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Core Sound 20 Mk 3 -- #4 "Chessie" . .


Pete McCrary

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Steve if it matters, I clamped a spreader mid cabin and clamped and used the spreader till the hull was fair. At this point I was looking for a fair line in place of actual dimisions. I had to screw a block onto bulkhead #1 to keep it from bowing under the stress of holding to hull apart, then mid cabin it was bowed out so I used Spanish windless to pull it into shape.

Looking back, my module was likely 1/4 inch high at the forward end. Didn't come to haunt till I installed the cabin top. Two swats with the little block plane set it rite.

Currently reworking the main hatch. Every trip I got a new divot in my noodle from the hatch. I will publish photos when it is complete and successful!

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Steve,...

When I picked up my hull Graham gave me advise that each cross member of the module should be individually fitted to the bottom profile before assembly. The precut pieces were machine cut as if no filleting was needed at the keel and chines. Every piece needed to have significant material removed at those points. Maybe you didn't have the benefit of that advice.

To fix what you now have -- try this:

A. Wedge up the module so that 1) at least one point on the module bottom (the "proudest") touches the hull's bottom, and then 2) adjust the module so that the top of the footwell sides are exactly above the lower edge of the rabbit in the transom cut for the cockpit deck a distance of D" and the corners of Blk#4 at the sheer are the same D" above the edge of both port & starboard strakes. If the transom isn't epoxied in place, it should be wired just where it should be so that its rabbit is in the correct position as a reference line. Holding everything steady, carefully find and measure the largest gap between the module and the hulls bottom -- that's your G" dimension. Your trim dimension T" is the minimum of D" and G".

B. Cut a small piece of wood T" thick.

C. Then, holding the module steady, mark every piece that should bare on the hull, using the thickness of the piece (cut for that purpose) as a guide for your marker. The only pieces not marked should be those that were at the G" maximum gap OR those where their gap is > T.

D. Remove the module, turn it over, and trim off all the "high" pieces to the lines you marked.

E. When the module is replaced it should be a pretty good fit if T is > G. If T < G, then some pieces will show a gap. But those should be less than before the trimming and you should be able to close the gaps with thickened epoxy.

I know it's a lot of trouble. Don't worry that a lot of material is removed near where the fillets are. It's at the edges of the fillets that should be close. And it's OK to expect the centers of the panels to show a little gap because of its natural bulging.

Maybe this will work for you.

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Thank you Pete. I screwed this up and made a bit of a mess. For those not aware of how I did it......basically I built the module. It is a think of beauty with a centerboard that opens like a switchblade with the tanks sealed nicely and ready to glue down when the right time comes. I should have then just put it in place. I got silly reading the CS17.3 directions and decided to put the bi-axial glass down the center. And then I went a bit further thinking Chick's spreading of a piece of glass across the footprint of the ballast tank was a good idea (it is). That made the problem of not pre-fitting the module slightly even worse. Unfortunately, since the filet is not perfect, the module doesn't fit as good as I would like. I think had the cross pieces been done the way Pete just talked about, not only could they be perfectly fit, the two cockpit support stringers could be trimmed a bit to compensate for the bit of glass below. I should have just cut the bi-axial glass into pieces as the manual also suggests.

 

So about fixing it. The freakin module is pretty heavy. Luckily by putting the glass down the center I can stand in it, but that creates problems. The hull flexes enough that the amount to trim varies if I'm in it. So I am reaching over it after supporting it evenly at the support bulkheads and scribing it with a compass. I got it really close, but that isn't good enough for me. And until Pete gave the dimensions of the hull width at different points, I was unwilling to trim it much knowing that flexing the sides in and out affects the bottom a bit. Once I put the cross pieces on it now is a shape I know is right other than the anchor locker bulkhead which is off a bit (see my thread on CS20.3 #3). I think maybe my tapered hull stringers are a bit stiff and bulkhead 2 is forcing the hull a bit wide there. This morning I put a couple of cup hooks into the stringers and using a piece of heavy string pulled the panels in and it's looking good and didn't take hardly any pressure.  

 

I didn't work on it much this weekend. Sometimes you just need to think about stuff.

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Pete, I just got back home early this morning. I will try to answer your email here so that everyone can follow.

 

This is how I put on the sheer strake on Carlita. (see picture)

 

I back screwed a 1 x 2 around the top edge of the hull sides. The top edge of the 1 x 2 stood about 1/4" above the side to form a lip to hold the sheer strake in place. The sheer strake sat in place mostly without any wires except for the bow, there will be screws at the bulkheads and transom at the sheer. The 1 x 2 keeps the intermediate sheer fair. You should not need any measurements for the 1 x 2 as it should bear at the many bulkheads and the transom. You need to add props only if it is unfair when viewed from above.

 

I elected to use an inwale rather than fillet and tape the cabin top to Sheer strake joint. I notched out the bulkheads so that the inwale ran from the bow, past the break in the sheer. I used the beam measurements at the hanging knee positions to keep the sheer strake as drawn, otherwise the hanging knees shapes will be wrong.

 

I will include the next installment later.

 

 

post-127-0-92918100-1457983300_thumb.jpg

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Graham,

I can instantly see the utility of the 1 x 2 back-screwed the entire length from stem to stern with a 1/4" proud lip. Perfectly solves the un-fairness problem that I saw between Blks 2&3 and Blk 5 & the transom. I'm assuming that you scarfed (with 8 to 1 slopes) two or more pieces together of clear straight-grain stock from the Home Depot (or local lumber yard). Did you back it with packaging tape to keep it from being glued to the hull and sheer strake?

But I'd like to consider gluing it on as a permanent rub rail -- tapered as it nears the stem and the transom. Rather than a 3/4 x 1-1/2 cross section -- that 1x 2 stock could be trimmed as an attractive oval on the outside and a shallow "v" on the inside to match the angle that the sheer strake makes with the side strake. Would ash or white oak (both available here in long lengths & good quality) be too heavy? Would yellow pine be OK? It could be topped with a SS half oval to resist scuffing at the docks.

Or is this not a very good idea?

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Gosh, I hate that you guys are having so much trouble with the module. Mine fit well except where I had to remove a little to adjust for the thickness the keel strip. The glass under the ballast tank didn't add enough thickness to matter. The rabbit in the transom lined up fine.

 

Just a thought, did you weight the hull bottom down so that it matched the three bulkheads of the building cradle?

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Pete,

 

Putting on a rub rail first is not a good idea. It is not as strong as a seam that is glassed on both sides first. I did not tape the outside joint but took care of it when the hull was glassed.

 

Yes, scarf the batten with an 8 :1 taper. I just tack welded the seam being careful not to force the epoxy through the joint and then removed the batten. You could tape the batten to be sure.

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Graham,

Yes, I can see that trying to make that batten double as a rub rail is just "a bridge too far." Better to take on just one thing at a time. Today I'll shop for some good & straight 1 x 2 stock. Can't wait to get those strakes on. Thanks for sharing your practical experience.

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Taking Graham's advice I just found a very nice piece of clear 1 x 8 Yellow Pine 16' long with grain straight as an arrow. Combined with an 8' piece of left-over cleat stock I can fabricate a pair of 1 x 2 battens the length of the sheer (just under 21') needing just one scarf each. Later, after trimming them to a desired cross section, I'll use them as rub rails.

The photos shows the planks with the scarf cuts made and ready for thickened epoxy.

post-4915-0-79333500-1458165463_thumb.jpeg post-4915-0-36333800-1458165493_thumb.jpeg

post-4915-0-10366900-1458165528_thumb.jpeg A scarfing jig I made I-don't-know-how-many years ago.

My neighbor and boating friend, Henry Felber, helped me steady that 16' board while ripping it and cutting the scarf wedges. I suppose it might be possible to do it alone -- but tricky and possibly dangerous.

Next I'll set up and glue the scarfs and let them cure over a few warm days before back screwing them to the outside of the sheer -- assuring fairness from stem to stern.

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Chick,...

 

I just set up the rig to scarf the two 16-footers to two 8-footers.  The photos shows the set up.  I'll try to do the epoxying this afternoon because we are expecting a bit of snow Saturday night.  I'll have to leave my garage door open while the epoxy cures

 

post-4915-0-29653600-1458243509_thumb.jpg post-4915-0-24906700-1458243551_thumb.jpg

 

Shown here is my present design concept for the cross-section of the rub rail.  It should be pretty easy to fabricate.  With the inboard shallow v-cut, it should be fairly easy to have her lay right on the sheer line.  I plan to taper each as they approach the stem.  Probably not [tapered] at the stern where they would provide some protection to the outboard edges of the transom.

 

post-4915-0-80638100-1458243843_thumb.jpg

I think I should have a SS half-oval the length of the rub rail.  Do you know the pros & cons as to the "solid" or "hollow-back" types?  Having done this already, do you have any suggestions?  Also, do you think it would be wise to attach the rub rail with screws and bedding compound so that it may be more easily replaced if damages -- as opposed to making it permanent with screws and thickened epoxy?

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I used a much narrower piece for mine. Only about 1 1/8 inches high by 3/4 inch thick.. I also mounted it below the hull/strake joint so I could eliminate the "V" notch in the back. It is cut on an angle to sorta match the slope of the side. A 3/4" hollow back just fits.

 

I don't have an opinion on hollow versus flat. I prefer to bed mine in case it needs removal. The rubrail was held in place against the hull with screws, while the epoxy cured,from inside except for the cockpit area, where I screwed from outside and the screws ran into the cockpit seat support. Towards the transom the support was too low, so I was able to get a screw from outside into the 3/4 inch transom doubler that goes across the top of the transom. I left the screws in where they were on the outside, but removed them in the cabin and anchor well area.

 

Just shows that we are "rugged individualists". Yours is fine. The Breeze and I look forward to sailing with you!

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Getting ready to attach the sheer strakes. Both sides are now forced into a fair sheer line from stem to stern. Graham's suggestion of a 1 x 2 batton back-screwed to the side plank leaving a 1/4" lip to channel the strake to its proper position did the trick.

NOTICE to builders -- when attaching the transom remember to put a bevel on its sides. Without a proper bevel, the side panels will start forward at a right angle (from the transom) instead of inline with a fair sheer. That will create a slight but noticeable "dimple" in the side panels just forward of the transom. See the photo showing the gap near the transom.

post-4915-0-84390300-1458764089_thumb.jpeg

I didn't want to force the dimple to be in line with the batton-- thinking that might force the epoxy to crack at the side panel / transom joint. Also, forcing the side panel to the batton wouldn't take the dimple out all the way down to the chine. If the dimple is obvious and ugly, I plan to eliminate it with epoxied fairing compound. QUESTION: Should that be done before or after glassing the bottom and sides?

post-4915-0-78018900-1458764277_thumb.jpeg post-4915-0-04044500-1458764324_thumb.jpeg

post-4915-0-75057500-1458764362_thumb.jpeg post-4915-0-70099700-1458764412_thumb.jpeg

post-4915-0-66417900-1458764453_thumb.jpeg post-4915-0-28633000-1458764487_thumb.jpeg

Next will be to firmly line up the sheer strakes to closely fit the side panels and FIX them in place with "spot welds."

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Jay put this rub rail on Southern Express. While it's a bit modern of a look, I think that the protection is worth it. You folks down south do a lot of beaching, so it probably isn't that important, but up here, everything has a dock. While fenders are critical, having a good rub rail is a blessing. I have one similar to this on my powerboat and it's kept the fiberglass looking like new even though it's 14 years old.

 

http://www.jamestowndistributors.com/userportal/show_product.do?pid=56893&familyName=Tessilmare+Radial+Flexible+Rub+Rail+Kits

 

That said I have a nice teak Rub rail on my Sea Pearl that has held up well and looks awesome. It might even be cheaper!

 

BTW....looking great. I've got the module sealed and the inside of the boat sealed. About to make it rigid. I got all surfaces to tight except a few small gaps that approach 1/8" They'll never see it from Broadway.

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Pete, the picture of your bow with test anchor on show the foredeck incorrectly positioned. The stem does not angle backward above the side panels. The anchor locker cutout near the tabernacle should be in line with the front edge of the tabernacle. The pic shows not enough lateral support for the tabernacle with foredeck positioned back where you show. I hope your sheer strakes are glued up correctly.

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Alan,...

Great record performance in the Ultimate Florida Challenge. To do that you had to be in terrific physical and mental shape. Gongratulations !!

The sheer strakes are wired [together] at the stem and nestled into the "lip" of the 1x 2 boat-length batton suggested by Graham. That back-screwed batton has set the inside beam measurements right at the dimensions you gave me earlier at the hanging knee positions. Blks 1, 2, 3 (in-place temporily), and 4 brackets aft set at 72.5 dgrs (2 ea P/S) have the sheer strakes at the required angle and very nicely set. The computer-drawn lines on the inboard side of the sheer strakes lineup VERY close (i.e., within a "line width or two") to the bulkhead positions. Amazing accuracy!

Haven't tac welded yet. It all needs just a little fine tuning with wires, wedges, etc. When you get a chance -- check out my last few posts. Really glad you're back safe and sound.

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Pete,

 

Alan is correct. The aft end of that little piece of foredeck ends 2" forward of the fore side of the forward bulkhead. There is no aft rake in the stem or bow profile, it is a fair line all of the way to the upper sheer. If the bow end of the sheer strake has an aft rake, you have something wrong.

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