Ship Speed vs Whale Kills

Reprinted (and slighly edited) from Lee Tepley

HSF has claimed that during whale season they will slow down to the speed of the cruise ships. They claim that is 25 knots.

Actually the MAXIMUM speed of the cruise ships is lower than that. But the ships rarely go their maximum speed.

Examples:

Pride of Aloha Facts
Max imum Speed: 23 knots
Calculated Actual Average Speed: 13 knots

Pride of Hawaii Cruise Ship Facts:
Maximum speed -- 22 knots
PWF's Survey of Average Speed: Less than 15 knots

The Maximum Speed is correct but does not tell the real story.

First, the two numbers above both refer to a quantity called "the cruising speed" . "the maximum speed" or "the maximum cruising speed". All these terms refer to the same thing which is the maximum speed that a cruise ship can travel without trapping itself in a trough created by its own bow and stern waves. If the ship tries to go faster, gas consumption will increase rapidly with little increase in speed. The "maximum cruising speed" is almost the same thing as "the hull speed" which you can calculate from a simple formula containing the length of the ship. To add to the confusion, the term "cruising speed" often refers to the speed at which the cruise ship actually cruises which can be a lot slower than the "maximum" cruising speed. Are you now totally confused??

So what?? For starters, the Superferry will not have a similar problem. It's bow and stern waves are very small so it will not get trapped in a trough.. It can go a lot faster than a conventional cruise ship.

OK. So now what?. As was pointed out above, during whale season HSF has claimed that the Superfery will slow down to the 25 knot speed of cruise ships (but only in whale dense areas) So if the Superferry could be forced to slow down a few more knots (like the two cruise ships above) would fewer whales get killed? Actually. yes - but this misses the main point. Although Dick pointed out that cruise ships rarely go their maximum speed, he did not comment on their actual speeds which turn out to be a lot slower.

Some months back I calculated the average speed of the "Pride of Aloha" as it traveled between ports of call. it came out to be 13.4 knots - a speed generally considered safe for whales. I think that this is a lot more significant than just stating that cruise ships rarely go their maximum speed of 22 or 23 knots.

I sent my results out on several long e-mail lists. I recently added the result to my website at http://web.mac.com/leeepley/iweb. The result is also in my new video which is also on my website. Finally I included the result in my recent verbal and written testimony on SB1276. Finally, Greg Kaufman of the Pacific Whale foundation presented a similar result in his testimony before the same committee. To quote his written testimony. We recently polled the top five cruise ship companies regularly traversing Hawaiian waters and found they are doing an average of 15 knots or less. This confirms my result.

Some of you might want to check out my calculations. They include two pictures with pretty colors.

Finally, there is a brand new scientific paper which analyzed earlier data and showed that the probability of both whale deaths and severe injuries increased by a factor of about 20 as ship speeds increased from 12 to 24 knots. This is a really dramatic result that HSF would prefer you not know about. I have attached a chart showing this result.