Convert a Hobie Cat From Sail to Power (Cheap Pontoon Boat)




About: four tires and wheel? you've got yourself a deal

This instructable will explain how to create a device to attach a small outboard motor to a Hobie 16 and turn it into a very fun cheap cruising boat...

Step 1: Philosophy

Sailing is a great art. Many people see no other way to enjoy the water. The Hobie cat 16 catamaran is a great intermediate sailboat that can be a blast. I have sailed my Hobie several times and I just wasn't having too much fun; I knew what the problem was: it just wouldn't go any old direction you point it. I knew I had to do something, so I set out to convert it to a motor vessel.

Step 2: Get Started

Obviously you will need a hobie cat for this project, craigslist is a great place to find cheap ones, try to find one that is missing sailing implements but has solid hulls (brings down cost) You should spend under $500 with trailer

The first thing I did was think, how would I get a "transom" on a catamaran, the rear crossmember of the cat looks like a good place to start. Basically what the motor mount is is six pieces of steel shaped like the number 4. The mount is bolted through the rear crossmember and the motor clamps onto the rear side of it.

After you have decided what motor you're going to use (I highly recommend the honda 2.3hp outboard, very reliable) It's time to make the mount.

The mount is mainly made of 12 guage 1 3/4"x1 3/4" square mild steel tubing and the end plates that the bolts go through are 1/4" steel plate ("borrowed" from a mower deck). The transom is 3/16" steel plate.

Other ingredients include

2x 1/2"x6" zinc plated bolts

2x 1/2" lock nuts

2x 1/2" wood screws

some scrap wood

2x 175lbs carebiners and some paracord (safety chain)

Once you have collected these materials, you are ready to make the mount

Step 3: Put Things Together

1. Remove the current steering stuff from the hobie cat along with any other sailing implements. (save these in case you want to sail it again someday as this process is easily reversible by removing the mount)

2. Cut your steel to the measurements in the plans, be sure the transom plate that you cut out is plenty wide for your outboard's clamp width. I cut my tubing with an abrasive chopsaw and my plate with a grinder with cutting disc. You may need to lengthen the bottom tube if your motor controls are longer. Be sure to angle the back edge of the bottom tube so the transom plate sits at an angle like in the pictures. IT IS ESPECIALLY IMPORTANT THAT THE DISTANCE BETWEEN THE TWO PLATES IS 2 7/8" otherwise it will be difficult to attach the mount

3. Drill two 1/2" holes in each plate on the hobie side of the mount. (I recommend using bits that aren't gold in color, the gold ones dull quickly.)

4. Drill two small holes in the transom plate for the screws to go through, does not matter where on the plate

5. Cut a piece of your scrap wood (not thicker than 1") the exact shape of the transom plate, except that is must have a channel cut in it to fit around the bottom tube

6. Weld the steel pieces together in the shape in the pictures (If you do not want to or can't weld, you will need to take yours parts to a weld shop to put it together for you.) Understand that this is not a good project to learn how to weld because it could cost you your outboard.

6 1/2. Test your mount by clamping it to a strong table and pushing hard on the transom plate (I sat on mine, don't recommend it), if it holds, you're in good shape

7. Take about two feet of the paracord and tie each end to a carebiner.

8. I highly recommend painting your mount to rust-proof it, 3 or 4 coats of any rustoleum will work fine. I did a metallic blue that I had lying around, but I think the color went well with the blue trampoline of the catamaran

Step 4: Attach Motor and Mount to Hobie Cat

After the paint is very dry, we are just about ready to get cruising. Screw the scrap wood onto the transom plate with the short screws, this wood's function is to facilitate better clamping pressure so the motor clamps do not loosen; it also protects the transom plate. Take your mount and put in over the rear crossmember and mark two holes through the ones already drilled through the plate, then drill these holes through the crossmember and repeat for the underside. Then place the two bolts through the holes (should be a total of four holes for each bolt to go through. You'll probably have to hammer them through because its difficult to line up the holes perfectly.

Once the mount is on and the nuts are tightened, connect one carebiner from the safety harness to shackle on the outboard and the other end to main sheet block eyelet on the catamaran.

Since I used a honda 2.3hp outboard, the fuel tank is inside the motor cowling, if your outboard needs an external fuel tank, I would recommend strapping it to the trampoline of the catamaran.

Step 5: Get Cruising and Performance Video

Now launch your "new" converted hobie cat pontoon boat after you have fueled it up and have some fun!

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    10 Discussions


    Question 11 months ago on Introduction

    Have you noticed how fast you can go without creating a wake? I’m in a 3 mile long no wake harbor with a 3mph current and am looking for a craft that can go 10mph without creating a wake. There are rowing crew coach boats with 20’ pontoons which look like Hobie pontoons. Might this work?


    2 years ago

    I love this! I am so glad to see that some one else who would put an engine on one. I want to make a solar/ electric one though

    Mark 42

    2 years ago

    I was thinking of doing a similar project with a discarded catamaran hulls set - but using a bicycle frame & pedals for the drive unit


    2 years ago

    Looks good, but using a 2.3HP motor should push you along a little faster than the video shows... looks like you are topping out your RPM's before you reach your max HP... Try a prop with more pitch (if available)...

    1 reply

    Reply 2 years ago

    it looks that way because I don't have the throttle wide open in the video, but trust me it's no speed demon


    2 years ago

    Very very nice.

    I would rather use laminated wood beams for platform structure matching the wood pontoons. But to each his own.

    Still, your project is quite sanitary.


    2 years ago

    Awesome!!! I too had this idea for a while but, have yet to find a hobie cat to execute it. My question would be could you deck it and then put 2 to 4 people on it and expect it to float?

    2 replies

    Reply 2 years ago

    Also keep in mind before removing the mast, boom, and rigging, that weight was part of the standard equipment. Putting a little outboard on like that is likely a lighter setup, not heavier. If you are going to deck it, lighter is better.

    I was thinking of doing this, but putting the outboard in the middle so it wouldn't cavitate or dunk in rough waters. But then you'd still need to use some parts of the rudder system or something similar to steer.

    Nice work though :)


    Reply 2 years ago

    Thanks for reminding me! I forgot to mention performance notes, I have had 700 lbs of people and chairs on it and only the rear part of the pontoon sank about 3-4 inches. I was very surprised by the flotation of the pontoons and by how well the honda pushed the weight along!


    2 years ago