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Core Sound 20: Hull #103


Alan Stewart

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Mike,

Yes that's exactly right.  The unpolished flat stock (3/4" x 1/8" x 6',  type 304 SS) came from McMaster-Carr for about $3/foot.  Initial sticker shock at JD strongly suggested that we should use this unpolished flat stock and drill, counter-sink, bevel (half-oval), and polish it ourselves.  Sure, why not.  In a moment of insanity I gave in to temptation and bought one section from JD (1/2" x 1/8" x 6' half oval) for the bow.  The other 3 sections came from McMaster-Carr.  During the installation we abandoned the idea of beveling and polishing the flat stock (for now, anyway)  --only because on further thought it didn't seem necessary!

That's the story, for whatever it's worth.  I'm speaking from genuine inexperience here.

The forum and all comments and suggestions are much appreciated !!!     

There's no way I'd get this boat built if I were doing it alone.  Fortunately, my son (Alan) and I make a good team  -- he's a budding boat builder/designer, experienced sailor, and engineering student at NCSU.  And I contribute something too, but I can't recall what it is.  We're having a great time on this project.  Icing on the cake if she floats.

Paul,

Thanks for your reply, if you don't mind I have another question. It looks like the machine screws holding the keel band in place are screwed into an oversized hole in the keel that was then filled with epoxy. Is there a nut buried in the bottom of the hole and is the green goo on the screw threads some sort of release agent? That looks like a very long lasting approach to the problem of rot around fastener holes.

Regards

Mike,

   Correct.  Oversize holes with epoxy fill was Alan's idea: so the screws and SS stips are removable and the screws do not touch any wood.  We had made the holes deep enough so that there should be 1/8" layer of epoxy below the bottom tip of the screw.  The diameter of the hole was 1/16" larger than the diameter of the nut.

   We drilled and countersunk the SS strip first.  We put all the screws in the SS strip, put all the nutes on the ends of the screws,  dry-fitted everything into the holes as a check.  With the hardware removed out of the way we wetted out the holes with thin epoxy,  then filled the holes with honey-thick epoxy (cabosil).  Each hole was filled to within about 1/8" from the top of the hole.  Next we squished the screws/nuts into the holes  --screws/nuts still being through the SS strip.  Having the strip in place insured that the screws were correctly positioned.  Let cure for 8 hours.  Then removed all screws and removed the SS strip to check results.   A couple of flaws were touched up.  We let the epoxy cure longer before putting it all back together, with a thin layer of silicone calk between the keel and SS strip.  After it was cured we cranked down on the screws for tightness.   

   Preliminary testing in a small scrap block of white pine 2x4:  with either PVA release agent or machine oil on just the screw,  the screw released easily 8-10 hours into curing. I suspect the PVA or oil was unnecessary.   When fully cured, we put a washer on top and cranked down on the skrew as hard as possible. The result was that the washer crushed into the surface of the white pine and the nut stayed firmly anchored down in the wood.

   We used 8-32 SS screws with lock-nuts.  Screw length varied consistent with 4/8" deep holes in the bow,  5/8" deep holes in front end of keel,  6/8" deep holes in keel back to the stern.   The several shorter screws in the bow required regular nuts instead of (taller) lock-nuts so that there would be a thick-enough layer of epoxy above those nuts.  A theadlocker goo can be applied to the threads whenever lock-nuts are not used.     

Pictures:  http://picasaweb.google.com/danceswithsandybottom/CS20_keel_guard__20080122

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  • 3 weeks later...

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I cannot believe how fast you did all this!  I guess the race date lights a fire under you, but even so!  I'm a little curious how your tabernacle is going to work with the cabin there.  Also, will that tall house interfere much with visibility from the helm?

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Alan,

  You might want to repeat your call for assistance here - There are several people within driving distance of Chapel Hill who might leap at the chance to see #103 in person...

Jeff,

  It looks like the pivot point on the tabernale is a reasonable height for the cabin.  Alan will be better able to answer, though.

  And I'm amazed at the work that's gone into this boat too.  I might have the record for the slowest-built CS and this boat is going together SO fast.  And so pretty.

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Thanks Ken, if you have not heard, we are planning to move the boat out of the basement THIS SATURDAY the 23rd at 3pm. If you are within  reasonable driving distance from Chapel Hill and want to lend a hand, or just want to see the boat up close and in person, feel free. I can send you details if your interested. I think we have about 15 people as of now so don't feel bad if your too far away, just watch from home :)

Jeff, yes we were pretty concerned with visibility with the cabin there but we sat in it for a while and while it does block the straight forward view slightly its not very bad especially if your sitting up on the rail which I think we will be. Graham also seemed to sit on the rail of the EC22 a lot for the same reason and when I got to sail the 22 at the end of the EC last year, I sat on the rail as well. Its a pretty natural perch. Also, I don't think that lowering the cabin roof a few inches would have significantly improved visibility but would have made it a little cramped in the cabin. In hindsight we would have probably tried to lower the cabin seat tops a little more and thus lower the roof height without sacrificing head room. BUT then we would be reducing the storage space significantly in the cabin. SOO many trade offs. I hope what we ended up with works well. If not, cut it off and build it up again. It is a wooden boat after all!

As for the tabernacle, we considered raising it enough to allow the mast to lie horizontal when lowered but decided that that was not so important and instead just ended up raising the pivot pin it by 3.5 inches and raising the base pin by 1.5 inches. This effectively raised the pivot point and simultaneously increased the mast bury by 2 inches. The problem with simply raising the pivot pin was that then the base would not clear the inside of the bow when it rotated out of the tabernacle hole. With the mast down, the raised tabernacle will allow the tip of the mast to be about 5 feet above the waterline so probably just high enough reach when its on the trailer.

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Hello, When will you be arriving in Tampa? 

I am also building one of these, we'll be racing next year.   I've been watching your progress and it it one cool looking boat..  I would like to come to chapel hill on saturday but I can't get off work...

I am comming to tampa to see your boat.. My son and I will be there on the 29 th...

Thanks, Otto + Kyle

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Hello Otto

Beginning late morning on  the 29th, everyone will gather at the east beach of Fort DeSoto park (turn left at the big flag and turn into the first parking lot on the right after the flagpole parking lot).  We'll be putting our boats on the beach ang rigging them.  It's a great place to look at all sorts of boats and talk with the builders/skippers.  Chief will call everyone together for his big speech around 3 PM.  Launch for the race is at 7 am on the 1st.  I look forward to seeing you there.

For details and to follow the race, go to watertribe.com.

Doug

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  • 3 weeks later...

No one is more proud of Alan and Paul than I, both in the quality of our new sailboat, and in their finishing the EC.  I hope they find time to write up a summary of thier experiences with the boat on Alan's blog soon http://sailnaway.blogspot.com/  Alan has already moved on, and just finished a 1/2 marathon at Virginia Beach today, where he though they might have beer at the water stations for St Pat's Day :)

There are still few minor repairs needed before I get my first ride, and there is some work to still complete, though mostly cosmetic.  I've volunteered to make a cover.  Does anyone have a suggestion on fabric for UV protection and where to order?  Not for trailering, but for sitting in the driveway.

Also, we'd like to paint part of the hull a color.  Is there something we should be considering painting on the hull for added salt water protection before the final color coat?  Interstingly, when the EC was over, we noticed some small bubbles on the hull, possibly the paint had not totally cured.

Thanks,

Dawn

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  Congratulations on what looked like a very challenging challenge, Dawn!

  I was half expecting to see you and Paul at Jordan today since the weather was so good and I know you must be really itching to finally get your hands on the tiller of Dawn Patrol (so Paul won the naming contest eh?).

  The only suggestion I can toss out for UV protection is Sunbrella but that would cost a mint.  I'll be interested in hearing what other fabrics would do the job.  And having seen the paint jobs on both boats I don't feel I'm qualified to answer your paint question  ;D (sorry)

  I hope to see you/Paul/Alan/Dawn Patrol out at Jordan soon.

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Dawn, are the bubbles above or below the water line?

Above the water line, they can be from not getting all of the waxy "blush" off the cured epoxy or the failure to let the epoxy cure enough (I have a bubble on the rudder cheek due to this.

Below the waterline, it may have to do with the quality of barrier paint and the work of osmosis.  The folks at Interlux told me (confirmed by the tech person at Jamestown) that, if the boat was to be in the water more than one day, iot need an osmotic barrier paint and that the paint I used on the deck and sides was not sufficient.  You will have to check with the folks at System 3 about their water based paints and osmosis.

I have been fixing all of the little things on Dillen Lewigh getting ready for a re-lauunch and taking Ann sailing, but I have to take the week off because 4 grandchildren are coming for the Easter week version of Camp Gramma Ann.

Hello to Paul and Alan.

Doug

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Gordy,

Thanks for posting those pics.  No matter how you cut it, Graham's Core Sound 20 design is easy on the eyes.  I never tire of admiring the lines of his EC-22. 

You captured some lovely lighting there  --- good job!

I heard your camera took some damage in the EC while you were helping us all out at checkpoint 3 / Flamingo.  I hope it survived.  Thanks a million for "being there" for all of us.  You did a great job!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

--Paul

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