50 amp to 30 amp

Good morning. Hope everyone had a terrific Thanksgiving. I am new to a 50 amp system, always having a 30 amp connection to the boat's power system. Simply plugged it in and it worked. I have tried the following and am unable to get power to the boat. I want to charge the batteries fully and...

My summer marina has a 50 amp connection which I can plug directly into. Where I am today prior to coming out of the water has 30 amp pylons (electrical towers with receptacles). What do you use to split the power. I have a Hubbel YQ230 but it isn't working - see picture. What other options...