My BRe had factory-fit halyard bags on the outside cabin bulkheads, port n Stbd. Must be pics on here somewhere?
These are attached with turn button fasteners, see here. Bags Easily removable for cleaning.
https://www.jclarkemarine.com/blogs/news/116462277-what-are-turnbuttonsI added two guard rail bags from C n J Marine in Chichester, inside cabin. Attached by extending the turnbutton fastenings thru the bulkhead. £18.
https://www.cjmarine.co.uk/product-category/marine/canvas-accessories/They will also fit on the cockpit side rails like Llafurio describes. The guard wire attachment, velcro securing flap (on the back of the pockets) can be heat cut, and modified so as to form "saddle bags" attached over the wooden rails, with no need for additional fasteners. The acrylic canvas does not fray if cut with a hot knife.
Excellent quality canvas work, and available to match my beige acrylic canvas original sailcover etc, reasonable prices, PROMPT delivery too (a great rarity for small canvas items, from sailmakers in my experience!). Imho...They look much better than "standard" chandler's stock items.
That good, I have ordered more for my "new" boat, including the large 3 pocket halyard bag (too big for BRe).
If you subscribe to their newsletter, you get 10% discount on first order too! Effectively freepost?
Obviously I'm just a satisfied customer.
In my experience velcro attachment of such items to boat is not a long-term solution.