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Old Mar 15, 2009, 09:09 PM
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Build Log
Building a mud puddle boat

Please note - To keep things from getting scattered around too much, I have changed this from a discussion to a build log for you enjoyment and perhaps inspiration.

The original idea started with the need for a small boat that could be run in shallow water, like a mud puddle. I live in the land of mud puddles and sometimes there just isn't enough water to run a Springer. The scope switched directions a couple times as the hull design started to evolve. Could it be built from easy to find or recycled and repurposed materials from around the house? Could it be built without power tools? Could it be attractive enough that someone else would want to build one too? Oh yes...the goal was to get it running on the pond for a cash outlay of under $100.00. So far I've come pretty darn close and if someone were to buy a second hand TX&RX for $15.00 or so, if my math adds up, I am sure it can be done.

A quick note about the hull: just like most mud puddles I come across, there ain't nothin' too pretty about it. It was simply designed to be simply built. Form follows function. Period, end of story.

So for those of you just joining our story, here was how this thread started:

I've had this little motor and gearbox since I tried to build a Graupner Pollux many many years ago. It seems to be a 280 motor that can handle 3 volts according to the label. (The newer units can handle 3-6 volts I believe). It is geared 2:1 and turns a 30mm plastic propeller.

I am trying to figure out what type of battery pack to get for this boa...er...project I am working on. It seems that ballast will definitely be an issue in this hull. I had orginally planned on using a RX pack at 4.8volts. Any idea how many amps this little guy might pull? Would it be okay to run this motor at 4.8 volts or even 6 volts?
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Last edited by Tugboat Andy; Mar 18, 2009 at 09:23 PM. Reason: Changed to a build log...
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Old Mar 15, 2009, 09:33 PM
In The Sorrano Triangle
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jim
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Old Mar 15, 2009, 10:04 PM
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Thanks Boz.

That motor is NOT going to come out of the mount. I already tried to fiddle with it. I can't afford to break it so I am trying to work with what I have.

I suppose a multimeter would be the tool for checking voltage as I increase power? I was planning on using my tamiya ESC because the mtroniks is a little noisy. Any thought on that?
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Old Mar 16, 2009, 05:18 AM
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Thinking back to my Pollux, the instructions suggested a 6 volt SLA, so assuming that the instructions have remained the same for the life of the kit, and assuming that the motor was correct at the time, it should be OK on up to 6 volts. A club near me has a fleet of these, and I believe that they have standardised on using 4 cell packs for drive and radio.
Anyway, use of an ammeter to check current draw is pretty vital, and digital multi meters are really cheap these days, and will pay for themselves after the first problem they solve. Unfortunately, checking the apparent voltage applied when using a PWM ESC has problems. The DMM takes sample voltages, and shows them on the display. With PWM these voltages are either full voltage or zero and this results in a confused display. A meter with a needle and dial smooths this out and gives a useful reading, but this type of meter costs a bit more and is more delicate.
What is the project?
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Old Mar 17, 2009, 07:26 PM
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Thanks mfr02, that is what I needed to know.

I'll start a thread on the project when it becomes more complete but here is a teaser pic. The hull is 9 inches long 4 inches wide and 2.5 inches deep.

When you say 4 cell packs, does 1 pack supply power to both rx and motor or are there multiple packs?
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Old Mar 18, 2009, 06:48 AM
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One pack with 4 cells to drive motor and RX. They were using C-cell size NiCads, these days of course NiMH would be the thing to use. One or two might have used D cells.
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Old Mar 18, 2009, 08:01 AM
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Hi Andy,

A friend of mine runs his Pollux (with the 4,8V motor) all day on four 1,5V NiMH/Nicads (penlights) or five 1,2V recheargable penlights; on exibitions he tows a 2m freighter, with a buddy (with his Pollux) on the stern of it to steer.

The motor is glued into the housing, and should come loose with carefully sticking thin flat objects along the motorhousing to work the (super) glue loose.
A replacement motor is fixed in place with a drop(!) of the same stuff.

Regards, Jan.
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Old Mar 18, 2009, 09:13 AM
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Hello,

I've done both on my Pollux, using a 4.8 volt, nicad battery pack for receiver and motor as well as the recommended 6 volt, 1.2 Ah lead acid battery. Both worked very well, however the pollux needed the weight of the lead acid battery to be stable.
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Old Mar 18, 2009, 07:52 PM
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Thanks for the replies!

I thought the Pollux would make a great easy to build boat...and I am sure it is, just not for me and my skill level at the time. I was pretty young and didn't know how to work with plastic.

<edit> for those that may have been following this thread, it has evolved into a mini-build a little ahead of schedule... I suggest you start from the beginning to fill in some blanks.
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Old Mar 18, 2009, 10:17 PM
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Initial sketches produced this little haywire contraption.

After some careful evaluation I decided to salvage the deck and use it for a template. About this time I started to wonder if I wasn't making this whole project a little too complicated. The project scope started to creep and creep...and creep.

Out came the hobby knife, a fresh sheet of carboard, and the CA. Thngs went together pretty fast and in a short afternoon I had glued up a simple little hull that seemed to fit the purpose of the project!
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Old Mar 18, 2009, 10:29 PM
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The cardboard came from a cereal box from the recycling. As an added challenge, I thought about trying to build the boat from no more than one cereal box. Turns out that was not much of a challenge; I have plenty of cardboard left over!

Things went together quickly and I was in a groove so I didn't take any pictures of this step. The cardboard is easily glued together with CA. Coarse sandpaper was used to trim edges flush. I coated the hull with a light coat of Z-poxy to seal the cardboard.

In the building frenzy something shifted and I wasn't completely happy with the hull. Multiple thin coats of Bondo faired the hull and as an added benefit stiffened up the hull plating. To simplify construction there are no internal bulkheads!
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Old Mar 18, 2009, 10:41 PM
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The hull was glassed with 2 oz Hobbico brand glass cloth and Z-poxy brand finishing epoxy. The z-poxy can be mixed easily in small batches and is easy to sand which, fit some of my requirements. I prefer West System but the metering pumps make bigger batches and it sands harder.

The deckhouse was built in 3/8" = 1 foot scale. It's modeled after a small tug known as a 'yarding tug'. They are commonly found operating on the Fraser River in BC Canada. They are used for shifting barges, log booms, and other jobs for which they are well suited. I found a couple I liked on the internet and took bits and pieces from each to build a generic deckhouse.

The deckhouse is cut out of some 1/32 midwest ply and a piece of basswood. The wood is all thin enough to easily be cut with a sharp hobby knife. No power tools...remember
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Old Mar 18, 2009, 11:07 PM
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The neat thing about not getting too hung up on the hull is that it opens a bunch of possibilities for finishing.

This silly little hull could become just about anything if scale is thrown out the window. I already have plans for an alternate top to make this look like a log bronc. It could also easily be converted into a fishing boat or a gunboat. I am experimenting with hull trim to help disguise the straight sheer. A little ballast in the stern and some fancy bulwarks and I don't think you'll ever notice.

I cut hull access holes for the lazarette (steering gear) and the foc'sle (battery and motor). Once the holes were cut the underside of the cardboard deck was reinforced with a few popsicle sticks glued with CA (in strategic places). The cardboard deck was scuffed up and glassed the same as the hull.

I added the flybridge to the deckhouse for the few days it is sunny enough for the skipper to run the boat outside.
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Old Mar 18, 2009, 11:16 PM
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Western N.Y. winemaking country
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Amazing what some modelers can come up with in a pinch---.

Or, how many beers did it take to build up the inspiration?
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Old Mar 18, 2009, 11:25 PM
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Quote:
Originally Posted by der kapitan
Amazing what some modelers can come up with in a pinch---.

Or, how many beers did it take to build up the inspiration?
I try not to make eye contact with the neighbors when I haul out the glass recycling bin on garbage day...

This has really been a fun project so far. I'll post a bill of materials later but including electronics this boat could be built for a little over $100.00 all up. So far I have used about $2.50 in epoxy, maybe 75 cents worth of glass cloth, a $1.00 worth of CA, 60 cents worth of cheap watercolor paintbrushes (dollar store), 10 cents worth of sandpaper, maybe $2.00 in ply, basswood and popsicle sticks, and a cheap hobby knife. The bondo I needed was an error on my part and could have easily been avoided.

Stay tuned for more fun at the TBA BoatWerks!
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