Sounds like your problems have been solved already, but for the sake of others who might be in the same dilemna, I'd advise staying away from nylon cord -- braided or laid. While it can be made to work, there are better alternatives.

Nylon is very slippery and knots tied in it can work themselves loose over time. as people working ieth nylon skins have noticed, it also stretches a wee bit when wet, which would loosen your lashings. Even when dry it can stretch under stress, which can either be a good thing or a bad thing, depending on what the stress is from.

There is a waxed polyester thread available at leathercraft stores and used with stitching awls which I like for light lashings. You can easily double or triple it for additional strength, or wrap your lashing with more turns.

Hope this helps

PGJ