1977 johnson 55hp will start at home

[tboat]

my 1977 55hp johnson,hard to start when in water,but start find at home.is something getting hot, for it be hard to start in the lake. thank you for your time.,

[tboat]

i have a johnson 55hp 1977 model, my problem is when i take it out to the lake ,it is hard to start,but when i'm at home it start up just find.is there something getting hot or something wrong with the ignition system.it start find at home. thank you for your help!