These are the listed colours used in lifeboats of the RNLI
Lifeboats Blue BS 381c Oxford Blue 105
Lifeboats Yellow BS 381c Bold Yellow 363
Lifeboats Red BS 381c Signal Red 537
Lifeboats Orange BS 381c Orange 557
Lifeboats Grey BS 381c Light Aircraft Grey 627
Grey for Non-Slip Deck BS 381c Dark Admiralty Grey 632
The exact combination used on the boat depends upon the period you are modelling. Early boats had blue hulls, grey superstructures, red fenders, then the tops had orange patches then full orange tops. As time passed the more modern boats had blue hulls with a single red band then blue with a red and yellow band. So make csure you have a decent picture to ensure you get it right or many ex-RNLI crew will nail you to the mast for sacriledge!!
Mike