Heavy Back end!!!

[Noelm]

A photo from side on, and from the rear would be nice, with the motor in the running position (trimmed down)

[shakey55]

I would say a fair chance that the engine is now mounted lower than it was on the old transom.

Do this test:

Find a nice smooth stretch of water in a river etc. Take one other responsible adult with you who can drive the boat ....

Launch and then get up on the plane at a medium/fast cruise speed. Trim the engine out to where she runs best.

Now, get your crew member to hold the wheel and keep things straight while you go down to the back and look over at the leg of the engine. You are looking for the Anti-ventilation plate (sometimes mistakenly called the cavitation plate), its the large plate directly above the prop.

If its skimming along the surface getting splashed that shows the engine height is perfect. But if its buried in the solid flow of water from under the hull, and you cant see it, the engine is set too deep, and needs to be lifted up until the plate skims along as previously described.

Great idea, but better still have your Deckee video the motor leg in water while planing


Sent from my iPhone using Ausfish mobile app

[scottar]

thanks for the replies.
i have experimented with heights until it cavitated. its more about the boats arse end being heavy. when i take off, whether its slow or fast, trim down, the nose comes up heaps more than it used to until up on the plane. i use twice as much fuel as before. and yes, i had to sikaflex nylon boards cut out around the motor to stop water coming into my motor well even on a small wave at the back end as it was much lower. i am not complaining about the workmanship of the transom repairer, he did a fantastic job. i believe its beefed up too much. i just wondered if there were any tips on correcting a heavy stern without breaking the bank. i like the sound of the buoyancy pods and will look more into them, although its adding more weight.

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Think engine height has already been looked at. Something else is at play.

[Fed]

Maybe the old transom was flexing so much that it gave you a lot more negative trim?
Another possibility is the hull was hooked & the transom rebuild corrected it?

I honestly can't see it being an additional weight problem and I'm sure water in the hull has been dismissed by pulling the bungs.

Thinking out loud, dipping the exhaust relief ports shouldn't make the motor run rough although it will sound different.

Even the first picture put up didn't look outrageously bad to me,

[Noelm]

Yep agree, the exhaust being under does not make it run rough, it's possible it's always been like that, and the repairs have made you aware of it. We still need pictures, just because the motor cavitated doesn't mean the height is wrong, there might be something else at play.

[Dignity]

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Think engine height has already been looked at. Something else is at play.

Totally agree, how the motor runs and how the boat now sits in the water after you posted that pic with 2 blokes towards the front of the cockpit and two batteries moved forward there is absolutely no way a refurbished transom could change it to that degree. I would still be interested in seeing a photo of the boat on the water prior to repairs, if you have one.

[nealeboy]

i appreciate all the feedback. i have attached a pic of the motor while running, and also the height compared to the bottom of the boat. im sorry but i cant find any pics of the old transom with the boat in the water. plenty of inside the boat. im waiting on a inspection camera to arrive so i can inspect further up the bung holes and report back.

regards,

[nealeboy]

this is the mounting height

[Noelm]

It's a bit hard to tell because the photos are very close, but, the one with the tape running to the motor appears to show the motor too low.

[Noelm]

Also the photo of the boat running I think shows the cav plate buried under water?

[shakey55]

Also the photo of the boat running I think shows the cav plate buried under water?

Noelm, you may well be right and I agree, but this would no way have anything to do with boat sitting way down in the water the way it does.

I’ve only seen pictures like most on here, but I can’t see any other reason for it sitting low in water other than weight. Even if it was possible to make the bow feather light, it still requires weight aft to make it sit low.

Unbelievable


Shakey - If only I lived near the coast

[Noelm]

Correct, it won't have anything to do with the boat trim, but it will get the motor up where it used to be, getting the exhaust out of the water, I still "think" the boat trim hasn't changed much, the motor being too low (for whatever reason) makes it appear so.

[Noelm]

Not too sure sticking an inspection camera up the bung is going to reveal much, anywhere you can run a camera will allow water to drain out, trapped water is the only possibility.

[Dignity]

Not too sure sticking an inspection camera up the bung is going to reveal much, anywhere you can run a camera will allow water to drain out, trapped water is the only possibility.

Agreed, but a photo of the bilge area might help.

[gazza2006au]

Im still thinking there has to be trapped water the side on pic the rear of the chines at the transom is really low in the water

As for the transom plywood varies from 550kg-900kg a 1 square meter even if the heaviest plywood wasused i cant see it sinking the hull that much as there is a huge amount of bouyancy in the hull as in air

Its just not adding up