by Eric Coleman

Capsize Test

Before describing this, a word or two about the meaning of "self righting". This is rather a loose term and means that the boat will recover from an angle of heel which is greater than one might expect with reasonable use. Take, for instance, a cruising yacht designed with ocean racing in mind. In “Yacht Design” by D Phillips-Birt A.M.I.N.A., the stability curve of such a yacht shows that the angle of vanishing stability is 125 deg. My design aim was 120 deg., this being a little less than the theoretical curve which indicated about 128 deg. These curves however were rough estimates. Roamer is based at Maldon but at Walton-on-Naze 30 miles up the coast, there is a sandy shore sloping steeply into the water, so Maureen and I decided to carry out the test whilst on holiday. We carried an inflatable dinghy; the arrangement was for her to take photos from the shore whilst I turned the boat over. First of all we stripped the boat of all cruising gear and removed the awning. Removal of these items might invalidate the test if it was touch and go but not if there was a considerable margin of stability. In any case, I drew the line at risking the gear with a soaking.

As I hoisted the sails the wind, of course, freshened and the jib threshed wildly so I had to lower it. Next, I emptied umpteen buckets of water into the boat until the depth inside was about 8”. Stepping into the inflatable, I hauled on a rope attached to the top of the mast but she would not come over and I was anxious about the strain on the unstayed portion of the mast, so back aboard and more buckets of water. Next time she came over and as the side decks submerged, some water actually flowed out of the boat. Forcing the mast below the surface and working my way along it towards the boat I was able to float over the forestay but found things more difficult as I progressed due to the decreasing leverage. About 5’ from the boat I had to stop because there was danger of the boat taking charge and heaving herself upright. I was nearly falling out of the inflatable in my efforts to get maximum weight on the mast and just then a motorboat came up and the crew said that they would soon have my capsized dinghy upright by heaving up on the mast. After hastily explaining that I was trying to get the boat over, they came alongside the exposed bottom and one of them heaved upwards on the keel (centreplate was up). The change in angle was only about 5 deg. so they gave up.

The only thing now was to get Maureen to take a photo end on so that the angle could be measured from this, but wind and tide had turned the boat so that this was impossible. Letting the boat up we arranged for her to take a photo from a nearby motor cruiser and once again I hauled Roamer over and the job was done. The angle of heel turned out to be 110 deg. and I can only estimate that the angle of vanishing stability would be at least 10 deg. more and leave it at that. There was no water in the main fore and aft compartments but the hatches were above water virtually all the time. The inspection hatch of a stern castle was awash for about 15 minutes and had leaked about 1 1/2 pints.

Stability Test

With centreplate in the up position George Dyer (11 1/2 stone) sat out, whilst I (12 1/2 stone) stood on the side deck. A stability test is only significant when considered in relation to the hull shape. My stability curves show that a boat with a centre section like a box will give the best result but it is unlikely to be the safest. The test is, of course, more severe for a boat with a large deck level beam.

Handling

One of the more important requirements is ease of reefing. Taking single-handed cruising, the mainsail is best lowered for reefing and when rehoisting, the windage aft helps the boat point up into the wind. Changing jibs, I usually sit on the foredeck using the toe rail for security and clip myself to the mast with a safety harness. The boat has to look after herself whatever the conditions and stability must not suffer because the crew is on the foredeck. The most effective way to make a boat insensitive to crew position is to make her heavy compared to the crew weight. An alternative approach for boats which are more sensitive is to use a reefing jib which avoids working on the foredeck. This can also be fitted to Roamer of course at some sacrifice of performance.

The drum winch for hoisting the centreplate makes light work of the job but has one snag when cruising. If the plate touches, the tension on the wire is removed and it can snarl up on the winch axle so that this has to be sorted out before hoisting. A cure for this would be to lead the wire through an eye attached to a piece of shock cord so that there is always tension on the wire and this is being tried out. At anchor in gale force winds the boat is wind rode. There is little tendency to sheer about and therefore no appreciable heeling.

Performance

Difficult to give a figure until the boat is raced and a Portsmouth Yardstick number is issued. The performance lies between a conventional dinghy and a racing dinghy and an outboard is not necessary when cruising. Our 35 mile passage to Walton took 6 hours with a fair wind of force 3 to 4 and neap tides.

Independent Test

Roamer was handed over to George Dyer, aged 65, to sail and sleep aboard. Winds were not strong enough to test rough weather capabilities. He made the following observations:-

“The cockpit is unobstructed and gives ample room for two air beds. There is comfortable sitting room under the awning but I found it awkward to lash up and stow single-handed. When sailing, there is ample comfortable seating for four persons. The boat is not slow in light airs in spite of the beam and can be compared with a Fairey Falcon or Enterprise. It is fast in a stronger breeze. I have sailed small boats for most of my life and this one is undoubtedly the most stable for its size. I hope to build one this winter”