|
Hi Alan.Good photos. The use of a bicycle innertube is a good idea as it
will expand and is easily replaced.
Might be a little thin though. The power steering boots I'm using are
pretty strong at about 3/16 inch thick.
I had originally planned on using a plastic tube bladder that
could collapse as the oil was drained away, like has been proposed for the
Minnkota motors for compensation but the actuators move more oil in/out than the
motors would, so I went with a larger bladder.
As for depth, well, it's true that the pressure is equalized. That's the
whole purpose of "oil compensation". But it just seems that a more "robust"
system like high pressure hydraulics would be more likely to withstand the
rigors of deep diving.
I really went with the electric actuator method because I liked the idea of
using electrical thru-hulls ( only takes one) over a supply/return hydraulic
system where two thru-hulls are needed. OK provided I can get it sealed
up.
That, and the fact that an electric pump and all the related plumbing and
pressurized oil reservoir of a HP hydraulic system makes the system more
complicated ( high maintenance) and expensive to build and
maintain/replace.
For "position sensing" I wonder if it's possible to add a magnet to the
stroke some where and then put a series of sealed magnetic switches next to it
to sense position. One problem I foresee would be the number of wires
needed to get the signal from several positions. The wires would be quite small
but a multi prong thru-hull can get pretty complicated.
Seems like it would be better to just shell out the money for the MinnKota
actuators and use the "off-the-shelf" rocker switch with the led graph. The
Lenco actuators can be had on Ebay and they too have an LED thing to show
position. Again, the wiring is a six wire cable making the thru-hull more
complicated.
I've been leaning toward adding another pair of windows to the sub on the
sides so the dive planes would be visible. My current window design needs some
additional work to reach my intended depth so when I fix that problem I will be
adding the other two windows also. Always better to have good visibility. For
now though, I'm still trying to get her ready for the July convention so any big
changes will have to wait for next year.
I made a quick sketch of the CV joint bladder. It fits in the little space
between the hull and ballast tank and if it works will be easily maintained.
Once all these components are fabricated I'll pressure test them in a bench-top
chamber to see what problems pop up.
Frank D.
|