does anybody have the answer

i really need help im new to the boating life i love it , anyway i just got a 25ft cobia i really like the boat but it does need some work heres my problem i need to get a battery for it never came with one the guy took it out so ,, DOES ANYBODY KNOW WHAT SIZE BATTERY I NEED ??????????????
THE MOTOR IS A 5.7L ALPHAONE MERCRUISER
THE BOAT IS A 1988 COBIA ODDESSY please help me thats the only problem i got right now ill be fine with everything else thank u so much hope to hear good news soon

 

just get the biggest cranking battery that will fit is the hole!!
batterys can nevr be too big, but they can be too small

 

Welcome aboard
A few points I can suggest for you.
- Figure out what you need to run off the battery. Is it just for starting the motor, or do you also have fishfinders, GPS, stereo, etc that you need to run with the engine off?
- Always err on the high side when it comes to battery capacity. The performance penalty for having an extra 10 kg of battery is far less trouble than finding a foot of water in the bilge, turning on the bilge pump, and having it whirr nicely to a stop in ten seconds.
- Writing in full sentences, no capslock, makes it a lot easier to read your questions and encourages more people to help out.
When you have a list of the equipment you need to run off your battery and how long you want to be able to run it for, get back to us and we'll be able to help you out a bit more.

 

Typically, you'd run a group 24, which is about 10 1/2" long, by 6 3/4" wide, by 9" tall. The cold cranking amps on these (a few different models) range from the low 400's to 700 amps. This is enough battery to start your engine, run your bilge pump, nav lights, radio, etc.

Batteries are matched to the load (as mentioned above). If you have a trolling motor or other extra load, that you expect to place on your battery(s), then you need a bigger battery or better yet, a duel battery setup (real simple to install).

There are also a number of different types of batteries. Some are designed to run steady and long duration loads (like a trolling motor) and others are like car batteries and designed to draw down hard and fast, but get charged right back up when the engine starts. They even sell "combo" type batteries, sold as a battery to do both.

If just starting up the 350 and running some pumps and a radio, a car battery will work fine. Get the most cold cranking amps you can.

If you will have other heavy loads, like a trolling motor, strongly consider getting a duel battery system. One will be the engine starting battery and the other a deep cycle trolling motor battery. In a pinch you can get either one or both to start the engine, so it's a good back up if you have a problem.

 

thanks

thank u all for all your help
i going to need more help with someother things so please look out for my questions thanks again

 

1 more question

hi again ,
i have a corvette motor do u think i can put that in my boat????
do i have to convert it in any way

 

Boats (most) do a lot of sitting idle. This type (AGM) hold a charge better than a "wet" (regular automotive) battery. I like em!
http://www.batterystuff.com/batteries/rv-marine/#241
.
When you ask about a corvette (small block?) engine, I assume you will have it done for you, right?
Short answer is yes, BUT........ it has to be marineized. Different starter, cam, exhaust, water pump, motor mounts, etc.. Google the process.
Still want to do it? Ir is a big step from not knowing about batteries to engine installations.
Enjoy the boat for a season or two, decide if "boating is for you.

 

It's very likely you have the basis for a LT1 (Vette motor) in your boat now. The heads, induction and a few other pieces are different (okay quite a few), but you do have a small journal, single piece rear main seal, 4 bolt main block there now, which could be converted to a Vette motor, but why. The Vette motor is fine in a car, but a performance motor in your boat is very different then a land based variant of the same engine family, even if they have the same HP.

I'd have to side with Ted on this. If you're having issue with battery selection and installation, then you're not ready to consider an engine swap without a lot of professional assistance. A 300 HP marine engine is like building a 450 HP car engine. A 300 HP car engine will develop about 200 marine HP.

A car uses 20% of it's available power 90% of the time. A marine engine uses 90% of it's available power 90% of the time it's in operation. This means the setup of the engine is quite different, not to mention (as Ted did) the conversion process, which can be pretty involved.

Enjoy your boat. Get it in fine shape and consider upgrades to what you have, plus regular maintenance to keep what you have in good working order. This is usually enough to eat up your spare cash quickly enough.