What size boat for saltwater is an open-ended question. For the Sound, the guys suggesting 15' are probably right. I used to have a 14' Smokercraft that did just fine.

But, now I fish the Strait mostly and except on really nice days, I wouldn't want that small of a boat. Midchannel Bank gets really choppy with any wind at all when the tide is running hard. Also, the afternoon winds at Sekiu are pretty nasty to get caught in.

If you want to fish the Strait or the ocean at all-- I go to Neah Bay a lot-- then you want something with some cover.

It also depends on the type of boat. I think a 17' Arima can handle the same water as most 21' boats. I fish a 15' Arima myself and have never enjoyed another boat as much. Not fast, but efficient, dry and I pull it with my Toyota 2wd. Saves on gas $$ towing.

Good luck. I went through the three bears routine myself-- too small, too big and then just right.