We stayed in Lagos over 2006/7 winter. V nice. However there is a boatyard in Faro that will keep boat on hard, I can not remember the name but we visited and spoke to a few 'residents' and it was safe, secure and much cheaper than Sopromar. The yard is just behind/near Faro railway station and I think the owner was called Fred??

I am sure a search on here or google will find it.

Good luck

Chox