After resting in sydney for a few weeks,Chichester set off o

你这句话完整吗?怎么看都不完整啊?要不你再检查检查.再说了,哪里有你说的“attempts to"?我反正只看见一个set off.我个人猜测,这个句子的完整版可以是：Chichester set off once more in spite of his friends asked him not to.或者是”in spite of his friends attempt to dissuade him.
你最好把原句再检查一下,不然没法回答你的问题~~