[Rhodes22-list] The Cat

[Robert Skinner]

I'm thinking that a major radar reflector AND plotting 
radar ping detector might be a damn good idea.  We Maine 
cruisers now have to deal with a 55 MPH catamaran ferry:

See http://www.catferry.com/the-ship/general-paticulars.php

>From http://www.catferry.com/press-room/press_2006_05_01.php :

"The CAT is a wave-piercing catamaran car and passenger ferry, 
manufactured by INCAT of Australia. The vessel is 320 feet 
long, and is powered by four 9,500 horsepower marine diesel 
engines that drive a water jet propulsion system that could 
fill an Olympic sized swimming pool in 33 seconds.  The CAT 
can travel at speeds up to 55 mph, while its trim tab and 
T-Foil ride control system ensures a comfortable ride for 
passengers. Constructed of enough high-strength aluminum to 
produce 32 million beverage cans, The CAT is a technological 
marvel."

Or from a coastal cruiser's point of view, a HOLY TERROR!

I am considering having a ping detector hooked up with an 
alarm to wake me if I'm snoozing.  At 55 mph, it is 
traveling just a bit less than a mile a minute, or 88.5 
KPH.  So what's the problem?

The straight line of sight distance d in kilometers to the 
true horizon on earth is approximately

         d = (13 x h) * 0.5

where h is the height in meters of the observer.

Given a radar unit on the Cat 20 meters above waterline, a 
reflector and/or detector on the top of my sailboat mast 6 
meters above waterline, and the curvature of the sea 
surface, I would be visible from a distance of about 25 Km.
At 88 KPH, that would allow 17 minutes to see my tiny blip 
and avoid my being sliced in half then ground into lobster 
bait.

I question the wisdom of expecting a coffee-swilling deck
hand on night watch to spot my little blip, get permission 
to take evasive action, and do it in time to save my butt.

So Edith P. better be able to detect the ping, sound an 
alarm, and plot a constant bearing closing.  Especially if 
I am (was) hove to for a nap.

Puts me in mind of "Bert & I"'s Bangor Packet story.*

/Robert "What Cat?" Skinner

* http://www.bertandi.net/
  http://www.bluewaterweb.com/BosunsLocker/Locker.asp?SKU=001015&TopicID=168