Battery Question

[Castor]

I need a new starting battery for my boat and was hoping to get some suggestions.

My boat is a 21' Chris Craft with a 185 Johnson. I have 2 deep cycle Trojans linked together to run the house lights and electronics. I went into a battery store yesterday to buy a Starting battery and the guy sold me a "dual purpose" battery. I thought that this was just a larger capacity starting battery but it looks like it may be more of a deep cycle battery that can be used as a starting battery. Is this over kill? Should I return it and get just a starting battey? Is this going to recharge as quickly as a regular starting battery? Any ideas on what is the best size battery for my engine?

Any help is totally appreciated.

Thanks.

Rob

[Mariner]

dual purpose batteries are junk. you want a cranking battery with 1000 mca's(marine cranking amps) we put interstates (24m-xhd) in all our sales boats. runs about $100.

[Castor]

Freek;

Thanks for the input.

[Kahuna]

dual purpose batteries are a sales pitch. Nothing more.