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CS17 MK3 Build - Seattle


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Hello everyone –

My family and I are building a CS17 MK3 in Seattle and I started what I thought was to be the final assembly of the cockpit structure. I’m having second thoughts about gluing it together – concerns about encapsulation put the brakes on it. I’m especially anxious about the end grain of the cleats in the ballast tanks, but also wonder about the edges of the plywood. I’ve coated both with clear epoxy but cleat ends will likely move around as the boat flexes and over years’ time, the coating could wear through and fail. I’m wondering if encapsulation is perhaps more of an ideal than a reality?


I’m using Home Depot ‘yellow pine’ for cleat stock, but it seems quite different than the yellow pine of the south east. Ours is blond, much less resinous, with a fair grain, and weighs much less than the pitchy, coarse-grained wood available in the southeast. Frankly, it’s probably closer to white pine than the stuff you have.  Ballast tanks being ballast tanks, should I lie awake nights lathering over cleats rotting? Should I swap out the cleats with cedar or something better suited to water? I’m sobered by the prospect but better now than 3 years from now. Attached are a few photos – with a close up of the sort of joint I’m bothered by.


Also – I’ve been checking in on this forum just about daily and I really, Really appreciate the thoughts and support everyone offers. It’s incredible. Thank you – I’ve learned tons from everyone’s give and take.


Fred Rowley





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I was down in my shop last night thinking about your dilemma. It's not like water ballast is new in plywood boats. I'm assuming the "deck" piece isn't glued in yet and that it doesn't get glued until the bond to the hull has been made. Assuming that to be true, I'd fill those cracks with some thickened (cabosil) epoxy, squeegeeing it in tight. I suspect that you will fillet all the seems after gluing the assembly to the hull. This will seal the end gain and prevent cracking. I haven't seen the manual for a MKIII, but my Spindrift 11N plans were very complete, but I did have to study them quite a bit before each step. I made a copy and marked them with lot's of notes and arrows each night and reviewed each morning before the next step.


I was looking at the pictures of Graham's boat and noticed there will be a deck hatch, so at the very least, you should be able to monitor the wood easily. The reason you want to keep the finish "clear".


I got the green light to build another boat and I am only trying to decide 17 or 20. I am watching your build carefully!

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thanks Steve - really glad to hear your thoughts.


No idea how much stuff flexes under sail, but I'm tending toward your idea the more I thought about it today, except that rather than fill the space between the joints with thickened epoxy,  I'm thinking I'd cut the cleats back enough so they can't rub, and then make sure the end grain is well coated before assembly. It'll all get coated once it's bonded to the boat, so this would just be insurance. Ponderings like this probably make real boat builders Crazy - just build the freakin' boat!

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I am glad to see you making progress. I agree that we have to pay attention to preventing rot in our ballast tank. It would have been better to have used western red cedar than whatever your white wood is. I used southern yellow pine but wrc would have been better. I would not tear out your cleats and change to wrc at this point. I think that you could open up your joints a bit more by running a saw through the joints and then running a fillet under the joint and up the side. You should now have a reservoir into which you can pour epoxy and fill the joint entirely.


Remember that okume ply is probably no more durable than your pine cleats. We have to be equally careful about the joints in the ply. I am planning to glass inside my tanks as well as the underside of the cockpit sole. I will leave the 6" hatch open whenever the boat is out of the water so that the tank can dry out.

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  • 3 months later...

Hi guys, my wife and I  are building Core Sound 20 MKlll sn #2.  I will be coating the ballast tank with 2 coats of epoxy, and a full coat of West 422 barrier coat in the 3rd coat.  I coated the inside of my C/B trunk, rudder blade and the centerboard with the 422 mixture.  My cleats are SYP, and with the precoat before bonding, then bonding with Graham's "fluffy" then 3 coats of epoxy I have a greater risk of a metorstrike than water intrusion.  My module is installed, boy that was a non event!  Just sat right in like it was designed to go there!   Next week home we will complete the fillet/tape game,  then complete the barrier coat in the ballast tank.  I have a cockpit sole replica laying in place to give access with out point loading the structure till the fillet/tape is complete, with out that this taping project will take a orangutan to reach the midline.  It is already a sail boat, everything you drop falls out of easy reach! 



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  • 2 weeks later...

Hi Steve and Jay,

Not a Lot of progress. I've glassed the ballast tank panels and assembled and taped most of the cockpit module. But then I ran into cold weather that caused some of my taping to delaminate. Since then Seattle has had record rainfall, which drove the humidity in my structure to 100% - prompting mold to grow on all all of the larger panels. I've since retreated to my 1-car garage, but it's kinda tight in there so progress is pretty Slow. With the NE now blanketed in several feet of snow, I'm not complaining. I don't have plans or a complete set of instructions yet, so it may be just as well. . All the best to everyone back East!


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Hi guys, probably should start my "own" thread on my CS20mkIII s/n 2 and I very likely will! But, we finished the module installation and as I told Graham we finished the "inverted ribbon toss!" I hardly recommend everybody to do ALL the module taping before lowering it into the boat. We did and it was still 2 days hanging upside down filet an taping the module to the hull. Hats off to Doug and all who enjoyed that task, taping the entire module that way! Our 20MKIII is basically boat looking and we have a very small bit of taping in the cabin area then the basic structure will be complete. i recommend leaving the cabin/coaming off till the lower hull is full taped. I installed one side in my zeal, it is tough to reach much. Ballast tank has 2 full coats of epoxy, when I get back home the 3rd coat coat with a dash of West System 422 will be added.

Sunny and 60ish in my personal boatyard, unfortunately I am gone at work for another week.


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Jay, yes. I'm leaving here on Valentines day, heading with my three kids to Washington for a couple of days and planning on being at B & B on the 16th. I am currently knocking my honey do list down so I can focus once I get back. I'm not going to hurry, but I'd like to have it finished by the spring of 2016, which seems feasible. 


Please keep some Mark III pictures coming!

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  • 4 years later...

As Deluge emerges from newborn to toddler-dom, it seems like time to update things a bit, with items that I haven't seen elsewhere but that seem to be working for me.


She'd been in the water less than a dozen times when the CB pendant broke; an epoxy spur I'd left in the pendant path had shredded the line. I replaced it with one made of dynema after cleaning things up.20181003_140257.thumb.jpg.f0313e0ee2d9b5d4967bc9ebf29617bd.jpg

I had to splice it in place, but fortunately it's really easy to splice the stuff. The challenge is the stopper knot - it's so slippery it's likely to slip off the end. The fibers, it turns out, are quick to absorb epoxy, so the solution is pretty simple. This is just an overhand knot I'd filled with epoxy inside a piece of PVC pipe.20181003_124912.thumb.jpg.19159ed29f8d7629722a583b35327d26.jpg

This didn't fit, so, gulp, I just ground it down till it did. I'm convinced it's plenty strong enough for the job.



In fact, I don't bother with the fancy knot they tie on the internet for soft shackles, I just do this:


The little rigging balls make nice 'stopper knots' and it's easier to make your shackle exactly the length you want it to be. I keep adding epoxy to the fur until it can't take any more, and I tie rigging twine at the neck to keep the epoxy from wicking down below the ball.


It wasn't long after launch that I'd bashed my transom with the rudder, since I had no rudder stops. I just made a very simple set with starboard and they've worked well. These, or something like them, are now probably on the drawings:



I've been impressed by how much the trailer and boat bounce around on Seattle's roads (they're often in terrible shape), and realized that the CB is bouncing around even more, secured only by the pendant (the CB slot doesn't align with my trailer bunks). So I put in a pedestal, capped with starboard, to keep the board from bouncing around when trailering.




Graham used a fixed bolt to secure his main mast, and I got a couple of the one-legged nuts he uses for it, but it turned out to be easier for me to bolt the mast from the front. I can manage everything from the foredeck, and for whatever reason, it was easier for me to build. The T bolt was my first shot at silver solder - a mysterious alchemy that had long intimidated me. It was pretty much like regular soldering only higher heat.



This is the aluminum receptacle - it's just tapped for the 5/16" bolt, and fixed in place with a couple of screws.


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I hadn't realized what a challenge spaghetti lines in the cockpit were til I started practicing donuts (sailing tight circles around a buoy to improve boat handling skills. Get so you can do tight circles in 15 kts of wind to build your confidence. Still working on it.)  I kept getting strangled, or tripped, or glasses torn off by spare lines as I ducked under to grab the far rail. I tried velcro tabs, but switched to this - a couple of washers with a stand-off between. Works better than the velcro for me, but still not completely satisfied.



Here's how I'm locking the cabin - I've sleeved the thru-hole with some SS tubing to make it a bit more durable.





I really like trailering with the sprits atop the masts - it's quicker to rig and the straps tighten up the masts while we're on the road. As nice as Graham's were, the layout looked like too much work. Mine look like pook, but they work ok and were simpler to make.





So, most of you will be horrified by my anchor roller, but I like it. I think it weighs something close to 2 lbs, but that's a mere fraction of the weight of 15' of chain in the anchor locker.



It keeps the anchor solidly fixed in place, and I can launch it from the cockpit. I keep it tethered like this underway and trailering.


And I've just run a line back to the cockpit that I can use to pop off the tether. I'll 'arm' it before coming in to anchor and cleat the rode off at, say, 50'. Haven't actually used this yet, but from the cockpit I'll be able to ease up to the anchorage and let it go.



Peg and I were recently in the San Juans. It was beautiful (altho the arrangement above would have been helpful).



But 10' tidal differences are common here. This lagoon actually dried out to the rock you see on the right. We moved the boat before that, but I'd beached Deluge at high tide in the new spot in a direct on-shore 15 kt breeze, and really hadn't sorted out in my head how you do clothesline anchoring. In any case, I was going to need Peg to help me anchor, and nor could I figure out how to get off the beach with her in the boat. Here's the result - water wasn't high enough to re-launch til 5pm the next day. (We had a Great time.)



I did eventually get something worked out:20190827_153617.thumb.jpg.7f1fe6399b9421df857cd84a0333d48d.jpg

But here's how I plan to do it from now on. This may be risky, but seems to me the risk is fairly small for over nights - to use a quick link in place of the standard horseshoe shackle. With it, I can quickly change the configuration between shackling the rode directly to the chain (for regular anchoring), and running the rode thru the link (for clothesline).


Regular anchoring:



and for clothesline anchoring:




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I like how you added that piece of rub rail on the inward side of your anchor roller to prevent wear, I like the cabin lock simplicity and I like your sprit saddles.  I'm going to copy all of them tonight. Not sure where to get SS tubing. I might have some aluminum around.


As for launching from the cockpit......put a longer piece of light line (3/16") right to the anchor shackle. Bring it back to the cockpit. With the way you have those stops you could angle it off to port easily. Put a cleat on the top deck just like the ones to starboard. When you deploy your anchor, this tether line goes right with it. I've been doing that for years, and other than the fact that that line can get pretty grungy in some cases, it has never seemed to interfere with the anchor. 


When you retrieve the anchor from forward, just grab the small line to bring aft and re-tether.


That is some pretty country up there.

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Your boat looks great!  

I really like your anchor roller, I have a Ronca anchor and you look like you have the best anchor roller.  I believe it would work perfectly on the Mathew Flinders. 

I leave the sprits with the mast, I use several pieces of pipe insulation to isolate the sprits from the mast.  We have trailered our boat likely  20,000 miles with no ill effects I can see.  It does make rigging ridiculously quick and I never found a really suitable spot for the unattached sprits.  I made a zip on cover that covers both masts, keeps the reefing lines from becoming a big rats nest.  I leave the battens in the sail and just zip the sail into the same sail cover we use......well as a sail cover.

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Wish I had thought about storing the boom on the mast.  My forward window always leaked so I replaced it with a fixed port.  After that the main boom would no longer fit into the Belhaven cabin for storage.  Talked a friend into building a two piece boom using the fittings sold by Ductworks.  It is too pretty to store outside.boom1.thumb.jpg.33f13ddc0ae601254ebca9a9f109771b.jpg


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