[Gerry Zagorski]

I've always used the blue and white bottle as well and like you I have mixed results... I've never used regular bottom paint because I was told it could interfear with the ducers performance. I just hit the bottom of the ducer with a 3m pad once and a while to keep it clean.

If your ducer is shot you might consider going with shoot through one... Not, through hull, but shoot through hull. It mounts inside the hull so it does not get fouled. You can mount it to the hull in a bed of chaulk. Just make sure you try and get any air bubles out between the ducer and your hull. You also need to make sure the area you mount it in is solid fiberglass and not cored. Coring is not as dense as fiberglass so it can hinder the performance of the ducer.