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Old Jul 13, 2010, 09:57 PM
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The next items to be installed are the spray rails which are made using the 1/8” X 1/4” X 36” basswood batten material. The bottom edge of the spray rails will follow the chine line of the hull, starting at a pencil mark at placed at 3/4” back from the bow. The spray rails will be shape sanded only on the top side of the 1/4” width of the plank. See drawing DWG #11. Remember that the front and rear of the spray rails must be also shaped with a slight radius from the width of the rail back into the hull.

Once the rail has been shape sanded, seal the gluing surface with the thin CA glue. Once the glue has dried and starting at the 3/4” pencil mark on the chine line, using masking tape to hold in position, tape the end of the spray rail against the hull. The working back every 2 or 3 inches at a time, making sure that the bottom of the spray rail in on the chine line, tape the rail against the hull with the masking tape.

Once the spray rail is taped in position, turn the hull up side down, and glue the spray rail in-between the hold tapes with the medium CA glue. Once the glue has set, remove the tapes and re-glue the rail were the tapes were removed. Turn the hull right side up and glue the edge of the rail against the hull with the medium CA glue.

The same procedure will be done on the opposite side of the hull with the other spray rail.

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Old Jul 14, 2010, 05:40 PM
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With the spray rails and the transom and quarter guards glued in place on the hull, give them a finial sanding with 400 grit sand paper to smooth out for finishing.

We stained the guards and the spray rails with the same color mix as we stained the mahogany hull with. (The proto type model was stained with a 50-50 mix of Burnt Sienna & Lipstick Red; water based acrylic paints from Folk Art, which was purchased at the local craft store). If you did not stain the mahogany of the hull, you will have to match the color of the hull with one of the colors available from the craft store.

Once stained, apply two coats of epoxy finishing resin to seal and sand smooth with 400 grit paper.
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Old Jul 14, 2010, 05:46 PM
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Now we must mask out the hull at the water line so primmer can be applied to the bottom of the hull. Using a 1/4” wide Fine Line masking tape first to mask out the water line will make it easier to tape out over the spray rail as you go to the bow. The Fine Line masking tape can be purchased at the local automotive store. Then tape with the painters masking tape and news paper to cover all the rest of the hull to prep for the spray painting of the primmer. One other precautions before painting is to plug the propeller and rudder stuffing boxes with some soft candle wax, along with the bearings in the strut, so that you do not spray paint the bearing surfaces.

The spray primer we used was Dupli-Color filler primer (#FP101 Grey), and was purchased at the local automotive store. Three good coats of primer were sprayed on making sure not to get any runs in the paint. Let the primer dry for at least 24 hours before handling, no matter what the instructions on the can say.
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Old Jul 14, 2010, 05:49 PM
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After the primer on the bottom has dried out, remove the masking tape and news paper from the hull. Now with the 1/4” Fine Line masking tape, tape out the just primered bottom of the hull from the water line down. This is in preparation of the hull for the final build up finish of polyurethane which is going to be applied to the hull.


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Old Jul 14, 2010, 05:54 PM
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At this time the engine hatch must be cut free from the hull using a razor saw and Xacto knife before going forward with the finishing of the model. Once the hatch is free, sand the sides of the hatch smooth and also the hatch opening in the boat, removing the temporary balsa shims.

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Old Jul 14, 2010, 05:56 PM
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With the hatch removed and the sides sanded smooth place a piece of masking tape down the center of the hatch. The hatch will be cut in half down the center between the hatch frame center frames (HFC). Once cut in half, carefully remove the masking tape and sand the hatches smooth with the frames. The two hatches will be finished with the rest of the deck, at the same time and for the same number of coats of finish.

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Old Jul 14, 2010, 06:01 PM
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The hull will receive a total of five coats of polyurethane clear coats. The first two coats will be with Minwax “Helmsman Spar Urethane” and the last three coats will be with Minwax Clear Satin Polyurethane.

The reason for the two different polyurethanes is that the “Helmsman Spar Urethane “ has UV protection to stop bleach out and color change of the finish from ultraviolet light. The down side is that the finish will keep getting darker with every coat of finish that is applied. That is why we start using the Minwax Clear Satin for the rest of the build up on the finish.

When applying the finish, do only one side at a time for each coat of finish that is applied, and have that side horizontal to the table. This is the same procedure used when applying the epoxy resin to the hull. After you have a coat of poly finish on the deck, sides, and transom, lightly wet sand the finish with 600 grit wet and dry paper. Wipe down with a wet paper towel and let dry before the next coat is applied. This is done for all five of the coats of urethane build up.

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Old Jul 14, 2010, 06:06 PM
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When the fifth coat of urethane is applied, it must dry out for at least 3 to 4 days. The reason is that even thought it is dry to the touch; the thinners in the urethane are still evaporating from the finish.

After the fourth day of dry out of the urethane, a final wet sanding of 600 grit sand paper is done to the hull followed with a wet sanding of 1200 grit paper. Once the wet sanding is finished wipe down the hull with fresh water and set aside for at least 5 days of final dry out before buffing of the hull for finish.

To rush into the buffing out the finish before the urethane can harden up, could cause blemishes in the finish, which cannot be removed unless stripped of the finish.

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Old Jul 14, 2010, 06:22 PM
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Very nice!
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Old Jul 14, 2010, 06:54 PM
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The interior cockpit side panels can be prepped while waiting for other operations such as resin or paint to dry. The two panels will have laser etched dotted lines on their faces or the interior side of the panel. With a ball point pen and a straight edge run the pen up and down the dotted line on the panel face, making a radius indent in the panel. This will mimic the two different color panels on the real boat.

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Old Jul 14, 2010, 06:59 PM
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Pressing on a piece of 180 grit sand paper with you thumb when sanding on the compartment openings on the panel, will give the gentle radius we need to mimic the upholstery wrapping into the hole openings.


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Old Jul 14, 2010, 07:04 PM
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The side cockpit panels must be pre-warped into the curve needed to conform with the inside of the cockpit sides which will run from frame #F5A, at the back of the cockpit, to frame #F1, under the front deck of the model.

Using the boat stand as the blocking under the bow end of the panels, and the use of the weights from earlier in the build, on the of the center of the wetted down panels, the panels will warp in to the form needed for the installation. Leave the panels thoroughly dry before removing the weights.
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Old Jul 15, 2010, 07:01 AM
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Once the cockpit side panels have taken their warped radiuses, turn them over (face side down) and coat the back side of the panels with a coat of penetrating finishing resin (thinned out with three caps of the Xylene). Once dry, turn the panels over and coat the front side with a regular coat of finishing resin (thinned out with one cap of Xylene. Once the resin is set, lightly sand with 180 grit sand paper and prime with the can spray primer, three good coats of primer. Set aside for finishing later in the build.

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Old Jul 15, 2010, 07:09 AM
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The next sub assembly will be the rear seat frame and cushions. The parts for the front and rear seats frames are on laser sheet S3. The rear seat frame is made up of parts, RSB, RFS, RFF, and RF (4 pcs). Using square to keep the frame from racking assemble the rear seat frame on a flat waxed paper surface using the assembly drawing DWG #1.

Once assembled, sand all the out side corners of the seat back and the seat front with 180 grit sand paper for a slight radius be fore resin sealing.

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Old Jul 15, 2010, 07:15 AM
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The rear seat cushions parts are on laser sheet S8. Each cushion is made up of two pieces of the 3/8” thick laser cut balsa. The rear seat bottom cushion has part RSBC1 glued with medium CA glue, on top of RSBC2. This will make a 3/4”thick cushion to be block sanded to shape. The rear seat cushion back is made up of two pieces also of the 3/8” thick balsa. Part RSCB1 will be glued on top of RSCB2 with medium CA glue. Note that the rear seat cushion back will have the laser etched lines on it face for the location of the seat welting on the two tone upholstery.

Take the rear seat cushion back and score the laser etched dotted lines on the face, top and bottom of the balsa formed block. Scoring can be done with a hack saw blade. Now start block sanding with 120 grit sand paper the rounded corners and gentle radius shapes of upholstery over a foam rubber form. (See photo of the finished parts)



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Last edited by frankg; Oct 15, 2010 at 07:27 PM.
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