"Porpoising" Ombrine

[foxgoose]

\"Porpoising\" Ombrine

Just relaunched our Beneteau Ombrine 960 in Gozo and took it round the island today for its "new season trial".

Sea was like a mirror - fairly rare in Maltese waters.

Anyway it was the first time I've ever opened her up in a flat calm and I was surprised how she "porpoised" at anything over 25 knots.

Last year I just put it down the the swells we were riding most of the time.

I tried trimming the drives between + and - 2ish and the negative trim seemed to help a bit but by no means killed the problem.

She's a very light boat with not much weight in front - is this the prob?

Anbody got any suggestions or comments?

Foxgoose

 

[Tekkie]

Re: \"Porpoising\" Ombrine

You say you trimmed in and it helped, would appear to me that a bit more weght in the bow is needed. If you have crew aboard get them to move forward and see.

Regards

Brian /forums/images/graemlins/wink.gif

 

[Riggy]

Re: \"Porpoising\" Ombrine

Is your 'leg' adjusted fully up when she starts 'porpoising'?
I have had this problem in certain sea conditions at 30+knots with trim tabs and leg fully adjusted up and pushing for max speed (35knts) and accidently found a cure by just lowering the drive leg back down in the water far enough to cure the problem.
Regards
Riggy.

 

[timgriffin]

Re: \"Porpoising\" Ombrine

Do you have trim tabs
you could try leaving the legs in/down and use the tabs to trim her up when on the plane. Then use small adjustments on the legs in trimming up/ out see if this makes a difference if no good more weight in the bow could help .
Regards Tim
www.griffmarineservices.co.uk

 

[Deleted User YDKXO]

Re: \"Porpoising\" Ombrine

Quite a common characteristic on outdrive powered boats. I had it on a Sealine 305 I used to own. Tucking the drives in a bit and lowering the trim tabs a bit used to reduce it but not too much because you might get other undesirable effects