Joe Haubenreich wrote:

Mushroom anchors are useful to keep the back of your boat from swinging
around, but your main anchor attached to your bow should be a type intended
to grip mud, rocks, or gravel bottom. I also use a Danforth anchor, but my
old partner made his own "gripper" anchors from lengths of iron pipe (mine
were house jack sections) filled with concrete and two 18-inch pieces of
rebar inserted through it at right angles. If I were to make my own today,
I'd probably use a piece of aluminum downspout and long steel bolts to
minimize corrosion.

Joe,
Concrete and Aluminum really don't mix well. There is a reaction between
the two that corrodes the aluminum and weakens the concrete.

pat