Making a Boom / Gaff Spar


This section covers the making of a boom or gaff spar for a Fowey 14’ river sailing dinghy. It uses a different technique than other solid wooden spars (see ‘Making a Wooden Spar’); in this example the spar is made in two halves to enable a boltrope channel to be machined into it.

A gaff is a spar attached to the mast and used to extend the upper edge of a fore-and-aft sail.

A boom is a long spar extending from the mast to hold or extend the foot of the sail.


The process is demonstrated in the accompanying video clip with a step-by-step guide. The conversation with the boat builder, in this case, Marcus Lewis is unscripted and covers the technique from his experience.

At the time of recording, Marcus Lewis had two Fowey River sailing dinghies in build, so he was planning to build two sets (two booms and two gaffs). The process covers a single build of a spar, however, the initial stages cover all the timbers for all the spars being produced at this time.

Video Content

Part 1

  • Step 1 ~ cut up the timber for all the spars required
  • Step 2 ~ planing the datum face on all the rough cut timber needed for the spars
  • Step 3 ~ pair the pieces of timber up
  • Step 4 ~ routering the straight slot in each half of the spar


Part 2

  • Step 5 ~ routering the curved slot in each half of the spar
  • Step 6 ~ prepare the two halves for gluing


Part 3

  • Step 7 ~ glue the two halves together
  • Step 8 ~ removing excess glue from the spar
  • Step 9 ~ clean the glue out of the groove
  • Step 10 ~ plane the spar to the required dimensions
  • Step 11 ~ mark the boom with key points and cut to length


Part 4

  • Step 12 ~ shaping the corners of the spar
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Tools Required

  • Section template
  • Class rules to check dimensions
  • Router
  • Clamps
  • Channel scraper (bespoke item)
  • Masking Tape
  • Hand saw
  • Electric planer
  • Suitable glue
  • Tape measure
  • Ruler
  • Sander
  • Personal Protective Equipment (PPE)
  • Pencil

Materials Required

  • Canadian Spruce