SailNet Community - View Single Post - Get a fix without using the chart (much)?
View Single Post
post #1 of Old 07-09-2008 Thread Starter
Senior Member
davidpm's Avatar
Join Date: Oct 2007
Location: Madison
Posts: 4,446
Thanks: 355
Thanked 75 Times in 66 Posts
Rep Power: 10
Get a fix without using the chart (much)?

Most of my "new" ideas are either common practice that I just never heard of before or a dumb idea. So what do you think about this idea?
The problem:
You are sailing in home waters and you can see a known mark but for whatever reason no other marks are visible and you want a fix without GPS. The solution of course is a running fix but you donít want to draw on your chart because these are home waters and keeping your chart readable is important.
You happen to have a few plotting worksheets in the nav kit that are just blank pieces of paper with a compass rose and a scale photocopied on an 8.5 by 11 inch copy paper.
So this is what you do to get a pretty good fix without having to draw on your chart.
1. Write down your course (150 degrees), time 0900, speed 6 knots, bearing to known mark 180 degrees.
2. On your worksheet you draw a line for the course (150 degrees). (Where doesnít matter, just make it the correct course.)
3. Draw another line representing the bearing to known mark (Where doesnít matter as long as it intersects the course). This represents your start point.
4. Put a mark on the bearing line to represent the known mark. (Where on the line doesnít matter just make it look about right and it has to be on the bearing line.
5. Decide how long you are going to maintain your current course lets say one-half hour. Multiply your time times your speed ( .5 x 6 = 3 miles)
6. Use any scale, 1" = 1 mile, 1.5" = 1 mile, it doesnít matter, and mark off the distance you are going to travel, in this case 3 miles from the start point along the course to new point, the DR point. Luckily our plotting worksheet has a couple of scales printed on the side for easy reference or you can use any handy scale.
7. Draw a line through the DR point parallel to the bearing to the known mark. This is the "Advance bearing".
8. All this takes about minute or less. Now all you have to do is relax for the predetermined length of time, in this case one-half hour and stay on course.
9. At the end of the time take a new bearing to the known mark.
10. Draw a line on the worksheet at the new bearing so that it intersects the known mark and the advance bearing line.
11. Using the same scale you used to advance the first bearing, find the distance from the known mark to the point where the advanced bearing and second bearing cross.
12. Now it is dead simple. On the real chart hold any straight edge, even an envelope, at the new bearing so it goes through the mark. Just do an eyeball distance, on my chart one thumb is one mile, from the mark along the bearing and you can put your finger on your position without marking up your chart.
This process is 95% from the book a standard running fix. The wrinkle is that I believe you can use this process on a blank worksheet and not mess up your chart.
What do you think?
davidpm is offline  
Quote Share with Facebook
For the best viewing experience please update your browser to Google Chrome