Inspiration

My wife and I loved kayaking, but as we got older it became less enticing to go out on a weekly basis. Sailing seems ideal at a distance, but in reality is a lot of work and maintenance. Hobie catamarans looked like a lot of fun, but my wife was pretty clear on her aversion to capsizing. My first boat was made from the hulls from a Hobie catamaran. I removed their hardware and made a stainless steel frame to connect them together and provide a floor.

The first motor was a trolling motor powered by 2 lead acid marine batteries.

We quickly found out that trolling motors are, oddly, only for trolling.

I upgraded to an electric outboard of my own design. It was essentially an 11  hp golf cart motor that drove the propeller via a cogged belt. The housing was a block of aluminum machined cut on my cnc milling machine.

Belt Driven Motor 

It was powered by 4 LiFePo4 Lithium 100 ampere/hour batteries. This was great for a calm river. We could cruise all day at 4 –5 knots with a maximum of about 8 knots. Its footprint was 20ft OAL (overall length) by an 8 ft beam (width).

The one problem with this motor was that the belt was enclosed in a tight space and the normal dust from a rubber belt built up and caused a failure. I made an improved version of the original motor using a Johnson lower end for the 2018 model.

Current Outboard and backup 

 

Evolution

We tried this in Long Island Sound, and it was obvious after the first waves, we discovered that, as they said in Jaws, ”we’re going to need a bigger boat.”  The problem with a bigger boat is that the maximum you can trailer without an escort is 102 inches. Winter storage is very expensive.

The boat in 2016

The 2016 boat will go from a 7 ft beam to 12 ft beam. You need a proportional length for that wide a boat. I added hull sections so that the OAL would go from 20 ft length to 33 ft. The 2018 boat goes from a trailer size of 7 ft by 20 ft to 14 ft by 37 ft on the water.

2018 Boat (v2.0) loaded on trailer

This is a very stable boat. The Hobie had dagger boards through the hull. Dagger boards are used to assist in making the boat more maneuverable and track in a straight line. The problem with a rigid board is that it’s unforgiving when (not if) you hit something. I mounted the dagger boards on a shaft so that they are spring loaded down and will be pushed back by rocks. A hydraulic cylinder lifts them up.

The design of this boat is a bit more elegant than the first model. It has a floor space that is 8 x 10ft. There are 4 plush upholstered chairs, a table in the middle and 2 marine coolers for storage or additional seats.

There is a nicely shaped, stylish console with 3 cabinets and 4 drawers.

It has a full array of instruments, controls, computer and monitor built in to the console that is visible in full sunlight (2000 knits). The console hinges forward revealing the 8 lithium batteries (2 banks) and the hydraulic pump and controls, sealing this compartment when it is set upright. The steering is and outboard lift is hydraulic.

I made a “Boat Float” out of eight 55 gal drums to keep growth off the hulls. I use a pool motor to pump water in and out of the barrels. Evacuation time is about 8 minutes

Boat raised out of water on float

 

The boat in 2017. There are nine 100 watt solar panels on top of a foldable Bimini top.

 

Rear view 2018 boat

I had originally tried the panels in front about a foot off the water, but unfortunately we had a very dramatic example of how heavy a 2 foot wave can be. It bent the panel supports and pushed it under water so that we could only travel backwards. For the current model I made my own bimini top structured to hold twelve 100 watt solar panels on top with fabric that snaps on underneath.

Front view 2018 boat

 

Cruising

We retract the main hulls and raise the rear ones when coming into our slip. This makes navigation easier, (the waterway isn’t as wide as it looks when you have a current and a wide boat). It also allows us to rent a more economical slip. Cruising is quiet, stable and peaceful (if the swells are less than 1ft). Our favorite area is the Thimble Islands. We go out on one bank of batteries with the solar panels assisting and return on the other.

There is plenty of power to be out all day. The excess comes in handy if the weather changes and you want to get back in a hurry. When at our destination we can cruise at 2 to 4 knots with just solar power depending on the time of day and year. Overall we go faster than the average sail boat without the work.

 

Performance

Technical information 2018 model:

• OAL – 37 ft extended – 21 ft fully contracted

• Beam – 14 ft extended – 7 ft fully contracted

• Weight – 2250 lbs

• Draft – 12 inches

• Motor – Motenergy ME1004 – 10.75 hp at 48 volt.

I run at 25 volt which produces about 6 hp

Batteries – 8 Lithium 12.6 volt LiFePo4 100 ampere hour

• These are run in serial/parallel for 25.2 volts

• 200 ampere hours per bank

PVC (solar panels)

• twelve 100 watt panels (at equator)

• In Connecticut they will output 80 watts at noon in July

• Max total –960 watts – approx 4 knots

Modes:

• Charge Bank 1

• Charge Bank 2

• Power Motor

Speed Data (approximate readings):

• 2 knots – 15 amps – 500 watts – 1/2 hp

• 3 knots – 20 amps – 500 watts – 2/3 hp

• 4 knots – 40 amps – 1000 watts – 1 1/3 hp

• 5 knots – 60 amps – 1500 watts – 2 hp

• 6 knots – 100 amps – 2500 watts –3 1/3 hp

• 7 knots – 160 amps – 4000 watts – 5 1/3 hp

• 8 knots – 250 amps – 6250 watts – 8 1/3 hp

Approximate Cruising Time without solar panels:

• 16 hours at 3 knots

• 8 hours at 4 knots

• 5 hours at 5 knots

Construction

I made a negative mould of one of the Hobie hulls. I then made a positive midsection that was 10 ft in length followed by the negative mould.

Beginning of plug with wood and screening

Plug coated with setting type plaster compound

 

Finished plug waxed with release agent- ready to cast negative mould 

I cast all these pieces individually. The reason for this is laying up fiberglass mat by hand is very labor intensive, as well as intoxicating. You will get a lighter hull if you can lay-up everything at once. A 20 ft section with 6 layers of mat would be difficult to do in the working time you have before the resin sets. After casting the actual hulls, I bolted and laminated the midsection and the rear section of the Hobie hull together. This gave me a main hull of 20 ft OAL. I attached the front Hobie hull with a hinge, and it is manually raised and lowered and bolted down into place. I made an additional 4 ft rear hull that is raised and lowered by hydraulic cylinders.

Stainless frame 

Battery box 

Raw hulls 

Raw console