hi would like some input on soundproofing . when steaming the noise level in my mitchell's wheelhouse is loud enough to stop all conversation. i have insulated the engine box but to no avail i have a n/a ford 120 and i know that they are noisey but any help would be appreciated. i think the main problem is that the boat has only one full bulkhead forward of the engine so the noise is carried throughout the under deck area and under the wheelhouse floor anyone had a similar problem or do lochins not suffer from this
Acoustic treatment is a science in its self and plenty of "experts" still get it wrong.
You say you have insulated the box but does the box totally enclose the engine or is it just a raised cover over the engine? If so, noise will still escape through the deck and every other imaginable path.
hi chas thanks for the reply , the box covrs over the top of the engine and sits down over the raised coaming on the deck. the problem is as you say the noise can pass down under the deck area that is open for 2/3 of thge length of the boat
It looks like there is a bulkhead forward of your engine so to do it properly you would need to insulate that and below the deck up to there.
Is there not a bulkhead somewhere aft of your engine?
There shouldn't be any gaps in the acoustic insulation, for example, whilst you have insulated the engine cover, the inside of the raised coaming also need treatment. The trouble will be that it would reduce access space but even the thinnest insulation would be better than nothing.
Also, what is your engine air intake arrangement? A good arrangement can reduce noise drastically.
Sound level will be naturally reduced by distance and changes of direction.
Chas i only have one bulkhead and that is at the forward end of the wheelhouse.. what you can see in the photo is the fuel tank. to seal off the engine bay would be a mammoth job as all the wiring and fuel line would have to be re run and possibly the fuel tank
Have you considered making sidepanels to box in the engine under the deck after insulating the bulkhead, making the removable for servicing and maintenance. Have seen this done in the past but have recently read an article on a new steel boat that fully enclosed the engine in a soundproof box .
i had thought about trying this but it would not be easy to totaly enclose the engine compartment due to the fact that the engine has bits protruding out at different angles and to fully enclose it would mean access would be limited if required in a hurry but i might give it a try
Hi Ocean tramp, I made soundproof panels around Tommie's engine. they are very simple to make from 12 mm plywood covered with 40 mm sound absorbent foam, or rock wool, kept in place under a perforated steel plate. I epoxy glued some wooden U forms on the bottom where the panels fit in, and fixed them on the topside with a wing nut. I remouve them in a minute. The panels are 30 mm from the bottom, as the engine has to breath. I covered the forward bulkhead as well in as outside with 80 mm pyramid foam. due this the noise level came down from 80 to 40 dbA. If the engine is running stationary (700 rpm) you hardly here it. At cruising speed I here the VHF loud and clear even with the cabin door open.
however sound panels don't help against noise from vibrations, caused by bad engine stud rubbers, worn propellor shaft, etc.etc.
thanks for the reply and the picture. i think that is a brilliant idea i did think about trying to box the engine in but was worried about access. your idea solves that problem and i could even do the same thing on the fore side of the engine as there is no bulkhead there . the only bulkhead is forward of the wheelhouse. all the engine bearers and flxible mounts are new and the flexible coupling and shaft are ok. so they should not be a problem can you tell me if you used the marine soundproof panels or some of the industrial stuff. as the price differance is substantial as far as i can see
From studying your photos again, it appears that you have access hatches either side of your engine. They could make adding detachable boxing around your engine a lot easier than I originally thought.
There seem to be a lot of acoustic materials on the market, the only thing you can do is compare the the sound attenuation properties and the suitablilty for purpose i.e. resistance to moisture, fire etc.
What is your engine air intake arrangement? A good arrangement there can make a huge difference. For example if you can form a longish attenuated duct especially with a couple of change of direction, that would potettially work wonders.
A plain open air intake hole at the back of the enging box is about the worst possible arrangement for noise breakout.
hi chas i think kees idea of theremovable panels is the way i am going to go just not sure if i should bite the bullet and go for marine sound proofing material or industrial alternative . my air inlet for the engine is fom under the deck and pulls air via a hatch in the floor of the wheelhouse side lockers that have access to air from the outside of the main deck high up regards mick
