March 2023     Cirrus

By Rob Wilkinson

I have always been interested in sailing and boats, but life has conspired to ensure that I have lived along the centre of the UK and often on a hill. Dinghies have been the way for me to get afloat, with a preference for “messing about in boats” rather than dashing around in circles. It was around 2000 that dinghy cruising became an entertaining direction to develop. Serendipity in the form of an ebay advert for a mostly complete John Welsford Pathfinder hull (5.2m) brought Cirrus into my life in 2013.

A winters work completed the rig (gaff yawl) and Cirrus was launched in 2014 on Ullswater. The plan was to enjoy “messing about in boats” during the summer with winters doing improvements towards the longer-term objective of dinghy cruising adventures on the sea! Coffee Mug holders and seat cushions were very satisfactory early additions.

The gaff yawl rig looked really good but had a few drawbacks. It took too long (hours) to rig/derig which impacted time on the water. The gaff main with a sprit boom was difficult to reef which created stress in changeable inland conditions. Then, in light airs, Cirrus didn’t move very much. The mizzen sail was great, particularly when stopped. I was on the look-out for a solution that would allow me to have a larger main sail that could be easily reefed and the whole lot rigged/de-rigged inside 40minutes. These requirements brought me to the Junk Rig Association. I was inspired by Slieve’s SJR design, though I did not consult directly with him.

There are a few design limitations to be considered when putting an unstayed rig into an existing open boat that is towed. I wanted to keep the mast length within the overall length of the trailer (6.4M). And to avoid losing cockpit space, by locating the mast near to an existing forward frame. Calculating the Centre of Effort (CoE) for the existing, nicely balanced rig gave me the target location for the new CoE. A spreadsheet allowed me to play around with all the variables. I settled on a 15.13m2 SJR, with 33.5% mast balance, that is to say, the mast centreline intersects the lower battens at 33.5% of the distance from the jib luff to the main leech (ie 33.5% of total chord), batten length of 3.4M, 5° rise angle, 35° yard angle.  To minimise weight aloft the area is split across 4 panels, and I started saving for carbon fibre battens.

Design and construction of the sail was developed from Sieve’s write-up. Starting off with 3D paper models of the sail shape followed by fabric models which were tested in the wind tunnel that is the passage down the side of my house.

Originally both the jiblets (12degree sheeting angle) and main panels were going to have 10% camber, but this was reduced to 8% in the main to improve air flow.

Our dining room floor was converted to a sail loft for the couple of weeks that it took to make the sail out of 4oz Ripstop nylon and the new rig was “launched” in 2020. The following year the aluminium mast was upgraded to carbon fibre. I am very happy with the SJR conversion. Cirrus points better than she did with the gaff sail. She moves in light airs and being able to reef immediately in just about any conditions is a revelation.

I am a much more relaxed dinghy cruising skipper.

From arriving at a slip Cirrus can be in the water within 40 minutes. My cruising area has expanded over the last couple of years to includer Northumberland and Scottish sea lochs. Added luxuries include a kitchen box, folding cuddy and tent which can provide overnight accommodation for three adults and a dog.

Our Featured Boat (or "Boat of the Month") Archive is here, and the forum discussion for comments and candidate suggestions is here