Sonihull Installation

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    Bill Robertson

    I recently completed installation of a PYI Sonihull Duo Ultrasonic Antifouling system on Remedy.  This system is advertised as a DIY project which I would say is accurate for most owners.  The installation instructions are pretty straight forward, however, they left out a couple pieces of information that might have saved some time and aggravation.   The system consists of a control box and 2 ultrasonic transducers.  The transducers must be mounted to in the inside of the hull.  The transducers screw into mounting collars that are glued to the deck with epoxy, provided with the unit.  Once the epoxy has cured, the transducer surfaces are coated with about a mm of Vaseline (also provided) and screwed into place.  There is a warning in the instructions not to over-tighten the transducers to avoid breaking the epoxy loose.

    Now for the information they didn’t include.  The mounting collars are made of molded plastic and the mounting surface of the collar is fairly smooth.  After the first attempt to install the first transducers failed, because the epoxy broke loose, I contact PYI customer service.  They said we should rough up the mounting collar sealing surface to help the epoxy adhere to the collar.  In hind site I probably should have recognized this on my own and roughed up the surface in the first place.

    The second piece of information was not quite as obvious.  When the transducer is screwed down into the collar it creates some hydraulic pressure due to the layer of Vaseline, that is applied.  The hydraulic pressure is what makes the epoxy break loose.  The epoxy sticks fine to the hull but not the collar.  PYI customer service suggested we drill a small hole through the collar beginning at the bottom screw thread that would allow any excess Vaseline to ooze out and thus eliminate the hydraulic pressure.  Sure enough, it worked like a charm.  Even though I tried to minimize the amount of Vaseline applied the excess oozed out of the hole just as described.

    I’m not sure why PYI doesn’t include this info in the installation instructions and if it’s really needed, why they don’t predrill the holes in the collars, for the customer.

    One last thing:  I bought the until on line and found about $700 difference between the highest and lowest price on the web, for the same exact thing.  Before you order be sure to shop around.





    Great advice.  How has it worked our four you?  Have you had time to notice if it keeps the bottom clean?






    Thank you for the install tips.  I just took delivery of a 2006 42 and am interested in Sonihull.

    Since it has been almost a year since you did the install, do you have any observations regarding the effectiveness of the product in reducing growth on both the hull and running gear?

    Thank you,

    Steve Countryman



    Doug Ford

    I installed the Clean-A-Hull system on my NT 37 in Sept 2018 and hauled it this week. Some history:

    Installed Sept 2018

    Zincs changed by diver July 2019. Diver was also going to clean the hull but said there was nothing to clean.

    Hauled this week. Some slime and a few barnacles son the prop, but clean everywhere. Other boats in my marina grow grass constantly.


    <p style=”text-align: center;”>Long term updates? Still impressed?</p>

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