How can I find a particular painter of seascapes?

First you should make sure you have the exact spelling. You may need to get a magnifying glass out to check it. Then you can do some more searching of the name under landscapes, sea scapes, ocean paintings, oil paintings etc. Check, also, to see if there is some kind of a date, either next to the signature or written somewhere on the back of the canvas or the frame. Are there any labels adhered to the frame that might have more information, like if it was a family painting, does it have the name of the family that owned it? If the painter is not someone of any renown, you may not have any luck.

You could also try calling your local art museum or historical society and ask them refer you to an appraisal company, or an expert in the type of painting that you have.

Does the painting look old, as in 25 years or more? If it is old, you could try contacting Antiques Road Show and they might be able to refer you to someone in your town who could look at the painting.

If it is just a run of the mill painting by a regular person (like me or you) the painting might be a one time only thing and the person may not be known at all.

I just found something on this shopgoodwill site that has a painting and a description similar to yours.

Could it possibly be Walter Lofthouse Dean? He was a famous oil painter of marine/seascapes.

edit: Me thinks Kardamom may have just found the answer.