Design Contest #6 - Entry 1 click here to read or make an observation about this  article
By David Becker - Eugene, Oregon - USA


Drawings - Statistics - Description - Budget - Bio


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LOA: 18’
Beam: 6’
Beam Main Hull: 2’
Beam Outrigger Hull: 1’
Draft: 6”

Main Hull: 800 LB
Outrigger: 350 LB
Total: 1150 LB

Headroom: 3’2”
Displacement Hull Speed: 5.6 KT.
D/L limited Speed: 9.37 KT
Prismatic Coeff: .68
Motor Capacity: 7.5 HP but 2.5HP recommended
Fuel: 6 Gallon tank strapped to the platform deck for ventilation


After a trip to the San Juan Islands this past summer, remembering how I had to deal with an old and cranky tow vehicle and having to step the mast and rig my 25ft sailboat, with 4800lb displacement a tow weight of 7000 lb. and a fixed keel with 4ft. draft, I started to think that there had to be an easier way to do this. After much thought and consideration, Sideboat was born.

Sideboat is an 18ft. Proa that is propelled with a single sculling sweep and an outboard motor, to power against the strong tide of the Puget Sound. You might say that the Sideboat is a kayak with its own dock, an outrigger or “Ama” for stability and outboard for auxiliary power.

My own experience in sailing in the Puget Sound is that the tide dictates when and where you go in a small sailboat. With very little wind in the summer, it is extremely difficult to use just sails for propulsion while cruising in the Puget Sound. About 80% of the time you must rely on auxiliary power. It’s great when you do get to sail, but you are paying a price for this in time to rig up the boat and the cost of the sails and rigging. If you forget about sailing, things get a lot simpler and cheaper.

Another choice in exploring without the hassle would be a sea kayak; however, I feel that I do not have the skills necessary to tour the Puget Sound in a sea kayak. Additionally, finding a place to camp, as well as setting up camp each night can be a problem. If you are on a boat, it is a lot easier to just drop the hook in some quit cove.

The main hull has sleeping quarters and a cabin for protection from the elements. A portable head is stored under the rear deck and there is storage for gear in the bow. The outrigger is used to store food, 1 gallon jugs of water and other supplies. The platform between the hulls is used for sculling the boat, relaxing in the sun, and cooking on a camp stove or BBQ. Dry bag storage is also always an option. A folding chair is also nice to sit on. There is enough room to carry a sea kayak and use Sideboat as a mother ship is another possibility. Sideboat could be pulled up on a beach, with the aide of large PVC pipe rollers and a block and tackle. One feature I especially enjoy is that the Sideboat can take to the ground at low tide on tide flats, where most other boats cannot venture.

The motor is mounted on the main hull, as far to starboard as possible, to counterbalance the outrigger hull. It might have to be turned a little to starboard. If this did not work, toe in the outrigger a little. More testing with a scale model or sea trials would be necessary. The motor could be mounted on the platform, but I do have a concern with the propeller coming out of the water in rough conditions.

The overall beam is kept to 6ft, so the boat will fit between the wheels of an 8ft wide trailer. An added plus is that the boat and trailer weight would be light, so a large tow vehicle would not be required.

Sideboat would be propelled with a sculling sweep, placed over the rear of the platform, while drifting with the tide or in slack water. This would be a quiet way of propelling a boat for viewing wildlife. When the current is too strong to scull against, you would use the outboard to go against the tide or when you are running out of time and need to get to an anchorage before dark. I like to scull, it takes very little effort to move my 4800lb. sailboat at about 2 knots; the biggest problem, however, is explaining to those not familiar with sculling, what the large paddle is used for. The sculling sweep is a curved oar positioned over the stern. It is pushed and pulled in such a way as to cause the blade to feather the precise amount for optimum thrust. A short handle, projecting at 90 degrees to the loom, at the inboard end, is used to control the feather of the blade as you sweep it from side to side. The blade and loom are thin enough to be somewhat flexible, so waggling it from side to side causes it to flick like a fish tail.

I did not design Sideboat to be a planning hull. I would try to keep the HP as low as possible, if Sideboat could make 5 or 6 knots under power that would be ideal. More speed would be terrific, but the expense would be higher for a bigger outboard along with higher fuel costs. I would try my 2.5 HP that drives my Montgomery 15 to 5 knots with no problem, which is about the same displacement as the Sideboat. Again, sea trials will be needed to verify speed.

If nothing else, Sideboat would make a great conversation piece or a good swimming platform.


Plywood: 10 sheets 3/8 Exterior plywood

Chimes & Stringers: 10 2’x4’x 8’ to be ripped into 1 ½” x 1 ¼” 200’ total


Cross Beams: 4 2’x8’x8’


Hand rails & Moorage Cleats: Made from scrap left over Plexiglas for windows: 8 square ft. of 1/8”

Anchor & Rode:
Mooring lines:
Anchor Light:
Depth Finder:
VWF Radio:
Power Supply:(See SCA May/June 2005)
Folding chair:
Outboard Motor: 5HP outboard
Total cost:


My first choice of material to build Sideboat would be aluminum, but that would go well beyond the $2500. To test out this design, I would first build a scale model using the “quick-cheap-and dirty but instant” method – where the construction would be made with exterior plywood, lumberyard wood for chimes, stringers 2x8 for cross beams, galvanize nails for fasteners, Weldwood Plastic Resin glue and scrap wood for mooring cleats and hand rails, and basic exterior Latex paint. Food could be purchase at local grocery store. Head, anchor, mooring lines, anchor light, depth finder, VHF radio, GPS, power supply and outboard motor prices are from West Marine catalog. Lumber prices are from local lumberyard.

Beer: ONE 6 pack to be use in the following manner: first beer cracked at the start of project, second beer opened at launch of boat, third beer guzzled at the start of cruise, fourth beer downed at end of cruise, fifth beer slammed at time of dumping boat – whether by selling, giving away, sinking, burning or blowing up, and the final beer sipped at the start of the next boat building project


I am a retired Railroad Engineer, with a terminal case boat obsession – from building to sailing. I own a 1976 Bahama 25, which I have rebuilt, designing and building a new interior, deck and cabin. Other boats that I have built include, Philip Bolger light dory, Recovery Skin-On -Frame kayak, a cradle boat for my granddaughter, and I am presently working on a new cradle boat for my next grandchild. I also own a Necky sea kayak and a Montgomery 15.

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