Get Home Power (emergency power)

In a recent discussion on Passagemaking Under Power, the subject of "Get Home Power" came up

The response was interesting:

We had looked at using a traction kite several years back on Swan Song. I had several emails, calls and proposals from a couple of companies interested in the project but when push came to shove nothing developed that could be purchased then.

There have been many kite advances in the past few years and I think that a kite is a very viable aux power system for a passagemaker. Both as a "get home" and fuel saver on long passages. Significant power can be developed with a traction ( as opposed to a sport kite) kite in the off wind passages that most of us favor. I for one really don't like slogging into head seas/winds for days on end even tho our recent Mexico-Hawaii passage had two full days of this. Beam and aft wind/seas are much preferable. Most passagemaking, as opposed to delivery passage planning, should focus on making major runs with the wind/sea aft of beam. This blends into the strength of the kite.

Kites can offer power from 110 degrees off the wind. This translates into a usable arc of ~140 degrees. All but 500 miles of our recent 2700 km passage, for example, would fit in this wind angle.

A kite with a nominal pull of 20-25 HP would have given us a ~ 4 kt speed under kite alone or decreased our fuel consumption by about half. So we'd have a "range extender" and Swan Song would have an 8000 km range vs. the 4000 miles we have based on the MX-HI trip. A significant advantage, IMHO.

How big a kite to do generate this pull? That is very dependant on the design. Spinnaker type kites are large but inexpensive and have several disadvantages mostly becoming a drogue :-( Rigid wing kites are much easier to fly, can be water launched and recovered from the water easily. They are controlled from a single control point with two or three lines. There are designs range from self inflating (not good for us). to ones with battens to those that are inflated with pressure for shape (best for us, I think). All of the rigid wings develop more power than the early spinnaker designs for a given size. Size and design is important in launching from a deck as we don't want to intentionally launch from the water nor have an unruly web of fabric/lines looking for a place to self destruct.

Launching from a foredeck pylon, aka a small mast, could be easy and once launched the kite flies from just above deck level to what ever altitude you desire. The higher it is the more wind there is thereby the more available power. Parked over head they develop no power. As you pull the control lines they move forward of the boat and generate incredible power. Easing the trim and they depower instantly. Using the trim to move them from side to side increase the average power even more.

Sitting a kite surfer of the foredeck in a chair strapped down to the deck with a seatbelt should be a good seat of the pants test as how one of these work and could be adapted to a passagemaker.

This certainly would be far cheaper than a wing engine, I couldn't see more than $15K for the whole system, and it would not have the issues of space and additional fuel consumption of twins.

I suspect we'll see someone doing this in the not to distant future...perhaps Patrick and his avid kite boarder friend can try it out and send us a picture with some data. Pulling around a Willard 40 in La Paz would be in the least a good tourist attraction and perhaps even a fun YouTube video ;-)