In force 7, gusting force 8…common sense suggested we put in a reef. Frankly it made little difference to her speed so we took it out…just after that she went on the plane and clocked 12 knots.

An Uncapsizable Dayboat?

Dave Greenwell sails a 20 feet long dayboat designed to be bomb-proof

 

It was a difficult brief. An open, centreboard, sea-going dayboat, around 20 feet overall, which would be fast on all points of sail, unsinkable, self-draining and, oh yes, completely self-righting even with her keel fully raised. And what Mike Reid, who was commissioning the design, really meant when he said self-righting, was uncapsizeable. The result was the Hawk 20 which took two-years to develop and is a quite remarkable boat to sail.
On the day I was to meet Chris Hawkins, her designer, for a test sail, I arrived at Lymington in a Force 7 gusting to gale F8. The brochure claims that she could happily sail in a Force 7 under full sail, and it looked as though I was going to discover the truth the hard way.

We motored out towards the Solent, pushed by a 4hp Mariner outboard neatly accommodated in an engine well on the centreline and beneath the small after deck. Having the prop directly in front of the rudder made her easy to manoeuvre and because it was also well forward of the transom, there was little chance of the propeller ventilating, even in rough water. Surprisingly, there was little turbulence in the engine well, even with the outboard working hard, but for added sailing efficiency the outboard lifts clear of the water and a pair of panels slot in to close the hole. Once in sight of open water, we hoisted sail in preparation for what was, for me, an ‘interesting’ experience. “Might as well put it all up,” suggested Chris with confidence.

 

So that’s what we did. Being more used to testing modern boats that make no bones about needing to be reefed at the top end of F3, I braced myself. But my fears were unfounded. Apart from setting off like a greyhound, nothing at all happened that would give cause for concern. She powered her way through the seas, shrugging aside a good deal of green water with virtually nothing coming aboard. Her steering remained light with just the right amount of feedback through the somewhat unusual tubular aluminium tiller. But there again, she is far from being a ‘usual’ boat. Soon, I was feeling far more relaxed about the whole experience and began to take note of the exclusive few who had ventured out when prudent sailors would have stayed in port.

 

We happened on a thirty footer with the reputation for good performance, struggling under a fully reefed mainsail and a pocket handkerchief jib. We gave a cheery wave as we overtook at about twice their speed.

Although she showed no signs of pounding – by then we were heading across a particularly lumpy stretch of sea on a windward beat – common sense suggested that we should slow her a little by putting one reef into the main. Frankly, it made little difference to her speed but we were no longer on a headlong crash through the waves. We were soon into calmer waters and turned onto a broad reach, by which time there seemed little need for the reef so we shook it out. It was just after that when she went on the plane and clocked 12 knots!

But for all that, she really felt very comfortable. As was only sensible, we sailed, mainsheet in hand, ready to spill the extra heavy gusts. To see what would happen when pressed hard with everything pinned in, I cleated her off and held on. Even in the heavy patches, she never got anywhere near getting her side decks in the water. I understand that although during development trials she was taken out in really severe weather with the express intention of inducing a capsize, they were unable to lay her flat. Certainly she’s very forgiving and whilst I’m very cautious of using the term, also very safe in terms of seaworthiness.

How’s it done?

Very simply the answer to her quite amazing performance is a combination of a powerful rig coupled with enormous stability and clean lines with fine entry plus broad after sections. Stability has been achieved by giving her multi-chine hull very stiff sections and a generous amount of ballast mainly comprising cast lead ingots secured low in the bilges. Indeed, her ballast ratio of nearly 50 per cent is equivalent to that of a heavy cruising yacht. Interestingly, she derives little in terms of righting ability from her swing keel which is of cast aluminium alloy rather than the more usual steel. This was not a weight-saving exercise but a deliberate attempt to give her the same self-righting characteristics regardless of whether the keel was up or down. Also, being cast it has a very clean and efficient profile, unlike a flat centre-board.

But the ability to stand up to full sail in a F7 has been at a cost which very much benefits the owner. During two years of development and testing, they broke a whole selection of fittings until they finally found the make and quality that would successfully withstand the loads. As a result, there’s no doubt that the Hawk 20 is very well put together with Blondecell of Sway, Lymington, making an excellent job of her mouldings.
Looking into the space between the hull and deck/cockpit mouldings and beneath the foredeck gives a good idea of just how strong she really is. She has substantial plywood bulkheads which not only add structural stiffness but also divides it into buoyancy compartments. Not satisfied with that, however, they also include close- cell foam blocks to keep her afloat if totally flooded. The space beneath the foredeck and under the side seats also provides ample dry stowage.

Why Hawk 20 is a remarkable design.

We do not know another boat which combines all Hawk’s attributes. Although a centreboard boat, she is self-righting from 90° in normal circumstances and self-draining sailing or moored, and unsinkable.

She self-rights mainly because of her ballast ratio, which is nearly half the weight of the whole of the boat and this is what makes her so stiff and would bring her back upright if knocked flat, so long as she is not prevented by crew error.

Capsizing is when a boat is knocked over 90° to the vertical. The way dinghy sailors deal with this is to climb over the side and stand on the centre plate and their weight usually brings the boat upright. If they are quick and agile they climb back aboard before being pitched into the water from which position it is difficult to get back aboard. If they handle the righting correctly they will be able to get under way again, but if not, the boat will often fall over the opposite way and they have to try again. They can become cold and exhausted and the boat remain full of water (and sink if it does not contain buoyancy). So it will be readily understood why a self-righting and unsinkable boat is so desirable. Considerable care has been taken with the design and construction of the hull and deck.

Hawk is not heavy for a boat of her size (she is of medium displacement). Her strength/weight ratio could only be achieved by using the best materials and highly skilled craftsmen to lay-up the hull and deck by hand. Had conventional chopped strand mat been used, or worse still machine sprayed chopped fibres in a resin-rich mixture, Hawk would either need to be much heavier (in which case she would not plane and would need a larger sailplan) or she would need to have far less ballast (and would not be self-righting). Ballast ratio is a percentage ratio indicating the relationship between a boat’s displacement and her ballast; 30% on a cruising yacht is considered low, 50% high. Hawk 20’s ballast ratio is close to 48%.
It took many months of experiment and painstaking development, sailing her single handed and crewed to achieve exactly the right ratio of ballast and to position it correctly both laterally and longitudinally.
Even the shape was critical. The lead ballast is machined after casting to ensure it is the shape and size and exactly the same weight on both sides. Owners will therefore appreciate why, having achieved exactly the right weight ratio of hull and deck, equipment and ballast, there is no intention to change anything or try to add a small cabin.

Conclusion

Our test sail certainly indicated that she lives up to all her builder’s claims. Her high stability and self-righting ability make her an ideal family day boat.

 

Reproduced from Practical Boat Owner, March 1993