is something wrong (trim ??s)

[8AteEight]

Hey all, <br /> Ive had my boat out a bunch this summer.(85 Tara/ merc 170, alpha one) I was also going through the forums here and noticing that most people can trim their outdrive till it starts porpoising. I cant do this. In Fact, the prop just starts to cavitate, and the RPMs rise. It also does this if Im trimmed all the way up and I take a moderate corner. It fixes itself if I trim it back down (mid-corner even), but there is NO porpoising. <br /><br />Is something wrong, or am I just paranoid??? If so, would a Hydrofoil or Trim tabs help?<br /><br />Thanx for all your advice, you all've been so helpful since I got of this site.<br /><br />Jon.

 

[Jdeagro]

Re: is something wrong (trim ??s)

Why would you want the boat to porpoise? It is uncomfortable! Be thankfull it does not!

 

[stevens]

Re: is something wrong (trim ??s)

If your boat will not porpoise even if trimmed all the way out, the weight is probably distributed quite far forward, keeping the bow down regardless of engine trim position.<br /><br />Is this a bad thing? Don't know, but it may lead to plowing, bow steer, and reduced speed. Or, then again, it may not. You could simply have a very well-balanced boat....<br /><br />Any foil or tabs would add lift at the stern, forcing the bow even further down. If you don't have a plowing problem already, foils or tabs might just give you one.<br /><br />Alternatively, it just struck me that there might be something wrong with your prop. If it starts spinning very easily, could it possibly have a damaged hub?<br /><br />But, hey, what do I know? I am sure someone will come along shortly with a more qualified answer.

 

[QC]

Re: is something wrong (trim ??s)

I will add that you may be able to get a little more speed out of her if she is close to porpoising at the top of trim, but you definitely don't want her to porpoise. My current boat did as you describe until I shifted a little more weight aft. Most guys are usually fighting the opposite. Anyway, now I can trim out a little further before it starts to ventilate and I probably gained 1 MPH Everyone has to trim in to get a good bite during turns though . . . You definitely don't need tabs or especially a hydrofoil unless you have trouble getting her to plane.

 

[8AteEight]

Re: is something wrong (trim ??s)

nope, not a real problem getting to plane. <br />Its a new(ish) prop, no hub slippage (but I will drop to a 14x17p for next year tho (takes too long to pull me up on a ski)) and It doesnt seem to plow either. <br />......SO, I guess Im just being paranoid again. I was just a lil worried about the prop cavitating at (well a lil bit past ) full trim. That never happened on any other boats Ive been around. <br /><br />I just got a carb back on, so hopefully sometime soon I can get it back out to see if there are any other lil quirks. Thanx for the help, Its nice not having to dump cash if I dont have to.

 

[QC]

Re: is something wrong (trim ??s)

Originally posted by 8AteEight:<br /> the prop cavitating at (well a lil bit past ) full trim.

Dude, This is like hitting yourself in the head. Stop doing it and things are much better . . .