Water over the transom

[bobmaggi]

I just got a new Zodiac Pro 12 with a 60Hp Mercury 4 stroke. Last Saturday on Lake Michigan myself and one other diver were starting to head back to the harbor in 5-6ft seas. We quickly found that we had water literally pouring in the back of the boat at low speeds (the battery box was totally underwater). I'm assuming this isn't normal and am looking for some advice.
I picked up an automatic bilge pump today to install but what can I do to keep most of the water in the lake on the outside of the boat? I noticed that the boat shop installed the motor mount about 1.5 inches up off the top of the transom, they said it was so the anti-cavitation plate would be even with the keel of the boat. They are suggesting lowering the engine..
I haven't read anything like this here yet so I thought I'd tap into your collective wisdom...

Bob

[simmons0]

I'd expect lowering the engine would make it worse.

Does it show any other signs that the engine could be too low in the water? Does it chine walk? Not reach the top speed you'd expect it to? Spray far too much water up of the gearcase at speed?

H

[Tim M]

What do you have in the way of electronics fitted on the boat? I have found that a badly installed transom mounted depth transducor can do this. Do you have one fitted?

[Stoo]

Are you saying that the water is coming is is from the lead edge of the engine... as opposed to waves coming over the transom from the rough water?

If it's the former, then I would say your engine is too low as well. If the engine is sitting above the transom, then my guess is that either you have an engine with a shaft that's too long, or someone has cut down the transom. (Don't laugh... I used to have a boat with that exact problem...)

Also, you say this happens at slow speed. How slow? "Slow" as in not yet on plane? If your engine is trimmed way up and you are not planing, this will push the stern way down into the water which might account for it as well...

You are right though. The basic purpose of a boat is to separate you from the water. Something is outtawhack!

[Polwart]

Are we talking - water pouring over the back rather than spray? And does it really just happen as you are about to stop (or at least when slowing down alot?).

I was taught that if slowing from the plane to a stop (or near stop) you either have to do it gradually or put a 90 deg turn on just at the end to stop your own bow wave overtaking you and launching over the transom (the instructor called this "pooping" but no idea if that is an established term or not.

[vince]

Is it a case of travelling too slow in a following sea? ie, not surfing with the wave? As you said, if the waves were 5-6ft, then the water would dump itself over the transom. Even more so if the wind is with the tide.

[frothy top]

I have a zodiac pro 4.2, when going at low speed water comes over the back i found that you just need to trim the outboard up a little it stops this from happening

[Stoo]

It'd be nice if Bob would respond wouldn't it?

[vince]

'Last Saturday on Lake Michigan myself and one other diver were starting to head back to the harbor in 5-6ft seas.'
Bob`s not responding cos he's just realised he was in reverse!

[Stoo]

Originally Posted by vince

...cos he's just realised he was in reverse!

That would explain it... pointy end goes first!