) not going A-sail any time soon*.  I also have one boat worth of parts. Not planning a campaign.

Really the only thing I'm not 100% sure I can do and inexpensively is the new rudder foils.  Haven't really run into any sites documenting that too deeply.  I'm aware of the NASA foils and the like.

If you knew how little I paid for all that I have you'd call me a criminal.  

*Maybe I'll go A-sail when everyone goes carbon mast.  :-D  But the other 2 Es on the lake are both symmetrical spins so by staying as is I can do some local OD racing. 
8/29/2013 8:50 AM
For what its worth lay out your costs to upgrade that boat.  Rudders, diamonds, aft spreaders, chainplates, asail conversion, newer sails...  you will be very close to buying a newer boat with all those things done.  There are all ready some nice used boats on the classified page.  If they're too expensive the guys buying those boats will have to sell their existing boats.  There is a lot of boat turnover in the off season.  The other thing to consider is that it is a johnson and all the current parts and tuning guides are geared towards melges. 
 
Good luck
 
 
 
8/28/2013 1:27 PM
This was the path I was thinking of going and your reply has confirmed my bias.  Thanks!

Now how to figure out how to convert my rudders to new foils...
Gotta do the diamond wire and loose those backstays.

Projects, projects.

Thanks again.
8/28/2013 7:11 AM
This message board is quiet but keep up the questions and you will get answers eventually.

Instead of buying a bridle get a bunch of 3/16 12 strand and teach your self to do eye splices.  That way you can make it fit your boat. Make sure you use captive pin shackles...   

The front legs to the chainplates are equal length.  The aft leg could be adjustable via a bowline until you find the right length.   

For the aft d ring make a backing plate from G10.  Mcmaster carr carries the stuff.

Good Luck and Have Fun
8/27/2013 3:20 PM
Yeah APS's E-Scows are all much newer than my 1983 JBW.  I saw one with a D ring.  I guess I can buy the APS bridle and mount some  point along the spine.  Hmmnnn there are two much older JBW  (73,74) scows at the lake maybe one of them has the third point.

Even with the measurements I'll bet the APS bridle is for the newer Melges and has different dimensions.

Thanks! for the reply... this forum is real quiet.  Maybe I should be posting somewhere else? SA?!
8/27/2013 1:31 PM
It looks as if the two holes in front of the bulkhead is where the lifting ring may have once been.  On newer boats it is located a little farther forward, though.
 
Take a look at the Annapolis Performance Sailing website - www.apsltd.com.  Go to One Design, choose E Scow, and there are a lot of reference photos of much newer boats - but the concept is the same.
 
J 
8/26/2013 10:34 PM
So I went to look for the rear attachment point.  The bolts are way too small and just support the block.  The wire connecting to the rear hiking straps is beefy.  Any ideas? Am I looking at the right location?
8/21/2013 7:31 AM
The bridle attaches to the chain plates and then to the center just forward of the mainsheet block. There should be a stainless attachment point therre.
size: ? (I'll measure it as soon as I locate it) Just got back from a regatta and can't seem to find it!
8/19/2013 9:56 PM
So I found The Reporter back issues... a wealth of information there.

I have one final hurdle.  There's a hoist at my club but the area where the boats go in is tight.  I'm not sure the E will fit.
I can launch off the trailer but that presents other hurdles.

Since I don't have a bridal I can use the straps and a spreader but I'd much rather use a bridal.  I don't want to purchase one and then never use it.  Also I'm not seeing any bridal attachment points.

Where do people typically attach?  
Would someone provide their bridal dimensions? I can make a great rope bridal to do the test drop.

Thanks.
8/13/2013 8:48 PM
So I bought an E.  The family just stepped the mast tonight. I'm stoked!

There are two other E scows on Lake Lemon (owned by Indiana University). 3's a fleet right? 

This is my first scow.  I've been a cat and dinghy sailor all my life so I'm excited to try something different.
I've read the Hoofer guide and the North Sails tuning guide.

What other resources are available?

I'm looking to do some upgrades this winter.
1- Foiled rudders
2- Newer mast step (any photos of these out there?)
3- Maybe Asym... probably next year.

Any more active E scow sites? SA?!

May try to attend the Carlyle Silver Cup... not so much to compete as I find regattas to be great learning experiences.

On deck it's marked W-11. Here's a pic of it's numbers.


Thanks all!
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