deep cycle battery's

went for deep cycle light and regular starters, guy at the store mentioned low amp for starting again.
merc startmotors need between 60 and 90 A
on the dash is a parralel starter switch (using both battery's right?)
looking at their site i see delphi 105 AH gives 690 A max start current

have books somewere but can anyone here briefly brush up my Amp Hour black out

 

I am setting my houseboat up with 3 batteries. 1 will be for cranking the motor and the generator while the reamining two will be used as house batteries (they will be deep cycle). I am also dedicating a solar panel to each house battery as well as a smaller solar panel to the cranking battery.

Over the years I have learned that you can be too prepared, especially for extended days on the water......

 

Deep cycles will work for starting. They're getting real popular for cars that have big mega-sized stereo systems, and many of my friends use them in place of their regular batteries with no premature failures that I'm aware of.

http://store.summitracing.com/egnsearch.asp?N=400089 115 4294889586

The difference in amps isn't all that much, either - the red-top size 34 automotive battery has 800 cold cranking amps, while the yellow-top deep cycle size 34 has 750 CCA's, as does the marine deep cycle version.

 

There are dual purpose batteries available
http://www.trojan-battery.com/Products/Marine.aspx