In 1789 a ship was stranded on a sandbank and the crew could not be rescued because of storm conditions.
A committee was formed to build a boat capable of effecting a rescue in such conditions.
Two models were submitted.
One, modelled in tin by William Wouldhave, was to be built of copper, made buoyant by the use of cork, and was incapable of being capsized.
The committee however disapproved of the idea of a copper boat, but Wouldhave was awarded one guinea for his trouble.
Greathead also made a submission, built of wood, but which floated bottom up when upset.
He was however rewarded by being employed to build a boat as directed by the committee.
Sometime after, two members of the committee presented a model which Greathead was instructed to build.
At his suggestion it was agreed that a curved keel should be used.
They decided that something akin to a Norway Yawl should be built.

The lifeboat constructed had a curved keel and rose more fore and aft than a Norway Yawl.
When full of water amidships, one third at each end would be out of water, and it could continue underway without foundering.
It could be rowed in either direction and was steered by an oar rather than a rudder.
It was rowed with ten short oars, these being more manageable in heavy seas than a full-length oar.
The boat was thirty feet long and ten feet broad.
The sides were cased with cork, four inches thick, weighing nearly 7 hundredweight and secured with copper plates.
It added considerably to the buoyancy of the boat, helping it recover quickly from any upset.
The curvature of the keel made her very easy to steer about her centre.
She was able to carry twenty people, and went out on her first trial on 30 January 1790.
In 1789 a ship was stranded on a sandbank and the crew could not be rescued because of storm conditions. A committee was formed to build a boat capable of effecting a rescue in such conditions. Two models were submitted. One, modelled in tin by William Wouldhave, was to be built of copper, made buoyant by the use of cork, and was incapable of being capsized. The committee however disapproved of the idea of a copper boat, but Wouldhave was awarded one guinea for his trouble. Greathead also made a submission, built of wood, but which floated bottom up when upset. He was however rewarded by being employed to build a boat as directed by the committee. Sometime after, two members of the committee presented a model which Greathead was instructed to build. At his suggestion it was agreed that a curved keel should be used. They decided that something akin to a Norway Yawl should be built.
The lifeboat constructed had a curved keel and rose more fore and aft than a Norway Yawl. When full of water amidships, one third at each end would be out of water, and it could continue underway without foundering. It could be rowed in either direction and was steered by an oar rather than a rudder. It was rowed with ten short oars, these being more manageable in heavy seas than a full-length oar. The boat was thirty feet long and ten feet broad. The sides were cased with cork, four inches thick, weighing nearly 7 hundredweight and secured with copper plates. It added considerably to the buoyancy of the boat, helping it recover quickly from any upset. The curvature of the keel made her very easy to steer about her centre. She was able to carry twenty people, and went out on her first trial on 30 January 1790.
Henry Greathead