cavitation issues

[gray duck]

I know there was some discussion on this topic in the past - boat is 2520 DV with twin 150s, standard props, stnd trim tabs. Problem was prop spinning out/cavitating with high rpms while going downhill in 4-5 foot seas. Both engines did it - stbd twice, port once. Had to come down all the way on the throttle to (?) get the airpocket to clear. Is the problem air around the prop? What is the solution? I had the tabs down once when it happened and up once too. it seems like they should be up when running with the waves. It would not be a great thing to happen if running a difficult inlet. Any help is much appreciated.
I was running around 40-42 rpms and the engine that lost its bite revved up to 47-50.

 

[mark]

I have had this same problem for 3 years. Mine is always the port side, usually worse in a following sea. Last time out probably did it 5 or 6 times running 70 miles or so. Tried everything short of swapping out props (still running the stockers even though I did rehub them) Would sure like to know that new props would fix the problem before I spend the $$.
If you get it figured out let us know as more than one of us have the same issue. Thanks

 

[Megabyte]

In a following sea, or running an inlet, the tabs should be full up.
Always.

 

[samj]

Gray Duck, we run the same set up as you. Use the author search. Search jjjansk once there look under "New 4 blades on the F150s" hope this info helps. Sam J.

 

[Bryan 2530]

I have found with my 2530 the port cavitates if I have the washdown seacock open.

I believe the problem stems from the location of the clamshell. Closing the valve helps a little bit. I would like to move it or put in a flushmount pickup like this. Not a true seacock but, something to think about.

http://www.gemlux.com/s.nl/sc.17/category.14065/.f

 

[mark]

If you are going with the waves then get on one and ride it in (kinda like surfing), going over and then down the front of a wave risks burrying the bow into the wave ahead of you and it could result in loss of control. Slow down.
If you heading into waves and you are blowing out the props then you are almost airborne and you will have no propulsion control to move you forward. The props are out fo the water and suckin air.

slow down
.
take a boating course which will help you learn the technical aspects of boat handling.

Care to share a few boat handling tricks to stop my port motor from doing this? Props are not out of the water, not stuffing the bow, not going to fast (maybe 4500 in 2-3 ft. swell (not wind chop). Can be running along for an hour or more just fine and then it happens with zero change in seas or handling. I am always eager to learn something new. By the way aboating course is an excellent idea everyone should do.
Bryan I think you may be right about the washdown pick up as it is worse when it is open but it will still do it when it is closed just not as often. Have you tried new props? I am thinking I might talk to a prop guy and see what my options are.

 

[gray duck]

Dan in queens - I've taken a boating course and have a 25 ton USCG license. I'm not asking for how to run an inlet but asking (like mark in WA) about cavitation when simply going "downhill" riding the Charleston chop back towards the jetties.
I'll check out the search for 4 blades - though I don't really want to spend $ on new props et al