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Old Dec 10, 2005, 09:14 AM
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Orca -- Another One Comes to Life!!!

Since there's always room in this world for another Orca I thought I'd share this build. Even though it's been done before, there will be some changes on this one to fix a couple things I know weren't right on the p-type.

It all started by laying out the hull parts patterns on 1/8 lite ply. The parts were cut out and all the 1/4 sq, balsa frame bracing added.
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Old Dec 10, 2005, 09:21 AM
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The Basic Hull Frame

Assembly begins with the keel. The front and rear sections are sandwiched between the aft doublers and clamped till the glue dries. The frames are assembled on the keel, and the whole assembly hot glued to the building board to keep it all straight. Finally, the chines were added using 3 laminations of 1/16 X 1/4 bqalsa and the whole assembly sanded to shape.
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Old Dec 10, 2005, 09:41 AM
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Planking theHull

Hull planking begins on the bottom at the keel. To keep the scale number of planks, 1/8 X 3 balsa sheets were ripped to 3/4" width so the right number of planks can be used.
The bow was planked crossways from frame #1 forward. It's a bunch easier then making the bottom planks twist into the stem!
The middle planks were cut in to clear the keel doublers and glued in place. A stealer was used to fill a gap at the front 1/3 of the hull. Then, working on both sides of the keel, one plank at a time, the rest of the planks are laid. Carpenters glue was used between the planks, and Cya was used to attach the planks to each frame. Clamps are used to keep the planks nice and uniform. The idea is that the lines between the planks will still show after all is sanded smooth.

PAT
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Old Dec 11, 2005, 09:42 PM
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Cool!!! Are you building this one full size to your original drawings or did you scale it down?
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Old Dec 12, 2005, 08:29 AM
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Aero, This one is going up full size. Will try a couple things to improve over the original too. Should be a fun project all around.
PAT
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Old Dec 14, 2005, 08:34 AM
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The Planking Process Continues

The last of the bottom planks are in place now, and the first two side planks are in place.
Once all the bottom planks were glued in the hull assembly was removed from the board and the deck sheers laminated up and sanded to shape.
Side planking begins at the top, and is laid in flush with the sheer. As with all the balsa planking, the planks are attached to the frames with Cya and white glue is used on the mating edge. The planks are then clamped to keep the edges as true as possible.
PAT
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Old Dec 15, 2005, 09:47 PM
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The Hull Planking is Done

Got the last of the hull planking on today. With all the planks glued in place, the bottom plank was trimmed flush with the chine and sanded flush. The planks laid down real well with very little bulging along their edges, so no "pre-sanding" was needed before the gaps were filled.

To fill the gaps between the planks, a medium mixture of drywall mud was mixed up and squegeed over the entire hull. Mixed a little thin like this was, the spackle will shrink into the gaps and when sanded won't hide the lines between the planks. As ratty as this boat was, you have to leave the gaps showing and the boards a little uneven to keep it all looking true to scale.
PAT
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Old Dec 16, 2005, 06:49 AM
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Pat
I have used drywall compound before but never thought of using it in a model boat. How does it hold up to being in water?

Steve
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Old Dec 16, 2005, 09:35 PM
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Steve, Drywall mud is my favorite filler for large areas for a couple of reasons. First and formost, "it's cheap", and second, because by using the dry mix the consistancy can be easily controled in any given situation. On a model like this you want it to crawl back in the gaps between the planks to insure a good seal, but you don't want to make the lines go away.
Sealing the dried mud isn't a problem, and so far I havent found anything that it's not compatable with. It accepts almost any kind of sealer much like balsa wood, and once sealed, sands just like balsa. On this one I'l probably seal it up with several coats of varnish , then prime and paint.
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Old Dec 22, 2005, 04:57 PM
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Sealing the Hull

With the filler applied to the outer hull and sanded, a coat of thinned resin was applied to the inside of the hull. Once cured, the stuffing box and rudder bearing tube were installed.
The stuffing box was madw frome 3/16 brass tubing with a 5/32 brass tube bushing in each end. The rudder tube is made from 5/32 tubing. Both were aligned and glued in place, then faired in with a mix of epoxy and micro balloons.
Once cured and sanded, the outer hull was given 4 coats of Nitrate dope to start the sealing process.
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Old Dec 22, 2005, 05:01 PM
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Mounting the Motor

The motor mount is made from 1/8 lite ply and 3/8 triangle stock and glued to the keel and ajoining bulkhead. The Dumas 6 volt high torque (Pitman) motor was secured to the mount with a gob of silicone and a pull tie. The Dumas dogbone coupler was used to connect the 1/8 wire prop shaft.

Work has already begun on the cabin and upper decks, will post up the photos as soon as they're "processed".
PAT
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Old Dec 22, 2005, 05:19 PM
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Looking great, Pat!
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Old Dec 22, 2005, 06:33 PM
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I have a question on electric boats. Is any type of gear reduction used on the propeller? I am thinking about building a hydroplane I have seen in a boat building book and wondered about the motor size verses the boat size, and propeller size. I would thank you for any input you can give. Also what about motor speed controls? Can you use one out of a car?
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Old Dec 23, 2005, 10:26 PM
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Fix, You can use a gear reduction unit on a boat, but you mention a hydro in the Question. The idea with a a gear drive is to turn a big prop more slowly to increase torque. With a fast boat, you want to turn a small prop real fast -- that's where the speed comes from. Typically, if you want slow speed and big torque, use a reduction unit. To go fast, go with direct drive.
You can definately use a car ESC in boats, and there's lots of them out there to choose from. However, you can also use airplane ESC's as well, but only if you don't need the reverse feature that only car controllers offer.
PAT
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Old Dec 24, 2005, 08:25 AM
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Building Up the Cabin

With the hull finished, the main deck in place and the whole thing pretty well sealed up, work can begin on the top side.
The cabin assembly began by framing up the cabin sides. This time, I lowered the bottom edge of the windows since that's the one thing on the original that always botthered me -- once I had noticed they were wrong!
The rest of the cabin was then cut out and glued in place. Another change on this one is that the aft cabin wall was made up in 3 pieces. The outer sections were glued in place on the cabin walls, the middle section will be glued to the cabin roof and will lift out with the roof to gain access to the Rx and ESC.
PAT
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