I got a cheapo depth finder from norcross d10d and tried to use it (with no hole) and I thought I'd share what I learned. I spent WAY too much time fiddlin with it, but I did learn a lot, even about the electronics. 1) I tried hard to just make a super smooth mount and put a dam around it and put in in with water. It worked intermittently for about a year. I'd say it worked about 90% of the time at first and then got worse and worse meh... 2) I tried to make it work better and epoxied it down. Results were it was a little better, but within a year it still got worse and worse until it only worked about 10%of the time3) I got out the big guns (a digital oscilloscope) and made a test rig I could go out with to see how it worked. Basically they are a 200khz speaker that can take a 100-200 volt signal and then they try and use the same speaker to see the tiny millivolt or evenmicrovolt response. I really couldn't even see the response with the oscilloscope because of some technical issues with the scope. and had to get 1000:1 probes to even see it.4) I ripped out the epoxied down one, I just got a totally different transducer (not the same brand) and made an adapter and it worked again. Basically I believe the transducer was "worn out" like an old speaker. I made an RCA jack to be easy to replace the transducer. 5) I made a totally different mount with a 4" threaded PVC pipe about 3" long and epoxied it down and put the transducer against the hull, but put a spring in with a pipe cap that I could thread down and the spring held the tranducer against the hull with light pressure. I then fill it with water. The pipe cap keeps the water from splashing out, but there is a little hole on top for the wire to come out. That works 100% of the time for the last year. Pretty big improvement and better thanwhen it was new. We will see over time. I bought a few extra transducers for only $15 a piece on eBay, so perhaps I have a lifetime supply now. Conclusions:Transducers wear out. I would be very wary of putting a hole thru the boat. (actually the whole point of the depth transducer is to AVOID putting holes in your boat...from rocks) Furthermore I think epoxying it down isn't much help regardless of what the manufacturer says, and if it doesn't work, you'll be to blame for "incorrect installation". I think just the spring is better than epoxy and it's a few minutes to replace. Anyway, that's my 2 cents. Hope it helps somebody sometime. If we don't halt population growth with justice and compassion, it will be done for us by nature, brutally and without pity - and will leave a ravaged world. Nobel Laureate Dr. Henry W. Kendall On Tuesday, April 2, 2019, 12:38:44 PM PDT, Thomas Buzzi <thomaspbuzzi@gmail.com> wrote: I have a thru hull set in by the keel housing. It is for a depth finder transducer. The unit also had a chart headsup too. VERY handy when you are cruising new waters. The depth reader is when you sail in murky water with hard bottom such as rocks. Monty 17's will sink if holed and you can't stop the ingress of the water. I looked into positive foam flotation and the amount necessary would make the boat uninhabitable. Tom B On Mon, Apr 1, 2019 at 7:37 PM Gerry Lempicki via montgomery_boats < montgomery_boats@mailman.xmission.com> wrote:
As I am stripping paint off this M17, I found a couple through hull holes that have been fiberglassed over and look to be done well. They were up front, so maybe were for depth instruments in the past. In the rear, about 6" forward of the transom, there is a through hull still there. It is capped with pipe plug fittings inside. I don't like the looks of some previous fiberglass work around it, so I am going to remove it and properly repair it. But this made me curious; what would it have been used for on an M17? It's not like one needs cooling water. Do any of you have through hulls in the bottom of a small boat?