1970 Sakonnet 16; Location of Battery and Fuel Tanks

[Skip Berry]

Give me advice on the placement of the battery and fuel tank [on a c.1970 16-footer].

[Do readers have] any ideas [about where to locate the battery and the fuel tanks on a c.1970 16-footer]?

The fuel tank placement does not have to be fancy. I plan to have one or two 6-gallon fuel tanks. I would like to keep as much of the deck open as possible. I plan to [utilize] the space below the console.

[Locating the fuel tanks under the] RPS may be another option.

Is there suitable space under the RPS for two 6-gallon fuel tanks?

BACKSTORY: [I am] getting close to finishing the restoration of a 1970 Katama [and making it into] a Sakonnet. The engine is an E-TEC 90, heavier than the original engine. I thought having more weight forward might be a good idea.

[biggiefl]

The console was designed to hold two 12-gallon fuel tanks.

I am not sure if I would want the battery next to the fuel tank in a semi-enclosed area however.

[jimh]

As NICK has noted, the original wooden console on the c.1970 SAKONNET or NAUSET was intended to hold fuel tanks. I don't see any reason not to locate the fuel tanks where Boston Whaler intended them to be located.

The wooden reversible pilot seat on a SAKONNET was not intended to be the location of the fuel tanks or the boat battery.

I am not clear on what sort of reversible pilot seat you have on your boat. Did you reproduce the original wooden reversible pilot seat from the SAKONNET model when you refurbished your KATAMA?

[jimh]

Moving the engine cranking battery to a more forward location such as under the center console from the stern is a common modification used to reduce weight in the stern of the boat to help compensate for increased engine weight. Small boat electrical topics are discussed in the SMALL BOAT ELECTRICAL forum.

...The engine is an E-TEC 90....

For advice on the manufacturer's recommendation for battery cable size for various distances of separation between engine battery, see my article

Recommended Battery Cable Size
viewtopic.php?f=9&t=2153&p=12497

The article excerpts specific advice from Evinrude for their E-TEC engines and battery cable size needed.

General advice about re-locating engine cranking batteries is given at:

General Advice on Moving Engine Battery to Console from Transom and Extending Battery Cables
viewtopic.php?f=9&t=5111&p=29325

Battery weight can also be reduced by using a battery with Lithium Ion chemistry instead of lead-acid chemistry. A Lithuim Ion battery will generally weight about half as much as a lead-acid battery, but its cost will be more than double. The increase in cost may be worth the expense because it eliminates the added expense of moving the battery farther away from the engine.

For more about lighter battery weight see

LiFePO Batteries for Marine Use
viewtopic.php?f=9&t=646

As you can infer from the three linked articles, advice about electrical wiring on small boats is best provided in the SMALL BOAT ELECTRICAL forum.

[jimh]

Regarding battery placement for Boston Whaler open boats: the battery location was always in the stern on the starboard side. There are several reasons for this location:

• a stern location puts the battery properly close to the battery's primary load, the outboard engine cranking motor
• the location on the starboard side creates a slight list to starboard in static trim, which may be helpful in correcting the tendency for a right-hand propeller on the outboard engine to tend to create a list to port
• although not in the 16-foot hull, on many other Boston Whaler classic hulls the cockpit sump is located on startboard aft, and a static trim list to starboard will facilitate water on the deck draining into the sump.

[Skip Berry]

Thanks to all for your ideas and advice. The console and RPS are mahogany reproductions of the original. It looks like I could leave the battery in the Stern and have two 12 gallon fuel tanks in the console or move the battery to the console position with one 12 gallon fuel tank. It looks like the distance between the console battery location and the engine is between 10 and 12 feet. So that would be 4 AWG or 2 AWG copper wire. Am I missing anything?

[jimh]

...the distance between the console battery location and the engine is between 10 and 12 feet. So that would be 4 AWG or 2 AWG copper wire.

Choosing the larger cable (2-AWG) will reduce the voltage drop. This will give better engine cranking motor performance. It may get the engine started some day when the battery charge is right on the edge of being sufficient. The short cables on the engine now are probably 4-AWG. Do not extend them or splice them. Get new cables that are long enough to reach without any splices or extensions. Each splice or extension adds voltage drop and creates a possible problem in the circuit. Never locate any splice in the rigging tunnel--it is too wet.

I'd hold off on moving the battery until you see how the boat's trim actually is with the battery still at the stern.

[biggiefl]

You do not usually need more than a 12gal tank with a modern engine unless you do a lot of running. With my 70hp Suzuki I only carried a 6gal tank and could run about 50-60miles @ cruising speed before running out. My usual cruise was 35miles round trip with a few slow speed zones so I barely used 1/2 a tank.