Jump to content

Core Sound 20 Mark I #174

Nick C

Recommended Posts

I got around to downloading the photos from my shop camera so it is time to report that I have made some progress on Core Sound 20 Mk1 #174. The boat was unfolded last October (I posted a few pics) and I had the naïve idea that I would be launching in the spring. But as someone on this forum said recently, Life Stuff keeps happening. If I was to name my boat after the process of building her, she would be “Timeout”, or “Hiatus”, or similar.


There hasn’t been much on the forum recently about Mk1 boats, but I wanted an open boat for day sailing. We had a Flying Scot for 30 years and sold it to reduce the fleet – we thought we would just sail our larger boat. But we miss it so I decided I would build a replacement. I was on track to build a Spindrift when I fell into a deal on a Nutshell Pram, so I decided to build a Core Sound 17. That idea got upgraded to a Core Sound 20 and Graham and Alan said they could produce a kit. They tweaked the plans and cut out the parts, and early last year I picked up the pieces and got started.


I have recorded most stages since I started and will post a condensed set of more interesting pics. I started out gluing up my centerboard blank while I was waiting for the kit to be cut out. I used some white oak I had – it qualifies as an antique since the tree was >100 years old when it was sawn into boards for a barn that was built >100 years ago. Anyway, it looked like a massive cutting board when it was planed flat by the CNC machine. Then watching the shaping was great. The curves were pretty furry but no match for a belt sander. I prepped the board for painting even though it looks like a craft project…


02a centerboard CNC (1).JPG

Link to comment
Share on other sites

The hull was leveled and set to correct measurements, inwales glued in, then chines were tack welded. I did not use a keel batten opting for overlapping biaxial fiberglass tape.

07 clampfest (2).JPG

07 clampfest (3).JPG

08 chine tacked & dryfits (1).JPG

08 keel tacked & filleted (1).JPG

Link to comment
Share on other sites

When I dry fitted the seats it seemed like a milestone. Also seen is my idea that I did not want the foredeck hatch so I cut off the bulkhead and extended the seat. I told visitors the hole was for the head.


08b 1st dry fit (3).JPG

Link to comment
Share on other sites

I picked Alan’s brain about motor mounts and decided on a built-in well in the aft deck.


10 framing and motor well (3).JPG

10 framing and motor well (4).JPG

10 framing and motor well (7).JPG

I added a transom ladder. After going to Capsize Camp and reading some posts, it seemed like longer would be better so I got a 3-step ladder. It is designed for a swim platform so I had to grind off part of the base to get it to lay flat against the transom.


I could see flexing in the transom in my first test, so I added more braces. You can see the revision in the photo.


I tested it by climbing in the boat and now there is no flex. I did not test the inverted position and hope I don’t need to use it that way.

15 transom ladder  1.JPG

15 transom ladder  2.JPG

15 transom ladder  3.JPG

15 transom ladder  4.JPG

Link to comment
Share on other sites

Another revision: I decided I didn’t really need the space forward of the centerboard so I closed it off with a bulkhead. Photo shows it just before taping. I wish I had thought of that before I finished the deck there.


I hope that will help with exclusion of dirt, water, mildew, bugs, etc. There should be no habitat loss for insects and spiders since I mitigated by opening up under the foredeck.


16 bulkhead revision (3).JPG

Link to comment
Share on other sites

Nick, thanks for documenting the build. And for choosing the CS 20 mk1. I obtained the partially completed hull of #80 three years ago and finished it. It was the boat I wanted since seeing a CS 17 the year before and has proven to be a great choice for  daysailing and short cruises. And it is fun to run past much larger keelboats when the wind is up.


I like your modification of the forward area. I added cargo netting under the foredeck hatch so I can toss in light gear without having it fall to the bottom out of reach. I attached a ladder similar to yours. It has worked well enough. If you can devise a way to have the bottom angle out from the boat it would be easier to use.


Please keep posting pictures.



Link to comment
Share on other sites

Good catch on the angle, Reacher. The bracket is designed to hold the ladder at an angle when mounted on top of a swim platform, which obviously won't work on a transom. I added an oak piece under the ladder for it to bear on. I just glued it on so I can plane it off an replace it if/when it gets beaten up.


The photo set is pretty much up to date. Given my track record it may be a while before another update...


15b transom ladder (1).JPG

15b transom ladder (2).JPG

15b transom ladder (3).JPG

Link to comment
Share on other sites

She's looking good! I've been trying to decide what size to make my motor well on my CS 20 MK3.  I don't have a small gas motor yet, I have a trolling motor which I hope to use mostly but on longer trips I think I may need the extended capability of the gas engine like a Honda 2.3 or something.  So I need to make sure I make the motor well large enough for that.  I also will be mounting a ladder from Garlick that fits in a tube and deploys out the transom.  Apparently Amos and someone else installed one too. My dilemma is I want to install Graham's wind vane too, I'm just not sure there is enough room on the transom for it all to work as designed, LOL.

Link to comment
Share on other sites

Mark, the tube ladder takes up very little room on the transom. I mounted mine to the left of the left longitudinal bulkhead, but I suppose it could be even further outboard. As for the motor mount, take the lack of a design seriously. The reverse transom makes for quite a bit of fiddling to get it right. I bought a Suzuki 2.5 three years ago to make sure I got it right. I also have a Honda 2 I made sure fit. The Honda is quite reliable but loud. At the time the Suzuki (water cooled) didn't have a long shaft version but now does.


BTW, this build looks really sweet.

Link to comment
Share on other sites

  • 4 weeks later...

And that is all the pieces from the kit!  Everything that came from the CNC machine (except centerboard and rudder parts) is now assembled. It felt like another milestone passed.


Almost done, right?    ... I hear snickering ...


Checking inventory of mask filters because I know I will be spending much time with sanders and epoxy coating.

20 all the parts (2).JPG

20 all the parts (5).JPG

20 all the parts (6).JPG

  • Like 1
Link to comment
Share on other sites

I tried using fillable caulking tubes to apply thickened epoxy and I wondered if others on the forum had experience with them. I decided to compare them to the plastic bag approach when gluing the deck on my boat since there were many linear feet of glue bead to lay down.

I have used cartridge system epoxies like West System Six10 or Pettit FlexPoxy for repairs, small jobs, and once in part of a building project (a glued lapstrake boat). The mixing nozzle is cool technology and the result is a perfect non-sagging mix. But there isn’t very much in the tube and it is an expensive alternative.


Thickened epoxy in a plastic bag works very well. I had the idea that a caulking gun might work better for me on vertical surfaces so I ordered some from Amazon.com.


My experience so far:

- I was working in hot weather so I had to have everything ready to go and then worked very quickly. Not quite frantic, but I had a vision of having a solid warm cylinder when the epoxy kicked.

- I cut the nozzle to 1/4-inch so I could use a dowel to push the plug back out

- It worked well. I think it is no better than the plastic bag method for horizontal surfaces but I did a better job on vertical. I was pleased with how well and quickly I could lay down a bead on a carlin then spread it with a small spreader of brush.

- So far I have gotten 4 uses out of one tube and it is still usable. Some epoxy remains at the nozzle end that I couldn’t get out but it still works; if it plugs up the nozzle I could drill the hardened epoxy with a long bit. The hassle was the plug – I was able to push it back out with a dowel but it is getting harder. Some say you can blow it out with compressed air but I didn’t try that (seems like an opportunity to make a mess)

- I think it would work well for delivering thickened epoxy into a corner to make a fillet but I have not tried it yet.


I could not find much about use in a web search, YouTube, etc and none on boatbuilding. How about this group?

Link to comment
Share on other sites


Looks awesome thanks for the pictures! I've not tried the caulk tube so thanks for giving that a go. I've wondered if it were possible to have a tool that would simultaneouslt lay down the exact right amount of thickened epoxy AND shape to a fillet all at once. in my mind that looks like a gun with some sort of wheel, a caulk tube and a shaper thing and then may some sort of edge scraper behind. 

Link to comment
Share on other sites

  • 2 months later...

Update:  I haven’t reported on progress in a while but I have made some. I managed to get the boat almost completed to go to the Messabout, but I couldn’t get the mast rigging done before Friday. So, no sailing but we did do a launch test – more about that later.


I don’t have many new photos to share since most of the work since my last batch was sanding, priming and painting. I have made a few custom additions so I will get pics together about those.


First, or maybe last, I diverted effort to refurbishing the trailer I bought from a CraigsList ad. I replaced bearings and seals, tires, lights, winch parts, roller bunks, etc. You know the story. I was considering the great keel roller design by Graham and Pete McCrary but I also had decided against a keel. At least initially – I may change my mind and add it later.


So rather than adding a few rollers and recovering the bunks I bought keel roller bunks. The bunks on my trailer are directly under and align with the longitudinal bulkheads so I wasn’t too worried about hull deflection. I selected galvanized sets made in the USA by Dutton-Lainson and got mine on sale from etrailer.com. Since my bunk boards are 8 feet long I got 2 sets of 4-foot roller bunks.


We did a launch test at the Messabout and Alan crouched under the boat and took a video – it is in his Messabout photo album (https://photos.app.goo.gl/orS7YxLEPGa3Wkd2A)  This long-winded explanation goes with that video, but the bottom line is that the boat rolled off without a push (so I need to be careful about unhooking at a ramp). There are 60 rollers! I will add a couple of centerline rollers and tweak the bunks but I am pleased with the results.

Link to comment
Share on other sites

I decided to add a centerboard gasket. I have had them on boats before and they probably make better sailors go faster but it also keeps crud out of the centerboard trunk. Sailing around here when (not if) I stick the board in the mud maybe it will act like a mud squeegee.


When the boat was on its side I installed the bailer and a gasket. I got some material from APS but unfortunately they don’t sell it any more. It is coated fabric but the ones I have had in the past are just sailcloth. I used 1/8 x 1/2-in. aluminum strips to secure it and lots of 4200. It probably is a vulnerable spot for water intrusion so I will keep an eye on it.






Link to comment
Share on other sites

I decided to route lines to the mainmast under the deck. Before I glued down the deck, I mounted turning blocks under the bow pieces and used them to align pilot holes in the deck and locate holes in the bulkhead. I used a piece of cord to where they were headed and lined up a piece of PEX pipe to go through the bulkhead and put fairleads on the deck beams.


I put screws through the pilot holes to keep drips out of the blocks below, then when epoxy and painting work was complete broke them out and drilled holes for Racelite through-deck fairleads.


Clamcleat makes a cleat with a roller fairlead on the bottom for the line to enter from below. It is a CL230 – looks just like the CL211. I made a little Starboard molding for the line to go over (under?) just before going through the deck. The two cleats shown are for the downhaul and halyard. I put the cleat for the snotter closer to the helm.


I think this is about equal in turns and friction to running lines above the deck. A little more trouble to run the lines. I had considered running the lines through lengths of 1/2-inch PEX but it might become mud dauber habitat.

lines below deck (5).JPG

lines below deck (3).JPG

lines below deck (2).JPG

  • Like 1
Link to comment
Share on other sites

Red is down haul and black is snotter?  So your down haul is direct haul? (no advantage)


I think you will find the extra block to come back up adds some friction. Hopefully not too much, it is a tidy install.  You can always add a pad eye and make your down haul 2:1 without disturbing your new feeds.  I did on my Lapwing.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Supporting Members

Supporting Members can create Clubs, photo Galleries, don't see ads and make messing-about.com possible! Become a Supporting Member - only $12 for the next year. Pay by PayPal or credit card.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.