Porpoising

[sunbird1986]

Finally had the boat out after 3 long years with the new SEI116(formerly OMC Cobra) and when I trim up even just a little it porpoises really badly on smooth water, it was funny for the first few minutes then became annoying, is there an easy fix like a hydrofoil or something?

The hull is smooth and never had an issue an issue with this.

[admin]

I think the issue is that it is not trimming down far enough, so when you go to trim it up some, you are really as high as you are supposed to be already.

The dive is modified to allow more down angle, but it is fairly common to have to modify it further so you get the proper amount of down trim.
I will email you a photo showing the area that is modified.

Tech Support

[sunbird1986]

I received the mod pic you emailed me and will check it out next week when I go back to it. Thanks

[Greg116]

Could you also send the photos to me? I have a similar issue with my 116 on an OMC gimbal housing. I trim it down all the way until it stops and the boat porpoises badly. I probably have 2 inches of trim ram travel remaining.
In the attached photos I circled where the protrusions on the outdrive make contact with the gimbal cross brace.
It looks like the protrusions haven't been modified, nor the gimbal housing. IMG_5852.jpgIMG_5850.jpgIMG_5848.jpgIMG_5849.jpg

[admin]

Attached is the picture. It is important to make sure that the shifter doesn't hit the support piece. Your trim cylinders will not go down as far as it did with the Cobra, because the rear pin is in a different spot,

Thanks,

Justin



OMC CKmod.jpg

[Greg116]

Thank you! It looks like my upper already has that modification but the gimbal support piece is hitting the lower finger on the upper that wasn't modified. I'll reduce the vertical height of the lower finger until it clears and hopefully that will let it come back to where the modification normally allows it to.