If you have some sewing skills, you can take your bears measurements and adapt a doll costume pattern to fit. For eg this free top pattern:
http://www.bellaonline.com/articles/art33288.asp
This author has books too (see bottom of website). You can check out your local library for doll and teddy bear patterns to adapt.
If you need a pattern for teddy bear clothing and assessory patterns, please contact Tailormaid Togs, Dept. SN, 4037 161st Ave. S.E., Bellevue, WA 98006. They have many multi-size patterns range for a variety of sizes of bears including your 13" tall one. I cannot find a phone number for you - please write to them. I think this is a home business and was current in 2000 (mentioned in a sewing magazine).
If they do not have a pirate costume, you can take another and adapt it.
In making the outfit, take for inspiration other pirate bear costumes like this one:
http://www.bearfamilygifts.com/bear/piratebear_heilbrun.jpg
http://www.buycostumes.com/ProductDetail.aspx?ProductID=20019&PCatID=Search+Results&ccatid=pirate
or these child's Captain Hook type costume for details:
http://www.fancycostumes.co.uk/captain_hook.htm
http://www.buycostumes.com/ProductDetail.aspx?ProductID=17021&PCatID=childcostumes&ccatid=childboysclassics
Edited by GemB on August 3 2006 at 10:21 AM
Hope this helps and that you will accept my help!