There's an entry in the Times in 1843
The Times, Thursday, Jul 13, 1843; pg. 8; Issue 18347; col
summarised: A boat from the coast-guard at Childock went to Charmouth carrying an officer, who, as he was not returning, gave the men permission to take the boat back along with some of their wives and children, who had been attending a fair. On the return, however, the boat capsized in rough water, and seven of the nine persons aboard perished.
Those who perished were: Mann (a boatman) Mrs Turner and child, Mary Hodder, and three children of a boatman named Dumble. Mrs Dumble was saved by a boatman named Phillips - when he reached her, she was holding the body of one of her children in her arms. The bodies of Mann and the eldest Dumble child were not recovered.
This family may be John Dumble, coast guard, aged 25, wife Mary, and children Mary, Elizabeth, John, and William in 1841. They are living in Dorset in 1841 but the parents were not born there.
There is also an 1842 reference to a Thomas Dumble, captain of the Bernard (witness in a court case).