Jump to content

Fixing soundproof sheets in engine bay


Rigpig

Featured Posts

Hi,

We've just bought our first boat and the soundproofing in the engine bay is in a very sorry state. My plan was to rip it all out and put new mats in. The suppliers of the mats recommend using either plastic fixing washers or wooden battens, but this entails drilling holes in the forward bulkhead which I'm very skeptical about! The use of contact glue alone is insufficient as the heat and moisture will deteriorate the bond over time (which is what's happened to the mats that are on the boat now) Each mat is also quite heavy (3 kg per 0.6 m2 sheet) So my plan now is to glue steel pins that have a square base (see attachment) to the bulkhead with Gorilla glue in addition to spray adhesive over the surface of the mat. Any thoughts or ideas before I go ahead and order? Thanks

Rob

801025_4.jpg

Link to comment
Share on other sites

36 minutes ago, Rigpig said:

Hi,

We've just bought our first boat and the soundproofing in the engine bay is in a very sorry state. My plan was to rip it all out and put new mats in. The suppliers of the mats recommend using either plastic fixing washers or wooden battens, but this entails drilling holes in the forward bulkhead which I'm very skeptical about! The use of contact glue alone is insufficient as the heat and moisture will deteriorate the bond over time (which is what's happened to the mats that are on the boat now) Each mat is also quite heavy (3 kg per 0.6 m2 sheet) So my plan now is to glue steel pins that have a square base (see attachment) to the bulkhead with Gorilla glue in addition to spray adhesive over the surface of the mat. Any thoughts or ideas before I go ahead and order? Thanks

Rob

 

Are you sure it's heat and moisture that degrade the bond and not bad prep? I suppose it all depends upon how long a period of time is but mine have been in for15 years but note that I did not use spray contact adhesive. I used an industrial "Evostick" type product, stuck it to a ply backing at home where I had better control of the environment. I could also stack them under weight so theytspent over a week drying while being pushed together. The assembled panels were then fitted to the boat to form a relatively easily assembled/disassembled box around the engine. The front panel is larger than the sound proofing and is help onto the bulkhead by use of four self drilling & tapping set screws (not self tappers) so installation was easy. No access is needed from the cabin side and the shanks are within the lining cavity. By boxing rather than gluing to the boat's structure you save on expensive sound proofing. If the worst did happen the holes made by the screws are already blocked by the screw so they should only weep at the worst.

As far as those pins go they look ideal to cause scratches and gashes when working around the engine.

Why would the glue for the steel be any better than glue for the mats? The contact area would be far lower so the point loading higher making it more likely to pull away.

Link to comment
Share on other sites

I installed sound proofing, and initially used the spray adhesive that to sound proving manufacturer provides.  It did not work well on the  horizontal surfaces and soon started to fall off.  I stuck them back with Evostick, and that is very much better, although I did add a few screws and big washer to be doubly sure.  You will spend a lot on Evostick though!

Link to comment
Share on other sites

I have just put sound insulation around our engine.  I've added a list of the supplies I used to complete the job.  On the iron sides of the boat I just relied on the spray on contact adhesive.  On the lid and front which is ply, I used the fixing washers as well.

One thing recommended is the use of a special foil tape which is used to join the panels and edge them.

I was very surprised to measure the reduction in noise - from over 80dB to 53dB.  (Admittedly, I was only using an app on my phone.)

 

5a7d5e8d7f257_Capture(1).jpg.4250a7b99837b33bab29841ec52c5471.jpg5a7d5e8cb0120_20171126_104510(1).jpg.f18d2c3c56d7c5af01d4ce1104a68abe.jpg

Link to comment
Share on other sites

Liberally applied Evostick will bond really heavy panels with ease on to a well prepared surface, and I very much doubt would fail over time.  This even applies to panels hung under a deck or floor.

As john6767 says though, expect to use a great deal of the stuff.  (We didn't do "blobs" we did all over every sheet).

I was on an Evostick "high" for days afterwards, though!

Edited by alan_fincher
Link to comment
Share on other sites

801025_4.jpg

 

 

Just a note of caution with these pins, on one ship I was on, they were left after being installed holding up sound proofing. At a later date an engineer was up doing some other work and stood up under one of these pins resulting in a very severe head injury. Cutting them as close as you can will only minimise the risk of injury and possibly reduce the effective holding power. From a safety point of view I would endeavour to find another fixing method.

Link to comment
Share on other sites

Thanks everyone. Much appreciated. It looks like a toss up between Evostick and making a box for the engine. The latter involves quite a bit of carpentry and materials so I might just try prepping the bulkhead and sticking it up with Evostick.

Link to comment
Share on other sites

2 hours ago, Tony Brooks said:

Are you sure it's heat and moisture that degrade the bond and not bad prep? I suppose it all depends upon how long a period of time is but mine have been in for15 years but note that I did not use spray contact adhesive. I used an industrial "Evostick" type product, stuck it to a ply backing at home where I had better control of the environment. I could also stack them under weight so theytspent over a week drying while being pushed together. The assembled panels were then fitted to the boat to form a relatively easily assembled/disassembled box around the engine. The front panel is larger than the sound proofing and is help onto the bulkhead by use of four self drilling & tapping set screws (not self tappers) so installation was easy. No access is needed from the cabin side and the shanks are within the lining cavity. By boxing rather than gluing to the boat's structure you save on expensive sound proofing. If the worst did happen the holes made by the screws are already blocked by the screw so they should only weep at the worst.

As far as those pins go they look ideal to cause scratches and gashes when working around the engine.

Why would the glue for the steel be any better than glue for the mats? The contact area would be far lower so the point loading higher making it more likely to pull away.

Mr Brooks

I have read several times in past threads your reference to the box you built around your engine . Your correct to say that this means using less soundproof sheet & therefore less expensive . 

Any chance of a picture or two as id be keen to see how you did it .

If its hassle , or if im just being a cheeky sod , no probs . 

Cheers 

Edited by chubby
Link to comment
Share on other sites

7 minutes ago, chubby said:

Mr Brooks

I have read several times in past threads your reference to the box you built around your engine . Your correct to say that this means using less soundproof sheet & therefore less expensive . 

Any chance of a picture or two as id be keen to see how you did it .

If its hassle , or if im just being a cheeky sod , no probs . 

Cheers 

If you do go the box route remember your alternator is air cooled so good airflow in the box is good as well.    Use dense thick or even doubled plywood for the box, this will also help deaden the sound.

Link to comment
Share on other sites

I can't see the pins being any better than a good glue: ultimately, they, too, rely on an adhesive bond.

The pins and washers were used were used on a trip boat I drive. To be honest, they were a bit of a nightmare, and there were always a few that were detached from the bulkhead. They were also a bit of a hazard to anyone working under the engine boards: even when cut short, these things are sharp! The trip boat ones were replaced with glue or,where possible, nuts, washers and bolts.

Link to comment
Share on other sites

1 hour ago, chubby said:

Mr Brooks

I have read several times in past threads your reference to the box you built around your engine . Your correct to say that this means using less soundproof sheet & therefore less expensive . 

Any chance of a picture or two as id be keen to see how you did it .

If its hassle , or if im just being a cheeky sod , no probs . 

Cheers 

Here is the box. There is also a soundproofed lid that lifts off and is not shown.

The panel across the bulkhead has an aluminium U section channel either side of the insulation that the ends of the plywood for the side panels fit into. I had to chamfer the edges of the side panels. The same applies to back panel the exhaust passes through.

There are a pair of panels bolted to the engine beds (A) with 50mm bolts in slotted holes, 3 in each. These are not soundproofed so they easily wipe free of oil. Again  aluminium channels are fitted to the outer edges. When the bolts are well undone the outer edges of these panels drop down sot he side panels can be fitted in place.
5a7d8b3029f51_boatengine2.JPG.7a2a1a23f4918278a1ab322e452805b2.JPG

When the bolts are tightened the panels lift and trap the side panels and soundproofing tightly against the cockpit floor.

The back panel screws into the side panels and the finger screws (B) on long rods  pull and secure the whole assembly tight against the front panel.

The space around nthe gearbox, exhaust and below the engine beds is left free so air can easily be drawn into the box by the engine intake.

The aluminium bar across the back panel is also screwed to the end panel and the exhaust hole insert because of a design fault (it bowed without being screwed).

When the bolts are tightened the panels lift and trap the side panels and soundproofing tightly against the cockpit floor.

The soundproofing on the side panes and top panels are cut away to make a snug fit against the insulation on the front and back panel.

The port side panel is in one piece but the starboard side is cut into three funny shapes that allow it to fit around the various pipes and cables.Where they join one half has a groove routed in the edge of the plywood and the other side has a thin wooden insert thereby making a tongue and groove joint. 

This, the near hospital silencer and re-routeing the exhaust so it pointed to the back allowed us to go from conversing loudly to conversing normally and now we can hear the birds. I have been asked when under way if its an electric boat and it is hard to hear the engine from the towpath when more that a few meters away.

The whole lot comes out in about 10 minutes but takes a little longer to put back. I use an 1mm socket in a drill to spin the bolts up or down.

If anyone is really interested I am happy to meet them at Calcutt so they can see and hear for themselves.

Link to comment
Share on other sites

I should have explained that the initial need for the horizontal boards screwed onto the engine beds was to give enough room around the engine for regular service work like access to the oil filter and getting a  container under the oil drain pump. It was only after this that I realised I could design the so the side panels  were held tight against the deck underside to perhaps minimise vibrations.

I should also explain that there is no soundproofing under the deck in front of the engine. That is maybe 15 inches because there was not enough headroom to give adequate access to the fan belt and alternator and also because I felt trying to glue onto 12 year old primed metal was not likely to be successful.

Link to comment
Share on other sites

Brilliant stuff cheers 

Id like to do fit soundproofing panels to my engine bay but the amount of panel needed would be 

expensive so i would need to build a box alot like this . There is a steel cross bar running directly above my engine tho onto which fit the boards covering the engine bay . There is very little clearance between top of engine & bottom of this steel cross brace so will need some working out .

As i say , ive read your references to your demountable soundproofing box & the " not quite hospital silencer " you got from TW marine ( if i remember rightly ) & wondered how you put it together , so thanks again

cheers

Link to comment
Share on other sites

48 minutes ago, chubby said:

Brilliant stuff cheers 

Id like to do fit soundproofing panels to my engine bay but the amount of panel needed would be 

expensive so i would need to build a box alot like this . There is a steel cross bar running directly above my engine tho onto which fit the boards covering the engine bay . There is very little clearance between top of engine & bottom of this steel cross brace so will need some working out .

As i say , ive read your references to your demountable soundproofing box & the " not quite hospital silencer " you got from TW marine ( if i remember rightly ) & wondered how you put it together , so thanks again

cheers

Although the steel bar you mention may support the edges of two floorboards that may allow sound out of the gap I would make two "lids". One in front of the beam and one behind. Then sit the floorboards on close cell foam (weed hatch tape?). This wills eal any gaps and help prevent the boards vibrating. It would be no different to the area under my deck at the front of the engine that has no insulation. You might be able to cut thefoam slightly oversize, not the board, so you have to compress it against the side of the beam to further stop sound leaking out.

Link to comment
Share on other sites

PU based glue thickly spread (or at a push spray foam filler) and then wedge or clamp the soundproofing between a ply sheet and the deckhead/bulkhead whilst the glue foams up and sets. I found two old car scissor jacks very useful. I haven't a clue how to get it off the soundproofing breaks first.

Link to comment
Share on other sites

Slightly related and perhaps a ridiculous idea but....... when applying insulation / soundproofing, could you press the bats into freshly applied sticky wet paint? Ours will be held up with battens, vapour barrier and internal cladding, I just though this idea might help to ensure the insulation is stuck to the steel all over with no voids for condensation to develop in?

 

Ian.

Link to comment
Share on other sites

6 hours ago, IanR said:

Slightly related and perhaps a ridiculous idea but....... when applying insulation / soundproofing, could you press the bats into freshly applied sticky wet paint? Ours will be held up with battens, vapour barrier and internal cladding, I just though this idea might help to ensure the insulation is stuck to the steel all over with no voids for condensation to develop in?

 

Ian.

Insulation, if it's of the slab rockwool type, is made to be a friction fit between battens and won't move.  On the other hand, sound insulation comes in heavy, rigid blocks and it needs proper adhesive to stick to the sides of the boat.  Wet paint as glue?  Not a hope :P.

 

Link to comment
Share on other sites

15 minutes ago, koukouvagia said:

Insulation, if it's of the slab rockwool type, is made to be a friction fit between battens and won't move.  On the other hand, sound insulation comes in heavy, rigid blocks and it needs proper adhesive to stick to the sides of the boat.  Wet paint as glue?  Not a hope :P.

 

I thought that would be the likely answer, it was a thought after unknowingly dropping a rag into some wet paint in the bilge and it really did stick very well!! I've just bought the slab insulation today and might just try a sample to see....

Ian.

Link to comment
Share on other sites

30 minutes ago, IanR said:

I thought that would be the likely answer, it was a thought after unknowingly dropping a rag into some wet paint in the bilge and it really did stick very well!! I've just bought the slab insulation today and might just try a sample to see....

Ian.

Paint goes hard by evaporating the solvent (or water in the case of emulsion paints) and then oxidising the resins to get then to cross link.  Soundproof materials tend to be poor for allowing vapour transmission, especially if faced with a plastic or aluminium film.  So I doubt it will work unlike your rag which allows for rapid solvent evaporation, and may even assist with evaporation if the solvent wicks up the fibres.  It might work if you were bonding to a porous substrate so the solvent/water can evaporate out the back, but not many surfaces are porous on a boat:giggles:

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.