How to take a photos while in a boat?

I was out in a small flat-bottom boat yesterday taking photos of birds (and anything else I could find). Problem I encountered was the constant rocking of the boat due to general movement, slightly choppy waters, etc. Needless to say, most of the photos are blurred. I am using a Canon D60 w/100-400L IS USM. I did have the 1.4TC on it, but removed it as I noticed the photos were just too blurry. That did not help much . Most areas were on the shady side which did not help with my shutter speed.

Does anyone know a good method for taking photos in these conditions? A tripod would not be the answer, as it would be rocking along with everything else in the boat.

Sue,
With D60 + 400mm @ f/5.6 and ISO 400 setting you should be able to come clean on a sunny day. You need a shutter speed of at least 1/1600s to freeze the rocking action. Otherwise I'd suggest you use flash or dail up the ISO setting to 800 for shady conditions.

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Sue, try timing your shot so you are either at the very top or very bottom of the wave motion. For a split second the boat is not moving. Also use the fastest aperture available.

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Sue:

Are you sure you had the IS on? After getting some really unsharp pictures on a windy day I realized I had shut the IS off.

Sue,

I made this same reply to your post over on NPN, but I'll make it here too because of different readership:

I've been using a Nikon 500/4 ED-IF on a shoulderstock (with a remote trigger on the handle where the index finger naturally goes) on pelagic trips for more than 15 years now, and wouldn't dream of doing it any other way. A few weeks ago, I tried the same thing using the Canon 500/4 USM-IS, and despite the additional weight I find this to also be a viable way to go. The shoulderstock gives at least an additional stop of acceptable stability, ditto for smaller lenses. Sharp results can be obtained this way even in fairly adverse conditions.