water over transom

muskie34 · Feb 16, 2013

I have a alumacraft 165 classic tiller with 50hp, every time I go to trim when on plane water comes over the transom. I am not sure how to fix this problem. I can run the motor full speed all the way down but when I try to trim that is when the water starts to come over and will quickly fill the transom and start coming in the boat. any ideas what might be causing this. Also I dont get top performance running the motor all the way down

GA_Boater · Feb 16, 2013

Re: water over transom

Welcome muskie. Did you change anything before this started? Pics would help. Sounds like the motor is mounted too high, but pics would eliminate guesses.

Silvertip · Feb 16, 2013

Re: water over transom

If it is spray coming over the back, then the motor is installed too high or too low. If it is a flood of water then there is a serious issue of another sort. You need to be more specific about how you are trimming when this happens. Since it is a tiller steered boat, you need to explain how the boat is loaded. Most are very stern heavy so perhaps moving some weight forward will help.

jigngrub · Feb 16, 2013

Re: water over transom

I don't understand how this could be happening unless it's like roostertail spray or something.

When I take off in my boat, I do so with the motor tilted all the way down. When I get on plane I start trimming the motor up, as I trim up the boat rises up out of the water.

smokeonthewater · Feb 16, 2013

Re: water over transom

Mr obvious asks: The motor isn't in reverse is it? LOL

J/K this is a case where you really need to look and see what path the water is taking... where is it coming from?

muskie34 · Feb 16, 2013

Re: water over transom

I have tryed running without the transducer on and it still floods the back. I dont take much gear with when i go out and what gear i have it is distributed evenly. When i take off I have the motor tilted all the way down and when im on plain i start to trim the boat and the transom starts to flood (raising the motor at all starts the flooding). I did look at the way it is mounted and the motor bracket is about half inch above the transom (so hear that it could be mounted to high makes sence).

ziggy · Feb 16, 2013

Re: water over transom

what is the relationship of the anti cavitaion (anti ventilation plate) to the bottom of the boat?
most are slightly above the bottom of the boat. at the stern, at the keel, at the transom, the very back.

bassman284 · Feb 16, 2013

Re: water over transom

Really need some pictures to get this going.

roscoe · Feb 16, 2013

Re: water over transom

I bet you motor is too low.

As you trim up, the front of the anti ventilation plate is catching the water and diverting =it upward.

Try raising the motor so the anti ventilation plate is 1 to 1.5" above the bottom of the hull.

The diagram below shows the anti ventilation plate even with the bottom of the hull. You want it to be above the bottom of the hull.

Actually, the plate should not be touching the water when the boat is on plane.

muskie34 · Feb 16, 2013

Re: water over transom

Not sure if these will help

smokeonthewater · Feb 16, 2013

Re: water over transom

nope.... need to see the engine in the down position.... Could be the angle of the pics but it looks like an awfully short transom for 50 hp boat tho..

A 20" motor on a 15" transom maybe??

Are you getting a spray or a standing wave that pours in or a stream from somewhere?

Do you have a hydrofoil on the engine?

muskie34 · Feb 16, 2013

Re: water over transom

i get a steady flow of water coming in and i do not have a foil

smokeonthewater · Feb 16, 2013

Re: water over transom

steady flow as in the back of the boat is being pushed below the standing wave and it is falling in or a stream being directed in by some outside force?

smokeonthewater · Feb 16, 2013

Re: water over transom

did a quick search... looks like you have a 20" transom and a max rating of 50 hp soooo next is to figure out if you have a 20" motor

check the height of the antivent plate as mentioned several times above.

when you are on plane does your boat run like the one pictured here or is the stern way low in the water?

muskie34 · Feb 17, 2013

Re: water over transom

the stern is lowwer and bow is higher

dan02gt · Feb 17, 2013

Re: water over transom

I think the only way you're going to figure this out is to have a buddy drive while you look at what's going on back there, or use a GoPro to record it.

81_chapparel194 · Feb 17, 2013

Re: water over transom

sounds like too much weight in stern area. is the bilge full of water maybe?

ziggy · Feb 17, 2013

Re: water over transom

tiller with 50hp,

since it's a tiller steer. when no ones around, look over the transom when the deficiency is noted and see what causing it. if ya don't wanna look. stick a camera over the stern and take some random pics.

Frank Acampora · Feb 17, 2013

Re: water over transom

View attachment 182220

smokeonthewater · Feb 17, 2013

Re: water over transom

I suspect that frank may be right but lets CHECK it first... go trim the engine down till the antivent plate is parallel with the keel and see how high or low it is in comparison.

water over transom

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