Charging deep cycle batteries??

[conan1]

I have a new Vector 2/10/20/40 charger with 100 amp start function, reconditioner and battery checker and automatic float function. Question is while charging my marine battery, after one day of charging, the amp reading initially went up to 40 amps and slowly dropped and stayed at about 2.8 amps. I opened up the vents and all six cells were boiling. I had previously filled them with distilled water, they were only a little low, no plates showing. The battery is not showing bad but I have no experience with deep cycle batteries. I would have thought the charger should have went into float instead of a continuous 2.8 amp charge. I have used this charger on other batteries and it does work. ?????? Thanks for any thoughts on this.
Eddy