aft bulkhead

[bmendenhall]

I am putting some soundown sound deadening material in our 1973 FBC we purchased this summer. It has 300 6bta's and runs like a dream but is incredibly loud. Currently the engine covers have no sound deadener. I spoke with Stever Moyer from Soundown who is a big fan of B31's and grew up in the shadow of the Bertram plant in Miami.

I don't believe ours has any sort of aft bulkhead and the huge cockpit and sides (It also has sides inside of the hull which are contiguous with the engine compartments) act s like a big base drum and the cockpit area is very noisy when running - not too bad when trolling.

He recommended fabricating some sort of bulkhead and filling in the sides in order to close of the engine compartment and the noise. I have air coming into the engines from 2 cowlings on top of the gunwale and 2 louvred inlets in the cockpit area. (these would need to be connected to a hose and baffled as these are actually on the sides of the cockpit near the engines.)

Will the engines get too hot if all this is done? How would the bulkhead affect the bilge. ( it is pretty wet.) And of course I would love to know anything that I have not thout of which is alot.

Take Care, Brian

[In Memory of Vicroy]

Good Doctor, start with lining the inside of the engine boxes with the one inch Soundown with the lead sheet in it. Then worry about bulkheads, etc. No, the engines will not get too hot and you can probably just blank off the louvers and let the engines draw thru the gunnel cowls and from the cockpit sides. When I became the Steward of AJ in the early 90s she had no insulation and the Cummins turbo whine and general diesel clatter was maddening. The Soundown did the trick, plus keeps the tops of the motor boxes from burning your ass.......

UV

[bmendenhall]

Thanks Uncle Vic, I can always count on you in a jam. You're better'n Corrosion X. by the Way I need another case of the big cans. I'll send you a check with my address on it. Send me a $ please. Thanks Again, Brian Better yet, I'll pick it up next time through.

[Bruce]

You have to have some sort of bulkhead to support the cockpit deck.
It may be cut wide open around the shafts though where it is drawing most of its air.

Any air vent into the cockpit area will produce quite a bit of noise. As long as the openings around the shaft and any subsequent openings from the deck side panels deliver enough air to the engines you can block them.

Those deck scoops don't deliver nearly enough air to feed those engines so if you decide to close up the aft bulkhead, you will most likely have to add side hull air vents.

[bmendenhall]

Thanks Bruce - I'll start with the engine covers and slowly make my way around. The side air vents sure look nice! Brian