I had to install a round transducer with 20 degrees angle on a hull with deadrise of much more than that. In this situation, when having a round transducer, a fairing block, as suggested in this video, is not needed. Instead, all you need to do is rotate your mobile phone slightly making it point away from the keel (while keeping the phone firmly against the hull), this will lower the deadrise angle reading. Instead of pointing the arrow on the transducer towards the keel you must point it slightly away under the same angle as you had to rotate your mobile phone to lower the measured deadrise angle. Of course this method also works to perfectly match the transducer angle with the hull, even if you would otherwise be somewhere in the allowed range. Please note that you can only LOWER the measured deadrise angle; so in order to get the perfect angle, the transducer angle must be lower than the maximum hull angle.
