Shipyard Memories #10: The Catboats: Framed Plywood Construction, Backbone and Structural Components

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Blog entry by shipwright posted 12-08-2010 01:45 AM 4194 reads 1 time favorited 12 comments Add to Favorites Watch
« Part 9: The Catboats: Framed Plywood Construction, Scarfing and Setup Part 10 of Shipyard Memories series Part 11: The Catboats: Framed Plywood Construction, Fitting Out »

Before going on to the backbone and structural components of the cats, I found a photo today that belongs in yesterday’s entry. This is what the jig looked like that both were built on. None of what you see here is part of the boat except for the chine pieces at the joining area between the bottom and the sides. My Skill 100 (best powerplane ever made) is sitting on the chine.

In this shot you see the substantial keel about to be assembled from two parts. It is made in two pieces to facilitate proper preparation of the centerboard slot. The centerboard swings down through the keel in the recessed area shown here freshly coated with epoxy and 6 oz. ‘glass cloth.

This is the centerboard trunk that sits above the slot in the keel and houses the centerboard when in the “up” position. It extends to well above the waterline and with it’s cover off you could look right down into the water. We used to talk about fishing through it but a problem would have arisen if we had caught anything more than 2” thick.

These boats have minimal framing and are really supported by their bulkheads, so when the hull is initially turned over, it is quite floppy and must be jigged back into shape and be held that way until the bulkheads are installed. Here the main bulkhead is being fitted. This is where Catspaw and Sylvester first start to differ. Catspaw, the economical, is all marine fir plywood while Sylvester, the POSH, as shown here has Brynzeel (African Mahogany) plywood for all the interior and cabinside areas.

Now the accomodation bulkheads and bunk framing have been installed. In a small boat it is a good idea to get as much painting and finishing as possible done before you get it all closed up. Also installed here are the foredeck beams and the chain locker bulkhead. You can see the forward half of the centerboard trunk also.

Once the cabinsides are in place they, along with the hull sides, get sheathed with 6 oz. ‘glass and epoxy and re-coated / sanded until glass smooth and transparent. This is probably after the first re-coat and before sanding. The bottom was sheathed when the boat was still upside down.

Here’s an interior shot from forward. Visible are the teak flooring and countertop, the centerboard case, half in and half outside the cabin, preliminary seating construction and roughed in hanging locker. Yes Hal, this is the biggest 19 footer ever! The tile for the wood stove is being laid out as well.

Same time frame but from the cockpit looking back in. The cockpit sole will be at the level of the top of the centerboard case so that the cockpit scupper is the case slot itself….cool! This photo also shows the massive forward vee berth. With no mast to contend with ( it’s forward in the chainlocker) and the beamy hull this is a comfortable berth for two and you can sleep with your heads together (sort of). Sylvester had a drop-in filler between the berths that made a very large berth indeed for a 19 footer.

Here’s a picture of the plywood deck about the same time. It was ‘glassed in Catspaw and non skid painted but here, in Sylvester it is not because it will be covered in 3/16” x about 2” teak strips with black epoxy seams.

This is the last picture for today. The hull is pretty well finished and the interior is complete as well. The teak decking has been laid and the seams filled with black epoxy although not all sanded yet. Next up will be the cabin top and cockpit.

Tomorrow we’ll get to the fitting out.

Thanks for checking in.

Please ask questions, comment or critique. I’m having a ball with all these old memories and am more than happy to discuss your thoughts.
Thanks again


-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese!

12 comments so far

View SPalm's profile


5325 posts in 4116 days

#1 posted 12-08-2010 02:15 AM

Hey Paul, I am enjoying the posts.
Tremendous work. Fun to watch the progress pictures.

Do you ever epoxy ply or wood for anything else now days? It always intrigued by its strength, for things liike shop built tools or jigs. I built lap strake ply canoe once, it was a fantastic journey, but nothing like this.

Still watching,

-- -- I'm no rocket surgeon

View sedcokid's profile


2735 posts in 3833 days

#2 posted 12-08-2010 03:04 AM

Paul, this is really a fasinating post. Fun to watch all that happens, the only water going vessel I ever had was a 18’ aluminum fishing boat. So I enjoy this!!

Thanks for sharing

-- Chuck Emery, Michigan,

View shipwright's profile


8184 posts in 3032 days

#3 posted 12-08-2010 03:42 AM

I have done all kinds of things with epoxy Steve, but There isn’t much around the shop that requires the strength or justifies the cost. I am toying with the idea of some cold molded furniture and that would have to be epoxy but nothing right now.
Thanks Chuck, glad you’re enjoying it. I know I am.

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese!

View dlmckirdy's profile


199 posts in 3368 days

#4 posted 12-08-2010 04:24 AM

These blogs are great! I helpe3d my uncle build a 21’ cabin cruise from a kit when I was in high school. I learned a lot about woodworking and fiberglassing on that build (so did he).

-- Doug, Bakersfield, CA - I measured twice, cut it twice, and it is still too short!

View sras's profile


4965 posts in 3363 days

#5 posted 12-08-2010 04:03 PM

Looks like a very effective cabin layout. Another fun story to follow!

-- Steve - Impatience is Expensive

View ND2ELK's profile


13495 posts in 4008 days

#6 posted 12-08-2010 05:53 PM

Very interesting and informative. Thank you for sharing. Where did you learn your craft?

God Bless

-- Mc Bridge Cabinets, Iowa

View shipwright's profile


8184 posts in 3032 days

#7 posted 12-08-2010 06:05 PM

Tom, I got the bug when I was in university and started building “one of those ferro cement sailboats”, a 35 footer in my early 20’s. Unlike many that were started in those days, I finished mine. The trouble was, after getting a job in a boat building yard to learn how to finish the thing, I realized that building was more appealing to me than setting off across oceans so I sold it and started my own yard when I was 27. That’s about where these blogs pick it up as I started “Smaug” about then. I’ve never regretted a day of it.

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese!

View dbray45's profile


3320 posts in 3011 days

#8 posted 12-08-2010 07:48 PM

I did some work on a ferro cement boat, welding steel reinforcement for a friend back in the mid 70s. He sailed off and never heard from him again. I had a few small boats after that be didn’t have the tools or space to fix them up. Still don’t have the space. Some day.

-- David in Damascus, MD

View Div's profile


1653 posts in 3175 days

#9 posted 12-08-2010 10:10 PM

Paul, you must stop posting pictures like this! You are getting me all revved up to build a boat again! :^)

-- Div @ the bottom end of Africa. "A woodworker's sharpest tool should be his mind."

View Russ's profile


357 posts in 3311 days

#10 posted 12-09-2010 12:43 AM

Cool boat. Great work on this.

-- Russ

View Bearpie's profile


2601 posts in 3252 days

#11 posted 12-09-2010 05:47 AM

I will probably never build a boat but I really enjoy reading about it. Having owned 6 different boats I can appreciate your blog. I still have the last 3, 2 kayaks and a folding boat! Thanks for posting!

Erwin, Jacksonville, FL

-- Erwin, Jacksonville, FL

View Napaman's profile


5530 posts in 4311 days

#12 posted 12-09-2010 07:30 AM

Love this post…it is so nice to see the layout of the cabin…great details…

The building process has so many similarities—-yet some differences to from my boat…

I think the cockpit is wider but not as long—-and there is more room taken up between the lazerette and transom on your boats…

I am excited to get building again seeing all these great picts!!! Will try to put my boat bottom onto my keel this weekend!!! Started cutting out the notch on the keel for the boat bottom to slide into…mine is different from the plans so I am really nervous but oh well…it will be my own boat!

Thanks for all…matt

-- Matt--Proud LJ since 2007

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