Water over the transom

bobmaggi · 16 May 2007, 23:13

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 · 16 May 2007, 23:17

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 · 16 May 2007, 23:27

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 · 16 May 2007, 23:32

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!

Poly · 17 May 2007, 13:12

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 · 17 May 2007, 13:18

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 · 17 May 2007, 16:01

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 · 17 May 2007, 23:16

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

vince · 18 May 2007, 05:59

'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 · 18 May 2007, 11:08

Quote:

Originally Posted by vince

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

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

bobmaggi · 18 May 2007, 20:34

Would have responded earlier but unable to get on the computer...
The water appears to be being 'pushed' into the boat over the entire transom, not just the cutout for the engine mount. We tried different trims, trimming up seemed to result in the least amount of water but by that time the stern was getting low due to the amount of water already in the boat.
We were unable to get on plane until we got some of the water out by running parallel with the waves, then once most of the water was out we tried to keep it on plane while traveling into the waves. Didn't get as much water in by that time. The majority of the water came in after we left the dive site and were traveling at only around 8-12 mph into the waves.
I know that when the boat shop was initially trying out props, triming the engine all the way in resulted in a lot of water coming over the transom, even on a calm river.
The boat shop is going to move the engine up once I get it in. Maybe that will help fix the problem. This weekend I will install the new bilge pump and see if that helps also.

Bob

walruz · 19 May 2007, 14:08

Quote:

Originally Posted by 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?

Had this prob on my searider - check your transducer.

Ian

bobmaggi · 19 May 2007, 23:27

I have a depth transducer - I checked the installation and it was installed in the location recommended by the vendor. I could see this as a problem if the water was coming up on just one side but it's equal on both sides of the engine.

Once the boat shop re-positions the engine I'll give it another go.

Bob

jwalker · 20 May 2007, 01:00

Quote:

Originally Posted by Polwart

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

Just watch the wave and as it reaches the transom blip the throttle.

Quote:

(the instructor called this "pooping" but no idea if that is an established term or not.

Hence, poop deck.

Hugh Jardon · 20 May 2007, 01:04

Quote:

Originally Posted by Stoo

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

cant understand why hes not on here now like us!!

Cookee · 21 May 2007, 11:51

Sounds like the transom is too low if the engine is up over the top of it! What length is your engine L?