Ventilation-Lower Outboard?

[HappyGaffer]

Hi:
I understand from past posts that the 210 and 215 tend to ventilate. I'm running in the Pacific and regularly encounter relatively rough seas. As a result the outboard often ventilates when coming over wave crests. Please share you opinion on lowering the engine one hole. It's a 215 with an F150. Thanks for your replies.

[Putershark]

What mounting position is the engine in at present?

[jack7265]

HappyGaffer, check the level of the water as it passes the anticavitation plate while you're on plane. The level of the water should be at about between the middle of the anticavitation plate to the top of the cavitation plate. On average boats, it is best to mount the engine so the cavitation plate is approximately even with the bottom of boats. These observations will give you an idea of whether to adjust the height of your engine.

[HappyGaffer]

It was in the second hole from the top (6000 RPM, 40 MPH+ W/easy ventilation). Now it is in the top hole (3100 RPM, 26 MPH, ventilation rare). I'm still running the same 17 pitch prop. As for the cavitation plate, do you mean that it should be even with the lowest part of the stern when trimmed parallel to the transom? Is it possible that the 215 was designed for the atlantic and just won't do well in the pacific slop?

Thanks!

[jack7265]

This is a web site that has some informationoh mounting an outboard engine http://www.marineroutboards.co.uk/enginechoice.php One of the web sites that I looked at suggested putting the anticavitation plate parallel to the bottom of the boat, and approximately even with the bottom of the boat, to within one inch below the bottom of the boat. Also, I'll attach a pdf file that I found, and it has information that you may find useful. Good Luck.

[Barry]

I have been fighting this problem for the past 3 years, I have had some sucess running the yamaha off shore prop with has larger blades, havs added cupping to the prop, and have moved the mount to the top hole. I may try moving to the second hole and give it a try. Most of the ventilation that I have experienced is in tight turns.

Barry

[fridaysoff]

Barry,
Most boats will ventilate in tight turns,especially if you have the engine trimmed up quite a bit. I would try what Jack7265 mentioned.The proper height for most outboard motors are when the cavitation plate on the motor is even with the lowest part of the V in your transom. Good Luck.
John D.

[jack7265]

Barry, when I get to a tight turn, I'll slow down the boat and trim the motor down a little. This will reduce your occurance of ventilation.

[HappyGaffer]

Barry:
What motor do you have? Did you experience a dramatic RPM drop when the outboard was mounted in the second hole (I'm assuming you tried lowering it one hole)? I'm considering going back to the first hole and trading out my prop for a replacement with a lot of rake.

[Barry]

I am running the yamaha 200 salt water series two stroke. I haven't had a chance to see the rpm/speed difference yet by raising to #2 hole with my present prop, but will try it as soon as the weather breaks. I have my motor fully trimed down most of the time including tight turns. The problem usually occures when I am towing my daughter on a tube and need to turn around in the inlet. I still don't buy the problem with tight turns and prop blow out, my other deep V boat did not blow out in the tight turns. I believe the problem stems from not having a perfectly straight hull, but this is what you have to live with with plastic boats.

Barry