The 150 foot figure is not a hard-and-fast rule. Consider it more of a rule-of-thumb.
Bizer wants to find and chart anything that is a hazard to normal navigation. However, the closer one is to the shore, the less likely the rock will be on the chart. As "jrc" pointed out, we have to draw the line somewhere. Even rocks that are more than 150 feet from shore are suspect. Should Bizer chart a rock that is six feet below the surface when only the Mount Washington could hit it?
These are not hard-and-fast rules, but Bizer normally takes the following into consideration:
- Distance to shore
- Distance to a boating route
- Distance to other rocks (e.g. If there are 5 rocks with 50 feet, Bizer only charts one, for space reasons)
- Depth of rock - Normally, rocks more than three feet below the surface at fall lake levels are not charted. If near a normal route of navigation, they may be represented with a "4" or other depth reading.
- Depth of surrounding area is a consideration. For example, a rock that is 18" below the surface may not be charted if it's on a sandbar 30" below the surface. To be charted, a rock typically should be more than 12"-18" above the surrounding area.
How we found rocks: Bizer puttered around the entire lake (most of it twice) about 100-150 feet from any shore at six MPH. Keep in mind that there is 278 miles of shoreline on this lake. Bizer stood up in a 15 foot outboard with polarized glasses looking for trouble. We (I) made the assumption that most rocks more than 150 feet from shore would be marked with a buoy, and that rocks less than 100 feet from shore should require cautious navigation and/or local knowledge.
Did we find them all? We hope so. In an effort to make the chart more accurate, Bizer offers a reward of $250 to anyone who finds a shallow area (less than 6 feet deep) that is not marked in blue on Bizer's chart. In nineteen years, three boaters have claimed that reward makeing Bizer's chart a little more accurate each time.
So if you see something, say something. Write/email/phone/text us. We want to know about anything and everything that boaters consider a hazard to navigation. As for "Jeanzb1" who started this thread, we'd love to hear where this rock was so that we can investigate this area when we do our annual survey of the lake in September. She obviously though it was important enough to mention. Even if it is in an area marked in blue on Bizer's chart, we may add this rock on our next edition.