would not hit the water without it.the best feature to me is being able to see where there are lightning strikes are.the temp map is helpfull but not as detailed as the computer versions,they use diffrent colors to show the temps.major breaks do show up.the only downfall is dealing with sirius customer service.dont give them a credit card number,they like to just charge whatever services on it they see fit.my wife spends 1 to 2 hrs every year dealing with those morons i have the raymarine versoin,i think they differ a little from raymarine to lowrance and the birds