engine exhaust question - sailboat diesel

[fdubois]

Not sure if this is the right forum for this but here goes. I'm running a Perkins 4-108 (50HP) in a 40 foot plus sailboat. The engine riser and mixer is 2.5 inches in outside diameter, the exhaust thru hull is also 2.5 inches. I'm using 2.5 inch exhaust hose. Problem is the water lift muffler (vetus) intake and exhaust are barely 2 and three eights so the hose is a bit sloppy. What can I use to increase the diameter of the intake and exhaust of the muffler? Preferably something that can be grabbed off the shelf of the local autoshop, west marine, or Williams Sonoma.....! Muffler material is plastic. Thanks for the help - this is my first post so feel free to redirect me to other sites that you feel may be more applicable. FD

[fdubois]

Boat was launched today, I found some plastic muffler tape at the local auto shop, apparently is designed to adhere to the muffler when hot. Wrapped this around the inlet and outlet on the vetus water lift, secured it in place with stainless wire, slathered it with copper/silicone hi-temp exhaust sealant, slid on the exhaust hose and clamped with hose clamps, ran the engine for half an hour, appears to be solid and secure. fd

[marshmat]

a little creativity and innovation goes a long way....
(a bit of some special tape or another always helps ;-) )

[JimCooper]

I reckon you will be ok

Once you get past the water injection you can fabricate and use plastic PVC and fibreglass fittings , those plastic mufflers are nothing fancy in the way of plastics just moulded chaep flexible goop. I have seen plastic household plumbing pipes used to good effect for exhausts and if you then wrap them in fibre glass bandage they are just about indestructable. Wouldn't pass muster though

Jim

[fdubois]

Motored for about 3 hours in light air over the weekend and no problems, of course, proof will be in a gale, shorthanded and trying to navigate a narrow channel with rocks on both sides! Frank
s/v Twilight
Perry 41

[FAST FRED]

"Once you get past the water injection you can fabricate and use plastic PVC and fibreglass fittings ,"

However IF the seawater pump dies or picks up refuse , these plastic parts in the exhaust can easily catch fire , one that is hard to put out and emits Poisin while burning.

An Aqualift muffler should be of metal or Fire Retardant GRP and the fittings shouldn't be designed to kill you! Metal works.

FAST FRED

[PowerTech]

them vetus water trap mufflers aren't the best I have seen a few melted.I still use them on tight instalations though.they are very skinny and have a adjustable nipples.On some repowers the exhauste size on the motor is differnt so I buy a premade fiberglass reducer I think it is made by centech or something like that for fiberglass pot mufflers.A few times I have glass in a new piece of tube the right size but the premade job is faster wam bam.But on the vetuses you can buy from them replacement nipples of a few different sizes that will fit the same muffler and that is handy,just loosen the clamp and pop it in.If you want to afro engineer your old muffler nipple a good cheap way would be to just wrap some fibergass cloth around it untill it is the right size.You can get that little bit of glass and resen for free or for the trade of a 6 pack.When I see PVC in exhaust systems I shake my head and laugh.That is some B.S. and a good way to sink a boat.

[cyclops]

What is the engine ? A steam engine of low pressure? If a gas or Diesel you can kiss it good by when coolant water goes into the hot exhaust valves and slowely sinks the boat if below sealevel. I see a big difference between cheap and not knowing what WILL happen.

[PowerTech]

Elaborate cyclops on what your last post is about exactly.I am confused it seems like a few brief vagely related statements.But what are you geting at.No offence.

[FAST FRED]

Most lift mufflers are as far below the engine exhaust flange as the hull shape , and size of the lift muffler will allow.

There is usually more drop than just running an exhaust line from the flange to the transom, as the lift muffler can be well below the waterline .

Usually the muffler (if of large enough diameter) will lift 4 ft without overloading the engine with back pressure.

The entire system is great , usually the only exhaust sound , is the sound of the exhaust cooling water hitting the surface , outside the boat. NICE!!!

In a small boat with a Perk I prefer to use a GRP 10 or 12 inch dia muffler , in conjunction with a Vetus METAL "waterlock".

This discharges over the side , next to the engine , or thru the transom, depending on space avilable.

Its GREAT not to hear the exhaust , and the side exhaust is probably better as many will motor downwing in light airs , where a transom exhaust STINKS the boat up.

FAST FRED