Then to collaborate their findings, they went to points further down on Columbus voyage, then backtracked according to the log nottions and again found that they landed not on Professor Morrison's Watling Island but on Samana Cay.

1 collaborate是不及物动词，不可能有宾语，后接findings也不合逻辑。故collaborate为elaborate之笔误，原文应为Then to elaborate their findings, they...

elaborate可以及物也可以不及物，此处为及物动词，意为： to bring (something, such as an idea or a plan) to a more advanced or developed state （《韦氏词典》）。

Then to elaborate their findings: 然后为了详细说明他们的研究结果。不定式短语作目的状语。

2 网友可能误以为to points further down on是短语动词的不定式形式。如果网友注意到points末尾的S，就知道这不是不定式，而是名词复数，went to points去了诸多地点。后接further down on Columbus voyage为副词性结构作points的限制性定语，说明他们（根据航海日志）沿哥伦布的航行路线又去了后面的几个停泊地点。

全句译文：

为了进一步说明他们研究结果，他们根据航海日志记录，沿着哥伦布的航行路线继续前行，去了其曾停靠过的几处地点，然后原路返回。他们再次发现他们登陆的地点不是 Professor Morrison's Watling Island，而是Samana Cay。.