19 foot Offshore Power Dory Build #6: Fairing the plywood for Fiberglass and First layer of Glass.

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Blog entry by English posted 02-16-2015 09:28 PM 5937 reads 0 times favorited 5 comments Add to Favorites Watch
« Part 5: Installing Bottom Plywood Planking Part 6 of 19 foot Offshore Power Dory Build series Part 7: Finishing the Fiberglass on the Boat »

I am at 153 hours on the build and the boat weighs 805 lbs.

In my last post I had finished installing all of the plywood. The bottom plywood still needed fairing to the edge of the side plywood and to the same angle as the side plywood. I had planned on doing this with a sander, after a comment from Paul (shipwright) I did this work with a power planer and man was that easy. I was able to keep the planer connected to my shop vac and there was no mess to be cleaned up either. Thanks, Paul.

Next I need to filll in all of the screw holes and the joints and seams between the sheets of plywood. To do this I mixed up some epoxy and wood flour. Wood flour cost $18.00 for 1/2 gallon. So having a 5 hp drum sander and plenty of scrap Douglass Fir left over from the frames I decided to make my own. I need the flour as fine as possible so I put a old 150 grit belt on the front drum of my sander, changed the bag in my duct collector and started sanding. Ten minutes later I had close to 3 gallons of Flour (fine saw dust).

I used this flour to mix with the epoxy to make the filler for filling all the holes and seams.

I then sanded this smooth and re-coated with filler and sanded again. Now it’s time to layout the first layer of fiberglass.

So I started on the bottom, then the sides, then the transom.

It took me 8 hours to get the bottom and one side wet out. I have discovered that I purchased the wrong grade cloth. What I have is 6 oz. 35×35 strands per inch cloth which is used as a finish cloth for airplane wings. You literally have to force the epoxy into the cloth. Regular 6 oz boat cloth is 18×18 strands per inch.

So I stopped for the night and the next morning I discovered that one of my 16 batches of epoxy from the day before was not curing. I gave it another day and after talking with Paul (shipwright) I decided to remove all of the fiberglass that was affected by the bad epoxy mix. Here is a video of the mess.

After removing the affected fiberglass I had to use Acetone to remove the uncured epoxy. Then I sanded the surface to get what had soaked into the wood fibers. I also sanded back into the good cured epoxy and fiberglass about 1 inch to give myself a good edge to bond to.

I then cut out fiberglass to fit my repair area and epoxied it in place. The next day I finished the other side and the transom.

The boat now has one layer of fiberglass on the entire outside of the hull. My plans call for two layers. I decided that I was not going to use any more of the finish grade cloth. Too much work. So I have ordered regular boat cloth from a boat parts supplier. I will add the next layer when it arrives. I will have to sand between coats to feather the edges of the fiberglass where it overlaps and sand off all runs and a light sanding on the entire boat to get a better bond with the next coat..

I will update in a week or so,

Thanks for looking.

-- John, Suffolk Virgina

5 comments so far

View johnstoneb's profile


3131 posts in 2777 days

#1 posted 02-16-2015 09:33 PM

Things are looking good. I always worry about mix when working with any epoxy.

-- Bruce, Boise, ID

View English's profile


682 posts in 2081 days

#2 posted 02-16-2015 09:36 PM

Yea I think I reversed the two containers and got the 2 to 1 ratio backwards. I am being very careful now.

-- John, Suffolk Virgina

View ronniebo's profile


129 posts in 3269 days

#3 posted 02-16-2015 10:30 PM

Aahh—-those seniors moments—I have `em all the time.
This will definitely be a “Power” boat after all the power you have invested in it.
Great work.

View shipwright's profile


8452 posts in 3402 days

#4 posted 02-16-2015 10:57 PM

You are doing great John. Those photos look very familiar. I’ve glassed a lot of upside down boats just about that size. Your work looks excellent.
I still can’t imagine why your designer wants two layers of glass. ....... ??


Keep us posted. This is exciting stuff.

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

View changeoffocus's profile


467 posts in 2221 days

#5 posted 03-02-2015 01:03 AM

I admire your patience as you work through the “learning curve”. We’re never too old to learn.
Keep up the great work.

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