Scratchbuilt Sardine Carrier (Hull No. 2) - RC Groups
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May 16, 2005, 10:38 AM
Tinkerer in Training
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Build Log

Scratchbuilt Sardine Carrier (Hull No. 2)

In November 2004 I completed my first scratchbuilt boat as a gift for my youngest son, and I immediately committed to building another for his brother.

These boats are built with three things in mind:
1) They need to be slow and easy to handle by young children.
2) They need to be virtually unsinkable.
3) They must be built as inexpensively as possible.

The plans for this boat are a perfect match for these criteria. This thread will fully detail the construction of "Mowgli", an 85' Atlantic sardine carrier based on H.H. Payson's plans for "Pauline":

The completed model is 31" long at 1/32 scale, powered by a direct drive 14V Pittman motor (thanks Tachikaze) turning a 1.5" prop. Power is provided by a 7.2V 3300 MAH NiMH battery pack, and the radio is a basic 2ch AM Tower Hobbies system. The ESC is a $15 Futaba MC230 clone I had on hand. (not recommended but see point 3 above)

(If this seems somehow familiar, this build is similar to "Hull Construction Techniques", but will have many more construction details, and include the things I wish I had known the first time around)
Last edited by RGinCanada; Jun 03, 2008 at 11:02 AM.
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May 16, 2005, 10:48 AM
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Humble Beginnings.

The plans call for this boat to be built using the bread-and-butter method. Since I still had all the templates I created the first time around, I decided to go ahead and follow the directions. Using this method, the hull is built in two halves, and then glued together.

The half-hull "lift" plans were originally redrawn in CAD and plotted to size, then glued to masonite and cut out.

Armed with two eight foot lengths of 2x4 pine and a table saw, I ripped the wood down into 9/16" thick planks. I wasn't too worried about getting a perfectly smooth cut, as a little roughness on the face of the plank gives the glue some "grip"

Cash outlay:
2x4x8' pine (2 pieces) - $16.50
Last edited by RGinCanada; May 17, 2005 at 05:16 AM.
May 16, 2005, 11:33 AM
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Laying out the lifts

The lift outlines were traced from the templates, with care taken to mark each hull station. There are 8 lifts per half hull, for a total of 16 pieces to layout. Once this was done, I headed for the bandsaw and spent the next 2 hours cutting.
Last edited by RGinCanada; May 16, 2005 at 08:35 PM.
May 17, 2005, 05:15 AM
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Gluing up the lifts

Next all the lifts were laid up, and both halves were notched to accomodate the drive. It took a little fussing around with AutoCAD to position the motor where it would be accessable when done, and still keep it inside the hull

Each half was then trimmed to the correct profile, and the two halves were joined with glue and clamps.

Cash Outlay
Marine Wood Glue: - $7.00
Total to Date: - $23.50
Last edited by RGinCanada; Jun 03, 2005 at 05:50 AM.
May 17, 2005, 05:23 AM
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Shaping the hull

Next came the fun part - taking a spokeshave, a loose surform blade, and some 80 grit sandpaper, and turning the stack of planks into a hull. Using templates at each stations, its easy to get the hull symmettrical and accurate, as long as you check frequently.
May 17, 2005, 05:39 AM
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Building a stuffing tube

The shaft on my motor is 4mm, which just happens to be within a few thousandths of an inch of 5/32".

The K & S metal center that most hobby shops carry has inch sized telescoping rod and tubing that makes building your own stuffing tube really easy.

My prop shaft is a length of 5/32" brass rod. I purchased a length of each of the next two sizes of telescoping tubing. I then cut the larger tube to the length of stuffing tube I required, and cut two 1/2" lenghts of the smaller tube.

These short lengths were soldered into each end of the stuffing tube, and act as bearings for the shaft.

Next a hole was cut into the stuffing tube near the inboard bearing and a short vertical tube was soldered into place. This will be the "lube tube", allowing the stuffing boz to be lubricated without removing the prop shaft.

As a final step, the both ends were cleaned up with a file.

Cash Outlay
K&S Metals Brass Rod and Tube - $4.00
Total to date - $27.50
May 17, 2005, 06:54 AM
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Installing the drive

I purchased a piece of aluminum plate to fabricate my motor and servo mounts from. With nothing more than a drill, a hacksaw and a file, it took me 30 minutes to create the motor mount.

I mounted the motor to the mount and screwed it into the hull (a solid wood hull has its advantages!)

Next I cut a short piece of "bearing" tube equal in length to the universal joint that was to be installed. The stuffing tube was put in place, and the shaft was temporarily connected to the motor with the short length of bearing tube. This ensures the alignment of the motor and shaft is right on.

I built a small "dam" of hot melt glue around the stuffing tube (Silver sparkle kind optional ), and then epoxied it in place. (The stuffing tube exit was blocked up with electrical tape to prevent the epoxy from running out). I poured the epoxy in three layers to avoid air bubbles or leaks.

Cash Outlay:
Aluminum plate: - $6.00
Stainless woodscrews and capscrews: - $3.00
Universal joint: - $7.00
Total to date: $43.50
Last edited by RGinCanada; May 17, 2005 at 09:13 AM.
May 17, 2005, 07:02 AM
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The keel

Four pieces of 1/4" x 1" pine were cut from the leftover wood and scarfed together to provide the keel and sternpost. The pattern was laid out on the assembled pieces, cut, and glued to the hull. It looks a little like a Viking ship with the high stem, but that will get trimmed back later.
May 18, 2005, 04:04 AM
all my boats are broken
ernest2's Avatar
wow, your boat is really beautiful!! and your building technique great!!! i am considering using this tech in building a grandbanks trawler. is it easy building this style compared to a planking method?
May 18, 2005, 05:18 AM
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Hi ernest2,

Thanks! I'm looking forward to seeing your model get underway. As far as how to build it, honestly, I can't say. This is only my second scratch build, and I've used this method both times. Most people seem to prefer plank on frame, but this method has worked for me.

Having said that, my next project will be plank on frame just to get the experience.

May 18, 2005, 05:43 AM
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The electrical system.

The last R/C model I added lighting to wound up with a rat's nest of flexible wiring looping around inside the hull. It looked messy, and Lord help me if anything ever goes wrong on that boat!!

On this model, I came up with a simple, effective way to keep it neat. After deciding where my power distribution center would be, I ran three wires in a bus from one end of the boat to the other. One wire is ground, one is nav lighting, and one is deck lighting. I used a short length of telephone wire, removing each of the color coded strands from their sheath, and run them through a series of blocks along the side of the hull.

When the deck is in place there will be a connection point at the base of both masts, and in the cabin. supplied voltage is 7.2V, which will be dropped with an appropriate resistor for each of the lights.
May 18, 2005, 06:26 AM
Useful Idiot
I've been thinking of bread and butter but using expanded polystyrene insulatin board which seem to come in about 1 1/4" thickness. Its very easy to work, makes the boat virtually unsinkable but has the disadvantage of being much less resistant to wear and tear than wood. Do you think covering with glass and epoxy would be viable? Also is there any advantage to horizontal against vertical sandwiches or, even cross section?
May 18, 2005, 06:41 AM
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Hi martin,

As long as the resin was compatable with the polystyrene, I think foam would work well. I know the airplane guys do this. Some of them then clear all the foam out, having used it only as a form. I'm not a fibreglass guy, though That advice is based on reading, not doing!

As far as which way you build up the sections, I think some boats would probably lend themselves more to using cross sections, and it may make fairing the hull even easier. As I am still very much a newbie, I decided to follow directions.

May 19, 2005, 05:21 AM
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Preliminary ballasting (or "I get to play in the tub")

Once the keel was on and the rudder post installed, I used a Dremel tool and notched the hull for the deck beams. I was cutting the beams and getting ready to glue them in, when I remembered how difficult it was to get the ballast under the deck the last time around

I slapped two rough coats of exterior grade varnish onto the hull, and dropped it into the tub to get a rough idea of how much ballast was needed and where.

I wasn't ready to install the masts yet, so I glued stubs in the mast steps. By placing a sleeve over the stubs I could install the masts later.

I used BB shot in zip lock baggies for weight, and moved them around untill I was just shy of the waterline all around.

Temporarily removing the shot bags, I used plastercine to create forms in the hull for my ballast. I mixed epoxy right in the baggies, smooshed it all around the ballast, and poured it into the forms. Afterwards, I mixed up some more epoxy and poured it over the ballast to keep everything in place.

Cash Outlay
Copper Coated BBs - $14.00
Slow cure epoxy - $4.00
Total to date: - $61.50
May 19, 2005, 07:29 AM
Useful Idiot
What a load of Whoops, I'd better not say in case a mod's lurking
I was thinking of leaving the foam in for buoyancy but that'd be a waste of time with all that ballast, or would it?

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