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Building and sailing an Ian Farrier F-39 trimaran

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Last updated: 2026-01-18

A painful but inevitable moment: adapting a nearly finished float to a late design change in the final F-39 beam dimensions.

Design change

After the summer holiday break I received an email from Ian Farrier announcing that the preliminary drawings had now been replaced by the final design plans, with a few minor changes.

One of those changes had a dramatic impact on the work done so far: the newly designed beams are significantly wider and no longer fit between the raised deck areas. The only solution was to take the saw and cut large openings in the deck—not a pleasant job. The final fairing had just been completed. On the positive side, I had not yet cut the lashing slots in the moulded wingnet rail due to my sailing holiday, so these could still be redistributed evenly along the rail.

Of course I was aware that the drawings were preliminary, but the motivation to start building was simply too strong to wait for the final plans. My own responsibility.

This photo gallery (36 images) shows the consequences of a late design change: cutting major openings in the deck, rebuilding the raised deck sections, re-laminating, and adapting the wingnet lashing rail to the wider beams.

Large openings cut into the raised deck area of the float to accommodate wider beams in the final F-39 design.
Large openings cut into the deck because the final beam design became wider, requiring the raised deck sections to be shortened at both fore and aft ends.