planning amp in offshore fishing boat

Hi Guys,

I would like to install an amp in my center console fishing boat but there are several areas of concern that I have.   It's a 21 foot boat and I would like to install the amp and two 8" subs in the compartment under the steering wheel.  I want to do it right, so please don't hate me for all the questions. 

1.  The compartment is fairly large and there is plenty of room for air to circulate in the compartment, however there is no vent or anything, just a panel that unlaches.   Will it sound ok or will it be muffled/muddy?   From a ventalation standpoint, will this be ok?  Even if the 110 gallon gas tank is below the deck compartment?  Althogth I never smell fumes in this area, I suppose the remote potential for it exists if something went wrong in my fuel line (crack or something).

2.   I have read several online posts/sites that say it's ok to ground to the battery.  If this is the case, why don't we do that in a car?   I feel like by doing this in a boat, i am compromising something.  i just don't want to compromise saftey given that I take this 35 miles out in the ocean and don't have a life raft.  I also don't want to become a target for lightning due to having and amp, ect.  not sure if this is even pausible, but wanted to bring that up.   The battery is located about 12 feet behind the center console, so it would probably use up all the standard 16-17 feet in an amp install kit.   Would it be ok to run the power wire on top of a metal gas tank or is this a really bad idea?   What if there is a thin layer of fiberglass between the tank and the wire?

3.  I already have 2 big marine deep cycle batteries in the boat.   II could install a 3rd battery in the compartment that I install the amp and subs in.   If I do this, I am not certain how I will charge this battery.  What would be the best way without havign to mess with the altenator/motor?   Is there any formula that would tell me how long a battery would last running two 8" subs on a 100W, 200W, 300w, 500w amp?   Would it be out of the question to recharge it using some type of  small&sleek solar panel?  

I appreciate your advice.   I have done a lot of searching on the internet and haven't found many good sites/info speficilly related to amps in boats.  If you know of any, please let me know.

Thanks,

Ted

Thanks for your help.   Do you think it will be ok to run a very 16' ground to the battery?  

Would I be better off with another battery in the Center console (but then i need to figure out how to repower it).

I am assuming that you left out the word large in your above sentence.  We do boats all the time, you will be fine with 16 foot of ground wire, as long as it is large enough. 

You should be able to find some shop that has a roll of 4 Ga. ground wire, that they will sell you by the foot.   You really need to inspect the wire before you purchase it.  Since the price of wire skyrocketed a while back, there are many companies selling you 4 Ga. insulation with 8 Ga. wire inside the insulation.

One more tidbit of information for you.  I do not care what precautions you take to protect your radio from the elements, those water resistant covers are NOT waterproof.  Do not think that you can take the hose pipe to the cover to remove salt.  I don't care if you buy the best marine radio money can buy, and the protective cover, it is still going to get wet.  It is funny when I tell them that it is going to be 75 dollars to repair all of the water damage, and they say to me, it couldn't have gotten wet I have one of those covers on it.  They still get wet.  The big problem is that the water gets in the deck and it all gathers at the back bottom of the circuit board, and stays there.  This is where the wiring harnesss and the output chip live.  If you want to really prolong the life of the radio, after every outing, take a blow dryer to the bottom cover of the deck for about 5 minutes,  or enough to heat it up to the point that you can not keep your hand on it.  This should be enough to make the water evaporate.  Contrary to popular belief, wet electronic parts still work, the problem is when they stay wet and corrode.

Hi Guys,

Thanks again for all the help.   I was looking at the boat today trying to figure out where I will run all the wires.   Will it be ok if I run the Amp Power and Groung (both 4 gauge) and speaker wire through a 6 foot piece of conduit?   Bascially, there is a 3" piece of pipe/conduit in the middle of the boat running from the battery to the center console.   I am concerned about introducing noise by having all these wires running in parrell with each other for about 6-7 feet.  I understand it is really important to keep the RCA cables away from the power and ground on the amp and will have no problem with that.

Best regards,

Ted

Thanks Guys,

Hooked it up today and sounds pretty good.   I bought a class D amp and am impressed with how it doesn't get hot.

-TC