93 Mercury 115hp Adding a 5" extension

[huggyb1972]

I seam to be fighting a water issue on my outboard after refiting my boat with a engine bracket. I have found a couple places that have a extension kit for my outboard that are brand new. Is there anything I should look out for doing a extension kit?

 

[huggyb1972]

think im picking up some water that's getting in the lower part of the cowl mostly during coming up on plane and and coming down from plane. I can run solid for about 10 minutes and then my rpms start dropping. I noticed this nasty looking emulsion in the air box and throat of the carbs. The thing runs line a top until then. It's not overheating judging by the water coming from the pee stream after a run, the fuel bulb is tight, it idles okay, and the fuel is fresh been though about 3 tanks in the last few weeks.

 

[GA_Boater]

When a bracket or jackplate is installed, the motor is raised above the bottom of the transom. An extension kit will make your issue worse, not better.

From the pic, it appears the motor may be too low. Is your water problem a lot of water splashing toward the transom.

Also you have to look at the tell-tell when running on the lake, not idling when the water pump is as deep as it will go.

 

[huggyb1972]

My cavitation plate is right on the surface of the water just fine at speed. My issue is the lower part if the engine cover is below the waterline during the time when im planning out or coming to a idle off a run. Some of that issue could be solved with redistributed weight. I just want the power head higher and the cavitation plate in the same spot or maybe just a hole lower. My original installation was 1 1/2" higher and the prop was blowing out at speed.

Im more concerned with is there anything I should know about these 5" extension kits and if anyone has had trouble with them.

 

[huggyb1972]

https://www.marinepartsguys.com/product-category/outboard-extension-kits/

 

[huggyb1972]

https://www.marineparts.com/partspages/Accessories/acc8.htm

 

[Chris1956]

Normally there is a seal between the lower cowling and the engine. This keeps water out of the powerhead area.

You might look to see what happened to yours.

Motors are made to run with waves splashing on and even over them. Seals keep the water out and baffles let the air in to feed the carbs.

 

[huggyb1972]

I don't disagree with you that the seals should maintain the dryness. Unfortunately in my particular application there's no boat back there to protect the outboard like a typical boat with an outboard. Im speculating im asking the question I want to know incorrectly. I have a lack of planning/floating surface so I need some height. I'm probably just gonna have to shoot from the hip and see how this extension kit goes. Eventually I'll get to the place I want to be, at least four the moment I get more fun out of the thing than before with the outdrive I had.

 

[Chris1956]

There are accessories that cover the bottom of the transom bracket to help keep down the spray. You might prototype something.

If you are getting water under the cowling while running, and you are still afloat, something is wrong.

JMO

 

[huggyb1972]

I had some spray from my transducer on the port side and yes I agree with the shielding thing which it's in the works. Im just trying to understand something here. If I raise the power head 5" and don't change anything else running depth wise what it's the worst that can happen? The bottom 6" of the cowl should not be submerged in my mind at any time.

 

[emoney]

It seems strange that your cowling is 6" underwater but your cavitation plate is correct. I agree with you; doesnt seem it should be submerged ever. Is the boat extremely stern-heavy now? I wish I could remember how my old OMC Seadrive was mounted, as it applies to caviation plate, because that's kinda close to the setback you have. Anyway to get floatation foam in the bracket? I know a lot of the aftermarket guys add it in order to help with the change in weigh distribution. Can you share a pic of the boat on a trailer so we can get a look at it overall?

 

[huggyb1972]

Im moving the deep cycle batteries forward. The bracket displaces roughly 350lbs of water. The water issue is only while the boat is on its its way to or from plane. Sitting static or idling it's good. The picture is with the front on a tire while tied up so it will naturally look a little rear heavy.

 

[huggyb1972]

The extension is in now. I need to call the folks who manufactured it as they made the water tube extension a 1/4" to short.

 

[huggyb1972]

Been a while since I posted. This year we got to play in the intercoastal and sound around Edisto Island, SC. The old repowered boat ran perfect and allowed us to go places you can't to by car. The extension did its job great made a world of difference keeping the powerhead up higher. I'm getting 42 mph out of the boat now which is faster than it ever has went. We were in some 2-3ft seas out in that sound which was a experience to say the least.