Getting Ventilation or cavitation anytime i trim up AT ALL and in following seas

[robertpel9]

I recently bought a 2005 260 Sundancer. 350 MAG with Bravo 3. Boat has been excellent all around and i have put 20 hours on it this week. One big issue i cannot figure out though

I cannot trip the outdrive up AT ALL. It has to stay all the way down, even moving it to 1 or 2 on the gauge i can feel cavitation or ventilation..... The boat rides fine and out on the ocean depending on condition i cruise around between 16 and 25 mph. I would like to get the bow down though. Trim tabs are all the way retracted and the props look perfect.

The boat came with 2 sets of props which the previous owner called a low set and a high set. I have no idea what this means... He said the low set gets on plane easier and i do have zero issue getting on plane...the high set of props is in my garage and have the bravo 3 insignia on it and look brand new

I also noticed as the last two days it was windier and the waves were 3-4 feet with 16 to 17 mph winds. In a head sea everything feels normal but on the way back into port in a following sea i get the same feeling i get when i try to trim the boat as stated above. The boat get a vibration (it is silky smooth except in these two conditions) and the engine sounds like it is picking up revs

This leads me to believe the the prop is ventilating but why would it do that this easily. Previous owner who has been great and helpful pre and post purchase said he never used the trim he would use the tabs instead and he also said he rarely cruise above 15 mph

Please help, the boat is perfect otherwise but this is driving me nuts...

 

[El Capitan]

It sounds like props/trim issues to me. Also I’ve read some folks install over sized trim tabs to get bow down. They tend to be ass heavy.

 

[scoflaw]

Tabs retracted or deployed?

 

[robertpel9]

Tabs retracted or deployed?

Tabs are fully retracted

 

[robertpel9]

think maybe this is my issue

I never had trim tabs on my other boats. The previous owner told me that pushing up on the switches retrats them and down deploys them .So belore leaving my dok i have been holding the switches up for 5 seconds to be sure they are retracted when it seems in fact i have been fully deploying them

this is likely why the boat gets on plane so fast but then in turn i assume i have created a bunch of stern lift and that is why i cannot trim out the engine and also why in following seas it is stuffing the bow and causing the prop to ventilate

does this make sense????

 

[BillK2632]

Yes, if your tabs are fully deployed in a “bow down” position then any trim up you add to the drive is going to be working against the tabs. With my 290da I would start with the drives trimmed down and the tabs deployed bow down. Once on plane I would reduce the tabs and adjust stb/port tabs to level ride. I did not trim the drives up at all if I had any tabs deployed. It’s counter to have tabs deployed bow down and drives trimmed up.

 

[scoflaw]

Drive tucked in, tabs down will get your bow down as far as it will go. Good posiTion for head seas.

Retract the tabs in a following sea and if that's not enough, trim the drive up a bit. With large waves don't go so fast that you go over the tops and land bow stuffed in the trough.