Placement of shoot thru hull tranducer on O'Day 25 swing keel

[Mike Whalen]

Greetings, S/O gave me a Unidine depth finder for B-day. I have a 25' with swing keel. Seems like I'd seen it suggested before that the transducer be placed just forward of the stub keel. Anybody else have any thoughts on the matter? This thing has a swivel base. Based gets glued to the floor. Transducer slips into a ring and is attached to the ring by a couple of screws. The the ring locks into the base which swivels to, as I understand it, make up for the slope in the hull. Anyone using one of these? I don't read enginering even of the most basic sort. It makes my head hurt.

Thanks,
Mike

 

[sailormanbigd]

od 25 transducer

i have an od 25 shoal draft swing keel as well. 1975. On my boat there is no place to put it forward of the keel. The bilge only goes to the compression post, then there is floor above the bottom of the hull. I would mount it down inside the cavern under the cockpit. I would think that you want to offset it to one side or the other of the keel to get it in "undesturbed water. The thru hulls that i am familiar with don't use any bracket or swivel. You need to be sure its a "thru hull" transducer. It sounds more like you have a transom mount, and in that case you position it away from the swing of the rudder and below the water line angled straight down or ever so slightly forward of straight down. On the thru hull transducers you can +temporarily use silicone caulk and stick it down to hull. The deal is you use a big blob of caulk and just squish the transducer in it to remove air bubbles. Its a temporary mount because any thing that rolls into it or bumps it can break it loose. People usually glass or epoxy a short piece of pvc tube to the hull and then mount it inside the tube with something more permanent. the goal is to not have any air between the bottom of the transducer and the hull, and to have the transducer aimed straight down. Patrick

 

[Shoaldrafter]

Re: od 25 transducer

Mike,

I suggest placement as forward as possible rather than under cockpit. Also just latteral of midline as to be away from Keel. The reasons are turbulence created by keel which could affect reading. However, most boats that I have seen mount the transducer aft and near midline. So that must work. I just would not want to try to shoot thru keel.

On the O'Day 26 it is possible to mount the transducer just inside V-beth and about 18 inches lateral of centerline. On my boat there is a way to feed wire to bilge then under seatees and then under cockpit.

The transducer should be mounted in such a way that it shoots straight down. In this matter I am not conviced that having some air space on one side is as much a issue as having transducer shoot exactly straight down.

The instuctions for each transducer usually show pictures or diagrams of best position. Remember if boat is out of water that hull level is not the same as in water.

Ed K
26

Other boats have tanks, plumbing, other wirering or bulkheads and fiberglass in way.

 

[Mike Whalen]

Re: od 25 transducer

No its thru hull. Seems like THEY have come up with the mounting piece INSTEAD of the PVC. The swiivel lets you adjust for the angle in the floor where you mount it. It is basically a thinner version of PVC with a larger flattened ring at the bottom to allow it to be glued to the floor. Its been a LONG time since I got under the Vberth in the bow. Iwas thinking there was access to the hull there. I may be wrong. We'll find out. If I can get the cable from there to the bilge then I can just follow the line from the bilge to the pump in the lazerett to get to the guage.