I was a dive instructor in Monterey for many years, and raced sailboats there extensively during that time. You'll learn quickly that a sailboat can't cut the corner on a kelp bed--even the smallest amount of kelp can stop a sailboat instantly, especially it low tide.
Watch how the tides effect the kelp. At low tide the kelp lies horizontal on top of the
water, while at high tide it barely reaches the surface. The lower the tide, the more drag the kelp will create. This is especially true if you're trying to swim through the kelp at the end of a dive. This is important: when
diving kelp, you want to make it all the way back to the boat underwater with air to spare.
Don't anchor in kelp. Realize that kelp only grows on rock, and that your
rode will tangle with kelp, and that overnight kelp can actually destroy nylon
rode. Find a sandy area just outside the kelp, preferably downcurrent from the kelp
bed where you want to dive, and anchor there.
Be aware of how your dive
gear will snag on kelp. For example, Monterey divers wear their knives strapped to the inside of their calves rather than outside. Kelp knows who the rookie kelp divers are, and it will make an extra effort to entangle them. If this happens, keep your cool; the best way to free yourself is to
work the problem slowly.
I retired as a dive instructor more than a decade ago, by the way, so be advised that I have no professional standing at this point to offer dive
advice.