How high is too high?

[496 Cubic Inches]

About a month ago I asked about getting my boat dialed in,and most everyone was in agreement that my engine was mounted way too low. I've finally found time to get the boat back to the dealer for a few days.<br /><br />I'm working with a new service manager,as the one that rigged my boat isn't working in the boat business anymore. I guess too many customer complaints has an adverse affect on your employment. <br /><br />As they raise the engine we'll be taking it out after each time to see the effect its had.<br /><br />What should I look for when determining if we've gone too high?

 

[Triton II]

Re: How high is too high?

A rule of thumb is the AV plate should be level with the skeg when the motor is trimmed dead level. <br /><br />My 16ft alloy boat came with the motor (FT60 Yam) set about half and inch below the ideal so I used a car engine hoist to raise it and bolted it back on one notch higher. The boat does about 2 kts better flat out on the same prop. It does however, ventilate with the motor trimmed fully up during tight turns but once I became aware of that I avoid using full up trim when manouevring. Trial and error is definitely worthwhile - at least it was in my case and it was iboats forum advice that led me to experiment. Good luck.

 

[walleyehed]

Re: How high is too high?

If you can still trim up all the way, engine is still too low.<br /><br />496CI, you will start to get some venting on hole-shot, and sometimes in the corners. Venting "occasionally" is normal. Keep raising until blow-out or venting is bad, then we need to look at another prop or drop down 1 hole.

 

[ob]

Re: How high is too high?

Make sure that once you settle on an adjustment height that the engine bracket bolts are sealed to prevent water intrusion into transom.

 

[Dhadley]

Re: How high is too high?

In addition to what Walleyehed said, make a note of your water pressure. As you go up keep an eye on it. If it starts bouncing or gets lower, you'll need to address that issue. Many of todays props still bite long after you lose water pressure.

 

[Dave Abrahamson]

Re: How high is too high?

Originally posted by Triton II:<br /> A rule of thumb is the AV plate should be level with the skeg when the motor is trimmed dead level.

I think he meant to say the anti-ventilation plate should be even with (or slightly above)the keel of the boat, not the skeg on the L/U.<br /><br />Dave

 

[496 Cubic Inches]

Re: How high is too high?

Originally posted by walleyehed:<br /> If you can still trim up all the way, engine is still too low.<br /><br />

Thats how it is now,I can trim the engine up enough that the trim gauge is maxed out,and I'm on the verge of going from trim to tilt.<br /><br />The engine never vents and only loses water pressure at the very highest trim position.

 

[496 Cubic Inches]

Re: How high is too high?

Originally posted by walleyehed:<br /> <br /><br /> Keep raising until blow-out or venting is bad, then we need to look at another prop or drop down 1 hole.

I have a big diameter stainless prop on it now. IIRC its 15 1/4",its about 1" in diameter bigger than the aluminum prop they put on my boat originally. IIRC Dhadley likes bigger dia. props when raising the engine.

 

[Dhadley]

Re: How high is too high?

What motor, what boat and what prop are we trying?