@Paul.
I was intrigued with your Dutch log trick in ascertaining boat speed. I'm very fond of slide rules (SR) in general but especially in how they may be applied to marine use. SRs have been used on ships since about 1620; well before the advent of electronics.
I copied the following from a text which describes how to use a SR to easily calculate boat speed. But what's more the user can do this for any length boat going any speed. The quote is paraphrased:
"Calculate Boat speed with a Dutch Log In the event your knotmeter fails. You may determine your boatspeed by putting the right index on C over .5925 on D Move the cursor over the C-scale value of the LOA of your boat in feet. Without moving the cursor further, adjust the slide until the number of seconds that passed for a chip of wood to move from the bow to the stern is under the cursor. Read the boatspeed under the C index. "
Just replace the LOA with log line length and this works for my log line idea in the original post.
I've tried the math with my SR and it works fine. In cases such as this an SR is much faster to use than a electronic calculater. Imagine, if you will, sitting on the pier watching a boat charge through the channel. By estimating its length, and timing it's passing of some marker on the water or opposite shore, one could calculate its speed quickly. Or already knowing its speed one could calculate its length. All by timing its passing.
BTW - .5925 is the inverse of 1.6878, so you multiply instead of divide using the decimal number.
Cheers
I was intrigued with your Dutch log trick in ascertaining boat speed. I'm very fond of slide rules (SR) in general but especially in how they may be applied to marine use. SRs have been used on ships since about 1620; well before the advent of electronics.
I copied the following from a text which describes how to use a SR to easily calculate boat speed. But what's more the user can do this for any length boat going any speed. The quote is paraphrased:
"Calculate Boat speed with a Dutch Log In the event your knotmeter fails. You may determine your boatspeed by putting the right index on C over .5925 on D Move the cursor over the C-scale value of the LOA of your boat in feet. Without moving the cursor further, adjust the slide until the number of seconds that passed for a chip of wood to move from the bow to the stern is under the cursor. Read the boatspeed under the C index. "
Just replace the LOA with log line length and this works for my log line idea in the original post.
I've tried the math with my SR and it works fine. In cases such as this an SR is much faster to use than a electronic calculater. Imagine, if you will, sitting on the pier watching a boat charge through the channel. By estimating its length, and timing it's passing of some marker on the water or opposite shore, one could calculate its speed quickly. Or already knowing its speed one could calculate its length. All by timing its passing.
BTW - .5925 is the inverse of 1.6878, so you multiply instead of divide using the decimal number.
Cheers