Motor Mounting Height - DC 265/Yamaha 350

[Relentless]

I have noticed what seems to be "early" ventilation/cavitation in my initial operation of my new boat, as if the motor was mounted "too high". If I trim out more than just 1 - 2 bubbles on the guage (3 - 4 seconds), at 4,000 RPM, cavitation occurs, and is exacerbated when turning (have to trim right in if you're going to make anything other than a very gentle turn to avoid cavitation). Motor is mounted to spec, and consistent with the Yamaha Performance Bulletin (2nd hole, ventilation plate 1" above bottom/keel of boat). I am wonderfing if anyone else experiences a similar trend - feeling as though you should have more usable trim range before cavitation/ventilation occurs (I am sure there is technically a correct word for the condition, just not sure which is right in this circumstance). Also, would salt water/fresh water call for any adjustment (I only use the boat in fresh water, I imagine Pursuit sets them up for use in salt water)? Thanks in advance for your insight.

[SBM2470]

Salt versus fresh makes no difference. Motor mounting height -- "one hole up" -- looks correct. 3 to 4 seconds on the trim up button can be quite a bit of trim. The trim gauge sender may require calibration. Post a picture of the boat at rest with the trim set where you get the ventilation.

[MarkT]

That sure looks like the right height. I have delivered a lot of new Pursuits and going higher than two bars on the trim gauge almost always resulted in cavitation. 3-4 seconds does seem like a lot of time to trim out also. At the dock trim the engine up a bit and then trim it in all the way. Watch the gauge and see if it bottoms out as the engine hits the trim stop. If not the gauge or sender may be off. No change for salt or fresh water.

[ironsinker]

That looks right to me as well. I wouldn't lower that any. I never go higher than 3 while on plane. Usually 2 dashes or so on the gauge.

[Relentless]

All of the feedback is reassuring and appreciated. I will attempt to capture the "at rest" image requested by SBM2470. Thank you.

[Relentless]

This image was taken with the engine trimmed out about 3 seconds (3 bubbles on the indicator display). The display does correspond with the motor position (down is down, etc.), with just a touch of lag (i.e., the motor, while trimming in, is all the way down but the display still shows two, then one bubble for a second or so half). In this position, the boat will cavitate/ventilate in some situations (typically lower speeds (26 mph or so)). I realize this is a tiny nit, and is probably not an issue - but thought it was worth a post. At this point, I am confident that the motor is correctly mounted and I just have some "getting used to" yet to go. Thank you, everyone, for your replies and insight.

[keezy]

If you rule out other issues it could be your prop

[Fullpower]

Hallo, have more or less the same problem with my C250 CC, but in my case, for some reason I ignore, the engines are mounted 1 hole higher than what Pursuit recommend, do you have any idea what can be the loss of performance in a case like this? Don't know if this can be the reason, but I am far away from the pursuit performance bulletin.

[MarkT]

may I suggest that you only go to 1-2 dashes on the gauge and use your trim tabs for all else? See what that does for you.