In order to be confident in sailing the National 18 as a day cruising boat with two crew, we wanted to be assured that it was possible to recover the boat from capsize with two people. The National 18 is a three person boat, so I was not sure whether a recovery with only two people was possible.
We took it to Bough Beech Reservoir and under the watchful eye of their club safety boat driver we conducted the experiment. The boat was cleared of all loose contents and made ready for capsize. There was no wind so we got deep enough by a tow in flat calm conditions away from the shore.
At the moment of capsize, before the inside filled with water, the boat sat very high.
And sat at rest for a moment (while, I imagine, the mast filled with water).
This is the moment when I realised that the downward pressure of the rigging hugely overwhelmed my weight hanging on the end of the centreboard – I was being lifted powerfully out of the water.
Despite both of us hanging off the hull, the mast was heading quickly to inversion.
At this point it became clear that two people are simply not enough to keep this National 18 with it’s mast level with the water, and the experiment was stopped and a third person joined us in the water to right the boat.
The boat became almost completely inverted, with the air escaping from the hull and centreboard as it settled with the waterline at floor level, and it was possible to get on the hull and onto the centreboard. It took the weight of two people on the centreboard to raise it, one standing and leaning back and the other hanging on to the end and pushing down.
Unfortunately, we had no one scooped in the boat for the first righting and it proved a point that I had speculated; with a ton of water above the buoyancy tank it would be unstable until drained., The weight of the water above the buoyancy made it highly unstable and it immediately capsized.
We established that it’s critical to have two on the centreboard to raise the boat and the third person must be scooped into the boat to dynamically stabilise it while it self-drains for about 30 seconds. The floor is about 2cm above the water line and the centreboard slot is level with the deck, so the water drains very quickly through the slot – a great safety feature.
It was easy to get back in. On shore there was little water in the buoyancy tanks.
Note: This experiment cannot be used to extrapolate to all National 18s. This is a 1974 Proctor hull which has been fitted with full length under floor buoyancy at the level of the centreboard case. We had no masthead buoyancy, and no righting lines, it was exactly as we raced it.
Conclusion: This National 18 cannot be raised from capsize by only two people. With both crew on the centreboard the boat will right and immediately capsize due to the instability due to the water above the buoyancy tanks. One person on the centreboard is insufficient weight to counteract the weight of the mast.