Slip while turning only?

[tvpear12]

My 90 horse rude will hook up fine while moving in a straight line but if i vere off one way or the other it sounds as if it may be catching air. the cavitation plate is where it should be to the best of my knoledge. what can i do to the boat or prop to stop this? iI am running a 13x19 prop. This happens only when at wot and fully trimmed.

 

[walleyehed]

Re: Slip while turning only?

Trim down slightly before turning...this is not uncommon. Also, make sure there isn't anything mounted to the transom, such as speedo tube, transducer, etc.. within 6" of the outer diameter of the imaginary circle of the prop.

 

[tvpear12]

Re: Slip while turning only?

Outer diameter of the imaginary circle of the prop?? please explain. where else can i hook the speedo tube?

 

[OBJ]

Re: Slip while turning only?

Hi tv....the prop's diameter circle. Anything hanging off the boat that can interfer with the flow of water into the prop's diameter circle can cause cavitation. But I would suspect, as walleyehed suggested, all you need do is trim down some before going into a turn. My rig does the same thing if I don't trim down a little.

 

[tvpear12]

Re: Slip while turning only?

Ok OBJ I got what you are saying, but what about just a slight vere, not really turning just vereing a tad. I dunno just seems like all it takes is a tad of vere and it will do this. seems like it just dont take much. what will i do about my speedo if i take it off the transom?

 

[OBJ]

Re: Slip while turning only?

How high on the transom is the engine mounted tv? The higher the mount, the more prone to cavitation in a turn you will be. Alternatives could be going to a four blade prop. The speedo can be mounted out further away from the water path to the prop.

 

[tvpear12]

Re: Slip while turning only?

OBJ, I have it mounted with a jack plate. I had to do that to lower the engine as it is a 20" shaft and i needed a 25". wot trimmed out all the way my cav plate is out of the water on the top of it and water is skimming the bottom of the plate. seems to be just right. what do you think? are there any down falls to a 4 blade prop i need to know about? as i am sure they are costly. what size prop should i go with in a 4 blade?

 

[ob]

Re: Slip while turning only?

Is your jackplate set as low as it goes when the prop loses bite? If so ,your only simple options are to trim the engine lower when veering or as OBJ suggests,go to a four blade.The rpms at wot that the engine is turning now , will dictate which dia and pitch four blade would be best.What are the rpms trimmed out with a light load at wot?

 

[tvpear12]

Re: Slip while turning only?

well it is a factory tracker marine tach, so i am not sure if it is reading right but says 5200 rpms.

 

[walleyehed]

Re: Slip while turning only?

About 600-800 low for a light load WOT.<br />Drop 2" in pitch, unless 3" less is "available" in a 4-blade, then go 3" less.

 

[OBJ]

Re: Slip while turning only?

Most 90hp's that I've run across have an operating range between 4500 and 5500rpm so your in the ball park and could probably drop 2" of pitch and stay there with a 4 blade. But just to be sure, can you post the year or model number tv?

 

[tvpear12]

Re: Slip while turning only?

90 horse v-4 crossflow.<br />model# TE90TLCEM What year is this engine?

 

[OBJ]

Re: Slip while turning only?

That's a 1989 tv. Operating range 4500 to 5500rpm. So ya' got room to play with.

 

[walleyehed]

Re: Slip while turning only?

As I said, (and I'm sure Dhadley will back me) prop it for 6000RPM with a light load, maybe 6200.<br />You want 5500-up for loaded conditions...

 

[OBJ]

Re: Slip while turning only?

LOL....I'm sure he will walley....I know these blocks like to have the crap run outta them...but I also hesitate to post out of limits numbers that go against OEM recommended numbers. Just my thoughts....that's all....