Transducers

[Dulcinea]

I finally got around to installing the ST60 guages I bought a few months ago.  The transducer for the depth guage that came with the instrument is a plastic thru hull that can't be installed to shoot straight down.  They (Airmar) make two alternatives.  The first is one just like I have but also comes in 12 degree and 20 degree models that internally compensate for the dead rise.  That's a P19.  The other one is a bronze long stem contraption that has to mounted in a fairing block that has to be cut to match the dead rise and screwed into the hull.  That's the B45 I believe.  The P19 looks like the much easier install and I would be inclined to go with it.  Any recent experience or thoughts appreciated.  Is one better than the other in terms of performance? Also, I believe the dead rise under the forward settee just aft of the head bulkhead is 20 degrees, am I right on that?
Thanks guys.

[selene]

FWIW, I got lazy.  I left the old transducer in place, and did a internal installation with some PVC tubing I got from Home Depot which I cut to the correct angle and glued to the hull.  The tube is filled with mineral oil, and the transducer sits in that.  The hull is solid, and so the signal from the transducer is unimpaired.

I get a clean signal, and the setup works fine.  I thought of removing the old transducer (which would require drilling it out, removing the old thru-hull, making good, installing new through-hull, etc) when I did my last haulout, but considering the cost and effort, I decided to stay with what I had!

A final thought - before installing, I tried a number of positions with the transducer in a plastic waterfilled bag (as I am sure you know, transducers don't like air pockets!).  Even in that small area (under the stbd fwd cabin locker) there was quite a lot of variation in reception strength.

[Libations Too]

When I replaced my Data Marine instruments with the ST60s, at the recommendation of the yard doing the transducer installation, I used the long-stem transducer with an external fairing block. Everything works fine so, at least for me, that approach has worked. I left the old transducer in place since it was still working and I saw no reason to remove it. Photos are on my website on the projects page.

[Dulcinea]

For what it's worth, closing out this thread, I went with the 20 degree depth transducer (P19) without the external fairing block.  To me it's a cleaner install and the 20 degree xducer matches the dead rise at that spot which is exactly 20 degrees so it shoots straight down.  Thanks to all who weighed in on this. Always helps to learn of others' experiences.