Starting with a 40 Foot Silverton hull

Ahoy crew of the Boat Design! I am on a mission to not pay the fuel man.
I found a 40 foot 1989 twin screw Silverton hull. Rudders and trim tabs are still aboard the hull. No engines, shafts or interior, striped. Dirty and a mess inside, the hull is sound and has the potential for my project.

The Plan: DC/SOLAR with a Generator.
The Objective: Design an economical DC system to power this hull at a speed of up to 10 Kts. Average speed looking for fish is 5 to 6 kts. ( these numbers are an estimate on my part, or should I say it is what I would Like for the boat to do.

Battery's, DC motors, and a GEN SET will be installed in a configuration that will provide the same ride as if the boat had 3/4 fuel and two V-8's for power.

24 - D8 deep cycle battery's will power two 50HP variable motors. Two independent systems for redundancy and safety. The generator will allow continual underway charging and direct power if needed. SOLAR charging will be for while dockside.

My Question = Are the numbers I am using close to an accurate assessment of what can be done with the currently available motor's and battery's. Or are there adjustments that I need to make?

I have Pictures of the mess, I mean, the hull, for you brave folks who what to take a stab at this.

Thank You, Captain Rocco

My marine influence: 6 years in the US Coast Guard, BM3 SAR boat Coxswain. After discharge in '86, I moved to Florida and started running Commercial Grouper and Snapper boats in the Gulf of Mexico.
1994 ~USCG Marine safety drill conductor course. Instruction and Procedures for underway emergency's, Mainly for the commercial fishing industry as required by law.

 

If all you need is 6k to fish two 15-20 hp diesels working efficiently would be lowest cost , use the least fuel and have the reliability you need.

Used from a truck reefer co would be a grand each , max, and the boat would be tons lighter , and that much easier to push.

10K would require at least 5X 8X the installed power , so the engines would be very underloaded and dieing rapidly in normal cruise.

Electric boats your size vwill be useful when battery tech takes a 100X jump .

FF

 

I was thinking along those line's if the DC aspect of this equation didn't pan out. Where is my faulty thinking from? Using 24 D-8 size battery's provide enough power?
Using 2 small generator's or one larger for power vs. the battery's, to power the motor..?

I am thinking about it...

 

The losses on charging batteries and then taking out the power, the overall cost, and the complication of maintenance is anything but economic. Those boats have a lot of windage and need power to maneuver. You could install a couple of 50HP diesels and putz around. However you'll never be up on a plane which is the comfortable ride on those boats.

 

Two diesels are what I have decided on. Thanks for the help back to reality.
At an ideal speed of 3 to 5 kts looking for fish and top speed not to much faster, say 8 to 10 kts, with the weight I am going to put into the boat in ice at 3000 pounds, 2 complete engines, 300 to 400 gallons of fuel, 100 fresh water, 6 D8 battery's, stove, ect, a Semi-displacement or deep V is a better platform then a flat bottom. After the engines are in and its back in the water I will do stability testing. She is going to be built by a Fisherman for a Fisherman, right down to the live wells incorporated into the stern with bulkheads built into the hull that allow free flow of water into two tanks. No Pumps to fail. Safety will be incorporated into the build of the boat to make it easy for when I am offshore. The boats construction will be for a single person to be able to run safely. I have yet to put pen to paper as I am doing here. Sort of going with the flow to design and build the perfect fishing boat that I can live on at the dock, fish the north Gulf and take off to the Keys for the winter.

 

"3 to 5 kts looking for fish and top speed not to much faster, say 8 to 10 kts,"

3-5 K will need perhaps 2-20hp engines,

"Not much faster" 8-10k will require close to 10x the power.

Sorry,but the SQ root of the LWL (a guess 36ft , ) would be 6K .

Use 6K as your cruise speed and tit would be cheap to keep, , perhaps 2 -40 hp engines.



FF

 

I looked up 40 hp and 50hp motors, They can get me the speed I am looking for. Most have 3 or 4 cylinder in that HP range. Pricing on two, with gears are well within range. That's what I will end up with when the time come's, Thank You for the nudge.
AC power while offshore I can use SOLAR and an inverter or some combination of power sources to achieve whats needed.

Rocco

 

"AC power while offshore I can use SOLAR and an inverter or some combination of power sources to achieve whats needed."


A good large frame truck Alt belted (dual belts) from one of the engines will be about $135 to $150 for 130A when on sale at the big truck supply store.

These have external regulators , so if you ever get a deep cycle large house batt bank, a sail boat 3 or 4 stage Voltage reg will be an EZ add on.

FF

 

I know a place in Holiday Florida that sells/rebuilds Alternators to those specs.
A 130 AMP twin belted should, and most likely will, be installed on both engines.
I figure that with two systems, 4 D8 deep cycle batteries on each, the chance of both going down is minimal. Voltage regulator(s) will be installed on each alt/system.

There are less issues, problems, stumbling blocks, that I am considering today, then there was a few months ago. Fred, your input is greatly appreciated.

Anyone know of a program that allows you to input the boats dimensions and specs that will allow me to custom design the layout of the boat..? Remember the hull is stripped, including the interior..... Thanks again Rocco