RC Sailboat & Model Sailing Guide

Hi, I found this wonderful article about students building a Marblehead model on the sailingmodels.blogspot.com and wanted to share it.

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

RC Sailboat Race – Open Class less 1m – Ohlenstedter Quellsee 21.09.2008

Duration : 0:6:33

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This article was published by the Gougeon Brothers manufacturers of the West System epoxies.

\\\”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.

I found this wonderful article on Servo motor conversions and as the geosite website where it comes from is no longer available I am going to share this via this blog (and hope that Pat is going to see it some time and contact me).

 

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.

 

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