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Tuesday, October 14, 2014

Kingfisher Drift Boat Build - Aft Knee Braces - Design Process

First I'l catch up a little with an update - I've got my dry boxes installed on both sides. This entailed using 5 minute epoxy to attach the front and two sides of each dry box  to the bottom and sides. The 5 minute epoxy was used in spots just to hold the pieces in place. Once they set, I mixed up some epoxy peanut butter, pretty darn thick and used it to fillet the pieces in place. The fillets form a cove that is a transition from horizontal to roughly vertical (floor to sides). Once the fillets are installed 4" glass tape is applied over them and then flow coated. A lot of busy work. It took a full day to get it done, and I mean a long day. That doesn't include the sanding once it's set up.






The photo above  is the aft pedestal in one of Jason Cajune's boats.

My next task of choice, not necessarily in the right order was to make a decision how to construct the aft knee brace. I like the idea of the flow through interior. I want to be able to get from the bow to the transom without crawling over a knee brace. I've decided to do a knee brace similar to the one that Jason Cajune does in his "Recurve" boat. The problem is, it ain't easy by any means. The one I'm constructing will look something like the photo above. I first thought they were a little too "George Jetson" for my taste. But as I've explored my options I've decided the Jetson's were cool.. There aren't any plans or instructions how to do this so I'll have to just dead reckon my way through it. I'm pretty good at that.


The reason I'm working on them now is that they attach somehow to the aft level floor step and are partially painted with the same material as the floor. So I've got to be able to;

(a) Figure out how to construct the darn thing.
(b) Figure out how to attach it
(c) Decide if it's permanent or removable
(d) Get it done or figured out before I paint the floors and the lower part of the sides and dry boxes.

Solving the Construction of the Aft Knee Brace

The knee brace is constructed by laminating 3 layers of 3mm Okoume plywood in what amounts to sort of a "Question Mark" shape. Pretty appropriate when you have no idea what you're doing. It will end up about 7/16" thick and glued together with thickened epoxy. I started out by cutting some different shapes out of scrap plywood to see what shape seemed "right". 



Here's a photo of one of the "Question Mark"s I cut out to see what it might look like. This one was too deep of a bend I thought. I cut  different shapes until I got one that seemed right. For me it's just sort of a trial thing. Try different curves until I thought "That's it". I'm shooting for a height of 27" above the aft level floor.




Once I determined the shape, I needed to construct a form to bend the plywood to the desired shape. I laid out the "Question Mark" on a 1/2" sheet of plywood and made to opposing pieces that will mate together with a 7/16" gap between them (the thickness of the laminated plywood). In the photo above you can see the 7/16" strip that is being cut out. I had to make two each in order to make a form that was approximately 24" wide.


Here's the forms assembled. I will be bending 3 pieces of plywood that are 24" wide by 48" long. All I have to do now is figure out how to get the 1/8" Okoume plywood to bend to the shape. Another "Question".

Next Up Steaming and Bending 1/8" Okoume Plywood 

A forewarning, It ain't Easy!

Monday, October 6, 2014

Kingfisher Driftboat Build - Dry Box Frame

Well, I've been doing my favorite thing. Epoxying and sanding. Sound familiar. I've got all the parts cut out and fit for the dry boxes and the four deck parts. I'll recap the process here.

It basically goes like this.

  • Cut and fit the rod beams
  • Cut and fit the deck support beams
  • Temporarily attach the deck beams and the deck support beams in place with screws.
  • Rough Cut, Scribe and final fit the deck parts
  • Fit the sides of the dry box to the sides
  • Fit the face of the dry box to the bottom and the bottom of the rod beam
  • Take it all apart and coat all sides with clear epoxy
Sounds easy, right, all except the last, Epoxy, sand, more epoxy, more sanding.

Deck Support Beams

  • The rod beam is temporarily held in place with 4 - 1" screws that are driven from the outside of the hull into the ends of the rod beam
  • I clamped an 8 foot long straight edge to the beam to keep it straight as I fit the support beams.
  • You can also attach a string line to assure the rod beam stays straight.
  • There are three main deck support beams and one at the junction of the side deck to the front deck
  • The deck support beams are temporarily installed with screws. 



This is the middle support beam. It is the same width and height as the rod beam.
13/16" x 2 1/2".


Here are three of the deck beams installed. The one at the front supports where the side deck meets the front deck. This support is laid flat.  I eventually added another support to reinforce the rear of the deck.

Side Deck Parts

  • The two side decks and the front decks are made from 1/4" Okoume plywood. 
  • They are rough cut to size and then scribed to fit the sides.
  • The interior straight edge of the side decks line up with the edge of the rod support shelf


Here is one of the side decks that has been scribed to the sides. The two openings for the dry boxes have been cut out. The top inside edge of the side deck aligns with the rod shelf. This is some tricky scribing. Take your time and get it right.

Front Deck Parts

  • The front deck is made from two pieces and glued together along the centerline of the boat.
  • It is made from two pieces so the grain of the front deck flows toward the rear of the boat.
  • The front deck has a half circle that is the same diameter as the distance between the two side decks once they are scribed in. (See photo below)
  • The front deck is raised about 2" high than the side decks at the stem (bow). This allows water to drain towards the rear of the boat.
  • It is important to make sure that the distance from the front of the pedestal to the apex of the circle is at least 16". Preferably 18". I had to make this about sixteen inches as my pedestal is larger than typical because it houses a cooler.


The front deck is temporarily clamped in place after it has been scribed in. The bow is two pieces.

Dry Box 

The dry boxes sit underneath the rod beams and are approximately 5 foot long centered on the rod beam length. (Approximate center of the boat)
  •  There are 4 pieces of 1/2" Okoume Plywood that are scribed into the sides that form the ends of the dry boxes (2 on each side)
  • The face of the dry box is made from 1/4" Okoume Plywood. The bottom of this piece is scribed to the bottom and fit under the rod beam.
  • This dry box face is set 1/4" back from the lip of the rod holder 1/4" plywood to allow a dadoed trim piece to be installed later.

Here the 1/2" Okoume Plywood is in the process of being scribed to the sides.


You can see the face of the dry box fit under the rod beam on te left. The face is held back 1/4".

Sealing the Parts





Now that everything is cut and fit, everything has to be disassembled and sealed with epoxy. The rod beam and deck support beams get flow coated with clear epoxy and finish sanded. The 1/4" Okoume plywood also gets flow coated and sanded. All of these parts are flow coated only and are not glassed. Oh boy!

Wednesday, October 1, 2014

Kingfisher Drift Boat Build - Rod Beams

Well it time to get back into some woodworking. I need a break from all the epoxying and sanding so the timing couldn't be better. I've glassed in the fore and aft pedestals and also the fore and aft level floors. The 3/4" conduit is installed for the anchor rope,

It's time to start on the "Rod Beams", the rod storage shelf, the dry boxes and the Decks. The rod beams, joists and dry boxes provide a lot of structure to the boat. It will stiffen up the boat once everything is epoxied into place. This will all be covered in the next number of posts.

1st Up - Build the Rod Beams


There are two lower level temporary spreaders that are about 10 1/2" on the floor. They give the boat structure will the dry storage boxes and the decks are installed. The rod beams set on top of these to establish the height off the floor. The rod beams are made from 4/4 stock milled to 13/16" x 2 1/2".

There are two rod beams that are 10' long, one each side of the boat, and the rift sawn white oak I have is 8'6". The first thing I have to do is to scarf two 6' long pieces together to make a 11' long piece. My board stretcher is busted.

I had to layout and cut scarf joints on each piece that are 8" long. I rough cut these on a jig I made for the table saw. and then made another jig to run a top bearing straight bit to fine tune the cut. (Difficult to explain without photos, sorry)

Once the cuts were made I sanded the scarfs with 80 grit to rough up the surface. I then mixed up some epoxy peanut butter and spread it on both scarf joints with an 1/8" notched trowel. I matched up the scarfs and clamped the joint together, careful not to starve the joint and squeeze out too much of the epoxy peanut butter.

The next day I took the clamps off and sanded the rod beams. I now have two 10'4" long pieces. I cut these to 10'1" long.

The next step is to cut 2 pieces of 1/4" Okoume plywood that are 2 1/2" wide by 8' long. These will be attached to the bottom of the rod beam forming a sort of "L". with the 1/4" piece oriented towards the interior of the boat. This 1/4" piece will become the rod holder. There will be rod storage on both sides.

This photo shows the 1/4' material that has been screwed to the bottom of the rod beam set on top of the lower temporary spreader. The 1/4" x 8' long piece is centered on the 10'long rod beam. There will eventually be a trim piece attached to the 1/4" shelf.

The 1/4" is screwed into the rod beam with 1" long stainless steel screws. These screws will be left in. and sealed with epoxy.

The rod beams with the 1/4" material attached are them placed in the boat on top of the spreaders and placed so they are touching the sides and the distance between the two rod beams measured across the boat are equal. This takes some fiddling around but once you get them parallel make a mark on top of the spreaders as a reference.

Now the rod beams must be scribed into the sides and then cut to length. The total length needs to be roughly 10' long. If they asre a little shorter once they are massaged to fit it's ok. Scribe the rod beams and then clamp the beams to a workbench and make the cuts with a Japanese pull saw. Once they are cut fine tune the cut by sanding the ends. take your time and get them to fit right.


Here's one of the ends of a rod beam scribed to fit the sides.

Once the rod beams are cut, both rod beams should be the same length and the distance between them should be the same. The two rod beams should be parallel. 

When you are satisfied that the fit is correct. Take a pencil and mark around the beam ends were they meet the sides (4 locations). Remove the rod beam and drill two pilot holes from the inside to the outside. Then put the rod beams back in place and screw them in place from the outside. The screws will be temporary.

So at this point the two rod beams should be parallel and straight.



Here is a photo of one of the rod beams in place, temporarily screwed in place from the outside and sitting on both of the spreaders. The two spreaders are parallel. 

Next Up - Deck Framing