Hi. I assume that you also intend to sail home to SMB eventually. Spending the night ashore or aboard? Your Mariner 19 is “day sailor” designed principally for sailing protected waters, such as bays and lakes, etc. Of course, everything is weather dependent. Good weather, good trip; poor weather, not so good, potentially. But “poor weather” for your trip in your daysailor might mean only slightly rougher conditions than forecast. A boat designed to sail in up to Force 4 conditions, maybe, might very well meet those conditions, or more, crossing the San Pedro Channel during a summer day’s afternoon. Also, as you might have noticed, it’s been pretty windy along the coast here nearly every afternoon for weeks on now. SMB may be calmer, however.
Consider. It might prove a “wet trip” in cold water. So you and you son should carry gear that will keep you dry against spray and protect against hypothermia. Once in the middle of the channel you could be two to three hours travel time to shore ahead or behind. Sail with the hatchboards in place, the cabin closed up to keep it as dry as possible. Make sure the cockpit scuppers remain clear of debris, etc., so can drain properly if so needed. Don’t store gasoline below; find a place in the cockpit. It would be best, IMHO, to have a second fuel tank that can be connected quickly to the engine if the first one runs out. It’s very hard to pour fuel from a jerry can into a fuel tank without making a mess when bouncing about. In my experience, small outboards are inherently unreliable. I recommend having yours serviced before leaving.
Take plenty of drinking water. I’d recommend a gallon each. As for sailing the boat in conditions near 15 kt TWS (true wind speed), 2-3 ft seas, you might wish to reef the mainsail. Although I doubt that mainsails of many daysailors have reef points b/c the boats are not really meant to stay out in it, I notice what looks to be a reef cringle in the leech of your mainsail. If so, I’d get the mainsail rigged for reefing. Otherwise if it gets too windy toward mid-afternoon you may opt to bring in your sails. That means going to the engine, and brother it had better start up and run, etc!
As you said, a lot to learn. I suppose you know that a hand-held VHF radio has a range of only a few miles. Put in fresh batteries and take extra. The bats go down pretty fast if transmitting. Also, take an Orion flare set and keep ‘em dry. You should have a compass aboad. Don’t rely on GPS alone. Check your GPS course against your compass course periodically so you’ll know your course if the GPS batteries go out. Take multiple spares there as well. And this probably sounds like overkill, but chart pages of the San Pedro Channel and Catalina Island north coast should be aboard folded to the relevant view and put inside a watertight ziplock bag so you can read it in the cockpit, even if there is water about.
Finally, leave a float plan behind with somebody (not the coast guard) that gives your expected time of departure, destination, and expected time of arrival, for each leg. Do not rely only on a cell phone to “check in” along the way. FYI. There is no cell service at mid-channel for at least five nautical miles either direction, could be a bit more. I’m sure others here will offer other suggestions.
KG