Kelsall SunCat 36 hull design plans ?

Hello all,
I am the 3rd owner of a 1996 Kelsall SunCat 36 (12m?). I have it hauled now due to discovery of poorly applied barrier coat (I believe Interlux Interprotect) peeling off, so figured this would be a good time to update sonar, since this has nothing but the original '96 era 200Khz transducer installed, feeding nothing but a digital readout on the bulkhead.

I have purchased a Simrad/B&G/Lowrance "3D" transducer to feed a new B&G Zeus 3S MFD, and would like to install that transducer in what looks like the perfect narrow flat area just ahead of the port side keel.

But I have no idea what the construction of that hull area consists of....and what I'd be getting myself into....cutting and drilling there....

....so came here hoping someone on Boat Design.Net might have access to the old plans for the Kelsall SunCat 36 (11m.?, docs say 12m, but I don't understand how they're measuring that...seems an exaggeration). My documentation of this boat lists a "Dennis Hetherington" of Brighton, Sussex, UK as original owner(builder?) in August 1996...but I have no docs of the build, he may have gotten his plans 2nd hand ?

I've attempted contact with Kelsall, with no reply.

Thanks to all for any insight or resouces.

 

You will not get a reply from Dereck Kelsall because he died in 2022 and the company died with him. I tried to get information about what happened from his son Liam but he no longer replies to my messages. If built to plan your boat is aired pvc foam sandwich with layers of grp.

 

"dam" the planned installation spot for the transducer off, fill with water, put td in & see if you have a return
alternative:
plastikbag filled wit td & water, wet installation spot, put bag with td there, attention that there is no air gap, see if you get return
if boat is hauled: drill 4mm hole & see...