19 foot Offshore Power Dory Build #5: Installing Bottom Plywood Planking

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Blog entry by English posted 01-28-2015 12:11 AM 3938 reads 0 times favorited 3 comments Add to Favorites Watch
« Part 4: Installing Plywood Planking on Sides Part 5 of 19 foot Offshore Power Dory Build series Part 6: Fairing the plywood for Fiberglass and First layer of Glass. »

I now have 120 hours in the build and the boat weight is 779 lb. I have been weighing each piece as it is installed.

A look from under the boat. with all the side plywood installed, This boat has a 8 foot beam and 19.5 ft long.

A inside look at one of the butt splice backer boards.

Next we have to trim the side panel down and fair them even with the top of the chine logs. I used a router with a flush trim bit to get the sides down to the small lip you see in this picture.

Here I am using a side grinder with 36 grit paper to make quick work of the fairing. I ran my dust collector with 3 – 6” ports open to the room and my overhead air cleaner and the dust didn’t get too bad. I will have a job cleaning the shop after this project.

This side has been faired and is ready for the bottom plywood.

After fairing the side plywood even with the top of the chine log I laid the first sheet of 5/8” Douglass Fir marine plywood on the frame lined it up and marked the underside for trimming and marked all of the frames touched by the panel. Latter I will paint on epoxy where it is marked.

Frame marking on the bottom of one of the panels I trimmed the panel alone the curved outer line with an circular saw.

Trimmed panel ready to be out back on boat.

All three panels on the starboard side ready to be epoxied and screwed in place.

Starboard side ready for epoxy and screws. Look at the grain patterns on the first long sheet on the bottom of the boat. This is rotary cut veneer on the Douglass Fir plywood. Wild patterns!!

Monday I will cut the other two panels for the port side and epoxy a screw all five sheets of plywood down.

I need to be able to hit the chine log with my screws every time, be in the middle of the board and not split the chine log. So I made this marking jig to mark the center of the chine log. Worked great.

Here is how the marking jig works. You just slide it around the boat and it marks the chine center dead on.

First bottom sheet epoxied and screwed down.

One side done working on the other side.

Each of the plywood panels were placed on the boat frame and marked from the inside where the boat frames touched the plywood. After the plywood panel were trimmed, I painted epoxy on to the panel where it touches the frame and on the frame. The plywood is so dry it soaks up most of what is painted on it. If you only put the epoxy only on the frame the plywood would soak up most of it and you may end up with a dry joint.

Frame and plywood panel covered with epoxy ready to put together.

Third sheet epoxied and screwed down.

All plywood now on boat!!!

All of the Marine Plywood is now installed on the hull. The only thing that will add more weight to the hull before it is turned over is the fiberglass and epoxy. I plan to put two layers of 6 oz fiberglass and at least three coats of epoxy on the entire outside of the hull. This should add another 50 lbs or so.

Next is to fair the bottom plywood to meet the side plywood and at the same angle as the sides. This will have to be done with hand plans and an array of sanders and rasps.

Thanks for Looking!!

-- John, Suffolk Virgina

3 comments so far

View shipwright's profile


7094 posts in 2219 days

#1 posted 01-28-2015 12:37 AM

Looks great John. ....... but you need a power plane. They are much faster and less dusty than all that grinding. :-)
At this point it looks a lot like a couple of sailing dories I once built.

Good photos and write-up as well. There’s really nothing better than building boats but watching someone build one is pretty close.

Thanks for this.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees.

View lightweightladylefty's profile (online now)


3127 posts in 3134 days

#2 posted 01-28-2015 03:51 AM


We are enjoying your blog, but we don’t agree with Paul. It is much nicer to read and enjoy vicariously than to think about lifting and struggling with those big pieces of plywood and trying to get everything in place and done right!

Thanks for sharing.


-- Jesus is the ONLY reason for ANY season.

View changeoffocus's profile


457 posts in 1039 days

#3 posted 01-28-2015 11:12 PM

Just finished reading #4 and #5, you are a man on a mission. Great narrative and pictures.
You will be in the water this spring at the rate you are going.
I look forward to #6 this is a very interesting project.

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