Here’s how to shorten your servo leads in a neat fashion.  Sometimes they’re just a little too long for your application so you want to shorten them up a little bit so they’re not hanging all over the place.

First thing you want to do is cut a small section of any fitting off or or other plastic tube, so you can use it to wrap around your wire.  You only need to cut about 2 sections of the plastic tube; each about 1/8” wide.  Then, you slide your section of fuel tubing over a pair of needle-nose pliers.  Take your servo wire and fold it to shorten it’s length.  Now use the pair of needle-nose pliers to stretch the fuel fitting over your wire.

And that’s it.  Nice and neat and ready to go in your RC Sailboat.

Marshallese Outrigger in full speed

Majuro, capital of the Republic of Marshall Island, rests on the tip of a 10,000 feet tall limestone spire of a reef caused by some volcanic eruption thousands of years ago. In one of its windward bays is home to famous sailing competitions for model Marshallese Outriggers or what locals refer to as “rewuits”. Annual races are held for these model sailboats that are fashioned after the traditional Marshallese Outrigger.

Their unique architecture includes an asymmetrical hull that allows the sailboat to sail right into the direction of the wind. It outrigger is a shock absorption system which improves the boat’s glide and efficiency and at the same time, maximizes the strength that can be taken from a gust of wind. On an ideal day for sailing when the tide is high and winds are stronger, locals and even government leaders enjoy an afternoon of sailing with their rewuits by the bay. When properly set up, these rewuits sail on a straight line relative to the wind. It is self steering in a sense that when waves hit or knock it, it instantly corrects course. No matter the enormous speeds that these rewuits display, they still stay on the course as provided by the hull and outrigger innovation that balances the sailboat no matter the direction of the wind.

This impressive sailboat design was fashioned by early Marshall Islanders for easy and fast navigation in the atoll thousands of years ago. They were made in such precision that a small canoe seating a maximum of two people requires communal effort for 8 months.

Here is a site on the background of the Marshallese Outrigger and on the bottom a link to the free model sailboat plans with detailed description on the parts of the Winner of the ‘Marshall Islands Independence Day Race 2000’

Marshallese Outrigger Model Sailboat Plan

Model Boat Plans DVD

This Model Boat DVD Compilation has all together over 600 plans + a number of how to documents. It definitely could use a little bit better organizatio of all the pictures and plans provided.

But all in all it was worth it’s money, especially when you consider how much easier it is to browse through a DVD than dozends of different websites for days to find even half the plans you can find on this DVD. For anybody looking for plans I can recommed to check it out. Click here

The concept came Johnn while working on his model rocket car (did I mention he is a RC genius)! After some discussions on the concept he wrote me a fantastic 6 page article explaining it in every detail including drawings. I want to thank him again and again for this.

I will post this article in parts as it is simply to long for one blog post. If you want to get the full article immediately or have any questions on the concept contact me

SEA SLIPPER high performance catamaran top view

The Concept in detail

Sea Slipper Control system Figure 1

The idea is simple as a concept, the ‘wings’ are used to create a counter force to the heeling motion imparted to the hull by the wind loading the sail/rigging and tilting the boat over.  This is usually countered by a deep bulb keel.  If you wanted to sail a RC boat, in say a shallow reflecting pond, the deep keel boats might not be able to pull it off.  To see how this works, let us look at the idea of a simple pendulum sensor to detect hull motion from side to side, but prevented from swinging fore and aft.

Sea Slipper Control system Figure 2

As the magnet swings over a hall-effect sensor, the magnetic field is detected, and a signal generated to tell the control circuit that a positional displacement has taken place.  This signal is used to create a positional displacement of the wing on a hull, to compensate for the roll effect.  A left leaning of the hull would cause the wing to create a right ‘lift’ to counter the displacement.  A harder lean would generate a harder countering force to the right to keep the hull as close to vertical as possible.  By how the sensors are located, and the number of ‘sensing’ steps used, a moderate heeling force would be allowed, and then a steady correction force can be generated to keep the hull firmly in control.

This same sensor system, using a pendulum fixed to swing only fore and aft, would adjust the wing sets to assist in smoothing the pitching motions of a small model in ‘non-scale’ waters (i.e. our world!)  Or if used on a full sized boat, it would aid in the ride of increasing wave action.  In this manner, 2-axis control would give the wings a dual action capability that would stabilize the craft and smooth the ride for better control (and for full-scale boats ease the motion for landlubbers like stabilizers on a cruise ship.)

As can been seen in the drawing of the model in Fig. 3, the craft has both a front and a rear set of split wings to give rapid easy control to sea conditions.  The split wing design allows half the wing to go up while the other goes down to create the anti-heel response with smaller wing movements.  Secondly, for a pitch correction (up or down) the wings will move together to counter pitch together as if a fixed wing. 

The next part discusses how this control system can be realised with a RC Sailboat. If you want the full article immediately or have any questions on the concept contact me

About the Author/Designer of the Sea Slipper Concept:

I’m a Mechanical Designer with an electronics background and degree, so I married my work and hobbies for increased fun and develop new ways to spend my money in strange ways (according to my wife!)
This is a winter project with an eye towards exploring electronic control to ease the job of the skipper (be it RC or full-sized), and give them a fast, better controlled boat.  The concept came to me as I developed a flap system for a model rocket car.  See Fig. 1 (to keep the dang thing on the ground, instead of becoming airborne so easy.  The last hit Mach 2 eighty feet off the ground!) 

Hello! I am Cathy Landergan a high school teacher. I’m not a shop teacher, my background is CADD (AutoCAD) and I wanted to create a connection between the plans and building the boats. My pre-engineering students built the classic Marblehead pond model from the Madcap plans. They start the class by creating the templates using CADD.

We have a full woodshop including band saw etc. And the kids did do the fiber-glassing, and we started from the CADD plans.

I’m also inviting local companies when possible to come into the classroom. Doyle Sailmakers helped us create the sails and we did a field trip to see the sails being made etc.

Here are some pictures of the Marblehead’s from last year at various stages. We made 4 boats, 3 of which were finished except for the electronics because we ran out of time.

Students worked in teams of 2 or 3. We sold one of the boats, and it’s my hope that we will be able to fund the program from the sale of these boats. It’s a little sad that the kids can’t keep the boats but there’s no way to split up a boat between three kids. At least they have the knowledge to make their own.

Read here the full article

Click here to find Sailboat Plans for your own project

\\\”This article appeared in the Fall 1999 issue of Epoxyworks, published by Gougeon Brothers, manufacturers of the West System epoxies.\\\” Brian Knight thanks Gougeon for permission to publish this in the December 1999 Falco Builders Letter. \\\”

Here are key excerpts for your review and discussion:

\\\”With wood, the best method of thinning epoxy with heat is to warm the wood and have the resin and hardener at room temperature. Mix the components and apply the mixture to the warm wood surface. Remove the heat source just before the epoxy is applied. When the epoxy mixture comes in contact with the warm wood, it gets warm and its viscosity becomes lower. As the temperature of the wood falls, the thin epoxy is drawn in deeply before it begins to gel. By heating the substrate instead of the components, you get the best of both worlds-low viscosity epoxy on the work surface and longer working time in the mixing pot.\\\”

Thinning epoxy with solvent
Adding solvent is a quick, simple method of thinning epoxy, but unlike using heat to thin it, the strength and moisture resistance of the cured epoxy are drastically affected. Below are some of the effects adding solvent has on West System epoxy. While there are a large number of chemicals available to thin epoxy, we selected acetone, lacquer thinner and denatured alcohol for this discussion because they are commonly available and do a good job of reducing viscosity. Additionally, these solvents evaporate quickly and are less likely to be trapped in the cured epoxy-an important characteristic. For a variety of reasons, fast evaporating lacquer thinner appears to be more appropriate for thinning purposes than acetone or alcohol.

Thank Pat Matthews for sharing the following post on servo hacks!

Servos are wonderful little devices! Not only do they provide an inexpensive way to activate mechanical linkages through radio control, but they can be hacked to provide inexpensive drive units for small boats and cars with their self-contained motors and electronic speed controls (ESC\’s), and they can serve as part of a simple on/off power control switch.

Basic servos can be found for less than $10

A servo is a little gear-motor, ESC, and a position sensing device in one package. Rip the guts out of the case, and you’ll have:
a) A lead from the Rx� it carries +5 volts, ground, and a signal wire.
b) A circuit board.
c) A small 5v motor, which may be soldered directly to the circuit board.
d) A pile of gears connecting the motor to the servo output. Bin these.
e) A potentiometer (pot, or variable resistor) connected to the circuit board with 3 leads, and mechanically connected to the servo output.

Step 1: A few screws loose, and things start to open up.

Step 2: Pressing on the two shafts popped the board out of the case. Don\’t pry directly on the board.

Step 3: Using desoldering braid to wick off the solder, makes it easier to pull off the motor.
Loose parts.

Hack 1: Going Pot Free

First trick in hacking a servo: Disconnect the pot from the servo output. Normally, as the pot moves with the servo output, it produces a varying voltage which is read by the circuit board, telling the servo that the output has moved to the desired position (or not). See Schematic 1. When you disconnect this little knob from the gear train and the servo output, leaving it in it\’s centered position, and then command servo movement at the radio, the circuit board never detects any movement, and thus keeps telling the motor to run.
So now center the stick, servo is happy, goes nowhere; forward stick, and the motor kicks in and just keeps buzzing; reverse stick, ditto the other way. You\’ll want to put a drop of glue on the pot to keep it from drifting.

Hack 1a: If the Pot itself doesn\’t suit you, you can replace it with a pair of 2.2k ohm resistors- both tied to the center tap\’s lead, opposite ends of the resistors to the pot\’s \”outer\” leads.

Another nice feature- most servos have a soft start, which means that a little bit of stick will give part throttleâ�¦ other than that, it\’s pretty much off/on.

Hack 2: Motor Swapping

Next hack: The little motors that comes with servos may not suit youâ�¦ they have tiny little short shafts. Any small 6v toy motor will do instead, as long as you don\’t load it heavily- the servo\’s ESC isn\’t designed to deliver much current! If the motor is connected to the circuit board with wires, no problem to swap them. If the motor is soldered directly to the board, you\’ll need to work a little more carefully. You can get \”solder braid\” from Radio Shack- braided copper wire that you heat with a soldering iron while pressing onto the board\’s soldered joint. The braid sucks up the solder, and you can pull the motor loose much more easily.

If you decide to keep the servo motor, no problem. You can leave the motor on the board- that\’s what I did on my plastic landing craft. And you can get tiny little plastic u-joints to press onto various miniature shaft sizes, metric and English, from Northwest Shortlines- catalog page at http://www.nwsl.com/Catalog/cat-UJoint.pdf

Servo motor still attached to board. Motor can is pressed into plastic structure.	Twin drive in landing craft.
Servo motor set in Revell Trawler	Close-up of NWSL U-Joint on servo motor\’s 1.5mm shaft. \”Horn\” is sized for 1/16\” prop shaft, which is only slightly larger than 1.5mm.

Tweaker with drum type sail control unit.

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A jib twicher is a rig that pulls the jib boom to port or to starboard when sailing down wind.

These to devices are often confused with each other