Upper Helm Chair on KK39

[z1nonlyone]

I know its a long shot, but has anyone mounted a pedastal mounted Helm Chair on the flybridge of a KK39? I am wondering if drilling mounting holes thru the deck and fixing some kind of backing plate would work, or would it compromise the deck structure?

 

[Comodave]

I did it on our boat, it had 1 helm seat and we wanted another one. I didn’t want to drop the headliner to put in a backing plate so I had to work from the top. I bought a Todd 6012 mounting ring. It is about 1/4” thick aluminum ring with a hole in the middle about 3” or so in diameter. I positioned it where I wanted the seat. Used a hole saw to cut a hole the same size as the hole in the middle of the mounting ring. The ring will bolt to the deck. I took 3/8” aluminum and cut 6 small pieces about 1” x 2” and drilled and tapped the aluminum pieces for 1/4”20 thread bolts. I slid the 6 pieces under the fiberglass deck and above the headliner and through bolted the mounting ring to the deck. Of course I bedded it with butyl tape. Then the seat pedestal just bolts to the mounting ring and you are done. The fiberglass deck on our flybridge was about 1/4” thick where I mounted the seat and it has held up just fine for about 3 years now.

 

[z1nonlyone]

Thanks for the response! That sounds like it would work and has worked for you. I am not sure if my deck has a "sandwhich" construction. If it did, I wonder if it would be damaged with too much compression. I know sometimes the manufacturer will sandwhich plywood in areas where thru bolted items exist. I guess I should contact Kadey Krogen and see if they have information on Hull #1 !!

 

[Comodave]

Yes, mine is not a cored deck but just solid glass. If yours is cored then that would change things. Normally I reef out the core and fill the area with thickened epoxy. However with the Todd mounting ring the holes would be quite a ways back from the large center hole. I suppose you could cut the big center hole and find a way to reef out the core or drill the 6 bolt holes and reef around them and then fill with epoxy. The big question would be is there room below the sandwich deck and above the headliner to slip in the aluminum plates that the bolts will go into. If there isn't room to slip in the aluminum plates above the headliner then you could have a S/S plate made to go under the headliner and through bolt all the way through the headliner and then put a nice polished S/S plate with acorn nuts on the bolts. You would see it in the pilothouse but a nicely polished plate wouldn't look bad. I would still want to reef out any core in the deck and fill with thickened epoxy so it wouldn’t crush the core.

 

[healhustler]

I have a cored deck on my KK Manatee and was, like you, concerned about the compression from a Stidd 500 helm chair. Stidd pedestals tubes are 4” so there is less flex of the tube itself, and more compression from the edges of a broader base. The answer was a 3/4” starboard spreader pad above and backing plate below. The lateral port to starboard forces placed on the pedestal base in this application are severe since the pilothouse floor is essentially the same leverage arm as a flybridge, and there are no accessorial roll dampening devices. Zero issues so far and no further tightening of the pedestal bolts (a sure indication of core compression) as been needed.

 

[healhustler]

Here’s the 3/4” backing plate, mounted purposely between the beams above the galley.