Donzi 29 ZF Transducer Question

[Mullet Slayer]

Just installed a high speed transducer on my boat. It will not lock on after about 10MPH. Anyone have any experience as to whether they work on Donzis?? Wondering if the air is causing a problem at high speed?

[DonziJosh]

Where did you install it and what did you use? There are a lot of variables here. We've had success with the Airmar P79 (and similar shoot-through-the-hull transducers) and the big Airmar M260 unit works even better. The most important consideration on stepped hull boats is that the transducer must be mounted just forward of the front step, clear from the aerated water that the steps produce. On a 29 ZF, the best access to this area will be the closeout panels inside the console. Positioned properly, it should read ok up to around the 40-45 mph range and perhaps on up to 50 or so. If you've mounted it aft, the turbulence from the steps will prevent the unit from reading at planing speeds, period. All the other rules apply, such as making sure you're shooting through solid fiberglass and that there are no air bubbles in your epoxy (quick-cure epoxy is a killer) but rule #1 for stepped bottom boats is location! Regardless, you should be aware that even with the perfect setup you may not get a very good reading at WOT, simply because your mounting location may be aired out at top speed - especially in rough waters.

[Mullet Slayer]

What some good advice!
We used an Airmar M260but it's mounted adjacent to the battery.
Thanks so much.
If we move it to where you are describing, if we shoot it through a plastic bag of water, will that allow us to move it around until we find where it best performs?
Sure do like my boat!

[DonziJosh]

That's what I'd do. Obviously at idle speeds it'll read fine from just about anywhere, but it might take a few runs while on plane to figure out the sweet spot. The 29 ZF has gotten a few different consoles over the years; there will be an inspection plate in the bottom of the console liner but it is most likely not large enough to slip the M260 through. Still, once you've removed one of the closeout panels you should be able to use the inspection plate access to move the transducer around a bit. It's a solid bottom, not cored, so the only potential obstruction should be the mounting block, maybe 6" x 6", where the fwd bilge pump is located.

I put the M260 in a 23 ZF and didn't have room to use that big plastic mounting tank, so I stuck the unit right to the hull without it. Worked fine to near 50 MPH. Obviously it's going to be a bit less accurate without the angle-correction the tank gives you, (but this wasn't a factory job and it was an acceptable tradeoff).

The 29 ZF is a great boat, and handles like a sports car. Hope you get a lot of enjoyment out of it!

Josh

[Mullet Slayer]

Sorry it's taken so long to reply.
I haven't had the chance to use it yet but my son and the installer from the shop took it out and tried it where you suggested using it over some water in a pastic bag. Appears to pick up MUCH better. Purchased a new mounting box and installed it. Will be able to use it Sat. and see how it works. I believe the guidance you gave us worked wonders! Will report after Saturday.
Thanks.
Really like the boat! Twin 250 Verados.