Mainsail boom

Introducing the mainsail boom, whittled from an old rotting mast.  I've also changed the sheeting arrangements, moving away from the traditional Drascombe 'W' pattern to a straightforward double block arrangement.

Having previously enjoyed both making and sailing with a mizzen boom, I had no real intention of moving on to the mainsail.  The decision to proceed was based, in part, on some very useful descriptions posted on the Drascombe Association Forum regarding methodology.  Additionally, it helped that I had an old mast which was waiting to be whittled into shape.  Lastly, there's nothing like a summer holiday for proceeding with a project.
The decision was not based on any real expectation of an improvement in sailing performance.  Daisy II already sailed perfectly well and I knew of no conclusive proof that a boom improves things other than heresay.  There are no doubts that a boom prevents the sail from collapsing in downwind situations.  Moreover, there was a realisation that the boom would change the way the boat performed and discovering exactly how was certainly a lure.

Boom length 310cm.  I planed an old, rotting coaster mast to a diameter of roughly 5.5cm.  This, handily, already had a slot for the intended outhaul, although it would be necessary to create a smaller wheel for this.

The wheel was created from an old wooden kitchen chopping board; the initial disc was cut from the wood and then centred on a screw bit mounting for a Dremel which, when rotating, enabled various sanding jobs to be done, including the concave groove on its diameter.

At the other end, a set of jaws, hewn from pine, were shaped, sanded and then glued to the main shaft.  Finally, I cut a curve to match the diameter of the mast against which the boom will rest.

Not photographed are the leather protectors glued to each end of the boom.

Rigging decisions involving sheeting, outhaul, topping lift and attachment to the mast can be observed from the following pictures of today's maiden sail.

I took the opportunity to change the sheeting arrangements.  The traditional Drascombe 'W' arrangement has been replaced with a simple pair of double blocks, one on the clew and the other, with becket, on the slider.  The latter was purchased and, although slightly oversized, is very effective.  The improvement in performance is manifest.  Sheeting in is much less effort and, when paying out during gusts, the sheet slides through with ease.  A fantastic and unexpected bonus from this modification.

Following advice on the Drascombe forum, the block attaches to the boom by means of a sliding strap which I made from an old trailer winching strop.  The idea is that the strap slides along the boom to match the foot of the sail depending on how it is reefed.  This worked well enough.  Initially, I had the clew outhaul passing through a loop in this strap, but I may dispense with this and have  the strap running free inside the outhaul.

The clew outhaul passes through the slot in the end of the boom and then along the boom to a clamcleat positioned halfway along the boom.  This will enable easy tensioning of the foot.  At the tack-end, the jaws are held against the mast by luff tension and the tack downhaul.  A pair of stainless steel eyes from an eyebolt and an eye nut above and below the jaws enable these attachments.

Another view of the sliding strap and clew outhaul.

The boom also provides a great place from which to hang various plastic bags which hopefully help to deter wildlife whilst on the mooring.

Fitting the boom was made more challenging due to several passing showers.

Once fitted, the rain showers seemed to stop and the reward was a pleasant 'maiden' sail up the Orwell, during which time lugger Truant was having a splendid sail.

The maiden sail for the boom involved full main and a few rolls in the jib.  Winds were F3-5 and the boat heeled over nicely during the gusts, and the new sheeting arrangements for the main worked exceptionally well.  She certainly feels different to sail, the mainsheet is more comfortable to hold and the sail feels more controlled.  The downside is the obvious boom swinging just above head height in the cockpit area, although in time one supposes this will be an extra thing to grab hold of when moving around the boat.

6.4nm