Thread:

thru hull exhust

Maybe someone might have some advice with this problem! A buddy recently purchased a 1998/99 ulltra Stealth with thru hull exhust, below the swin step and at idle it shakes the whole boat and makes it feel as if it missing. any ideas on how to cure it? pm or call 1-520=444-0487 thanks Al

Originally Posted by alboatsaz2

Maybe someone might have some advice with this problem! A buddy recently purchased a 1998/99 ulltra Stealth with thru hull exhust, below the swin step and at idle it shakes the whole boat and makes it feel as if it missing. any ideas on how to cure it? pm or call 1-520=444-0487 thanks Al

tune it up....

Originally Posted by alboatsaz2

If it where that easy! If the boat is on the trailer in the water but the swin steps not touching the water it runs perfect, when you drop it in the water all the way in netural or in gear the whole boat shakes, once you bring the rpm up to 1,000/1200 range its almost quites shaking and any higher its perfect. we are going to put hose over the exhust and run it closer to being out from under the swin plate. was checking to see if any one had heard of this or had other ideas. thanks Al

Sounds to me like the exhaust is getting trapped under the swim step creating and air pocket. I have seen this on molded swim steps before....as far as what to do.....maybe try to extend the tail pipes a few inches , enough to get the exhaust out.

Or just get a sawsall and cut off the swim step. Just kidding...sorry couldn't resist.

Seriously maybe call someone like IMCO who makes tailpipes and get there idea on it.

Nothing is free. Our friends Shockwave has the low-exh option, where large S-tubes snake the exh down below the swim step and thus- below the water line. It has Rex full-time mufflers, but the vibration/rumble is from the water being disturbed and the exh bubbles rapping against the swim step.

Mine is ABOVE the water line and sound like two cannons - but no vibration from the disturbed water.

There's not much to do - it's just a matter of hot air being blown into the water.

The only option is to put a switchable exhaust on it, like "Captain's Call" or similar, where electric (or air powered) diverter valves send the exhaust down to exit from the center of the prop. This his how low-power setups are from the factory. There is a large Y-pipe that collects both exhaust sides and funnels them down to a bellow in the outdrive. It then channels the exhaust down to the hub of the prop and exits quietly.

With this system, it can either be manual OR automatic. Some guys put a throttle switch on to activate the thru-prop at idle and then switch back when the throttle is advanced. Most just leave it manual on a switch.

Would probably be $2,000 by the time it's all said and done. If the Y pipe is not in there already (usually removed / not installed when thru-hull is installed), you have to pull the motor to put it in. No choice on that part.