Pete,

I noticed a distinct dearth of replies to your question.

Of the more than a few rudders and have never made a strip
planked one.

There is no reason why you could not, but there are some
considerations that you should think through.

A rudder must contain structure to secure it to the
shank/shaft with complete confidence as anything less will
be a serious problem at some inopportune point.

Most rudders live their entire lives submerged (and you are
thinking - so does the hull), but unlike the hull they have
a required breach where the shank enters the structure
and/or is fastened. Treating this breach like a
through-hull fitting is not applicable as there will be
forces and loads present that are much different than a
static fitting.

With any possible breach, the core (be it wood or foam) will
absorb water.

So, If you have a plan that can make it work, go for it.
That fact that it hasn’t been dome before is not a reason.

By the by - a foam rudder as you are calling it gets little
or none of its strength from the foam. The foam is just
there to a: either be a form for the laminate to build on or
b: something to keep the rudder from completely filling with
water.

Best of Luck

Matt Colie a Lifelong Waterman, Licensed Mariner and
Congenital Sailor

pete wrote:
Well its time to make my rudder, for a tiller steered 34 foot Van de
Stadt. Now Van de Stadt have given me a nice drawing showing three
types of construction:

wood strips with a gap of around 1 3/4" between the strips, filled
with polyurethane foam, and covered with a plywood skin.

Solid plywood panels glued together and shaped

foam with a epoxy and glass fibre skin.

any of the above seems ok (apart from perhaps the plywood one may be a
bit heavy?)

but is it possible ( perhaps the stupid question) to make a rudder the
salme way as my hull ie; western red cedar strips laminated with a
fibreglass and epoxy skin? Its seems pretty tough now my hull is made
and for me it may be easier to make and fit on my rudder stock. It
seems to me it would be at least as strong as a foam rudder, and
almost as light.

BTW, the first construction method doesn't make the rudder shaft
manufactureres (Jefa) squeal with joy.