As seen in Speedboat Magazine’s June 2019 Issue.
Taking on Water
I have a 2002 21′ Ultra with a 496 Mag and Bravo One drive. I’ve been banging my head trying to ﬁgure out why it takes on water. At ﬁrst I thought the rear vents were taking on water via the wake when I come off plane, but I conﬁrmed that is not the case today by temporarily blocking them off.
I spent a lot of time idling/ﬂoating today while I looked around the engine compartment and I could not ﬁnd the leak. The water level in the bilge while ﬂoating seems to stay the same. It appears to only take on water when the boat is moving. Of course, I was by myself today so unfortunately, I was not able to have someone drive for me while I looked for the source. The best I could do was to abruptly close throttle and run back to see if water came pouring in from the rub rail seam, or a through-hull bolt, or something like that, but nothing obvious. This leads me to believe the source is down below the engine. It’s not a small amount of water, either. The boat can deﬁnitely take on a good amount in a short ride.
The bellows look OK to me. They are clamped securely, with no visible cracks. I’m not sure if this matters, but the exhaust bellow is the type that clamps only on the transom end while the other end just slips over the drive when trimmed down. My exhaust is through-hull anyway. Hull and transom are very clean with no dam-age or cracks. I followed all the hoses that contain water and everything is secured and in good shape. When I got home today, I ran it on the garden hose and revved it up while in neutral to see if maybe the leak showed up at higher RPM but still no sign of it. I’m so lost!
I already removed the rear seat. I guess my next step is to remove the hatch and take it for another spin with a driver so I can spend my time in the back looking for the leak. Can you think of any other possible ideas or recommendations for me? I’m attaching some photos, just in case.
Matt Gleason Long Beach, CA
I think you are on the right track. The usual way to ﬁnd a mysterious leak is to ﬁrst make sure that the bilge and boat is completely dry. Then with the hatch off and the back seat out, take it to the ramp and back it in a little at a time. Observe the bilge at every level that you back the boat in for water entering. If it starts leaking right away, it could be the drain plug assembly. If it starts leaking when the transom assembly is partially submerged, it could be that the transom assembly is not properly sealed to the hull. If water starts entering from the outside corners, it could be from trim tabs, swim platforms, or anything mounted to the transom. Some manufacturers do not properly seal the rub rail and it will leak water into the boat especially if the rub rail is submerged during launching activities. If it were the bellows, water would leak in when the boat is at rest. The same is true for the transom assembly or anything attached to the transom.
It does sound like you have covered most of the items in the above para-graph. I suspect that your leak is created by engine water pressure. At this point, after doing the above checks, you need to have someone run the boat while you observe the underside of the engine. It is important that you begin your test with everything completely dry. I suspect that you have a hole worn through a molded hose or a leaking cooler. Double-check the housing that the inlet hose connects to that is mounted to the inner transom plate. It is also possible that the raw water pump housing has a crack from being over-tightened. If the boat is equipped with a water pressure speedometer, check the hose that supplies pressure to the speedometer. Also check the fuel cooler that is mounted on the port side of the engine just inside the motor mount. A cooling hose is routed through this cooler. If it appears that water is coming from somewhere higher on the motor, check the heat exchange end caps. It is common for them to develop cracks. I am sure that you will be able to identify the leak if you get everything dry and watch the engine while someone else drives the boat.
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