Jim Builds a Boat!

Yahoo, I finally started building my boat!

After more than a little armchair research I settled on “Jonsboat” by Jim Michalak, it looks pretty ideal for a small fishing boat, and simple to build.

The first step in this build was to mark out the frames & bulkheads on a sheet of 1/4″ plywood. These are the basic structural elements that help the boat keep its shape, and they also form the foundation for the bench seats. This is very straightforward, and involved nothing more than drawings straight lines, double checking all the measurements (seriously… do this), and cutting along the lines with a circular saw.

The only complication here is that I was making the sides 2″ taller to get a tad more freeboard (I want the missus to enjoy this boat too, and this should help), which meant that I needed to raise the height of the frames. This was easy enough, I simply drew the frames as designed, and extended the lines for the sides an extra 2″. This will also yield a little more room under the bench seats for the battery & other odds & ends.

After the frames, the next step was to cut the panels for the sides. These are a little more interesting, since they have some curved cuts, and their length of nearly 16′ requires splicing 2 pieces of plywood together.

So how do you draw out that lovely curve that defines the bow section of the boat? It’s pretty easy actually. The plans give co-ordinates where you drive a temporary finishing nail, every 24″ along the long side of a sheet of plywood. This boat has a pretty simple curve and you only need 3 of these points. Then you take a scrap piece of something (I used a strip of MDF I had laying about) and clamp it to the nails, which gives you a nice curved edge you can trace through all of the given points. It looks something like this:

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Cutting these curved pieces is not much harder than cutting the frames, and you can cut a nice curve with a circular saw if you set the depth just right. Alternatively, you can use a jigsaw, but I find the circular saw gives a really smooth result.

Once the side pieces are cut, you have to splice them together. There are several tried & true methods of doing this, and I elected the simplest (and the one specified in the plans) which is the butt strap. This is nothing more than a piece of plywood ripped to 6″ wide, and the length of the joint. the strap is smeared with glue and screwed to the sides. This is very strong and very reliable. I used PL Premium for the glue, its a polyurethane adhesive, and its serious stuff. Don’t get it on your hands. I like to spread it evenly with a notched trowel to make sure I get a good bond. Here is one of the straps, smeared with PL:

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Then all you have to do is butt the sides together, lay them down on the strap, and drive in some screws to clamp it all good & tight. I found it helpful to drive in a few nails to pin the pieces together so they don’t slip while you screw them together. Here’s the result:P1060532P1060533

That was about all the fun I could handle for one day, it was awful cold out in the garage. About 4 man hours so far and all frames & bulkheads were cut, sides cut & spliced.

The next step in the construction of my as yet unnamed boat  was to finish the frames. Most of this happened over the course of a workweek with an hour or two here and there in the evenings. Good fun table saw stuff, ripping douglas fir structural lumber down to size, then gluing & screwing the pieces to the perimeter of the plywood frames. Bump the man hours up to maybe 8 or so.

Unfortunately, the following weekend I didn’t get a whole lot of new construction done but I did completely dismantle the old SeaRay. Feels a little wrong to dismantle an old boat… but I gave away the hull so hopefully the old gal will work out for someone yet.

Fast forward another week and assembly took a huge step forward: gone 3D!!!

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Hey, that kind of looks like a boat!

Here you can see the sides being fastened to the frames. Once again, liberal use of PL Premium and stainless screws. I did have to come up with some way to pull the bow portion of the sides together to screw into the bow block, the traditional way to do it is to use a Spanish windlass but I used ratchet straps, mainly because there is almost always a pair of ratchet straps within arms reach in my shop. This whole process took a couple hours, so we’re up to maybe 10 man hours at this point.

I intend to completely close in the middle bench seat so I build an extra frame beyond what the plans call for. The plans do call for a temporary frame to be used during assembly, I substituted my extra frame for this temporary one and you can see it in the middle of the picture above.

The next step was to cut & install chine logs. These are the structural bits that hold the sides & bottom together.  I picked out a few select pieces from the 2×4 pile at my local home depot (had to sort through a lot of lumber… I dont’ think they like me much there). More tablesaw work here, buzzing them down and adding a 19° bevel so that after screwing them to the flared sides, there’s a nice flat surface on the bottom side to fasten the bottom panels to.

These chine logs get glued & screwed to the bottom of the side panels, which means they have to take a fairly substantial bend. I formed the bend progressively using cabinet clamps to provide the bending force. Bend a little, drive a screw. Bend a little more, drive another screw. You can see the chine log taking its shape here:

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Now, on the first try, I got a little too exuberant with my use of the clamp and next thing I knew… BANG!!! Pieces of chine log flying all around the shop. This is a fairly substantial piece of wood and it doesn’t like to bend that much, especially since I made them beefier than the plans call for because I’m planning to use a bit more than the suggested 10 HP motor.  Here’s the result:

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For the second try, I snuck an iron out to the garage, and by draping the chine logs with damp rags & hitting them with the hot iron as I bent them, I was able to coax them into shape.

Next little project was to cut limber holes, the little passages at the bottom of the frames that allow water to drain to the back of the boat. I used a forstner bit and drilled them to roughly the same od as a piece of PVC pipe I had laying about, then smeared the pvc (roughed it up beforehand) with PL Premium and bedded it down into the hole:

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Then I just cut the pipe flush with the bottom of the frame & sanded everything smooth. I wasn’t certain how well the PL Premium would bond to the PVC, but when it was cured I tried to budge it and it was clearly not going anywhere.

Next step was to spend some time sanding & evening out all of the chine logs & frame bottoms to prep for installing the bottom. Once that was done to my liking I checked the structure for squareness by measuring between opposing corners, and it was within 1/16″. Plenty square.

Installing the bottom was fairly straightforward, although an extra pair of hands would’ve been useful for sure. The bottom is made up of 2 full sheets of ply, and I started at the transom by laying down a bed of glue on the frames & chine logs and laying down the first panel. The biggest difficulty was that the panels like to slide around on the PL, so I used a couple temporary nails to keep it from sliding while I screwed the bottom down. Here’s a picture of the first piece installed:

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The second panel got a little more interesting, since this is the one that needs to take a pretty substantial bend. I joined the two pieces with a temporary splice plate screwed to the inside, this is to keep the two pieces flush until they’re fiberglassed. Once I got the rear of the panel secured I worked forward, drawing it down into position with screws:

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That panel is surprisingly stiff, I had to sit on it as I screwed it down to help it take that bend, but eventually I got it well secured. With the bottom in place, the hull stiffened up considerably.

Now, you’re not really supposed to flip the hull over at this point, but I just had to see what she was going to feel like when complete, and she’s light enough I can flip her by myself so I went ahead.  She feels bigger than I had expected, this is a pretty good size boat as you can tell in this picture:

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Got her turned the rest of the way over and sat inside.  The level of excitement here rivaled being 6 years old on Christmas morning.

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The next big step was to install the gunwhales. This was another fun tablesaw project, they are laminated from 3 strips of douglass fir, and beveled 19° to match the sides. I used scarph joints because I couldn’t find any clear lumber long enough for the job. I got the starboard side done by myself, but this is a job that really benefits from an extra pair (or two) of hands, and I was fortunate enough to have the help of Rob & Daniel, a couple buddies from church, on the port side. Much easier.

                        P1060572                        P1060571

At this point I spent an evening or two just putting some of my normal fishing/boating gear around in different places, trying to get some ideas for the final layout. In other words, playing. That was fun but I did have to get back to business, so I flipped the hull back over to fiberglass the exterior of the hull.

To prep for fiberglassing, I filled any nicks & knotholes with thickened epoxy, and roughed everything up with a 60 grit pad & an orbital sander. I don’t have any pictures of the fiberglassing process unfortunately because its hard to take pictures when you’re all stickied up with epoxy, plus I was perpetually concerned (needlessly as it turned out) about the resin starting to harden too early. I like to do my fiberglass work with a paintbrush & bondo spreader, a lot of people prefer a roller but I find I’m able to get pretty good results this way. Here are some before & after shots:

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Came out real nice.

At this point I had to make the stiffeners for the bottom. All boats flex some when they pound into choppy water, and flat bottom boats take a particularly hard beating (on the plus side though, the flat bottom makes superb use of small amounts of power). Generally you don’t notice this because factory boats typically have a false bottom. On this boat the bottom really is the bottom, so you have to take measures to prevent flex. I made 3 skids from 1 by lumber, each one made of 2 layers laminated together.  These I scarphed with a hand plane by clamping them all together, offset by a specific amount, then planing them to a smooth bevel:

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Securing these to the bottom raises a few questions. The easiest way to do it would be to run screws down through the hull into the skids with plenty of glue, zip zip done. However the thought of putting any holes into the hull really puckered my sphincter… any through hull holes have to be taken very seriously because ultimately they are usually the source of leaks & rot. So, I decided to try and see if I could get away with simply gluing them down with PL Premium and a whole bunch of clamps & ratchet straps. Here are the results:

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Looks like it should work.

You’ll notice that I did not fiberglass these skids. My expectation is that they will be “sacrificial”, basically If they get banged up & scraped up, I sand them down & paint them again. I’ll be able to run her right up onto a beach without worrying about what’s happening to the hull. for the cost of a few pine boards, if they rot in a few years, I’ll just pull them off & replace them.

I primed & painted the bottom, using Killz primer & home depot porch enamel:

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Then I flipped the hull over to fiberglass the interior.

Once the interior had been glassed, I had to notch the transom for my outboard. I did not finish the transom yet though, because I was not sure if the motor would be low enough. The only way to tell for sure was to give it a sea trial! Just a quick test, still with the interior unfinished, but it was a pretty exiting moment!

I met up with Rob &  Daniel, and trailered her down to Lake Marburg, a reservoir near Hanover PA that allows gas motors up to 20 H.P. First impression: it floats on practically nothing, without anyone on board the chines are bareley even submerged.

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We hopped on board, fired up the motor & pulled away from the launch. Once I got out of the launch cove, I opened the taps on the motor, and she planed up practically instantly. This boat handles beautifully, and with 15 H.P. she really flies (no gps on board unfortunately).  Very stable on plane, and banks into turns really well. She’s a ton of fun to drive! We motored around the lake until we got too cold to stay out any longer, but I did a final little loop in the launch cove & had Rob snap this picture :

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That was a pretty good day.

At this point the only thing left was the finishing work, and with warm weather approaching rapidly, I quickly got her painted & worked on hatches, hinges, lights, fishfinder etc., here she is, finished to “fishing standards” and emerging as such from the garage for the first time!

emergence of the boat

Had a christening ceremony with my brother, brother in law, and my dad, and we took her out for the maiden fishing trip. She worked like a dream, although with 4 adults and a spare trolling motor battery on board, we were probably at the limit of what 15 H.P.  can plane.

Update 7-17-13

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So I’ve been using my “Johnsboat” for a couple months now, and I’ve had a chance to put it through its paces. Here are my thoughts so far:

15 Horsepower is ample power for this boat. Alone, with a 9.5×10 “slightly damaged” prop on my 89 2 stroke Johnson I clocked it via GPS at 24 MPH. At that speed it did start to porpoise, so I backed off pretty quickly. Get her on plane, and you can cruise comfortably at half throttle. I am planning to get a new 9 pitch prop that may improve the performance a little bit, particularly with 4 dudes on board. She handles very well, well enough that I’ve on occasion given up fishing just to go for a little joyride (it takes a lot to distract me from fishing). She’s also very economical to run, I use a 6 gallon tank and I’ve never used more than maybe a quarter of a tank in a day.

I’ve used both 40lb. and 50lb. transom mount trolling motors. 40lb is enough to be comfortable even with a pretty stiff wind, and is what I’d probably recommend. I picked up a 50lb. just in case I ever need it for a bigger boat, plus the local bass pro had it on sale.

As a fishing platform, Johnsboat is superb for up to maybe 4 people, and this is my primary use. The shallow draft and great stability make her very capable.

I will say that I’m glad I added the extra freeboard. No, it doesn’t turn it into an oceangoing craft, but I do feel a little more comfortable riding out a big wake or leaning over the side. Probably not necessary though.

Hopefully I’ll have more updates as time goes on. I plan to use her a lot.

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Me & the missus out on Lake Marburg on a beautiful Saturday.

Video update: I took the boat out on the Severn River with my brother in law Steve for some crabbing. The day started with a beautiful sunrise just as we were motoring out of Spa Creek, but eventually got a little too rough and we had to head for home, although we should’ve done so sooner than we did, with what was according to the NOAA a 2′-3′ chop as we got back towards the ramp. White knuckle ride for sure, and she took a real beating, but she got us back safely.

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8 thoughts on “Jim Builds a Boat!

    • Regular old home depot BC exterior pine. I dug through the pile some to find the better looking pieces, still had a few knot holes to fill on the “C” side, but I’d use it again. Might go with a higher grade if I was using either 3/8″ or 1/4″ though, since you get less plies, and the BC in those grades looked pretty scruffy.

  1. Nice Work! I actually came across this site while doing a google search about pinholes in outboard gas tanks. 3d printed boat parts caught my eye as I’ve been printing nylon gaskets for my carb float bowl. Interestingly enough, I’m also repairing a fly rod right now and I’ve been mulling over possibly building a stitch and glue boat. Great stuff on here!

    • Thanks, glad you found it interesting! I no longer own the old boat that had that leaky tank, but the fix was still good 2 years after I applied it. Nylon bowl gaskets, good idea. I’ve been dabbling with nylon myself, though I’m using weed trimmer line. Seems to me there’s a lot of possibility to get some older motors back up and running with these techniques, being able to replace very hard to find parts.

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