How-to Article ...by Frank E. Mintz
A reader shares his knowledge on how to easily setup a race course using a common handheld GPS unit and the included Excell spreadsheet calculator!
Let's face it, if you are into the radio control hobbies, running model boats is not very challenging. After you master getting it back to the shoreline with regularity, running around by your self gets boring. Even going really fast, it's still two dimensional until you add a second boat or begin to time laps for speed. RACING...ahh..., Now that's where the challenge of model boating really begins. Racing starts with a course and courses need to be defined. Since we are running serious machines, we can't go with a course marked by existing objects in the water like pilings, stumps or "the kid with the beach ball". We need a way to place courses on water that is repeatable because they may not be permanent. Most organized clubs have water and they are very fortunate. Often, clubs use of water is limited because they must remove the buoys at he end of an event. Sometimes it is difficult to even lay out a course because measurement from the shore line is impossible.
Because of the latter points, my home club, Capitol RC Model Boat Club in IMPBA District 12, needed an easy way of setting buoys in water that was close enough for racing practice and even sanctioned events within the district. I also wanted to layout a course for practice off my dock.
Since I was already using my hand held GPS to determine max MPH on my boats, I thought "How about using it to locate course buoys?" The challenge then was where to place them in relation to one another so they form an acceptable course with the right dimensions and shape. Also, what data do you need to start with to lay out a proper course? Looking into the IMPBA course regulations I found that dimensions are very well defined for several courses depending on the boat class. I concentrated on the 1/6th mile course as that is the most popular for nitro and gas boats and is used for Straight Away (SAW) speed trials. There are smaller courses for electrics and small nitro defined as well.
The answer to all this is found in the capability of the Microsoft Excel spreadsheet. After looking at the problem analytically, I found that you only need two pieces of information to generate the course plot data and latitude/longitude for each buoy.
Factor One. You must decide where buoy #2 will go on the course. I selected it because it is the outer most point of one end of the 365.05ft long course and generally is the most critical placement from a racing space standpoint. To determine this, take a man carrying boat on the water with the GPS in LAT/LON mode. The GPS must be reading in degrees to five decimal places, not minutes and seconds. Determine the position of buoy #2 for the course allowing for as many "lanes" as possible between the proposed course and any obstacles (see above ref to "beach ball"). You must, at this point, guess at the other buoy positions so be ready to adjust your placement of buoy two. The remainder of the course is plotted from the placement of this buoy and one other critical factor.
Factor Two. You must determine the compass heading of the front chute. This needs to be parallel to the drivers stand shore line if possible. The GPS can determine this as well. Put it in tracking mode and walk parallel to the course and in the direction the boats will go on the course. Record the heading on the GPS. It is not necessary to be on the course in the man carrying boat to get the correct heading. This is simply a compass direction determined by movement of the GPS.
Take the two data elements and enter them in the Data Entry tab in the spread sheet. Open the plot tab and see if the course plotted in the graph is in the direction you expected. Remember, in model boat courses, the boats go around clockwise so the buoys are numbered accordingly, 1 thru 6. The T1 and T2 markers are the placement of the entrance buoys for the respective turns. The center of the course is also marked with a buoy representing the start finish line.
When you go to actually place the buoys using the GPS, take your time. Be ready to drop the buoy anchors when you reach the designated lat/lon location. It's a lot easier if you have some one maneuvering the boat as you watch the GPS readout with anchor in hand. Remember this is NOT as precise as measuring with a tape and transit as is necessary for IMPBA sanctioned record courses. It will get you in the ball park however.
A couple more things about the spread sheet; the sheet is protected from modification except where the data needs to be entered. I have password protected it to insure functionality. If you are compelled to change anything you can copy the sheets and play to your hearts content. If you want to change the size of the course, the X/Y parameters of buoy location relative to buoy #2 are in feet in the top table. Changing them will modify the size of the course.
My intent in placing this spread sheet in MGB is to expand the interest in model boating and racing in particular. If you use it, please let the editors of MGB know your story. It will be very gratifying to hear from you.
Click here to access the spreadsheet!
Frank Mintz
IMPBA 19427S