I have a SailRite LSZ-1 UltraFeed. This is a walking foot zigzag machine.

It is heavy and can handle very thick canvas and sail material..
The main drawback with this machine is the lack of room under the arm.

In general you can get buy with a lesser machine and one without the walking
foot feature.. I have in the past.. The real advantage of the walking foot
is better control of both upper and lower layers of the material.. With a
standard machine, with only lower feed dogs, the material on the bottom
tends to feed slightly faster that the top, so you have to manually
compensate for this. (been there done that).

It is true that you can find commercial machines, cheap that are walking
foot, but it is rare and expensive for a walking foot zigzag machine.

I would also say that zigzag is most important to sail making while canvas
work can be done with straight stitch alone (especially if your using
syntetics and use a hot knife for cutting and sealing the edges).

Sail Rite is a well established mail order company.. Family owned and when
you call you can be assured you will get very good information and
attentions from one of these family members. I have never had any complaint
with their products, material or service.

Sail Rite has a facility to computer design and cut sails for you and
deliver them all match marked so you just sew them together and finish the
the edges, etc.

They have instructional videos for most sail and canvas projects.

Prices of for raw materials are slightly higher but often you won't mind
since someone will be talking your through you project and make sure you get
the right stuff.

Enough Said.

Steve
s/v Good Intentions